/* * linux/fs/locks.c * * Provide support for fcntl()'s F_GETLK, F_SETLK, and F_SETLKW calls. * Doug Evans (dje@spiff.uucp), August 07, 1992 * * Deadlock detection added. * FIXME: one thing isn't handled yet: * - mandatory locks (requires lots of changes elsewhere) * Kelly Carmichael (kelly@[142.24.8.65]), September 17, 1994. * * Miscellaneous edits, and a total rewrite of posix_lock_file() code. * Kai Petzke (wpp@marie.physik.tu-berlin.de), 1994 * * Converted file_lock_table to a linked list from an array, which eliminates * the limits on how many active file locks are open. * Chad Page (pageone@netcom.com), November 27, 1994 * * Removed dependency on file descriptors. dup()'ed file descriptors now * get the same locks as the original file descriptors, and a close() on * any file descriptor removes ALL the locks on the file for the current * process. Since locks still depend on the process id, locks are inherited * after an exec() but not after a fork(). This agrees with POSIX, and both * BSD and SVR4 practice. * Andy Walker (andy@lysaker.kvaerner.no), February 14, 1995 * * Scrapped free list which is redundant now that we allocate locks * dynamically with kmalloc()/kfree(). * Andy Walker (andy@lysaker.kvaerner.no), February 21, 1995 * * Implemented two lock personalities - FL_FLOCK and FL_POSIX. * * FL_POSIX locks are created with calls to fcntl() and lockf() through the * fcntl() system call. They have the semantics described above. * * FL_FLOCK locks are created with calls to flock(), through the flock() * system call, which is new. Old C libraries implement flock() via fcntl() * and will continue to use the old, broken implementation. * * FL_FLOCK locks follow the 4.4 BSD flock() semantics. They are associated * with a file pointer (filp). As a result they can be shared by a parent * process and its children after a fork(). They are removed when the last * file descriptor referring to the file pointer is closed (unless explicitly * unlocked). * * FL_FLOCK locks never deadlock, an existing lock is always removed before * upgrading from shared to exclusive (or vice versa). When this happens * any processes blocked by the current lock are woken up and allowed to * run before the new lock is applied. * Andy Walker (andy@lysaker.kvaerner.no), June 09, 1995 * * Removed some race conditions in flock_lock_file(), marked other possible * races. Just grep for FIXME to see them. * Dmitry Gorodchanin (pgmdsg@ibi.com), February 09, 1996. * * Addressed Dmitry's concerns. Deadlock checking no longer recursive. * Lock allocation changed to GFP_ATOMIC as we can't afford to sleep * once we've checked for blocking and deadlocking. * Andy Walker (andy@lysaker.kvaerner.no), April 03, 1996. * * Initial implementation of mandatory locks. SunOS turned out to be * a rotten model, so I implemented the "obvious" semantics. * See 'Documentation/mandatory.txt' for details. * Andy Walker (andy@lysaker.kvaerner.no), April 06, 1996. * * Don't allow mandatory locks on mmap()'ed files. Added simple functions to * check if a file has mandatory locks, used by mmap(), open() and creat() to * see if system call should be rejected. Ref. HP-UX/SunOS/Solaris Reference * Manual, Section 2. * Andy Walker (andy@lysaker.kvaerner.no), April 09, 1996. * * Tidied up block list handling. Added '/proc/locks' interface. * Andy Walker (andy@lysaker.kvaerner.no), April 24, 1996. * * Fixed deadlock condition for pathological code that mixes calls to * flock() and fcntl(). * Andy Walker (andy@lysaker.kvaerner.no), April 29, 1996. * * Allow only one type of locking scheme (FL_POSIX or FL_FLOCK) to be in use * for a given file at a time. Changed the CONFIG_LOCK_MANDATORY scheme to * guarantee sensible behaviour in the