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Diffstat (limited to 'drivers/staging/lustre/lustre/include/cl_object.h')
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diff --git a/drivers/staging/lustre/lustre/include/cl_object.h b/drivers/staging/lustre/lustre/include/cl_object.h new file mode 100644 index 000000000000..4bb68801d3a9 --- /dev/null +++ b/drivers/staging/lustre/lustre/include/cl_object.h @@ -0,0 +1,3279 @@ +/* + * GPL HEADER START + * + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 only, + * as published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License version 2 for more details (a copy is included + * in the LICENSE file that accompanied this code). + * + * You should have received a copy of the GNU General Public License + * version 2 along with this program; If not, see + * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf + * + * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, + * CA 95054 USA or visit www.sun.com if you need additional information or + * have any questions. + * + * GPL HEADER END + */ +/* + * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved. + * Use is subject to license terms. + * + * Copyright (c) 2011, 2012, Intel Corporation. + */ +/* + * This file is part of Lustre, http://www.lustre.org/ + * Lustre is a trademark of Sun Microsystems, Inc. + */ +#ifndef _LUSTRE_CL_OBJECT_H +#define _LUSTRE_CL_OBJECT_H + +/** \defgroup clio clio + * + * Client objects implement io operations and cache pages. + * + * Examples: lov and osc are implementations of cl interface. + * + * Big Theory Statement. + * + * Layered objects. + * + * Client implementation is based on the following data-types: + * + * - cl_object + * + * - cl_page + * + * - cl_lock represents an extent lock on an object. + * + * - cl_io represents high-level i/o activity such as whole read/write + * system call, or write-out of pages from under the lock being + * canceled. cl_io has sub-ios that can be stopped and resumed + * independently, thus achieving high degree of transfer + * parallelism. Single cl_io can be advanced forward by + * the multiple threads (although in the most usual case of + * read/write system call it is associated with the single user + * thread, that issued the system call). + * + * - cl_req represents a collection of pages for a transfer. cl_req is + * constructed by req-forming engine that tries to saturate + * transport with large and continuous transfers. + * + * Terminology + * + * - to avoid confusion high-level I/O operation like read or write system + * call is referred to as "an io", whereas low-level I/O operation, like + * RPC, is referred to as "a transfer" + * + * - "generic code" means generic (not file system specific) code in the + * hosting environment. "cl-code" means code (mostly in cl_*.c files) that + * is not layer specific. + * + * Locking. + * + * - i_mutex + * - PG_locked + * - cl_object_header::coh_page_guard + * - cl_object_header::coh_lock_guard + * - lu_site::ls_guard + * + * See the top comment in cl_object.c for the description of overall locking and + * reference-counting design. + * + * See comments below for the description of i/o, page, and dlm-locking + * design. + * + * @{ + */ + +/* + * super-class definitions. + */ +#include <lu_object.h> +#include <lvfs.h> +# include <linux/mutex.h> +# include <linux/radix-tree.h> + +struct inode; + +struct cl_device; +struct cl_device_operations; + +struct cl_object; +struct cl_object_page_operations; +struct cl_object_lock_operations; + +struct cl_page; +struct cl_page_slice; +struct cl_lock; +struct cl_lock_slice; + +struct cl_lock_operations; +struct cl_page_operations; + +struct cl_io; +struct cl_io_slice; + +struct cl_req; +struct cl_req_slice; + +/** + * Operations for each data device in the client stack. + * + * \see vvp_cl_ops, lov_cl_ops, lovsub_cl_ops, osc_cl_ops + */ +struct cl_device_operations { + /** + * Initialize cl_req. This method is called top-to-bottom on all + * devices in the stack to get them a chance to allocate layer-private + * data, and to attach them to the cl_req by calling + * cl_req_slice_add(). + * + * \see osc_req_init(), lov_req_init(), lovsub_req_init() + * \see ccc_req_init() + */ + int (*cdo_req_init)(const struct lu_env *env, struct cl_device *dev, + struct cl_req *req); +}; + +/** + * Device in the client stack. + * + * \see ccc_device, lov_device, lovsub_device, osc_device + */ +struct cl_device { + /** Super-class. */ + struct lu_device cd_lu_dev; + /** Per-layer operation vector. */ + const struct cl_device_operations *cd_ops; +}; + +/** \addtogroup cl_object cl_object + * @{ */ +/** + * "Data attributes" of cl_object. Data attributes can be updated + * independently for a sub-object, and top-object's attributes are calculated + * from sub-objects' ones. + */ +struct cl_attr { + /** Object size, in bytes */ + loff_t cat_size; + /** + * Known minimal size, in bytes. + * + * This is only valid when at least one DLM lock is held. + */ + loff_t cat_kms; + /** Modification time. Measured in seconds since epoch. */ + time_t cat_mtime; + /** Access time. Measured in seconds since epoch. */ + time_t cat_atime; + /** Change time. Measured in seconds since epoch. */ + time_t cat_ctime; + /** + * Blocks allocated to this cl_object on the server file system. + * + * \todo XXX An interface for block size is needed. + */ + __u64 cat_blocks; + /** + * User identifier for quota purposes. + */ + uid_t cat_uid; + /** + * Group identifier for quota purposes. + */ + gid_t cat_gid; +}; + +/** + * Fields in cl_attr that are being set. + */ +enum cl_attr_valid { + CAT_SIZE = 1 << 0, + CAT_KMS = 1 << 1, + CAT_MTIME = 1 << 3, + CAT_ATIME = 1 << 4, + CAT_CTIME = 1 << 5, + CAT_BLOCKS = 1 << 6, + CAT_UID = 1 << 7, + CAT_GID = 1 << 8 +}; + +/** + * Sub-class of lu_object with methods common for objects on the client + * stacks. + * + * cl_object: represents a regular file system object, both a file and a + * stripe. cl_object is based on lu_object: it is identified by a fid, + * layered, cached, hashed, and lrued. Important distinction with the server + * side, where md_object and dt_object are used, is that cl_object "fans out" + * at the lov/sns level: depending on the file layout, single file is + * represented as a set of "sub-objects" (stripes). At the implementation + * level, struct lov_object contains an array of cl_objects. Each sub-object + * is a full-fledged cl_object, having its fid, living in the lru and hash + * table. + * + * This leads to the next important difference with the server side: on the + * client, it's quite usual to have objects with the different sequence of + * layers. For example, typical top-object is composed of the following + * layers: + * + * - vvp + * - lov + * + * whereas its sub-objects are composed of + * + * - lovsub + * - osc + * + * layers. Here "lovsub" is a mostly dummy layer, whose purpose is to keep + * track of the object-subobject relationship. + * + * Sub-objects are not cached independently: when top-object is about to + * be discarded from the memory, all its sub-objects are torn-down and + * destroyed too. + * + * \see ccc_object, lov_object, lovsub_object, osc_object + */ +struct cl_object { + /** super class */ + struct lu_object co_lu; + /** per-object-layer operations */ + const struct cl_object_operations *co_ops; + /** offset of page slice in cl_page buffer */ + int co_slice_off; +}; + +/** + * Description of the client object configuration. This is used for the + * creation of a new client object that is identified by a more state than + * fid. + */ +struct cl_object_conf { + /** Super-class. */ + struct lu_object_conf coc_lu; + union { + /** + * Object layout. This is consumed by lov. + */ + struct lustre_md *coc_md; + /** + * Description of particular stripe location in the + * cluster. This is consumed by osc. + */ + struct lov_oinfo *coc_oinfo; + } u; + /** + * VFS inode. This is consumed by vvp. + */ + struct inode *coc_inode; + /** + * Layout lock handle. + */ + struct ldlm_lock *coc_lock; + /** + * Operation to handle layout, OBJECT_CONF_XYZ. + */ + int coc_opc; +}; + +enum { + /** configure layout, set up a new stripe, must be called while + * holding layout lock. */ + OBJECT_CONF_SET = 0, + /** invalidate the current stripe configuration due to losing + * layout lock. */ + OBJECT_CONF_INVALIDATE = 1, + /** wait for old layout to go away so that new layout can be + * set up. */ + OBJECT_CONF_WAIT = 2 +}; + +/** + * Operations implemented for each cl object layer. + * + * \see vvp_ops, lov_ops, lovsub_ops, osc_ops + */ +struct cl_object_operations { + /** + * Initialize page slice for this layer. Called top-to-bottom through + * every object layer when a new cl_page is instantiated. Layer + * keeping private per-page data, or requiring its own page operations + * vector should allocate these data here, and attach then to the page + * by calling cl_page_slice_add(). \a vmpage is locked (in the VM + * sense). Optional. + * + * \retval NULL success. + * + * \retval ERR_PTR(errno) failure code. + * + * \retval valid-pointer pointer to already existing referenced page + * to be used instead of newly created. + */ + int (*coo_page_init)(const struct lu_env *env, struct cl_object *obj, + struct cl_page *page, struct page *vmpage); + /** + * Initialize lock slice for this layer. Called top-to-bottom through + * every object layer when a new cl_lock is instantiated. Layer + * keeping private per-lock data, or requiring its own lock operations + * vector should allocate these data here, and attach then to the lock + * by calling cl_lock_slice_add(). Mandatory. + */ + int (*coo_lock_init)(const struct lu_env *env, + struct cl_object *obj, struct cl_lock *lock, + const struct cl_io *io); + /** + * Initialize io state for a given layer. + * + * called top-to-bottom once per io existence to initialize io + * state. If layer wants to keep some state for this type of io, it + * has to embed struct cl_io_slice in lu_env::le_ses, and register + * slice with cl_io_slice_add(). It is guaranteed that all threads + * participating in this io share the same session. + */ + int (*coo_io_init)(const struct lu_env *env, + struct cl_object *obj, struct cl_io *io); + /** + * Fill portion of \a attr that this layer controls. This method is + * called top-to-bottom through all object layers. + * + * \pre cl_object_header::coh_attr_guard of the top-object is locked. + * + * \return 0: to continue + * \return +ve: to stop iterating through layers (but 0 is returned + * from enclosing cl_object_attr_get()) + * \return -ve: to signal error + */ + int (*coo_attr_get)(const struct lu_env *env, struct cl_object *obj, + struct cl_attr *attr); + /** + * Update attributes. + * + * \a valid is a bitmask composed from enum #cl_attr_valid, and + * indicating what attributes are to be set. + * + * \pre cl_object_header::coh_attr_guard of the top-object is locked. + * + * \return the same convention as for + * cl_object_operations::coo_attr_get() is used. + */ + int (*coo_attr_set)(const struct lu_env *env, struct cl_object *obj, + const struct cl_attr *attr, unsigned valid); + /** + * Update object configuration. Called top-to-bottom to modify object + * configuration. + * + * XXX error conditions and handling. + */ + int (*coo_conf_set)(const struct lu_env *env, struct cl_object *obj, + const struct cl_object_conf *conf); + /** + * Glimpse ast. Executed when glimpse ast arrives for a lock on this + * object. Layers are supposed to fill parts of \a lvb that will be + * shipped to the glimpse originator as a glimpse result. + * + * \see ccc_object_glimpse(), lovsub_object_glimpse(), + * \see osc_object_glimpse() + */ + int (*coo_glimpse)(const struct lu_env *env, + const struct cl_object *obj, struct ost_lvb *lvb); +}; + +/** + * Extended header for client object. + */ +struct cl_object_header { + /** Standard lu_object_header. cl_object::co_lu::lo_header points + * here. */ + struct lu_object_header coh_lu; + /** \name locks + * \todo XXX move locks below to the separate cache-lines, they are + * mostly useless otherwise. + */ + /** @{ */ + /** Lock protecting page tree. */ + spinlock_t coh_page_guard; + /** Lock protecting lock list. */ + spinlock_t coh_lock_guard; + /** @} locks */ + /** Radix tree of cl_page's, cached for this object. */ + struct radix_tree_root coh_tree; + /** # of pages in radix tree. */ + unsigned long coh_pages; + /** List of cl_lock's granted for this object. */ + struct list_head coh_locks; + + /** + * Parent object. It is assumed that an object has a well-defined + * parent, but not a well-defined child (there may be multiple + * sub-objects, for the same top-object). cl_object_header::coh_parent + * field allows certain code to be written generically, without + * limiting possible cl_object layouts unduly. + */ + struct cl_object_header *coh_parent; + /** + * Protects consistency between cl_attr of parent object and + * attributes of sub-objects, that the former is calculated ("merged") + * from. + * + * \todo XXX this can be read/write lock if needed. + */ + spinlock_t coh_attr_guard; + /** + * Size of cl_page + page slices + */ + unsigned short coh_page_bufsize; + /** + * Number of objects above this one: 0 for a top-object, 1 for its + * sub-object, etc. + */ + unsigned char coh_nesting; +}; + +/** + * Helper macro: iterate over all layers of the object \a obj, assigning every + * layer top-to-bottom to \a slice. + */ +#define cl_object_for_each(slice, obj) \ + list_for_each_entry((slice), \ + &(obj)->co_lu.lo_header->loh_layers, \ + co_lu.lo_linkage) +/** + * Helper macro: iterate over all layers of the object \a obj, assigning every + * layer bottom-to-top to \a slice. + */ +#define cl_object_for_each_reverse(slice, obj) \ + list_for_each_entry_reverse((slice), \ + &(obj)->co_lu.lo_header->loh_layers, \ + co_lu.lo_linkage) +/** @} cl_object */ + +#ifndef pgoff_t +#define pgoff_t unsigned long +#endif + +#define CL_PAGE_EOF ((pgoff_t)~0ull) + +/** \addtogroup cl_page cl_page + * @{ */ + +/** \struct cl_page + * Layered client page. + * + * cl_page: represents a portion of a file, cached in the memory. All pages + * of the given file are of the same size, and are kept in the radix tree + * hanging off the cl_object. cl_page doesn't fan out, but as sub-objects + * of the top-level file object are first class cl_objects, they have their + * own radix trees of pages and hence page is implemented as a sequence of + * struct cl_pages's, linked into double-linked list through + * cl_page::cp_parent and cl_page::cp_child pointers, each residing in the + * corresponding radix tree at the corresponding logical offset. + * + * cl_page is associated with VM page of the hosting environment (struct + * page in Linux kernel, for example), struct page. It is assumed, that this + * association is implemented by one of cl_page layers (top layer in the + * current design) that + * + * - intercepts per-VM-page call-backs made by the environment (e.g., + * memory pressure), + * + * - translates state (page flag bits) and locking between lustre and + * environment. + * + * The association between cl_page and struct page is immutable and + * established when cl_page is created. + * + * cl_page can be "owned" by a particular cl_io (see below), guaranteeing + * this io an exclusive access to this page w.r.t. other io attempts and + * various events changing page state (such as transfer completion, or + * eviction of the page from the memory). Note, that in general cl_io + * cannot be identified with a particular thread, and page ownership is not + * exactly equal to the current thread holding a lock on the page. Layer + * implementing association between cl_page and struct page has to implement + * ownership on top of available synchronization mechanisms. + * + * While lustre client maintains the notion of an page ownership by io, + * hosting MM/VM usually has its own page concurrency control + * mechanisms. For example, in Linux, page access is synchronized by the + * per-page PG_locked bit-lock, and generic kernel code (generic_file_*()) + * takes care to acquire and release such locks as necessary around the + * calls to the file system methods (->readpage(), ->prepare_write(), + * ->commit_write(), etc.). This leads to the situation when there are two + * different ways to own a page in the client: + * + * - client code explicitly and voluntary owns the page (cl_page_own()); + * + * - VM locks a page and then calls the client, that has "to assume" + * the ownership from the VM (cl_page_assume()). + * + * Dual methods to release ownership are cl_page_disown() and + * cl_page_unassume(). + * + * cl_page is reference counted (cl_page::cp_ref). When reference counter + * drops to 0, the page is returned to the cache, unless it is in + * cl_page_state::CPS_FREEING state, in which case it is immediately + * destroyed. + * + * The general logic guaranteeing the absence of "existential races" for + * pages is the following: + * + * - there are fixed known ways for a thread to obtain a new reference + * to a page: + * + * - by doing a lookup in the cl_object radix tree, protected by the + * spin-lock; + * + * - by starting from VM-locked struct page and following some + * hosting environment method (e.g., following ->private pointer in + * the case of Linux kernel), see cl_vmpage_page(); + * + * - when the page enters cl_page_state::CPS_FREEING state, all these + * ways are severed with the proper synchronization + * (cl_page_delete()); + * + * - entry into cl_page_state::CPS_FREEING is serialized by the VM page + * lock; + * + * - no new references to the page in cl_page_state::CPS_FREEING state + * are allowed (checked in cl_page_get()). + * + * Together this guarantees that when last reference to a + * cl_page_state::CPS_FREEING page is released, it is safe to destroy the + * page, as neither references to it can be acquired at that point, nor + * ones exist. + * + * cl_page is a state machine. States are enumerated in enum + * cl_page_state. Possible state transitions are enumerated in + * cl_page_state_set(). State transition process (i.e., actual changing of + * cl_page::cp_state field) is protected by the lock on the underlying VM + * page. + * + * Linux Kernel implementation. + * + * Binding between cl_page and struct page (which is a typedef for + * struct page) is implemented in the vvp layer. cl_page is attached to the + * ->private pointer of the struct page, together with the setting of + * PG_private bit in page->flags, and acquiring additional reference on the + * struct page (much like struct buffer_head, or any similar file system + * private data structures). + * + * PG_locked lock is used to implement both ownership and transfer + * synchronization, that is, page is VM-locked in CPS_{OWNED,PAGE{IN,OUT}} + * states. No additional references are acquired for the duration of the + * transfer. + * + * \warning *THIS IS NOT* the behavior expected by the Linux kernel, where + * write-out is "protected" by the special PG_writeback bit. + */ + +/** + * States of cl_page. cl_page.c assumes particular order here. + * + * The page state machine is rather crude, as it doesn't recognize finer page + * states like "dirty" or "up to date". This is because such states are not + * always well defined for the whole stack (see, for example, the + * implementation of the read-ahead, that hides page up-to-dateness to track + * cache hits accurately). Such sub-states are maintained by the layers that + * are interested in them. + */ +enum cl_page_state { + /** + * Page is in the cache, un-owned. Page leaves cached state in the + * following cases: + * + * - [cl_page_state::CPS_OWNED] io comes across the page and + * owns it; + * + * - [cl_page_state::CPS_PAGEOUT] page is dirty, the + * req-formation engine decides that it wants to include this page + * into an cl_req being constructed, and yanks it from the cache; + * + * - [cl_page_state::CPS_FREEING] VM callback is executed to + * evict the page form the memory; + * + * \invariant cl_page::cp_owner == NULL && cl_page::cp_req == NULL + */ + CPS_CACHED, + /** + * Page is exclusively owned by some cl_io. Page may end up in this + * state as a result of + * + * - io creating new page and immediately owning it; + * + * - [cl_page_state::CPS_CACHED] io finding existing cached page + * and owning it; + * + * - [cl_page_state::CPS_OWNED] io finding existing owned page + * and waiting for owner to release the page; + * + * Page leaves owned state in the following cases: + * + * - [cl_page_state::CPS_CACHED] io decides to leave the page in + * the cache, doing nothing; + * + * - [cl_page_state::CPS_PAGEIN] io starts read transfer for + * this page; + * + * - [cl_page_state::CPS_PAGEOUT] io starts immediate write + * transfer for this page; + * + * - [cl_page_state::CPS_FREEING] io decides to destroy this + * page (e.g., as part of truncate or extent lock cancellation). + * + * \invariant cl_page::cp_owner != NULL && cl_page::cp_req == NULL + */ + CPS_OWNED, + /** + * Page is being written out, as a part of a transfer. This state is + * entered when req-formation logic decided that it wants this page to + * be sent through the wire _now_. Specifically, it means that once + * this state is achieved, transfer completion handler (with either + * success or failure indication) is guaranteed to be executed against + * this page independently of any locks and any scheduling decisions + * made by the hosting environment (that effectively means that the + * page is never put into cl_page_state::CPS_PAGEOUT state "in + * advance". This property is mentioned, because it is important when + * reasoning about possible dead-locks in the system). The page can + * enter this state as a result of + * + * - [cl_page_state::CPS_OWNED] an io requesting an immediate + * write-out of this page, or + * + * - [cl_page_state::CPS_CACHED] req-forming engine deciding + * that it has enough dirty pages cached to issue a "good" + * transfer. + * + * The page leaves cl_page_state::CPS_PAGEOUT state when the transfer + * is completed---it is moved into cl_page_state::CPS_CACHED state. + * + * Underlying VM page is locked for the duration of transfer. + * + * \invariant: cl_page::cp_owner == NULL && cl_page::cp_req != NULL + */ + CPS_PAGEOUT, + /** + * Page is being read in, as a part of a transfer. This is quite + * similar to the cl_page_state::CPS_PAGEOUT state, except that + * read-in is always "immediate"---there is no such thing a sudden + * construction of read cl_req from cached, presumably not up to date, + * pages. + * + * Underlying VM page is locked for the duration of transfer. + * + * \invariant: cl_page::cp_owner == NULL && cl_page::cp_req != NULL + */ + CPS_PAGEIN, + /** + * Page is being destroyed. This state is entered when client decides + * that page has to be deleted from its host object, as, e.g., a part + * of truncate. + * + * Once this state is reached, there is no way to escape it. + * + * \invariant: cl_page::cp_owner == NULL && cl_page::cp_req == NULL + */ + CPS_FREEING, + CPS_NR +}; + +enum cl_page_type { + /** Host page, the page is from the host inode which the cl_page + * belongs to. */ + CPT_CACHEABLE = 1, + + /** Transient page, the transient cl_page is used to bind a cl_page + * to vmpage which is not belonging to the same object of cl_page. + * it is used in DirectIO, lockless IO and liblustre. */ + CPT_TRANSIENT, +}; + +/** + * Flags maintained for every cl_page. + */ +enum cl_page_flags { + /** + * Set when pagein completes. Used for debugging (read completes at + * most once for a page). + */ + CPF_READ_COMPLETED = 1 << 0 +}; + +/** + * Fields are protected by the lock on struct page, except for atomics and + * immutables. + * + * \invariant Data type invariants are in cl_page_invariant(). Basically: + * cl_page::cp_parent and cl_page::cp_child are a well-formed double-linked + * list, consistent with the parent/child pointers in the cl_page::cp_obj and + * cl_page::cp_owner (when set). + */ +struct cl_page { + /** Reference counter. */ + atomic_t cp_ref; + /** An object this page is a part of. Immutable after creation. */ + struct cl_object *cp_obj; + /** Logical page index within the object. Immutable after creation. */ + pgoff_t cp_index; + /** List of slices. Immutable after creation. */ + struct list_head cp_layers; + /** Parent page, NULL for top-level page. Immutable after creation. */ + struct cl_page *cp_parent; + /** Lower-layer page. NULL for bottommost page. Immutable after + * creation. */ + struct cl_page *cp_child; + /** + * Page state. This field is const to avoid accidental update, it is + * modified only internally within cl_page.c. Protected by a VM lock. + */ + const enum cl_page_state cp_state; + /** Linkage of pages within group. Protected by cl_page::cp_mutex. */ + struct list_head cp_batch; + /** Mutex serializing membership of a page in a batch. */ + struct mutex cp_mutex; + /** Linkage of pages within cl_req. */ + struct list_head cp_flight; + /** Transfer error. */ + int cp_error; + + /** + * Page type. Only CPT_TRANSIENT is used so far. Immutable after + * creation. + */ + enum cl_page_type cp_type; + + /** + * Owning IO in cl_page_state::CPS_OWNED state. Sub-page can be owned + * by sub-io. Protected by a VM lock. + */ + struct cl_io *cp_owner; + /** + * Debug information, the task is owning the page. + */ + task_t *cp_task; + /** + * Owning IO request in cl_page_state::CPS_PAGEOUT and + * cl_page_state::CPS_PAGEIN states. This field is maintained only in + * the top-level pages. Protected by a VM lock. + */ + struct cl_req *cp_req; + /** List of references to this page, for debugging. */ + struct lu_ref cp_reference; + /** Link to an object, for debugging. */ + struct lu_ref_link *cp_obj_ref; + /** Link to a queue, for debugging. */ + struct lu_ref_link *cp_queue_ref; + /** Per-page flags from enum cl_page_flags. Protected by a VM lock. */ + unsigned cp_flags; + /** Assigned if doing a sync_io */ + struct cl_sync_io *cp_sync_io; +}; + +/** + * Per-layer part of cl_page. + * + * \see ccc_page, lov_page, osc_page + */ +struct cl_page_slice { + struct cl_page *cpl_page; + /** + * Object slice corresponding to this page slice. Immutable after + * creation. + */ + struct cl_object *cpl_obj; + const struct cl_page_operations *cpl_ops; + /** Linkage into cl_page::cp_layers. Immutable after creation. */ + struct list_head cpl_linkage; +}; + +/** + * Lock mode. For the client extent locks. + * + * \warning: cl_lock_mode_match() assumes particular ordering here. + * \ingroup cl_lock + */ +enum cl_lock_mode { + /** + * Mode of a lock that protects no data, and exists only as a + * placeholder. This is used for `glimpse' requests. A phantom lock + * might get promoted to real lock at some point. + */ + CLM_PHANTOM, + CLM_READ, + CLM_WRITE, + CLM_GROUP +}; + +/** + * Requested transfer type. + * \ingroup cl_req + */ +enum cl_req_type { + CRT_READ, + CRT_WRITE, + CRT_NR +}; + +/** + * Per-layer page operations. + * + * Methods taking an \a io argument are for the activity happening in the + * context of given \a io. Page is assumed to be owned by that io, except for + * the obvious cases (like cl_page_operations::cpo_own()). + * + * \see vvp_page_ops, lov_page_ops, osc_page_ops + */ +struct cl_page_operations { + /** + * cl_page<->struct page methods. Only one layer in the stack has to + * implement these. Current code assumes that this functionality is + * provided by the topmost layer, see cl_page_disown0() as an example. + */ + + /** + * \return the underlying VM page. Optional. + */ + struct page *(*cpo_vmpage)(const struct lu_env *env, + const struct cl_page_slice *slice); + /** + * Called