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authorLinus Torvalds <torvalds@linux-foundation.org>2013-07-03 09:10:19 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-07-03 09:10:19 -0700
commit790eac5640abf7a57fa3a644386df330e18c11b0 (patch)
tree08de20bde44f59e51b91ff473a71047c2957e8c9 /Documentation/filesystems
parent0b0585c3e192967cb2ef0ac0816eb8a8c8d99840 (diff)
parent48bde8d3620f5f3c6ae9ff599eb404055ae51664 (diff)
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull second set of VFS changes from Al Viro: "Assorted f_pos race fixes, making do_splice_direct() safe to call with i_mutex on parent, O_TMPFILE support, Jeff's locks.c series, ->d_hash/->d_compare calling conventions changes from Linus, misc stuff all over the place." * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (63 commits) Document ->tmpfile() ext4: ->tmpfile() support vfs: export lseek_execute() to modules lseek_execute() doesn't need an inode passed to it block_dev: switch to fixed_size_llseek() cpqphp_sysfs: switch to fixed_size_llseek() tile-srom: switch to fixed_size_llseek() proc_powerpc: switch to fixed_size_llseek() ubi/cdev: switch to fixed_size_llseek() pci/proc: switch to fixed_size_llseek() isapnp: switch to fixed_size_llseek() lpfc: switch to fixed_size_llseek() locks: give the blocked_hash its own spinlock locks: add a new "lm_owner_key" lock operation locks: turn the blocked_list into a hashtable locks: convert fl_link to a hlist_node locks: avoid taking global lock if possible when waking up blocked waiters locks: protect most of the file_lock handling with i_lock locks: encapsulate the fl_link list handling locks: make "added" in __posix_lock_file a bool ...
Diffstat (limited to 'Documentation/filesystems')
-rw-r--r--Documentation/filesystems/Locking35
-rw-r--r--Documentation/filesystems/vfs.txt24
2 files changed, 37 insertions, 22 deletions
diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking
index 9858f337529c..fe7afe225381 100644
--- a/Documentation/filesystems/Locking
+++ b/Documentation/filesystems/Locking
@@ -11,10 +11,8 @@ be able to use diff(1).
prototypes:
int (*d_revalidate)(struct dentry *, unsigned int);
int (*d_weak_revalidate)(struct dentry *, unsigned int);
- int (*d_hash)(const struct dentry *, const struct inode *,
- struct qstr *);
- int (*d_compare)(const struct dentry *, const struct inode *,
- const struct dentry *, const struct inode *,
+ int (*d_hash)(const struct dentry *, struct qstr *);
+ int (*d_compare)(const struct dentry *, const struct dentry *,
unsigned int, const char *, const struct qstr *);
int (*d_delete)(struct dentry *);
void (*d_release)(struct dentry *);
@@ -66,6 +64,7 @@ prototypes:
int (*atomic_open)(struct inode *, struct dentry *,
struct file *, unsigned open_flag,
umode_t create_mode, int *opened);
+ int (*tmpfile) (struct inode *, struct dentry *, umode_t);
locking rules:
all may block
@@ -93,6 +92,7 @@ removexattr: yes
fiemap: no
update_time: no
atomic_open: yes
+tmpfile: no
Additionally, ->rmdir(), ->unlink() and ->rename() have ->i_mutex on
victim.