case where file system modules might * be compiled with different options than the kernel itself. * Andy Walker (andy@lysaker.kvaerner.no), May 15, 1996. * * Added a couple of missing wake_up() calls. Thanks to Thomas Meckel * (Thomas.Meckel@mni.fh-giessen.de) for spotting this. * Andy Walker (andy@lysaker.kvaerner.no), May 15, 1996. * * Changed FL_POSIX locks to use the block list in the same way as FL_FLOCK * locks. Changed process synchronisation to avoid dereferencing locks that * have already been freed. * Andy Walker (andy@lysaker.kvaerner.no), Sep 21, 1996. * * Made the block list a circular list to minimise searching in the list. * Andy Walker (andy@lysaker.kvaerner.no), Sep 25, 1996. * * Made mandatory locking a mount option. Default is not to allow mandatory * locking. * Andy Walker (andy@lysaker.kvaerner.no), Oct 04, 1996. * * Some adaptations for NFS support. * Olaf Kirch (okir@monad.swb.de), Dec 1996, * * Fixed /proc/locks interface so that we can't overrun the buffer we are handed. * Andy Walker (andy@lysaker.kvaerner.no), May 12, 1997. * * Use slab allocator instead of kmalloc/kfree. * Use generic list implementation from . * Sped up posix_locks_deadlock by only considering blocked locks. * Matthew Wilcox , March, 2000. * * Leases and LOCK_MAND * Matthew Wilcox , June, 2000. * Stephen Rothwell , June, 2000. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #define IS_POSIX(fl) (fl->fl_flags & FL_POSIX) #define IS_FLOCK(fl) (fl->fl_flags & FL_FLOCK) #define IS_LEASE(fl) (fl->fl_flags & FL_LEASE) int leases_enable = 1; int lease_break_time = 45; #define for_each_lock(inode, lockp) \ for (lockp = &inode->i_flock; *lockp != NULL; lockp = &(*lockp)->fl_next) LIST_HEAD(file_lock_list); EXPORT_SYMBOL(file_lock_list); static LIST_HEAD(blocked_list); static kmem_cache_t *filelock_cache; /* Allocate an empty lock structure. */ static struct file_lock *locks_alloc_lock(void) { return kmem_cache_alloc(filelock_cache, SLAB_KERNEL); } /* Free a lock which is not in use. */ static void locks_free_lock(struct file_lock *fl) { if (fl == NULL) { BUG(); return; } if (waitqueue_active(&fl->fl_wait)) panic("Attempting to free lock with active wait queue"); if (!list_empty(&fl->fl_block)) panic("Attempting to free lock with active block list"); if (!list_empty(&fl->fl_link)) panic("Attempting to free lock on active lock list"); if (fl->fl_ops) { if (fl->fl_ops->fl_release_private) fl->fl_ops->fl_release_private(fl); fl->fl_ops = NULL; } if (fl->fl_lmops) { if (fl->fl_lmops->fl_release_private) fl->fl_lmops->fl_release_private(fl); fl->fl_lmops = NULL; } kmem_cache_free(filelock_cache, fl); } void locks_init_lock(struct file_lock *fl) { INIT_LIST_HEAD(&fl->fl_link); INIT_LIST_HEAD(&fl->fl_block); init_waitqueue_head(&fl->fl_wait); fl->fl_next = NULL; fl->fl_fasync = NULL; fl->fl_owner = NULL; fl->fl_pid = 0; fl->fl_file = NULL; fl->fl_flags = 0; fl->fl_type = 0; fl->fl_start = fl->fl_end = 0; fl->fl_ops = NULL; fl->fl_lmops = NULL; } EXPORT_SYMBOL(locks_init_lock); /* * Initialises the fields of the file lock which are invariant for * free file_locks. */ static void init_once(void *foo, kmem_cache_t *cache, unsigned long flags) { struct file_lock *lock = (struct file_lock *) foo; if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) != SLAB_CTOR_CONSTRUCTOR) return; locks_init_lock(lock); } /* * Initialize a new lock from an existing file_lock structure. */ void locks_copy_lock(struct file_lock *new, struct file_lock *fl) { new->fl_owner = fl->fl_owner; new->fl_pid = fl->fl_pid; new->fl_file = fl->fl_file; new->fl_flags = fl->fl_flags; new->fl_type = fl->fl_type; new->fl_start = fl->fl_start; new->fl_end = fl->fl_end; new->fl_ops = fl->fl_ops; new->fl_lmops = fl->fl_lmops; if (fl->fl_ops && fl->fl_ops->fl_copy_lock) fl->fl_ops->fl_copy_lock(new, fl); if (fl->fl_lmops && fl->fl_lmops->fl_copy_lock) fl->fl_lmops->fl_copy_lock(new, fl); } EXPORT_SYMBOL(locks_copy_lock); static inline int flock_translate_cmd(int cmd) { if (cmd & LOCK_MAND) return cmd & (LOCK_MAND | LOCK_RW); switch (cmd) { case LOCK_SH: return F_RDLCK; case LOCK_EX: return F_WRLCK; case LOCK_UN: return F_UNLCK; } return -EINVAL; } /* Fill in a file_lock structure with an appropriate FLOCK lock. */ static int flock_make_lock(struct file *filp, struct file_lock **lock, unsigned int cmd) { struct file_lock *fl; int type = flock_translate_cmd(cmd); if (type < 0) return type; fl = locks_alloc_lock(); if (fl == NULL) return -ENOMEM; fl->fl_file = filp; fl->fl_pid = current->tgid; fl->fl_flags = FL_FLOCK; fl->fl_type = type; fl->fl_end = OFFSET_MAX; *lock = fl; return 0; } static int assign_type(struct file_lock *fl, int type) { switch (type) { case F_RDLCK: case F_WRLCK: case F_UNLCK: fl->fl_type = type; break; default: return -EINVAL; } return 0; } /* Verify a "struct flock" and copy it to a "struct file_lock" as a POSIX * style lock. */ static int flock_to_posix_lock(struct file *filp, struct file_lock *fl, struct flock *l) { off_t start, end; switch (l->l_whence) { case 0: /*SEEK_SET*/ start = 0; break; case 1: /*SEEK_CUR*/ start = filp->f_pos; break; case 2: /*SEEK_END*/ start = i_size_read(filp->f_dentry->d_inode); break; default: return -EINVAL; } /* POSIX-1996 leaves the case l->l_len < 0 undefined; POSIX-2001 defines it. */ start += l->l_start; if (start < 0) return -EINVAL; fl->fl_end = OFFSET_MAX; if (l->l_len > 0) { end = start + l->l_len - 1; fl->fl_end = end; } else if (l->l_len < 0) { end = start - 1; fl->fl_end = end; start += l->l_len; if (start < 0) return -EINVAL; } fl->fl_start = start; /* we record the absolute position */ if (fl->fl_end < fl->fl_start) return -EOVERFLOW; fl->fl_owner = current->files; fl->fl_pid = current->tgid; fl->fl_file = filp; fl->fl_flags = FL_POSIX; fl->fl_ops = NULL; fl->fl_lmops = NULL; return assign_type(fl, l->l_type); } #if BITS_PER_LONG == 32 static int flock64_to_posix_lock(struct file *filp, struct file_lock *fl, struct flock64 *l) { loff_t start; switch (l->l_whence) { case 0: /*SEEK_SET*/ start = 0; break; case 1: /*SEEK_CUR*/ start = filp->f_pos; break; case 2: /*SEEK_END*/ start = i_size_read(filp->f_dentry->d_inode); break; default: return -EINVAL; } start += l->l_start; if (start < 0) return -EINVAL; fl->fl_end = OFFSET_MAX; if (l->l_len > 0) { fl->fl_end = start + l->l_len - 1; } else if (l->l_len < 0) { fl->fl_end = start - 1; start += l->l_len; if (start < 0) return -EINVAL; } fl->fl_start = start; /* we record the absolute position */ if (fl->fl_end < fl->fl_start) return -EOVERFLOW; fl->fl_owner = current->files; fl->fl_pid = current->tgid; fl->fl_file = filp; fl->fl_flags = FL_POSIX; fl->fl_ops = NULL; fl->fl_lmops = NULL; switch (l->l_type) { case F_RDLCK: case F_WRLCK: case F_UNLCK: fl->fl_type = l->l_type; break; default: return -EINVAL; } return (0); } #endif /* default lease lock manager operations */ static void lease_break_callback(struct file_lock *fl) { kill_fasync(&fl->fl_fasync, SIGIO, POLL_MSG); } static void lease_release_private_callback(struct file_lock *fl) { if (!fl->fl_file) return; f_delown(fl->fl_file); fl->fl_file->f_owner.signum = 0; } static int lease_mylease_callback(struct file_lock *fl, struct file_lock *try) { return fl->fl_file == try->fl_file; } static struct lock_manager_operations lease_manager_ops = { .fl_break = lease_break_callback, .fl_release_private = lease_release_private_callback, .fl_mylease = lease_mylease_callback, .fl_change = lease_modify, }; /* * Initialize a lease, use