when \a io acquires this page into the exclusive + * ownership. When this method returns, it is guaranteed that the is + * not owned by other io, and no transfer is going on against + * it. Optional. + * + * \see cl_page_own() + * \see vvp_page_own(), lov_page_own() + */ + int (*cpo_own)(const struct lu_env *env, + const struct cl_page_slice *slice, + struct cl_io *io, int nonblock); + /** Called when ownership it yielded. Optional. + * + * \see cl_page_disown() + * \see vvp_page_disown() + */ + void (*cpo_disown)(const struct lu_env *env, + const struct cl_page_slice *slice, struct cl_io *io); + /** + * Called for a page that is already "owned" by \a io from VM point of + * view. Optional. + * + * \see cl_page_assume() + * \see vvp_page_assume(), lov_page_assume() + */ + void (*cpo_assume)(const struct lu_env *env, + const struct cl_page_slice *slice, struct cl_io *io); + /** Dual to cl_page_operations::cpo_assume(). Optional. Called + * bottom-to-top when IO releases a page without actually unlocking + * it. + * + * \see cl_page_unassume() + * \see vvp_page_unassume() + */ + void (*cpo_unassume)(const struct lu_env *env, + const struct cl_page_slice *slice, + struct cl_io *io); + /** + * Announces whether the page contains valid data or not by \a uptodate. + * + * \see cl_page_export() + * \see vvp_page_export() + */ + void (*cpo_export)(const struct lu_env *env, + const struct cl_page_slice *slice, int uptodate); + /** + * Unmaps page from the user space (if it is mapped). + * + * \see cl_page_unmap() + * \see vvp_page_unmap() + */ + int (*cpo_unmap)(const struct lu_env *env, + const struct cl_page_slice *slice, struct cl_io *io); + /** + * Checks whether underlying VM page is locked (in the suitable + * sense). Used for assertions. + * + * \retval -EBUSY: page is protected by a lock of a given mode; + * \retval -ENODATA: page is not protected by a lock; + * \retval 0: this layer cannot decide. (Should never happen.) + */ + int (*cpo_is_vmlocked)(const struct lu_env *env, + const struct cl_page_slice *slice); + /** + * Page destruction. + */ + + /** + * Called when page is truncated from the object. Optional. + * + * \see cl_page_discard() + * \see vvp_page_discard(), osc_page_discard() + */ + void (*cpo_discard)(const struct lu_env *env, + const struct cl_page_slice *slice, + struct cl_io *io); + /** + * Called when page is removed from the cache, and is about to being + * destroyed. Optional. + * + * \see cl_page_delete() + * \see vvp_page_delete(), osc_page_delete() + */ + void (*cpo_delete)(const struct lu_env *env, + const struct cl_page_slice *slice); + /** Destructor. Frees resources and slice itself. */ + void (*cpo_fini)(const struct lu_env *env, + struct cl_page_slice *slice); + + /** + * Checks whether the page is protected by a cl_lock. This is a + * per-layer method, because certain layers have ways to check for the + * lock much more efficiently than through the generic locks scan, or + * implement locking mechanisms separate from cl_lock, e.g., + * LL_FILE_GROUP_LOCKED in vvp. If \a pending is true, check for locks + * being canceled, or scheduled for cancellation as soon as the last + * user goes away, too. + * + * \retval -EBUSY: page is protected by a lock of a given mode; + * \retval -ENODATA: page is not protected by a lock; + * \retval 0: this layer cannot decide. + * + * \see cl_page_is_under_lock() + */ + int (*cpo_is_under_lock)(const struct lu_env *env, + const struct cl_page_slice *slice, + struct cl_io *io); + + /** + * Optional debugging helper. Prints given page slice. + * + * \see cl_page_print() + */ + int (*cpo_print)(const struct lu_env *env, + const struct cl_page_slice *slice, + void *cookie, lu_printer_t p); + /** + * \name transfer + * + * Transfer methods. See comment on cl_req for a description of + * transfer formation and life-cycle. + * + * @{ + */ + /** + * Request type dependent vector of operations. + * + * Transfer operations depend on transfer mode (cl_req_type). To avoid + * passing transfer mode to each and every of these methods, and to + * avoid branching on request type inside of the methods, separate + * methods for cl_req_type:CRT_READ and cl_req_type:CRT_WRITE are + * provided. That is, method invocation usually looks like + * + * slice->cp_ops.io[req->crq_type].cpo_method(env, slice, ...); + */ + struct { + /** + * Called when a page is submitted for a transfer as a part of + * cl_page_list. + * + * \return 0 : page is eligible for submission; + * \return -EALREADY : skip this page; + * \return -ve : error. + * + * \see cl_page_prep() + */ + int (*cpo_prep)(const struct lu_env *env, + const struct cl_page_slice *slice, + struct cl_io *io); + /** + * Completion handler. This is guaranteed to be eventually + * fired after cl_page_operations::cpo_prep() or + * cl_page_operations::cpo_make_ready() call. + * + * This method can be called in a non-blocking context. It is + * guaranteed however, that the page involved and its object + * are pinned in memory (and, hence, calling cl_page_put() is + * safe). + * + * \see cl_page_completion() + */ + void (*cpo_completion)(const struct lu_env *env, + const struct cl_page_slice *slice, + int ioret); + /** + * Called when cached page is about to be added to the + * cl_req as a part of req formation. + * + * \return 0 : proceed with this page; + * \return -EAGAIN : skip this page; + * \return -ve : error. + * + * \see cl_page_make_ready() + */ + int (*cpo_make_ready)(const struct lu_env *env, + const struct cl_page_slice *slice); + /** + * Announce that this page is to be written out + * opportunistically, that is, page is dirty, it is not + * necessary to start write-out transfer right now, but + * eventually page has to be written out. + * + * Main caller of this is the write path (see + * vvp_io_commit_write()), using this method to build a + * "transfer cache" from which large transfers are then + * constructed by the req-formation engine. + * + * \todo XXX it would make sense to add page-age tracking + * semantics here, and to oblige the req-formation engine to + * send the page out not later than it is too old. + * + * \see cl_page_cache_add() + */ + int (*cpo_cache_add)(const struct lu_env *env, + const struct cl_page_slice *slice, + struct cl_io *io); + } io[CRT_NR]; + /** + * Tell transfer engine that only [to, from] part of a page should be + * transmitted. + * + * This is used for immediate transfers. + * + * \todo XXX this is not very good interface. It would be much better + * if all transfer parameters were supplied as arguments to + * cl_io_operations::cio_submit() call, but it is not clear how to do + * this for page queues. + * + * \see cl_page_clip() + */ + void (*cpo_clip)(const struct lu_env *env, + const struct cl_page_slice *slice, + int from, int to); + /** + * \pre the page was queued for transferring. + * \post page is removed from client's pending list, or -EBUSY + * is returned if it has already been in transferring. + * + * This is one of seldom page operation which is: + * 0. called from top level; + * 1. don't have vmpage locked; + * 2. every layer should synchronize execution of its ->cpo_cancel() + * with completion handlers. Osc uses client obd lock for this + * purpose. Based on there is no vvp_page_cancel and + * lov_page_cancel(), cpo_cancel is defacto protected by client lock. + * + * \see osc_page_cancel(). + */ + int (*cpo_cancel)(const struct lu_env *env, + const struct cl_page_slice *slice); + /** + * Write out a page by kernel. This is only called by ll_writepage + * right now. + * + * \see cl_page_flush() + */ + int (*cpo_flush)(const struct lu_env *env, + const struct cl_page_slice *slice, + struct cl_io *io); + /** @} transfer */ +}; + +/** + * Helper macro, dumping detailed information about \a page into a log. + */ +#define CL_PAGE_DEBUG(mask, env, page, format, ...) \ +do { \ + LIBCFS_DEBUG_MSG_DATA_DECL(msgdata, mask, NULL); \ + \ + if (cfs_cdebug_show(mask, DEBUG_SUBSYSTEM)) { \ + cl_page_print(env, &msgdata, lu_cdebug_printer, page); \ + CDEBUG(mask, format , ## __VA_ARGS__); \ + } \ +} while (0) + +/** + * Helper macro, dumping shorter information about \a page into a log. + */ +#define CL_PAGE_HEADER(mask, env, page, format, ...) \ +do { \ + LIBCFS_DEBUG_MSG_DATA_DECL(msgdata, mask, NULL); \ + \ + if (cfs_cdebug_show(mask, DEBUG_SUBSYSTEM)) { \ + cl_page_header_print(env, &msgdata, lu_cdebug_printer, page); \ + CDEBUG(mask, format , ## __VA_ARGS__); \ + } \ +} while (0) + +static inline int __page_in_use(const struct cl_page *page, int refc) +{ + if (page->cp_type == CPT_CACHEABLE) + ++refc; + LASSERT(atomic_read(&page->cp_ref) > 0); + return (atomic_read(&page->cp_ref) > refc); +} +#define cl_page_in_use(pg) __page_in_use(pg, 1) +#define cl_page_in_use_noref(pg) __page_in_use(pg, 0) + +/** @} cl_page */ + +/** \addtogroup cl_lock cl_lock + * @{ */ +/** \struct cl_lock + * + * Extent locking on the client. + * + * LAYERING + * + * The locking model of the new client code is built around + * + * struct cl_lock + * + * data-type representing an extent lock on a regular file. cl_lock is a + * layered object (much like cl_object and cl_page), it consists of a header + * (struct cl_lock) and a list of layers (struct cl_lock_slice), linked to + * cl_lock::cll_layers list through cl_lock_slice::cls_linkage. + * + * All locks for a given object are linked into cl_object_header::coh_locks + * list (protected by cl_object_header::coh_lock_guard spin-lock) through + * cl_lock::cll_linkage. Currently this list is not sorted in any way. We can + * sort it in starting lock offset, or use altogether different data structure + * like a tree. + * + * Typical cl_lock consists of the two layers: + * + * - vvp_lock (vvp specific data), and + * - lov_lock (lov specific data). + * + * lov_lock contains an array of sub-locks. Each of these sub-locks is a + * normal cl_lock: it has a header (struct cl_lock) and a list of layers: + * + * - lovsub_lock, and + * - osc_lock + * + * Each sub-lock is associated with a cl_object (representing stripe + * sub-object or the file to which top-level cl_lock is associated to), and is + * linked into that cl_object::coh_locks. In this respect cl_lock is similar to + * cl_object (that at lov layer also fans out into multiple sub-objects), and + * is different from cl_page, that doesn't fan out (there is usually exactly + * one osc_page for every vvp_page). We shall call vvp-lov portion of the lock + * a "top-lock" and its lovsub-osc portion a "sub-lock". + * + * LIFE CYCLE + * + * cl_lock is reference counted. When reference counter drops to 0, lock is + * placed in the cache, except when lock is in CLS_FREEING state. CLS_FREEING + * lock is destroyed when last reference is released. Referencing between + * top-lock and its sub-locks is described in the lov documentation module. + * + * STATE MACHINE + * + * Also, cl_lock is a state machine. This requires some clarification. One of + * the goals of client IO re-write was to make IO path non-blocking, or at + * least to make it easier to make it non-blocking in the future. Here + * `non-blocking' means that when a system call (read, write, truncate) + * reaches a situation where it has to wait for a communication with the + * server, it should --instead of waiting-- remember its current state and + * switch to some other work. E.g,. instead of waiting for a lock enqueue, + * client should proceed doing IO on the next stripe, etc. Obviously this is + * rather radical redesign, and it is not planned to be fully implemented at + * this time, instead we are putting some infrastructure in place, that would + * make it easier to do asynchronous non-blocking IO easier in the + * future. Specifically, where old locking code goes to sleep (waiting for + * enqueue, for example), new code returns cl_lock_transition::CLO_WAIT. When + * enqueue reply comes, its completion handler signals that lock state-machine + * is ready to transit to the next state. There is some generic code in + * cl_lock.c that sleeps, waiting for these signals. As a result, for users of + * this cl_lock.c code, it looks like locking is done in normal blocking + * fashion, and it the same time it is possible to switch to the non-blocking + * locking (simply by returning cl_lock_transition::CLO_WAIT from cl_lock.c + * functions). + * + * For a description of state machine states and transitions see enum + * cl_lock_state. + * + * There are two ways to restrict a set of states which lock might move to: + * + * - placing a "hold" on a lock guarantees that lock will not be moved + * into cl_lock_state::CLS_FREEING state until hold is released. Hold + * can be only acquired on a lock that is not in + * cl_lock_state::CLS_FREEING. All holds on a lock are counted in + * cl_lock::cll_holds. Hold protects lock from cancellation and + * destruction. Requests to cancel and destroy a lock on hold will be + * recorded, but only honored when last hold on a lock is released; + * + * - placing a "user" on a lock guarantees that lock will not leave + * cl_lock_state::CLS_NEW, cl_lock_state::CLS_QUEUING, + * cl_lock_state::CLS_ENQUEUED and cl_lock_state::CLS_HELD set of + * states, once it enters this set. That is, if a user is added onto a + * lock in a state not from this set, it doesn't immediately enforce + * lock to move to this set, but once lock enters this set it will + * remain there until all users are removed. Lock users are counted in + * cl_lock::cll_users. + * + * User is used to assure that lock is not canceled or destroyed while + * it is being enqueued, or actively used by some IO. + * + * Currently, a user always comes with a hold (cl_lock_invariant() + * checks that a number of holds is not less than a number of users). + * + * CONCURRENCY + * + * This is how lock state-machine operates. struct cl_lock contains a mutex + * cl_lock::cll_guard