@@ -344,25 +344,38 @@ prototypes:
locking rules:
- file_lock_lock may block
+ inode->i_lock may block
fl_copy_lock: yes no
fl_release_private: maybe no
----------------------- lock_manager_operations ---------------------------
prototypes:
int (*lm_compare_owner)(struct file_lock *, struct file_lock *);
+ unsigned long (*lm_owner_key)(struct file_lock *);
void (*lm_notify)(struct file_lock *); /* unblock callback */
int (*lm_grant)(struct file_lock *, struct file_lock *, int);
void (*lm_break)(struct file_lock *); /* break_lease callback */
int (*lm_change)(struct file_lock **, int);
locking rules:
- file_lock_lock may block
-lm_compare_owner: yes no
-lm_notify: yes no
-lm_grant: no no
-lm_break: yes no
-lm_change yes no
+
+ inode->i_lock blocked_lock_lock may block
+lm_compare_owner: yes[1] maybe no
+lm_owner_key yes[1] yes no
+lm_notify: yes yes no
+lm_grant: no no no
+lm_break: yes no no
+lm_change yes no no
+
+[1]: ->lm_compare_owner and ->lm_owner_key are generally called with
+*an* inode->i_lock held. It may not be the i_lock of the inode
+associated with either file_lock argument! This is the case with deadlock
+detection, since the code has to chase down the owners of locks that may
+be entirely unrelated to the one on which the lock is being acquired.
+For deadlock detection however, the blocked_lock_lock is also held. The
+fact that these locks are held ensures that the file_locks do not
+disappear out from under you while doing the comparison or generating an
+owner key.
--------------------------- buffer_head -----------------------------------
prototypes:
diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt
index e6bd1ffd821e..1f0ba30ae47e 100644
--- a/Documentation/filesystems/vfs.txt
+++ b/Documentation/filesystems/vfs.txt
@@ -360,6 +360,8 @@ struct inode_operations {
int (*removexattr) (struct dentry *, const char *);
void (*update_time)(struct inode *, struct timespec *, int);
int (*atomic_open)(struct inode *, struct dentry *,
+ int (*tmpfile) (struct inode *, struct dentry *, umode_t);
+} ____cacheline_aligned;
struct file *, unsigned open_flag,
umode_t create_mode, int *opened);
};
@@ -472,6 +474,9 @@ otherwise noted.
component is negative or needs lookup. Cached positive dentries are
still handled by f_op->open().
+ tmpfile: called in the end of O_TMPFILE open(). Optional, equivalent to
+ atomically creating, opening and unlinking a file in given directory.
+
The Address Space Object
========================
@@ -901,10 +906,8 @@ defined:
struct dentry_operations {
int (*d_revalidate)(struct dentry *, unsigned int);
int (*d_weak_revalidate)(struct dentry *, unsigned int);
- int (*d_hash)(const struct dentry *, const struct inode *,
- struct qstr *);
- int (*d_compare)(const struct dentry *, const struct inode *,
- const struct dentry *, const struct inode *,
+ int (*d_hash)(const struct dentry *, struct qstr *);
+ int (*d_compare)(const struct dentry *, const struct dentry *,
unsigned int, const char *, const struct qstr *);
int (*d_delete)(const struct dentry *);
void (*d_release)(struct dentry *);
@@ -949,25 +952,24 @@ struct dentry_operations {
d_hash: called when the VFS adds a dentry to the hash table. The first
dentry passed to d_hash is the parent directory that the name is
- to be hashed into. The inode is the dentry's inode.
+ to be hashed into.
Same locking and synchronisation rules as d_compare regarding
what is safe to dereference etc.
d_compare: called to compare a dentry name with a given name. The first
dentry is the parent of the dentry to be compared, the second is
- the parent's inode, then the dentry and inode (may be NULL) of the
- child dentry. len and name string are properties of the dentry to be
- compared. qstr is the name to compare it with.
+ the child dentry. len and name string are properties of the dentry
+ to be compared. qstr is the name to compare it with.
Must be constant and idempotent, and should not take locks if
- possible, and should not or store into the dentry or inodes.
- Should not dereference pointers outside the dentry or inodes without
+ possible, and should not or store into the dentry.
+ Should not dereference pointers outside the dentry without
lots of care (eg. d_parent, d_inode, d_name should not be used).
However, our vfsmount is pinned, and RCU held, so the dentries and
inodes won't disappear, neither will our sb or filesystem module.
- ->i_sb and ->d_sb may be used.
+ ->d_sb may be used.
It is a tricky calling convention because it needs to be called under
"rcu-walk", ie. without any locks or references on things.