that protects struct fields. + * + * - mutex is taken, and cl_lock::cll_state is examined. + * + * - for every state there are possible target states where lock can move + * into. They are tried in order. Attempts to move into next state are + * done by _try() functions in cl_lock.c:cl_{enqueue,unlock,wait}_try(). + * + * - if the transition can be performed immediately, state is changed, + * and mutex is released. + * + * - if the transition requires blocking, _try() function returns + * cl_lock_transition::CLO_WAIT. Caller unlocks mutex and goes to + * sleep, waiting for possibility of lock state change. It is woken + * up when some event occurs, that makes lock state change possible + * (e.g., the reception of the reply from the server), and repeats + * the loop. + * + * Top-lock and sub-lock has separate mutexes and the latter has to be taken + * first to avoid dead-lock. + * + * To see an example of interaction of all these issues, take a look at the + * lov_cl.c:lov_lock_enqueue() function. It is called as a part of + * cl_enqueue_try(), and tries to advance top-lock to ENQUEUED state, by + * advancing state-machines of its sub-locks (lov_lock_enqueue_one()). Note + * also, that it uses trylock to grab sub-lock mutex to avoid dead-lock. It + * also has to handle CEF_ASYNC enqueue, when sub-locks enqueues have to be + * done in parallel, rather than one after another (this is used for glimpse + * locks, that cannot dead-lock). + * + * INTERFACE AND USAGE + * + * struct cl_lock_operations provide a number of call-backs that are invoked + * when events of interest occurs. Layers can intercept and handle glimpse, + * blocking, cancel ASTs and a reception of the reply from the server. + * + * One important difference with the old client locking model is that new + * client has a representation for the top-lock, whereas in the old code only + * sub-locks existed as real data structures and file-level locks are + * represented by "request sets" that are created and destroyed on each and + * every lock creation. + * + * Top-locks are cached, and can be found in the cache by the system calls. It + * is possible that top-lock is in cache, but some of its sub-locks were + * canceled and destroyed. In that case top-lock has to be enqueued again + * before it can be used. + * + * Overall process of the locking during IO operation is as following: + * + * - once parameters for IO are setup in cl_io, cl_io_operations::cio_lock() + * is called on each layer. Responsibility of this method is to add locks, + * needed by a given layer into cl_io.ci_lockset. + * + * - once locks for all layers were collected, they are sorted to avoid + * dead-locks (cl_io_locks_sort()), and enqueued. + * + * - when all locks are acquired, IO is performed; + * + * - locks are released into cache. + * + * Striping introduces major additional complexity into locking. The + * fundamental problem is that it is generally unsafe to actively use (hold) + * two locks on the different OST servers at the same time, as this introduces + * inter-server dependency and can lead to cascading evictions. + * + * Basic solution is to sub-divide large read/write IOs into smaller pieces so + * that no multi-stripe locks are taken (note that this design abandons POSIX + * read/write semantics). Such pieces ideally can be executed concurrently. At + * the same time, certain types of IO cannot be sub-divived, without + * sacrificing correctness. This includes: + * + * - O_APPEND write, where [0, EOF] lock has to be taken, to guarantee + * atomicity; + * + * - ftruncate(fd, offset), where [offset, EOF] lock has to be taken. + * + * Also, in the case of read(fd, buf, count) or write(fd, buf, count), where + * buf is a part of memory mapped Lustre file, a lock or locks protecting buf + * has to be held together with the usual lock on [offset, offset + count]. + * + * As multi-stripe locks have to be allowed, it makes sense to cache them, so + * that, for example, a sequence of O_APPEND writes can proceed quickly + * without going down to the individual stripes to do lock matching. On the + * other hand, multi-stripe locks shouldn't be used by normal read/write + * calls. To achieve this, every layer can implement ->clo_fits_into() method, + * that is called by lock matching code (cl_lock_lookup()), and that can be + * used to selectively disable matching of certain locks for certain IOs. For + * exmaple, lov layer implements lov_lock_fits_into() that allow multi-stripe + * locks to be matched only for truncates and O_APPEND writes. + * + * Interaction with DLM + * + * In the expected setup, cl_lock is ultimately backed up by a collection of + * DLM locks (struct ldlm_lock). Association between cl_lock and DLM lock is + * implemented in osc layer, that also matches DLM events (ASTs, cancellation, + * etc.) into cl_lock_operation calls. See struct osc_lock for a more detailed + * description of interaction with DLM. + */ + +/** + * Lock description. + */ +struct cl_lock_descr { + /** Object this lock is granted for. */ + struct cl_object *cld_obj; + /** Index of the first page protected by this lock. */ + pgoff_t cld_start; + /** Index of the last page (inclusive) protected by this lock. */ + pgoff_t cld_end; + /** Group ID, for group lock */ + __u64 cld_gid; + /** Lock mode. */ + enum cl_lock_mode cld_mode; + /** + * flags to enqueue lock. A combination of bit-flags from + * enum cl_enq_flags. + */ + __u32 cld_enq_flags; +}; + +#define DDESCR "%s(%d):[%lu, %lu]" +#define PDESCR(descr) \ + cl_lock_mode_name((descr)->cld_mode), (descr)->cld_mode, \ + (descr)->cld_start, (descr)->cld_end + +const char *cl_lock_mode_name(const enum cl_lock_mode mode); + +/** + * Lock state-machine states. + * + * \htmlonly + * <pre> + * + * Possible state transitions: + * + * +------------------>NEW + * | | + * | | cl_enqueue_try() + * | | + * | cl_unuse_try() V + * | +--------------QUEUING (*) + * | | | + * | | | cl_enqueue_try() + * | | | + * | | cl_unuse_try() V + * sub-lock | +-------------ENQUEUED (*) + * canceled | | | + * | | | cl_wait_try() + * | | | + * | | (R) + * | | | + * | | V + * | | HELD<---------+ + * | | | | + * | | | | cl_use_try() + * | | cl_unuse_try() | | + * | | | | + * | | V ---+ + * | +------------>INTRANSIT (D) <--+ + * | | | + * | cl_unuse_try() | | cached lock found + * | | | cl_use_try() + * | | | + * | V | + * +------------------CACHED---------+ + * | + * (C) + * | + * V + * FREEING + * + * Legend: + * + * In states marked with (*) transition to the same state (i.e., a loop + * in the diagram) is possible. + * + * (R) is the point where Receive call-back is invoked: it allows layers + * to handle arrival of lock reply. + * + * (C) is the point where Cancellation call-back is invoked. + * + * (D) is the transit state which means the lock is changing. + * + * Transition to FREEING state is possible from any other state in the + * diagram in case of unrecoverable error. + * </pre> + * \endhtmlonly + * + * These states are for individual cl_lock object. Top-lock and its sub-locks + * can be in the different states. Another way to say this is that we have + * nested state-machines. + * + * Separate QUEUING and ENQUEUED states are needed to support non-blocking + * operation for locks with multiple sub-locks. Imagine lock on a file F, that + * intersects 3 stripes S0, S1, and S2. To enqueue F client has to send + * enqueue to S0, wait for its completion, then send enqueue for S1, wait for + * its completion and at last enqueue lock for S2, and wait for its + * completion. In that case, top-lock is in QUEUING state while S0, S1 are + * handled, and is in ENQUEUED state after enqueue to S2 has been sent (note + * that in this case, sub-locks move from state to state, and top-lock remains + * in the same state). + */ +enum cl_lock_state { + /** + * Lock that wasn't yet enqueued + */ + CLS_NEW, + /** + * Enqueue is in progress, blocking for some intermediate interaction + * with the other side. + */ + CLS_QUEUING, + /** + * Lock is fully enqueued, waiting for server to reply when it is + * granted. + */ + CLS_ENQUEUED, + /** + * Lock granted, actively used by some IO. + */ + CLS_HELD, + /** + * This state is used to mark the lock is being used, or unused. + * We need this state because the lock may have several sublocks, + * so it's impossible to have an atomic way to bring all sublocks + * into CLS_HELD state at use case, or all sublocks to CLS_CACHED + * at unuse case. + * If a thread is referring to a lock, and it sees the lock is in this + * state, it must wait for the lock. + * See state diagram for details. + */ + CLS_INTRANSIT, + /** + * Lock granted, not used. + */ + CLS_CACHED, + /** + * Lock is being destroyed. + */ + CLS_FREEING, + CLS_NR +}; + +enum cl_lock_flags { + /** + * lock has been cancelled. This flag is never cleared once set (by + * cl_lock_cancel0()). + */ + CLF_CANCELLED = 1 << 0, + /** cancellation is pending for this lock. */ + CLF_CANCELPEND = 1 << 1, + /** destruction is pending for this lock. */ + CLF_DOOMED = 1 << 2, + /** from enqueue RPC reply upcall. */ + CLF_FROM_UPCALL= 1 << 3, +}; + +/** + * Lock closure. + * + * Lock closure is a collection of locks (both top-locks and sub-locks) that + * might be updated in a result of an operation on a certain lock (which lock + * this is a closure of). + * + * Closures are needed to guarantee dead-lock freedom in the presence of + * + * - nested state-machines (top-lock state-machine composed of sub-lock + * state-machines), and + * + * - shared sub-locks. + * + * Specifically, many operations, such as lock enqueue, wait, unlock, + * etc. start from a top-lock, and then operate on a sub-locks of this + * top-lock, holding a top-lock mutex. When sub-lock state changes as a result + * of such operation, this change has to be propagated to all top-locks that + * share this sub-lock. Obviously, no natural lock ordering (e.g., + * top-to-bottom or bottom-to-top) captures this scenario, so try-locking has + * to be used. Lock closure systematizes this try-and-repeat logic. + */ +struct cl_lock_closure { + /** + * Lock that is mutexed when closure construction is started. When + * closure in is `wait' mode (cl_lock_closure::clc_wait), mutex on + * origin is released before waiting. + */ + struct cl_lock *clc_origin; + /** + * List of enclosed locks, so far. Locks are linked here through + * cl_lock::cll_inclosure. + */ + struct list_head clc_list; + /** + * True iff closure is in a `wait' mode. This determines what + * cl_lock_enclosure() does when a lock L to be added to the closure + * is currently mutexed by some other thread. + * + * If cl_lock_closure::clc_wait is not set, then closure construction + * fails with CLO_REPEAT immediately. + * + * In wait mode, cl_lock_enclosure() waits until next attempt to build + * a closure might succeed. To this end it releases an origin mutex + * (cl_lock_closure::clc_origin), that has to be the only lock mutex + * owned by the current thread, and then waits on L mutex (by grabbing + * it and immediately releasing), before returning CLO_REPEAT to the + * caller. + */ + int clc_wait; + /** Number of locks in the closure. */ + int clc_nr; +}; + +/** + * Layered client lock. + */ +struct cl_lock { + /** Reference counter. */ + atomic_t cll_ref; + /** List of slices. Immutable after creation. */ + struct list_head cll_layers; + /** + * Linkage into cl_lock::cll_descr::cld_obj::coh_locks list. Protected + * by cl_lock::cll_descr::cld_obj::coh_lock_guard. + */ + struct list_head cll_linkage; + /** + * Parameters of this lock. Protected by + * cl_lock::cll_descr::cld_obj::coh_lock_guard nested within + * cl_lock::cll_guard. Modified only on lock creation and in + * cl_lock_modify(). + */ + struct cl_lock_descr cll_descr; + /** Protected by cl_lock::cll_guard. */ + enum cl_lock_state cll_state; + /** signals state changes. */ + wait_queue_head_t cll_wq; + /** + * Recursive lock, most fields in cl_lock{} are protected by this. + * + * Locking rules: this mutex is never held across network + * communication, except when lock is being canceled. + * + * Lock ordering: a mutex of a sub-lock is taken first, then a mutex + * on a top-lock. Other direction is implemented through a + * try-lock-repeat loop. Mutices of unrelated locks can be taken only + * by try-locking. + * + * \see osc_lock_enqueue_wait(), lov_lock_cancel(), lov_sublock_wait(). + */ + struct mutex cll_guard; + task_t *cll_guarder; + int cll_depth; + + /** + * the owner for INTRANSIT state + */ + task_t *cll_intransit_owner; + int cll_error; + /** + * Number of holds on a lock. A hold prevents a lock from being + * canceled and destroyed. Protected by cl_lock::cll_guard. + * + * \see cl_lock_hold(), cl_lock_unhold(), cl_lock_release() + */ + int cll_holds; + /** + * Number of lock users. Valid in cl_lock_state::CLS_HELD state + * only. Lock user pins lock in CLS_HELD state. Protected by + * cl_lock::cll_guard. + * + * \see cl_wait(), cl_unuse(). + */ + int cll_users; + /** + * Flag bit-mask. Values from enum cl_lock_flags. Updates are + * protected by cl_lock::cll_guard. + */ + unsigned long cll_flags; + /** + * A linkage into a list of locks in a closure. + * + * \see cl_lock_closure + */ + struct list_head cll_inclosure; + /** + * Confict lock at queuing time. + */ + struct cl_lock *cll_conflict; + /** + * A list of references to this lock, for debugging. + */ + struct lu_ref cll_reference; + /** + * A list of holds on this lock, for debugging. + */ + struct lu_ref cll_holders; + /** + * A reference for cl_lock::cll_descr::cld_obj. For debugging. + */ + struct lu_ref_link *cll_obj_ref; +#ifdef CONFIG_LOCKDEP + /* "dep_map" name is assumed by lockdep.h macros. */ + struct lockdep_map dep_map; +#endif +}; + +/** + * Per-layer part of cl_lock + * + * \see ccc_lock, lov_lock, lovsub_lock, osc_lock + */ +struct cl_lock_slice { + struct cl_lock *cls_lock; + /** Object slice corresponding to this lock slice. Immutable after + * creation. */ + struct cl_object *cls_obj; + const struct cl_lock_operations *cls_ops; + /** Linkage into cl_lock::cll_layers. Immutable after creation. */ + struct list_head cls_linkage; +}; + +/** + * Possible (non-error) return values of ->clo_{enqueue,wait,unlock}(). + * + * NOTE: lov_subresult() depends on ordering here. + */ +enum cl_lock_transition { + /** operation cannot be completed immediately. Wait for state change. */ + CLO_WAIT = 1, + /** operation had to release lock mutex, restart. */ + CLO_REPEAT = 2, + /** lower layer re-enqueued. */ + CLO_REENQUEUED = 3, +}; + +/** + * + * \see vvp_lock_ops, lov_lock_ops, lovsub_lock_ops, osc_lock_ops + */ +struct cl_lock_operations { + /** + * \name statemachine + * + * State machine transitions. These 3 methods are called to transfer + * lock from one state to another, as described in the commentary + * above enum #cl_lock_state. + * + * \retval 0 this layer has nothing more to do to before + * transition to the target state happens; + * + * \retval CLO_REPEAT method had to release and re-acquire cl_lock + * mutex, repeat invocation of transition method + * across all layers; + * + * \retval CLO_WAIT this layer cannot move to the target state + * immediately, as it has to wait for certain event + * (e.g., the communication with the server). It + * is guaranteed, that when the state transfer + * becomes possible, cl_lock::cll_wq wait-queue + * is signaled. Caller can wait for this event by + * calling cl_lock_state_wait(); + * + * \retval -ve failure, abort state transition, move the lock + * into cl_lock_state::CLS_FREEING state, and set + * cl_lock::cll_error. + * + * Once all layers voted to agree to transition (by returning 0), lock + * is moved into corresponding target state. All state transition + * methods are optional. + */ + /** @{ */ + /** + * Attempts to enqueue the lock. Called top-to-bottom. + * + * \see ccc_lock_enqueue(), lov_lock_enqueue(), lovsub_lock_enqueue(), + * \see osc_lock_enqueue() + */ + int (*clo_enqueue)(const struct lu_env *env, + const struct cl_lock_slice *slice, + struct cl_io *io, __u32 enqflags); + /** + * Attempts to wait for enqueue result. Called top-to-bottom. + * + * \see ccc_lock_wait(), lov_lock_wait(), osc_lock_wait() + */ + int (*clo_wait)(const struct lu_env *env, + const struct cl_lock_slice *slice); + /** + * Attempts to unlock the lock. Called bottom-to-top. In addition to + * usual return values of lock state-machine methods, this can return + * -ESTALE to indicate that lock cannot be returned to the cache, and + * has to be re-initialized. + * unuse is a one-shot operation, so it must NOT return CLO_WAIT. + * + * \see ccc_lock_unuse(), lov_lock_unuse(), osc_lock_unuse() + */ + int (*clo_unuse)(const struct lu_env *env, + const struct cl_lock_slice *slice); + /** + * Notifies layer that cached lock is started being used. + * + * \pre lock->cll_state == CLS_CACHED + * + * \see lov_lock_use(), osc_lock_use() + */ + int (*clo_use)(const struct lu_env *env, + const struct cl_lock_slice *slice); + /** @} statemachine */ + /** + * A method invoked when lock state is changed (as a result of state + * transition). This is used, for example, to track when the state of + * a sub-lock changes, to propagate this change to the corresponding + * top-lock. Optional + * + * \see lovsub_lock_state() + */ + void (*clo_state)(const struct lu_env *env, + const struct cl_lock_slice *slice, + enum cl_lock_state st); + /** + * Returns true, iff given lock is suitable for the given io, idea + * being, that there are certain "unsafe" locks, e.g., ones acquired + * for O_APPEND writes, that we don't want to re-use for a normal + * write, to avoid the danger of cascading evictions. Optional. Runs + * under cl_object_header::coh_lock_guard. + * + * XXX this should take more information about lock needed by + * io. Probably lock description or something similar. + * + * \see lov_fits_into() + */ + int (*clo_fits_into)(const struct lu_env *env, + const struct cl_lock_slice *slice, + const struct cl_lock_descr *need, + const struct cl_io *io); + /** + * \name ast + * Asynchronous System Traps. All of then are optional, all are + * executed bottom-to-top. + */ + /** @{ */ + + /** + * Cancellation callback. Cancel a lock voluntarily, or under + * the request of server. + */ + void (*clo_cancel)(const struct lu_env *env, + const struct cl_lock_slice *slice); + /** + * Lock weighting ast. Executed to estimate how precious this lock + * is. The sum of results across all layers is used to determine + * whether lock worth keeping in cache given present memory usage. + * + * \see osc_lock_weigh(), vvp_lock_weigh(), lovsub_lock_weigh(). + */ + unsigned long (*clo_weigh)(const struct lu_env *env, + const struct cl_lock_slice *slice); + /** @} ast */ + + /** + * \see lovsub_lock_closure() + */ + int (*clo_closure)(const struct lu_env *env, + const struct cl_lock_slice *slice, + struct cl_lock_closure *closure); + /** + * Executed bottom-to-top when lock description changes (e.g., as a + * result of server granting more generous lock than was requested). + * + * \see lovsub_lock_modify() + */ + int (*clo_modify)(const struct lu_env *env, + const struct cl_lock_slice *slice, + const struct cl_lock_descr *updated); + /** + * Notifies layers (bottom-to-top) that lock is going to be + * destroyed. Responsibility of layers is to prevent new references on + * this lock from being acquired once this method returns. + * + * This can be called multiple times due to the races. + * + * \see cl_lock_delete() + * \see osc_lock_delete(), lovsub_lock_delete() + */ + void (*clo_delete)(const struct lu_env *env, + const struct cl_lock_slice *slice); + /** + * Destructor. Frees resources and the slice. + * + * \see ccc_lock_fini(), lov_lock_fini(), lovsub_lock_fini(), + * \see osc_lock_fini() + */ + void (*clo_fini)(const struct lu_env *env, struct cl_lock_slice *slice); + /** + * Optional debugging helper. Prints given lock slice. + */ + int (*clo_print)(const struct lu_env *env, + void *cookie, lu_printer_t p, + const struct cl_lock_slice *slice); +}; + +#define CL_LOCK_DEBUG(mask, env, lock, format, ...) \ +do { \ + LIBCFS_DEBUG_MSG_DATA_DECL(msgdata, mask, NULL); \ + \ + if (cfs_cdebug_show(mask, DEBUG_SUBSYSTEM)) { \ + cl_lock_print(env, &msgdata, lu_cdebug_printer, lock); \ + CDEBUG(mask, format , ## __VA_ARGS__); \ + } \ +} while (0) + +#define CL_LOCK_ASSERT(expr, env, lock) do { \ + if (likely(expr)) \ + break; \ + \ + CL_LOCK_DEBUG(D_ERROR, env, lock, "failed at %s.\n", #expr); \ + LBUG(); \ +} while (0) + +/** @} cl_lock */ + +/** \addtogroup cl_page_list cl_page_list + * Page list used to perform collective operations on a group of pages. + * + * Pages are added to the list one by one. cl_page_list acquires a reference + * for every page in it. Page list is used to perform collective operations on + * pages: + * + * - submit pages for an immediate transfer, + * + * - own pages on behalf of certain io (waiting for each page in turn), + * + * - discard pages. + * + * When list is finalized, it releases references on all pages it still has. + * + * \todo XXX concurrency control. + * + * @{ + */ +struct cl_page_list { + unsigned pl_nr; + struct list_head pl_pages; + task_t *pl_owner; +}; + +/** + * A 2-queue of pages. A convenience data-type for common use case, 2-queue + * contains an incoming page list and an outgoing page list. + */ +struct cl_2queue { + struct cl_page_list c2_qin; + struct cl_page_list c2_qout; +}; + +/** @} cl_page_list */ + +/** \addtogroup cl_io cl_io + * @{ */ +/** \struct cl_io + * I/O + * + * cl_io represents a high level I/O activity like + * read(2)/write(2)/truncate(2) system call, or cancellation of an extent + * lock. + * + * cl_io is a layered object, much like cl_{object,page,lock} but with one + * important distinction. We want to minimize number of calls to the allocator + * in the fast path, e.g., in the case of read(2) when everything is cached: + * client already owns the lock over region being read, and data are cached + * due to read-ahead. To avoid allocation of cl_io layers in such situations, + * per-layer io state is stored in the session, associated with the io, see + * struct {vvp,lov,osc}_io for example. Sessions allocation is amortized + * by using free-lists, see cl_env_get(). + * + * There is a small predefined number of possible io types, enumerated in enum + * cl_io_type. + * + * cl_io is a state machine, that can be advanced concurrently by the multiple + * threads. It is up to these threads to control the concurrency and, + * specifically, to detect when io is done, and its state can be safely + * released. + * + * For read/write io overall execution plan is as following: + * + * (0) initialize io state through all layers; + * + * (1) loop: prepare chunk of work to do + * + * (2) call all layers to collect locks they need to process current chunk + * + * (3) sort all locks to avoid dead-locks, and acquire them + * + * (4) process the chunk: call per-page methods + * (cl_io_operations::cio_read_page() for read, + * cl_io_operations::cio_prepare_write(), + * cl_io_operations::cio_commit_write() for write) + * + * (5) release locks + * + * (6) repeat loop. + * + * To implement the "parallel IO mode", lov layer creates sub-io's (lazily to + * address allocation efficiency issues mentioned above), and returns with the + * special error condition from per-page method when current sub-io has to + * block. This causes io loop to be repeated, and lov switches to the next + * sub-io in its cl_io_operations::cio_iter_init() implementation. + */ + +/** IO types */ +enum cl_io_type { + /** read system call */ + CIT_READ, + /** write system call */ + CIT_WRITE, + /** truncate, utime system calls */ + CIT_SETATTR, + /** + * page fault handling + */ + CIT_FAULT, + /** + * fsync system call handling + * To write out a range of file + */ + CIT_FSYNC, + /** + * Miscellaneous io. This is used for occasional io activity that + * doesn't fit into other types. Currently this is used for: + * + * - cancellation of an extent lock. This io exists as a context + * to write dirty pages from under the lock being canceled back + * to the server; + * + * - VM induced page write-out. An io context for writing page out + * for memory cleansing; + * + * - glimpse. An io context to acquire glimpse lock. + * + * - grouplock. An io context to acquire group lock. + * + * CIT_MISC io is used simply as a context in which locks and pages + * are manipulated. Such io has no internal "process", that is, + * cl_io_loop() is never called for it. + */ + CIT_MISC, + CIT_OP_NR +}; + +/** + * States of cl_io state machine + */ +enum cl_io_state { + /** Not initialized. */ + CIS_ZERO, + /** Initialized. */ + CIS_INIT, + /** IO iteration started. */ + CIS_IT_STARTED, + /** Locks taken. */ + CIS_LOCKED, + /** Actual IO is in progress. */ + CIS_IO_GOING, + /** IO for the current iteration finished. */ + CIS_IO_FINISHED, + /** Locks released. */ + CIS_UNLOCKED, + /** Iteration completed. */ + CIS_IT_ENDED, + /** cl_io finalized. */ + CIS_FINI +}; + +/** + * IO state private for a layer. + * + * This is usually embedded into layer session data, rather than allocated + * dynamically. + * + * \see vvp_io, lov_io, osc_io, ccc_io + */ +struct cl_io_slice { + struct cl_io *cis_io; + /** corresponding object slice. Immutable after creation. */ + struct cl_object *cis_obj; + /** io operations. Immutable after creation. */ + const struct cl_io_operations *cis_iop; + /** + * linkage into a list of all slices for a given cl_io, hanging off + * cl_io::ci_layers. Immutable after creation. + */ + struct list_head cis_linkage; +}; + + +/** + * Per-layer io operations. + * \see vvp_io_ops, lov_io_ops, lovsub_io_ops, osc_io_ops + */ +struct cl_io_operations { + /** + * Vector of io state transition methods for every io type. + * + * \see cl_page_operations::io + */ + struct { + /** + * Prepare io iteration at a given layer. + * + * Called top-to-bottom at the beginning of each iteration of + * "io loop" (if it makes sense for this type of io). Here + * layer selects what work it will do during this iteration. + * + * \see cl_io_operations::cio_iter_fini() + */ + int (*cio_iter_init) (const struct lu_env *env, + const struct cl_io_slice *slice); + /** + * Finalize io iteration. + * + * Called bottom-to-top at the end of each iteration of "io + * loop". Here layers can decide whether IO has to be + * continued. + * + * \see cl_io_operations::cio_iter_init() + */ + void (*cio_iter_fini) (const struct lu_env *env, + const struct cl_io_slice *slice); + /** + * Collect locks for the current iteration of io. + * + * Called top-to-bottom to collect all locks necessary for + * this iteration. This methods shouldn't actually enqueue + * anything, instead it should post a lock through + * cl_io_lock_add(). Once all locks are collected, they are + * sorted and enqueued in the proper order. + */ + int (*cio_lock) (const struct lu_env *env, + const struct cl_io_slice *slice); + /** + * Finalize unlocking. + * + * Called bottom-to-top to finish layer specific unlocking + * functionality, after generic code released all locks + * acquired by cl_io_operations::cio_lock(). + */ + void (*cio_unlock)(const struct lu_env *env, + const struct cl_io_slice *slice); + /** + * Start io iteration. + * + * Once all locks are acquired, called top-to-bottom to + * commence actual IO. In the current implementation, + * top-level vvp_io_{read,write}_start() does all the work + * synchronously by calling generic_file_*(), so other layers + * are called when everything is done. + */ + int (*cio_start)(const struct lu_env *env, + const struct cl_io_slice *slice); + /** + * Called top-to-bottom at the end of io loop. Here layer + * might wait for an unfinished asynchronous io. + */ + void (*cio_end) (const struct lu_env *env, + const struct cl_io_slice *slice); + /** + * Called bottom-to-top to notify layers that read/write IO + * iteration finished, with \a nob bytes transferred. + */ + void (*cio_advance)(const struct lu_env *env, + const struct cl_io_slice *slice, + size_t nob); + /** + * Called once per io, bottom-to-top to release io resources. + */ + void (*cio_fini) (const struct lu_env *env, + const struct cl_io_slice *slice); + } op[CIT_OP_NR]; + struct { + /** + * Submit pages from \a queue->c2_qin for IO, and move + * successfully submitted pages into \a queue->c2_qout. Return + * non-zero if failed to submit even the single page. If + * submission failed after some pages were moved into \a + * queue->c2_qout, completion callback with non-zero ioret is + * executed on them. + */ + int (*cio_submit)(const struct lu_env *env, + const struct cl_io_slice *slice, + enum cl_req_type crt, + struct cl_2queue *queue); + } req_op[CRT_NR]; + /** + * Read missing page. + * + * Called by a top-level cl_io_operations::op[CIT_READ]::cio_start() + * method, when it hits not-up-to-date page in the range. Optional. + * + * \pre io->ci_type == CIT_READ + */ + int (*cio_read_page)(const struct lu_env *env, + const struct cl_io_slice *slice, + const struct cl_page_slice *page); + /** + * Prepare write of a \a page. Called bottom-to-top by a top-level + * cl_io_operations::op[CIT_WRITE]::cio_start() to prepare page for + * get data from user-level buffer. + * + * \pre io->ci_type == CIT_WRITE + * + * \see vvp_io_prepare_write(), lov_io_prepare_write(), + * osc_io_prepare_write(). + */ + int (*cio_prepare_write)(const struct lu_env *env, + const struct cl_io_slice *slice, + const struct cl_page_slice *page, + unsigned from, unsigned to); + /** + * + * \pre io->ci_type == CIT_WRITE + * + * \see vvp_io_commit_write(), lov_io_commit_write(), + * osc_io_commit_write(). + */ + int (*cio_commit_write)(const struct lu_env *env, + const struct cl_io_slice *slice, + const struct cl_page_slice *page, + unsigned from, unsigned to); + /** + * Optional debugging helper. Print given io slice. + */ + int (*cio_print)(const struct lu_env *env, void *cookie, + lu_printer_t p, const struct cl_io_slice *slice); +}; + +/** + * Flags to lock enqueue procedure. + * \ingroup cl_lock + */ +enum cl_enq_flags { + /** + * instruct server to not block, if conflicting lock is found. Instead + * -EWOULDBLOCK is returned immediately. + */ + CEF_NONBLOCK = 0x00000001, + /** + * take lock asynchronously (out of order), as it cannot + * deadlock. This is for LDLM_FL_HAS_INTENT locks used for glimpsing. + */ + CEF_ASYNC = 0x00000002, + /** + * tell the server to instruct (though a flag in the blocking ast) an + * owner of the conflicting lock, that it can drop dirty pages + * protected by this lock, without sending them to the server. + */ + CEF_DISCARD_DATA = 0x00000004, + /** + * tell the sub layers that it must be a `real' lock. This is used for + * mmapped-buffer locks and glimpse locks that must be never converted + * into lockless mode. + * + * \see vvp_mmap_locks(), cl_glimpse_lock(). + */ + CEF_MUST = 0x00000008, + /** + * tell the sub layers that never request a `real' lock. This flag is + * not used currently. + * + * cl_io::ci_lockreq and CEF_{MUST,NEVER} flags specify lockless + * conversion policy: ci_lockreq describes generic information of lock + * requirement for this IO, especially for locks which belong to the + * object doing IO; however, lock itself may have precise requirements + * that are described by the enqueue flags. + */ + CEF_NEVER = 0x00000010, + /** + * for async glimpse lock. + */ + CEF_AGL = 0x00000020, + /** + * mask of enq_flags. + */ + CEF_MASK = 0x0000003f, +}; + +/** + * Link between lock and io. Intermediate structure is needed, because the + * same lock can be part of multiple io's simultaneously. + */ +struct cl_io_lock_link { + /** linkage into one of cl_lockset lists. */ + struct list_head cill_linkage; + struct cl_lock_descr cill_descr; + struct cl_lock *cill_lock; + /** optional destructor */ + void (*cill_fini)(const struct lu_env *env, + struct cl_io_lock_link *link); +}; + +/** + * Lock-set represents a collection of locks, that io needs at a + * time. Generally speaking, client tries to avoid holding multiple locks when + * possible, because + * + * - holding extent locks over multiple ost's introduces the danger of + * "cascading timeouts"; + * + * - holding multiple locks over the same ost is still dead-lock prone, + * see comment in osc_lock_enqueue(), + * + * but there are certain situations where this is unavoidable: + * + * - O_APPEND writes have to take [0, EOF] lock for correctness; + * + * - truncate has to take [new-size, EOF] lock for correctness; + * + * - SNS has to take locks across full stripe for correctness; + * + * - in the case when user level buffer, supplied to {read,write}(file0), + * is a part of a memory mapped lustre file, client has to take a dlm + * locks on file0, and all files that back up the buffer (or a part of + * the buffer, that is being processed in the current chunk, in any + * case, there are situations where at least 2 locks are necessary). + * + * In such cases we at least try to take locks in the same consistent + * order. To this end, all locks are first collected, then sorted, and then + * enqueued. + */ +struct cl_lockset { + /** locks to be acquired. */ + struct list_head cls_todo; + /** locks currently being processed. */ + struct list_head cls_curr; + /** locks acquired. */ + struct list_head cls_done; +}; + +/** + * Lock requirements(demand) for IO. It should be cl_io_lock_req, + * but 'req' is always to be thought as 'request' :-) + */ +enum cl_io_lock_dmd { + /** Always lock data (e.g., O_APPEND). */ + CILR_MANDATORY = 0, + /** Layers are free to decide between local and global locking. */ + CILR_MAYBE, + /** Never lock: there is no cache (e.g., liblustre). */ + CILR_NEVER +}; + +enum cl_fsync_mode { + /** start writeback, do not wait for them to finish */ + CL_FSYNC_NONE = 0, + /** start writeback and wait for them to finish */ + CL_FSYNC_LOCAL = 1, + /** discard all of dirty pages in a specific file range */ + CL_FSYNC_DISCARD = 2, + /** start writeback and make sure they have reached storage before + * return. OST_SYNC RPC must be issued and finished */ + CL_FSYNC_ALL = 3 +}; + +struct cl_io_rw_common { + loff_t crw_pos; + size_t crw_count; + int crw_nonblock; +}; + + +/** + * State for io. + * + * cl_io is shared by all threads participating in this IO (in current + * implementation only one thread advances IO, but parallel IO design and + * concurrent copy_*_user() require multiple threads acting on the same IO. It + * is up to these threads to serialize their activities, including updates to + * mutable cl_io fields. + */ +struct cl_io { + /** type of this IO. Immutable after creation. */ + enum cl_io_type ci_type; + /** current state of cl_io state machine. */ + enum cl_io_state ci_state; + /** main object this io is against. Immutable after creation. */ + struct cl_object *ci_obj; + /** + * Upper layer io, of which this io is a part of. Immutable after + * creation. + */ + struct cl_io *ci_parent; + /** List of slices. Immutable after creation. */ + struct list_head ci_layers; + /** list of locks (to be) acquired by this io. */ + struct cl_lockset ci_lockset; + /** lock requirements, this is just a help info for sublayers. */ + enum cl_io_lock_dmd ci_lockreq; + union { + struct cl_rd_io { + struct cl_io_rw_common rd; + } ci_rd; + struct cl_wr_io { + struct cl_io_rw_common wr; + int wr_append; + int wr_sync; + } ci_wr; + struct cl_io_rw_common ci_rw; + struct cl_setattr_io { + struct ost_lvb sa_attr; + unsigned int sa_valid; + struct obd_capa *sa_capa; + } ci_setattr; + struct cl_fault_io { + /** page index within file. */ + pgoff_t ft_index; + /** bytes valid byte on a faulted page. */ + int ft_nob; + /** writable page? for nopage() only */ + int ft_writable; + /** page of an executable? */ + int ft_executable; + /** page_mkwrite() */ + int ft_mkwrite; + /** resulting page */ + struct cl_page *ft_page; + } ci_fault; + struct cl_fsync_io { + loff_t fi_start; + loff_t fi_end; + struct obd_capa *fi_capa; + /** file system level fid */ + struct lu_fid *fi_fid; + enum cl_fsync_mode fi_mode; + /* how many pages were written/discarded */ + unsigned int fi_nr_written; + } ci_fsync; + } u; + struct cl_2queue ci_queue; + size_t ci_nob; + int ci_result; + unsigned int ci_continue:1, + /** + * This io has held grouplock, to inform sublayers that + * don't do lockless i/o. + */ + ci_no_srvlock:1, + /** + * The whole IO need to be restarted because layout has been changed + */ + ci_need_restart:1, + /** + * to not refresh layout - the IO issuer knows that the layout won't + * change(page operations, layout change causes all page to be + * discarded), or it doesn't matter if it changes(sync). + */ + ci_ignore_layout:1, + /** + * Check if layout changed after the IO finishes. Mainly for HSM + * requirement. If IO occurs to openning files, it doesn't need to + * verify layout because HSM won't release openning files. + * Right now, only two opertaions need to verify layout: glimpse + * and setattr. + */ + ci_verify_layout:1; + /** + * Number of pages owned by this IO. For invariant checking. + */ + unsigned ci_owned_nr; +}; + +/** @} cl_io */ + +/** \addtogroup cl_req cl_req + * @{ */ +/** \struct cl_req + * Transfer. + * + * There are two possible modes of transfer initiation on the client: + * + * - immediate transfer: this is started when a high level io wants a page + * or a collection of pages to be transferred right away. Examples: + * read-ahead, synchronous read in the case of non-page aligned write, + * page write-out as a part of extent lock cancellation, page write-out + * as a part of memory cleansing. Immediate transfer can be both + * cl_req_type::CRT_READ and cl_req_type::CRT_WRITE; + * + * - opportunistic transfer (cl_req_type::CRT_WRITE only), that happens + * when io wants to transfer a page to the server some time later, when + * it can be done efficiently. Example: pages dirtied by the write(2) + * path. + * + * In any case, transfer takes place in the form of a cl_req, which is a + * representation for a network RPC. + * + * Pages queued for an opportunistic transfer are cached until it is decided + * that efficient RPC can be composed of them. This decision is made by "a + * req-formation engine", currently implemented as a part of osc + * layer. Req-formation depends on many factors: the size of the resulting + * RPC, whether or not multi-object RPCs are supported by the server, + * max-rpc-in-flight limitations, size of the dirty cache, etc. + * + * For the immediate transfer io submits a cl_page_list, that req-formation + * engine slices into cl_req's, possibly adding cached pages to some of + * the resulting req's. + * + * Whenever a page from cl_page_list is added to a newly constructed req, its + * cl_page_operations::cpo_prep() layer methods are called. At that moment, + * page state is atomically changed from cl_page_state::CPS_OWNED to + * cl_page_state::CPS_PAGEOUT or cl_page_state::CPS_PAGEIN, cl_page::cp_owner + * is zeroed, and cl_page::cp_req is set to the + * req. cl_page_operations::cpo_prep() method at the particular layer might + * return -EALREADY to indicate that it does not need to submit this page + * at all. This is possible, for example, if page, submitted for read, + * became up-to-date in the meantime; and for write, the page don't have + * dirty bit marked. \see cl_io_submit_rw() + * + * Whenever a cached page is added to a newly constructed req, its + * cl_page_operations::cpo_make_ready() layer methods are called. At that + * moment, page state is atomically changed from cl_page_state::CPS_CACHED to + * cl_page_state::CPS_PAGEOUT, and cl_page::cp_req is set to + * req. cl_page_operations::cpo_make_ready() method at the particular layer + * might return -EAGAIN to indicate that this page is not eligible for the + * transfer right now. + * + * FUTURE + * + * Plan is to divide transfers into "priority bands" (indicated when + * submitting cl_page_list, and queuing a page for the opportunistic transfer) + * and allow glueing of cached pages to immediate transfers only within single + * band. This would make high priority transfers (like lock cancellation or + * memory pressure induced write-out) really high priority. + * + */ + +/** + * Per-transfer attributes. + */ +struct cl_req_attr { + /** Generic attributes for the server consumption. */ + struct obdo *cra_oa; + /** Capability. */ + struct obd_capa *cra_capa; + /** Jobid */ + char cra_jobid[JOBSTATS_JOBID_SIZE]; +}; + +/** + * Transfer request operations definable at every layer. + * + * Concurrency: transfer formation engine synchronizes calls to all transfer + * methods. + */ +struct cl_req_operations { + /** + * Invoked top-to-bottom by cl_req_prep() when transfer formation is + * complete (all pages are added). + * + * \see osc_req_prep() + */ + int (*cro_prep)(const struct lu_env *env, + const struct cl_req_slice *slice); + /** + * Called top-to-bottom to fill in \a oa fields. This is called twice + * with different flags, see bug 10150 and osc_build_req(). + * + * \param obj an object from cl_req which attributes are to be set in + * \a oa. + * + * \param oa struct obdo where attributes are placed + * + * \param flags \a oa fields to be filled. + */ + void (*cro_attr_set)(const struct lu_env *env, + const struct cl_req_slice *slice, + const struct cl_object *obj, + struct cl_req_attr *attr, obd_valid flags); + /** + * Called top-to-bottom from cl_req_completion() to notify layers that + * transfer completed. Has to free all state allocated by + * cl_device_operations::cdo_req_init(). + */ + void (*cro_completion)(const struct lu_env *env, + const struct cl_req_slice *slice, int ioret); +}; + +/** + * A per-object state that (potentially multi-object) transfer request keeps. + */ +struct cl_req_obj { + /** object itself */ + struct cl_object *ro_obj; + /** reference to cl_req_obj::ro_obj. For debugging. */ + struct lu_ref_link *ro_obj_ref; + /* something else? Number of pages for a given object? */ +}; + +/** + * Transfer request. + * + * Transfer requests are not reference counted, because IO sub-system owns + * them exclusively and knows when to free them. + * + * Life cycle. + * + * cl_req is created by cl_req_alloc() that calls + * cl_device_operations::cdo_req_init() device methods to allocate per-req + * state in every layer. + * + * Then pages are added (cl_req_page_add()), req keeps track of all objects it + * contains pages for. + * + * Once all pages were collected, cl_page_operations::cpo_prep() method is + * called top-to-bottom. At that point layers can modify req, let it pass, or + * deny it completely. This is to support things like SNS that have transfer + * ordering requirements invisible to the individual req-formation engine. + * + * On transfer completion (or transfer timeout, or failure to initiate the + * transfer of an allocated req), cl_req_operations::cro_completion() method + * is called, after execution of cl_page_operations::cpo_completion() of all + * req's pages. + */ +struct cl_req { + enum cl_req_type crq_type; + /** A list of pages being transfered */ + struct list_head crq_pages; + /** Number of pages in cl_req::crq_pages */ + unsigned crq_nrpages; + /** An array of objects which pages are in ->crq_pages */ + struct cl_req_obj *crq_o; + /** Number of elements in cl_req::crq_objs[] */ + unsigned crq_nrobjs; + struct list_head crq_layers; +}; + +/** + * Per-layer state for request. + */ +struct cl_req_slice { + struct cl_req *crs_req; + struct cl_device *crs_dev; + struct list_head crs_linkage; + const struct cl_req_operations *crs_ops; +}; + +/* @} cl_req */ + +enum cache_stats_item { + /** how many cache lookups were performed */ + CS_lookup = 0, + /** how many times cache lookup resulted in a hit */ + CS_hit, + /** how many entities are in the cache right now */ + CS_total, + /** how many entities in the cache are actively used (and cannot be + * evicted) right now */ + CS_busy, + /** how many entities were created at all */ + CS_create, + CS_NR +}; + +#define CS_NAMES { "lookup", "hit", "total", "busy", "create" } + +/** + * Stats for a generic cache (similar to inode, lu_object, etc. caches). + */ +struct cache_stats { + const char *cs_name; + atomic_t cs_stats[CS_NR]; +}; + +/** These are not exported so far */ +void cache_stats_init (struct cache_stats *cs, const char *name); + +/** + * Client-side site. This represents particular client stack. "Global" + * variables should (directly or indirectly) be added here to allow multiple + * clients to co-exist in the single address space. + */ +struct cl_site { + struct lu_site cs_lu; + /** + * Statistical counters. Atomics do not scale, something better like + * per-cpu counters is needed. + * + * These are exported as /proc/fs/lustre/llite/.../site + * + * When interpreting keep in mind that both sub-locks (and sub-pages) + * and top-locks (and top-pages) are accounted here. + */ + struct cache_stats cs_pages; + struct cache_stats cs_locks; + atomic_t cs_pages_state[CPS_NR]; + atomic_t cs_locks_state[CLS_NR]; +}; + +int cl_site_init (struct cl_site *s, struct cl_device *top); +void cl_site_fini (struct cl_site *s); +void cl_stack_fini(const struct lu_env *env, struct cl_device *cl); + +/** + * Output client site statistical counters into a buffer. Suitable for + * ll_rd_*()-style functions. + */ +int cl_site_stats_print(const struct cl_site *site, struct seq_file *m); + +/** + * \name helpers + * + * Type conversion and accessory functions. + */ +/** @{ */ + +static inline struct cl_site *lu2cl_site(const struct lu_site *site) +{ + return container_of(site, struct cl_site, cs_lu); +} + +static inline int lu_device_is_cl(const struct lu_device *d) +{ + return d->ld_type->ldt_tags & LU_DEVICE_CL; +} + +static inline struct cl_device *lu2cl_dev(const struct lu_device *d) +{ + LASSERT(d == NULL || IS_ERR(d) || lu_device_is_cl(d)); + return container_of0(d, struct cl_device, cd_lu_dev); +} + +static inline struct lu_device *cl2lu_dev(struct cl_device *d) +{ + return &d->cd_lu_dev; +} + +static inline struct cl_object *lu2cl(const struct lu_object *o) +{ + LASSERT(o == NULL || IS_ERR(o) || lu_device_is_cl(o->lo_dev)); + return container_of0(o, struct cl_object, co_lu); +} + +static inline const struct cl_object_conf * +lu2cl_conf(const struct lu_object_conf *conf) +{ + return container_of0(conf, struct cl_object_conf, coc_lu); +} + +static inline struct cl_object *cl_object_next(const struct cl_object *obj) +{ + return obj ? lu2cl(lu_object_next(&obj->co_lu)) : NULL; +} + +static inline struct cl_device *cl_object_device(const struct cl_object *o) +{ + LASSERT(o == NULL || IS_ERR(o) || lu_device_is_cl(o->co_lu.lo_dev)); + return container_of0(o->co_lu.lo_dev, struct cl_device, cd_lu_dev); +} + +static inline struct cl_object_header *luh2coh(const struct lu_object_header *h) +{ + return container_of0(h, struct cl_object_header, coh_lu); +} + +static inline struct cl_site *cl_object_site(const struct cl_object *obj) +{ + return lu2cl_site(obj->co_lu.lo_dev->ld_site); +} + +static inline +struct cl_object_header *cl_object_header(const struct cl_object *obj) +{ + return luh2coh(obj->co_lu.lo_header); +} + +static inline int cl_device_init(struct cl_device *d, struct lu_device_type *t) +{ + return lu_device_init(&d->cd_lu_dev, t); +} + +static inline void cl_device_fini(struct cl_device *d) +{ + lu_device_fini(&d->cd_lu_dev); +} + +void cl_page_slice_add(struct cl_page *page, struct cl_page_slice *slice, + struct cl_object *obj, + const struct cl_page_operations *ops); +void cl_lock_slice_add(struct cl_lock *lock, struct cl_lock_slice *slice, + struct cl_object *obj, + const struct cl_lock_operations *ops); +void cl_io_slice_add(struct cl_io *io, struct cl_io_slice *slice, + struct cl_object *obj, const struct cl_io_operations *ops); +void cl_req_slice_add(struct cl_req *req, struct cl_req_slice *slice, + struct cl_device *dev, + const struct cl_req_operations *ops); +/** @} helpers */ + +/** \defgroup cl_object cl_object + * @{ */ +struct cl_object *cl_object_top (struct cl_object *o); +struct cl_object *cl_object_find(const struct lu_env *env, struct cl_device *cd, + const struct lu_fid *fid, + const struct cl_object_conf *c); + +int cl_object_header_init(struct cl_object_header *h); +void cl_object_header_fini(struct cl_object_header *h); +void cl_object_put (const struct lu_env *env, struct cl_object *o); +void cl_object_get (struct cl_object *o); +void cl_object_attr_lock (struct cl_object *o); +void cl_object_attr_unlock(struct cl_object *o); +int cl_object_attr_get (const struct lu_env *env, struct cl_object *obj, + struct cl_attr *attr); +int cl_object_attr_set (const struct lu_env *env, struct cl_object *obj, + const struct cl_attr *attr, unsigned valid); +int cl_object_glimpse (const struct lu_env *env, struct cl_object *obj, + struct ost_lvb *lvb); +int cl_conf_set (const struct lu_env *env, struct cl_object *obj, + const struct cl_object_conf *conf); +void cl_object_prune (const struct lu_env *env, struct cl_object *obj); +void cl_object_kill (const struct lu_env *env, struct cl_object *obj); +int cl_object_has_locks (struct cl_object *obj); + +/** + * Returns true, iff \a o0 and \a o1 are slices of the same object. + */ +static inline int cl_object_same(struct cl_object *o0, struct cl_object *o1) +{ + return cl_object_header(o0) == cl_object_header(o1); +} + +static inline void cl_object_page_init(struct cl_object *clob, int size) +{ + clob->co_slice_off = cl_object_header(clob)->coh_page_bufsize; + cl_object_header(clob)->coh_page_bufsize += ALIGN(size, 8); +} + +static inline void *cl_object_page_slice(struct cl_object *clob, + struct cl_page *page) +{ + return (void *)((char *)page + clob->co_slice_off); +} + +/** @} cl_object */ + +/** \defgroup cl_page cl_page + * @{ */ +enum { + CLP_GANG_OKAY = 0, + CLP_GANG_RESCHED, + CLP_GANG_AGAIN, + CLP_GANG_ABORT +}; + +/* callback of cl_page_gang_lookup() */ +typedef int (*cl_page_gang_cb_t) (const struct lu_env *, struct cl_io *, + struct cl_page *, void *); +int cl_page_gang_lookup (const struct lu_env *env, + struct cl_object *obj, + struct cl_io *io, + pgoff_t start, pgoff_t end, + cl_page_gang_cb_t cb, void *cbdata); +struct cl_page *cl_page_lookup (struct cl_object_header *hdr, + pgoff_t index); +struct cl_page *cl_page_find (const struct lu_env *env, + struct cl_object *obj, + pgoff_t idx, struct page *vmpage, + enum cl_page_type type); +struct cl_page *cl_page_find_sub (const struct lu_env *env, + struct cl_object *obj, + pgoff_t idx, struct page *vmpage, + struct cl_page *parent); +void cl_page_get (struct cl_page *page); +void cl_page_put (const struct lu_env *env, + struct cl_page *page); +void cl_page_print (const struct lu_env *env, void *cookie, + lu_printer_t printer, + const struct cl_page *pg); +void cl_page_header_print(const struct lu_env *env, void *cookie, + lu_printer_t printer, + const struct cl_page *pg); +struct page *cl_page_vmpage (const struct lu_env *env, + struct cl_page *page); +struct cl_page *cl_vmpage_page (struct page *vmpage, struct cl_object *obj); +struct cl_page *cl_page_top (struct cl_page *page); + +const struct cl_page_slice *cl_page_at(const struct cl_page *page, + const struct lu_device_type *dtype); + +/** + * \name ownership + * + * Functions dealing with the ownership of page by io. + */ +/** @{ */ + +int cl_page_own (const struct lu_env *env, + struct cl_io *io, struct cl_page *page); +int cl_page_own_try (const struct lu_env *env, + struct cl_io *io, struct cl_page *page); +void cl_page_assume (const struct lu_env *env, + struct cl_io *io, struct cl_page *page); +void cl_page_unassume (const struct lu_env *env, + struct cl_io *io, struct cl_page *pg); +void cl_page_disown (const struct lu_env *env, + struct cl_io *io, struct cl_page *page); +int cl_page_is_owned (const struct cl_page *pg, const struct cl_io *io); + +/** @} ownership */ + +/** + * \name transfer + * + * Functions dealing with the preparation of a page for a transfer, and + * tracking transfer state. + */ +/** @{ */ +int cl_page_prep (const struct lu_env *env, struct cl_io *io, + struct cl_page *pg, enum cl_req_type crt); +void cl_page_completion (const struct lu_env *env, + struct cl_page *pg, enum cl_req_type crt, int ioret); +int cl_page_make_ready (const struct lu_env *env, struct cl_page *pg, + enum cl_req_type crt); +int cl_page_cache_add (const struct lu_env *env, struct cl_io *io, + struct cl_page *pg, enum cl_req_type crt); +void cl_page_clip (const struct lu_env *env, struct cl_page *pg, + int from, int to); +int cl_page_cancel (const struct lu_env *env, struct cl_page *page); +int cl_page_flush (const struct lu_env *env, struct cl_io *io, + struct cl_page *pg); + +/** @} transfer */ + + +/** + * \name helper routines + * Functions to discard, delete and export a cl_page. + */ +/** @{ */ +void cl_page_discard (const struct lu_env *env, struct cl_io *io, + struct cl_page *pg); +void cl_page_delete (const struct lu_env *env, struct cl_page *pg); +int cl_page_unmap (const struct lu_env *env, struct cl_io *io, + struct cl_page *pg); +int cl_page_is_vmlocked (const struct lu_env *env, + const struct cl_page *pg); +void cl_page_export (const struct lu_env *env, + struct cl_page *pg, int uptodate); +int cl_page_is_under_lock(const struct lu_env *env, struct cl_io *io, + struct cl_page *page); +loff_t cl_offset (const struct cl_object *obj, pgoff_t idx); +pgoff_t cl_index (const struct cl_object *obj, loff_t offset); +int cl_page_size (const struct cl_object *obj); +int cl_pages_prune (const struct lu_env *env, struct cl_object *obj); + +void cl_lock_print (const struct lu_env *env, void *cookie, + lu_printer_t printer, const struct cl_lock *lock); +void cl_lock_descr_print(const struct lu_env *env, void *cookie, + lu_printer_t printer, + const struct cl_lock_descr *descr); +/* @} helper */ + +/** @} cl_page */ + +/** \defgroup cl_lock cl_lock + * @{ */ + +struct cl_lock *cl_lock_hold(const struct lu_env *env, const struct cl_io *io, + const struct cl_lock_descr *need, + const char *scope, const void *source); +struct cl_lock *cl_lock_peek(const struct lu_env *env, const struct cl_io *io, + const struct cl_lock_descr *need, + const char *scope, const void *source); +struct cl_lock *cl_lock_request(const struct lu_env *env, struct cl_io *io, + const struct cl_lock_descr *need, + const char *scope, const void *source); +struct cl_lock *cl_lock_at_pgoff(const struct lu_env *env, + struct cl_object *obj, pgoff_t index, + struct cl_lock *except, int pending, + int canceld); +static inline struct cl_lock *cl_lock_at_page(const struct lu_env *env, + struct cl_object *obj, + struct cl_page *page, + struct cl_lock *except, + int pending, int canceld) +{ + LASSERT(cl_object_header(obj) == cl_object_header(page->cp_obj)); + return cl_lock_at_pgoff(env, obj, page->cp_index, except, + pending, canceld); +} + +const struct cl_lock_slice *cl_lock_at(const struct cl_lock *lock, + const struct lu_device_type *dtype); + +void cl_lock_get (struct cl_lock *lock); +void cl_lock_get_trust (struct cl_lock *lock); +void cl_lock_put (const struct lu_env *env, struct cl_lock *lock); +void cl_lock_hold_add (const struct lu_env *env, struct cl_lock *lock, + const char *scope, const void *source); +void cl_lock_hold_release(const struct lu_env *env, struct cl_lock *lock, + const char *scope, const void *source); +void cl_lock_unhold (const struct lu_env *env, struct cl_lock *lock, + const char *scope, const void *source); +void cl_lock_release (const struct lu_env *env, struct cl_lock *lock, + const char *scope, const void *source); +void cl_lock_user_add (const struct lu_env *env, struct cl_lock *lock); +void cl_lock_user_del (const struct lu_env *env, struct cl_lock *lock); + +enum cl_lock_state cl_lock_intransit(const struct lu_env *env, + struct cl_lock *lock); +void cl_lock_extransit(const struct lu_env *env, struct cl_lock *lock, + enum cl_lock_state state); +int cl_lock_is_intransit(struct cl_lock *lock); + +int cl_lock_enqueue_wait(const struct lu_env *env, struct cl_lock *lock, + int keep_mutex); + +/** \name statemachine statemachine + * Interface to lock state machine consists of 3 parts: + * + * - "try" functions that attempt to effect a state transition. If state + * transition is not possible right now (e.g., if it has to wait for some + * asynchronous event to occur), these functions return + * cl_lock_transition::CLO_WAIT. + * + * - "non-try" functions that implement synchronous blocking interface on + * top of non-blocking "try" functions. These functions repeatedly call + * corresponding "try" versions, and if state transition is not possible + * immediately, wait for lock state change. + * + * - methods from cl_lock_operations, called by "try" functions. Lock can + * be advanced to the target state only when all layers voted that they + * are ready for this transition. "Try" functions call methods under lock + * mutex. If a layer had to release a mutex, it re-acquires it and returns + * cl_lock_transition::CLO_REPEAT, causing "try" function to call all + * layers again. + * + * TRY NON-TRY METHOD FINAL STATE + * + * cl_enqueue_try() cl_enqueue() cl_lock_operations::clo_enqueue() CLS_ENQUEUED + * + * cl_wait_try() cl_wait() cl_lock_operations::clo_wait() CLS_HELD + * + * cl_unuse_try() cl_unuse() cl_lock_operations::clo_unuse() CLS_CACHED + * + * cl_use_try() NONE cl_lock_operations::clo_use() CLS_HELD + * + * @{ */ + +int cl_enqueue (const struct lu_env *env, struct cl_lock *lock, + struct cl_io *io, __u32 flags); +int cl_wait (const struct lu_env *env, struct cl_lock *lock); +void cl_unuse (const struct lu_env *env, struct cl_lock *lock); +int cl_enqueue_try(const struct lu_env *env, struct cl_lock *lock, + struct cl_io *io, __u32 flags); +int cl_unuse_try (const struct lu_env *env, struct cl_lock *lock); +int cl_wait_try (const struct lu_env *env, struct cl_lock *lock); +int cl_use_try (const struct lu_env *env, struct cl_lock *lock, int atomic); + +/** @} statemachine */ + +void cl_lock_signal (const struct lu_env *env, struct cl_lock *lock); +int cl_lock_state_wait (const struct lu_env *env, struct cl_lock *lock); +void cl_lock_state_set (const struct lu_env *env, struct cl_lock *lock, + enum cl_lock_state state); +int cl_queue_match (const struct list_head *queue, + const struct cl_lock_descr *need); + +void cl_lock_mutex_get (const struct lu_env *env, struct cl_lock *lock); +int cl_lock_mutex_try (const struct lu_env *env, struct cl_lock *lock); +void cl_lock_mutex_put (const struct lu_env *env, struct cl_lock *lock); +int cl_lock_is_mutexed (struct cl_lock *lock); +int cl_lock_nr_mutexed (const struct lu_env *env); +int cl_lock_discard_pages(const struct lu_env *env, struct cl_lock *lock); +int cl_lock_ext_match (const struct cl_lock_descr *has, + const struct cl_lock_descr *need); +int cl_lock_descr_match(const struct cl_lock_descr *has, + const struct cl_lock_descr *need); +int cl_lock_mode_match (enum cl_lock_mode has, enum cl_lock_mode need); +int cl_lock_modify (const struct lu_env *env, struct cl_lock *lock, + const struct cl_lock_descr *desc); + +void cl_lock_closure_init (const struct lu_env *env, + struct cl_lock_closure *closure, + struct cl_lock *origin, int wait); +void cl_lock_closure_fini (struct cl_lock_closure *closure); +int cl_lock_closure_build(const struct lu_env *env, struct cl_lock *lock, + struct cl_lock_closure *closure); +void cl_lock_disclosure (const struct lu_env *env, + struct cl_lock_closure *closure); +int cl_lock_enclosure (const struct lu_env *env, struct cl_lock *lock, + struct cl_lock_closure *closure); + +void cl_lock_cancel(const struct lu_env *env, struct cl_lock *lock); +void cl_lock_delete(const struct lu_env *env, struct cl_lock *lock); +void cl_lock_error (const struct lu_env *env, struct cl_lock *lock, int error); +void cl_locks_prune(const struct lu_env *env, struct cl_object *obj, int wait); + +unsigned long cl_lock_weigh(const struct lu_env *env, struct cl_lock *lock); + +/** @} cl_lock */ + +/** \defgroup cl_io cl_io + * @{ */ + +int cl_io_init (const struct lu_env *env, struct cl_io *io, + enum cl_io_type iot, struct cl_object *obj); +int cl_io_sub_init (const struct lu_env *env, struct cl_io *io, + enum cl_io_type iot, struct cl_object *obj); +int cl_io_rw_init (const struct lu_env *env, struct cl_io *io, + enum cl_io_type iot, loff_t pos, size_t count); +int cl_io_loop (const struct lu_env *env, struct cl_io *io); + +void cl_io_fini (const struct lu_env *env, struct cl_io *io); +int cl_io_iter_init (const struct lu_env *env, struct cl_io *io); +void cl_io_iter_fini (const struct lu_env *env, struct cl_io *io); +int cl_io_lock (const struct lu_env *env, struct cl_io *io); +void cl_io_unlock (const struct lu_env *env, struct cl_io *io); +int cl_io_start (const struct lu_env *env, struct cl_io *io); +void cl_io_end (const struct lu_env *env, struct cl_io *io); +int cl_io_lock_add (const struct lu_env *env, struct cl_io *io, + struct cl_io_lock_link *link); +int cl_io_lock_alloc_add(const struct lu_env *env, struct cl_io *io, + struct cl_lock_descr *descr); +int cl_io_read_page (const struct lu_env *env, struct cl_io *io, + struct cl_page *page); +int cl_io_prepare_write(const struct lu_env *env, struct cl_io *io, + struct cl_page *page, unsigned from, unsigned to); +int cl_io_commit_write (const struct lu_env *env, struct cl_io *io, + struct cl_page *page, unsigned from, unsigned to); +int cl_io_submit_rw (const struct lu_env *env, struct cl_io *io, + enum cl_req_type iot, struct cl_2queue *queue); +int cl_io_submit_sync (const struct lu_env *env, struct cl_io *io, + enum cl_req_type iot, struct cl_2queue *queue, + long timeout); +void cl_io_rw_advance (const struct lu_env *env, struct cl_io *io, + size_t nob); +int cl_io_cancel (const struct lu_env *env, struct cl_io *io, + struct cl_page_list *queue); +int cl_io_is_going (const struct lu_env *env); + +/** + * True, iff \a io is an O_APPEND write(2). + */ +static inline int cl_io_is_append(const struct cl_io *io) +{ + return io->ci_type == CIT_WRITE && io->u.ci_wr.wr_append; +} + +static inline int cl_io_is_sync_write(const struct cl_io *io) +{ + return io->ci_type == CIT_WRITE && io->u.ci_wr.wr_sync; +} + +static inline int cl_io_is_mkwrite(const struct cl_io *io) +{ + return io->ci_type == CIT_FAULT && io->u.ci_fault.ft_mkwrite; +} + +/** + * True, iff \a io is a truncate(2). + */ +static inline int cl_io_is_trunc(const struct cl_io *io) +{ + return io->ci_type == CIT_SETATTR && + (io->u.ci_setattr.sa_valid & ATTR_SIZE); +} + +struct cl_io *cl_io_top(struct cl_io *io); + +void cl_io_print(const struct lu_env *env, void *cookie, + lu_printer_t printer, const struct cl_io *io); + +#define CL_IO_SLICE_CLEAN(foo_io, base) \ +do { \ + typeof(foo_io) __foo_io = (foo_io); \ + \ + CLASSERT(offsetof(typeof(*__foo_io), base) == 0); \ + memset(&__foo_io->base + 1, 0, \ + (sizeof *__foo_io) - sizeof __foo_io->base); \ +} while (0) + +/** @} cl_io */ + +/** \defgroup cl_page_list cl_page_list + * @{ */ + +/** + * Last page in the page list. + */ +static inline struct cl_page *cl_page_list_last(struct cl_page_list *plist) +{ + LASSERT(plist->pl_nr > 0); + return list_entry(plist->pl_pages.prev, struct cl_page, cp_batch); +} + +/** + * Iterate over pages in a page list. + */ +#define cl_page_list_for_each(page, list) \ + list_for_each_entry((page), &(list)->pl_pages, cp_batch) + +/** + * Iterate over pages in a page list, taking possible removals into account. + */ +#define cl_page_list_for_each_safe(page, temp, list) \ + list_for_each_entry_safe((page), (temp), &(list)->pl_pages, cp_batch) + +void cl_page_list_init (struct cl_page_list *plist); +void cl_page_list_add (struct cl_page_list *plist, struct cl_page *page); +void cl_page_list_move (struct cl_page_list *dst, struct cl_page_list *src, + struct cl_page *page); +void cl_page_list_splice (struct cl_page_list *list, + struct cl_page_list *head); +void cl_page_list_del (const struct lu_env *env, + struct cl_page_list *plist, struct cl_page *page); +void cl_page_list_disown (const struct lu_env *env, + struct cl_io *io, struct cl_page_list *plist); +int cl_page_list_own (const struct lu_env *env, + struct cl_io *io, struct cl_page_list *plist); +void cl_page_list_assume (const struct lu_env *env, + struct cl_io *io, struct cl_page_list *plist); +void cl_page_list_discard(const struct lu_env *env, + struct cl_io *io, struct cl_page_list *plist); +int cl_page_list_unmap (const struct lu_env *env, + struct cl_io *io, struct cl_page_list *plist); +void cl_page_list_fini (const struct lu_env *env, struct cl_page_list *plist); + +void cl_2queue_init (struct cl_2queue *queue); +void cl_2queue_add (struct cl_2queue *queue, struct cl_page *page); +void cl_2queue_disown (const struct lu_env *env, + struct cl_io *io, struct cl_2queue *queue); +void cl_2queue_assume (const struct lu_env *env, + struct cl_io *io, struct cl_2queue *queue); +void cl_2queue_discard (const struct lu_env *env, + struct cl_io *io, struct cl_2queue *queue); +void cl_2queue_fini (const struct lu_env *env, struct cl_2queue *queue); +void cl_2queue_init_page(struct cl_2queue *queue, struct cl_page *page); + +/** @} cl_page_list */ + +/** \defgroup cl_req cl_req + * @{ */ +struct cl_req *cl_req_alloc(const struct lu_env *env, struct cl_page *page, + enum cl_req_type crt, int nr_objects); + +void cl_req_page_add (const struct lu_env *env, struct cl_req *req, + struct cl_page *page); +void cl_req_page_done (const struct lu_env *env, struct cl_page *page); +int cl_req_prep (const struct lu_env *env, struct cl_req *req); +void cl_req_attr_set (const struct lu_env *env, struct cl_req *req, + struct cl_req_attr *attr, obd_valid flags); +void cl_req_completion(const struct lu_env *env, struct cl_req *req, int ioret); + +/** \defgroup cl_sync_io cl_sync_io + * @{ */ + +/** + * Anchor for synchronous transfer. This is allocated on a stack by thread + * doing synchronous transfer, and a pointer to this structure is set up in + * every page submitted for transfer. Transfer completion routine updates + * anchor and wakes up waiting thread when transfer is complete. + */ +struct cl_sync_io { + /** number of pages yet to be transferred. */ + atomic_t csi_sync_nr; + /** error code. */ + int csi_sync_rc; + /** barrier of destroy this structure */ + atomic_t csi_barrier; + /** completion to be signaled when transfer is complete. */ + wait_queue_head_t csi_waitq; +}; + +void cl_sync_io_init(struct cl_sync_io *anchor, int nrpages); +int cl_sync_io_wait(const struct lu_env *env, struct cl_io *io, + struct cl_page_list *queue, struct cl_sync_io *anchor, + long timeout); +void cl_sync_io_note(struct cl_sync_io *anchor, int ioret); + +/** @} cl_sync_io */ + +/** @} cl_req */ + +/** \defgroup cl_env cl_env + * + * lu_env handling for a client. + * + * lu_env is an environment within which lustre code executes. Its major part + * is lu_context---a fast memory allocation mechanism that is used to conserve + * precious kernel stack space. Originally lu_env was designed for a server, + * where + * + * - there is a (mostly) fixed number of threads, and + * + * - call chains have no non-lustre portions inserted between lustre code. + * + * On a client both these assumtpion fails, because every user thread can + * potentially execute lustre code as part of a system call, and lustre calls + * into VFS or MM that call back into lustre. + * + * To deal with that, cl_env wrapper functions implement the following + * optimizations: + * + * - allocation and destruction of environment is amortized by caching no + * longer used environments instead of destroying them; + * + * - there is a notion of "current" environment, attached to the kernel + * data structure representing current thread Top-level lustre code + * allocates an environment and makes it current, then calls into + * non-lustre code, that in turn calls lustre back. Low-level lustre + * code thus called can fetch environment created by the top-level code + * and reuse it, avoiding additional environment allocation. + * Right now, three interfaces can attach the cl_env to running thread: + * - cl_env_get + * - cl_env_implant + * - cl_env_reexit(cl_env_reenter had to be called priorly) + * + * \see lu_env, lu_context, lu_context_key + * @{ */ + +struct cl_env_nest { + int cen_refcheck; + void *cen_cookie; +}; + +struct lu_env *cl_env_peek (int *refcheck); +struct lu_env *cl_env_get (int *refcheck); +struct lu_env *cl_env_alloc (int *refcheck, __u32 tags); +struct lu_env *cl_env_nested_get (struct cl_env_nest *nest); +void cl_env_put (struct lu_env *env, int *refcheck); +void cl_env_nested_put (struct cl_env_nest *nest, struct lu_env *env); +void *cl_env_reenter (void); +void cl_env_reexit (void *cookie); +void cl_env_implant (struct lu_env *env, int *refcheck); +void cl_env_unplant (struct lu_env *env, int *refcheck); + +/** @} cl_env */ + +/* + * Misc + */ +void cl_attr2lvb(struct ost_lvb *lvb, const struct cl_attr *attr); +void cl_lvb2attr(struct cl_attr *attr, const struct ost_lvb *lvb); + +struct cl_device *cl_type_setup(const struct lu_env *env, struct lu_site *site, + struct lu_device_type *ldt, + struct lu_device *next); +/** @} clio */ + +int cl_global_init(void); +void cl_global_fini(void); + +#endif /* _LINUX_CL_OBJECT_H */ |