the default lock manager operations */ static int lease_init(struct file *filp, int type, struct file_lock *fl) { if (assign_type(fl, type) != 0) return -EINVAL; fl->fl_owner = current->files; fl->fl_pid = current->tgid; fl->fl_file = filp; fl->fl_flags = FL_LEASE; fl->fl_start = 0; fl->fl_end = OFFSET_MAX; fl->fl_ops = NULL; fl->fl_lmops = &lease_manager_ops; return 0; } /* Allocate a file_lock initialised to this type of lease */ static int lease_alloc(struct file *filp, int type, struct file_lock **flp) { struct file_lock *fl = locks_alloc_lock(); int error = -ENOMEM; if (fl == NULL) goto out; error = lease_init(filp, type, fl); if (error) { locks_free_lock(fl); fl = NULL; } out: *flp = fl; return error; } /* Check if two locks overlap each other. */ static inline int locks_overlap(struct file_lock *fl1, struct file_lock *fl2) { return ((fl1->fl_end >= fl2->fl_start) && (fl2->fl_end >= fl1->fl_start)); } /* * Check whether two locks have the same owner. */ static int posix_same_owner(struct file_lock *fl1, struct file_lock *fl2) { if (fl1->fl_lmops && fl1->fl_lmops->fl_compare_owner) return fl2->fl_lmops == fl1->fl_lmops && fl1->fl_lmops->fl_compare_owner(fl1, fl2); return fl1->fl_owner == fl2->fl_owner; } /* Remove waiter from blocker's block list. * When blocker ends up pointing to itself then the list is empty. */ static void __locks_delete_block(struct file_lock *waiter) { list_del_init(&waiter->fl_block); list_del_init(&waiter->fl_link); waiter->fl_next = NULL; } /* */ static void locks_delete_block(struct file_lock *waiter) { lock_kernel(); __locks_delete_block(waiter); unlock_kernel(); } /* Insert waiter into blocker's block list. * We use a circular list so that processes can be easily woken up in * the order they blocked. The documentation doesn't require this but * it seems like the reasonable thing to do. */ static void locks_insert_block(struct file_lock *blocker, struct file_lock *waiter) { if (!list_empty(&waiter->fl_block)) { printk(KERN_ERR "locks_insert_block: removing duplicated lock " "(pid=%d %Ld-%Ld type=%d)\n", waiter->fl_pid, waiter->fl_start, waiter->fl_end, waiter->fl_type); __locks_delete_block(waiter); } list_add_tail(&waiter->fl_block, &blocker->fl_block); waiter->fl_next = blocker; if (IS_POSIX(blocker)) list_add(&waiter->fl_link, &blocked_list); } /* Wake up processes blocked waiting for blocker. * If told to wait then schedule the processes until the block list * is empty, otherwise empty the block list ourselves. */ static void locks_wake_up_blocks(struct file_lock *blocker) { while (!list_empty(&blocker->fl_block)) { struct file_lock *waiter = list_entry(blocker->fl_block.next, struct file_lock, fl_block); __locks_delete_block(waiter); if (waiter->fl_lmops && waiter->fl_lmops->fl_notify) waiter->fl_lmops->fl_notify(waiter); else wake_up(&waiter->fl_wait); } } /* Insert file lock fl into an inode's lock list at the position indicated * by pos. At the same time add the lock to the global file lock list. */ static void locks_insert_lock(struct file_lock **pos, struct file_lock *fl) { list_add(&fl->fl_link, &file_lock_list); /* insert into file's list */ fl->fl_next = *pos; *pos = fl; if (fl->fl_ops && fl->fl_ops->fl_insert) fl->fl_ops->fl_insert(fl); } /* * Delete a lock and then free it. * Wake up processes that are blocked waiting for this lock, * notify the FS that the lock has been cleared and * finally free the lock. */ static void locks_delete_lock(struct file_lock **thisfl_p) { struct file_lock *fl = *thisfl_p; *thisfl_p = fl->fl_next; fl->fl_next = NULL; list_del_init(&fl->fl_link); fasync_helper(0, fl->fl_file, 0, &fl->fl_fasync); if (fl->fl_fasync != NULL) { printk(KERN_ERR "locks_delete_lock: fasync == %p\n", fl->fl_fasync); fl->fl_fasync = NULL; } if (fl->fl_ops && fl->fl_ops->fl_remove) fl->fl_ops->fl_remove(fl); locks_wake_up_blocks(fl); locks_free_lock(fl); } /* Determine if lock sys_fl blocks lock caller_fl. Common functionality * checks for shared/exclusive status of overlapping locks. */ static int locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl) { if (sys_fl->fl_type == F_WRLCK) return 1; if (caller_fl->fl_type == F_WRLCK) return 1; return 0; } /* Determine if lock sys_fl blocks lock caller_fl. POSIX specific * checking before calling the locks_conflict(). */ static int posix_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl) { /* POSIX locks owned by the same process do not conflict with * each other. */ if (!IS_POSIX(sys_fl) || posix_same_owner(caller_fl, sys_fl)) return (0); /* Check whether they overlap */ if (!locks_overlap(caller_fl, sys_fl)) return 0; return (locks_conflict(caller_fl, sys_fl)); } /* Determine if lock sys_fl blocks lock caller_fl. FLOCK specific * checking before calling the locks_conflict(). */ static int flock_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl) { /* FLOCK locks referring to the same filp do not conflict with * each other. */ if (!IS_FLOCK(sys_fl) || (caller_fl->fl_file == sys_fl->fl_file)) return (0); if ((caller_fl->fl_type & LOCK_MAND) || (sys_fl->fl_type & LOCK_MAND)) return 0; return (locks_conflict(caller_fl, sys_fl)); } static int interruptible_sleep_on_locked(wait_queue_head_t *fl_wait, int timeout) { int result = 0; DECLARE_WAITQUEUE(wait, current); __set_current_state(TASK_INTERRUPTIBLE); add_wait_queue(fl_wait, &wait); if (timeout == 0) schedule(); else result = schedule_timeout(timeout); if (signal_pending(current)) result = -ERESTARTSYS; remove_wait_queue(fl_wait, &wait); __set_current_state(TASK_RUNNING); return result; } static int locks_block_on_timeout(struct file_lock *blocker, struct file_lock *waiter, int time) { int result; locks_insert_block(blocker, waiter); result = interruptible_sleep_on_locked(&waiter->fl_wait, time); __locks_delete_block(waiter); return result; } struct file_lock * posix_test_lock(struct file *filp, struct file_lock *fl) { struct file_lock *cfl; lock_kernel(); for (cfl = filp->f_dentry->d_inode->i_flock; cfl; cfl = cfl->fl_next) { if (!IS_POSIX(cfl)) continue; if (posix_locks_conflict(cfl, fl)) break; } unlock_kernel(); return (cfl); } EXPORT_SYMBOL(posix_test_lock); /* This function tests for deadlock condition before putting a process to * sleep. The detection scheme is no longer recursive. Recursive was neat, * but dangerous - we risked stack corruption if the lock data was bad, or * if the recursion was too deep for any other reason. * * We rely on the fact that a task can only be on one lock's wait queue * at a time. When we find blocked_task on a wait queue we can re-search * with blocked_task equal to that queue's owner, until either blocked_task * isn't found, or blocked_task is found on a queue owned by my_task. * * Note: the above assumption may not be true when handling lock requests * from a broken NFS client. But broken NFS clients have a lot more to * worry about than proper deadlock detection anyway... --okir */ int posix_locks_deadlock(struct file_lock *caller_fl, struct file_lock *block_fl) { struct list_head *tmp; next_task: if (posix_same_owner(caller_fl, block_fl)) return 1; list_for_each(tmp, &blocked_list) { struct file_lock *fl = list_entry(tmp, struct file_lock, fl_link); if (posix_same_owner(fl, block_fl)) { fl = fl->fl_next; block_fl = fl; goto next_task; } } return 0; } EXPORT_SYMBOL(posix_locks_deadlock); /* Try to create a FLOCK lock on filp. We always insert new FLOCK locks * at the head of the list, but that's secret knowledge known only to * flock_lock_file and posix_lock_file. */ static int flock_lock_file(struct file *filp, struct file_lock *request) { struct file_lock *new_fl = NULL; struct file_lock **before; struct inode * inode = filp->f_dentry->d_inode; int error = 0; int found = 0; lock_kernel(); for_each_lock(inode, before) { struct file_lock *fl = *before; if (IS_POSIX(fl)) break; if (IS_LEASE(fl)) continue; if (filp != fl->fl_file) continue; if (request->fl_type == fl->fl_type) goto out; found = 1; locks_delete_lock(before); break; } if (request->fl_type == F_UNLCK) goto out; new_fl = locks_alloc_lock(); if (new_fl == NULL) goto out; /* * If a higher-priority process was blocked on the old file lock, * give it the opportunity to lock the file. */ if (found) cond_resched(); for_each_lock(inode, before) { struct file_lock *fl = *before; if (IS_POSIX(fl)) break; if (IS_LEASE(fl)) continue; if (!flock_locks_conflict(request, fl)) continue; error = -EAGAIN; if (request->fl_flags & FL_SLEEP) locks_insert_block(fl, request); goto out; } locks_copy_lock(new_fl, request); locks_insert_lock(&inode->i_flock, new_fl); new_fl = NULL; out: unlock_kernel(); if (new_fl) locks_free_lock(new_fl); return error; } EXPORT_SYMBOL(posix_lock_file); static int __posix_lock_file(struct inode *inode, struct file_lock *request) { struct file_lock *fl; struct file_lock *new_fl, *new_fl2; struct file_lock *left = NULL; struct file_lock *right = NULL; struct file_lock **before; int error, added = 0; /* * We may need two file_lock structures for this operation, * so we get them in advance to avoid races. */ new_fl = locks_alloc_lock(); new_fl2 = locks_alloc_lock(); lock_kernel(); if (request->fl_type != F_UNLCK) { for_each_lock(inode, before) { struct file_lock *fl = *before; if (!IS_POSIX(fl)) continue; if (!posix_locks_conflict(request, fl)) continue; error = -EAGAIN; if (!(request->fl_flags & FL_SLEEP)) goto out; error = -EDEADLK; if (posix_locks_deadlock(request, fl)) goto out; error = -EAGAIN; locks_insert_block(fl, request); goto out; } } /* If we're just looking for a conflict, we're done. */ error = 0; if (request->fl_flags & FL_ACCESS) goto out; error = -ENOLCK; /* "no luck" */ if (!(new_fl && new_fl2)) goto out; /* * We've allocated the new locks in advance, so there are no * errors possible (and no blocking operations) from here on. * * Find the first old lock with the same owner as the new lock. */ before = &inode->i_flock; /* First skip locks owned by other processes. */ while ((fl = *before) && (!IS_POSIX(fl) || !posix_same_owner(request, fl))) { before = &fl->fl_next; } /* Process locks with this owner. */ while ((fl = *before) && posix_same_owner(request, fl)) { /* Detect adjacent or overlapping regions (if same lock type) */ if (request->fl_type == fl->fl_type) { /* In all comparisons of start vs end, use * "start - 1" rather than "end + 1". If end * is OFFSET_MAX, end + 1 will become negative. */ if (fl->fl_end < request->fl_start - 1) goto next_lock; /* If the next lock in the list has entirely bigger * addresses than the new one, insert the lock here. */ if (fl->fl_start - 1 > request->fl_end) break; /* If we come here, the new and old lock are of the * same type and adjacent or overlapping. Make one * lock yielding from the lower start address of both * locks to the higher end address. */ if (fl->fl_start > request->fl_start) fl->fl_start = request->fl_start; else request->fl_start = fl->fl_start; if (fl->fl_end < request->fl_end) fl->fl_end = request->fl_end; else request->fl_end = fl->fl_end; if (added) { locks_delete_lock(before); continue; } request = fl; added = 1; } else { /* Processing for different lock types is a bit * more complex. */ if (fl->fl_end < request->fl_start) goto next_lock; if (fl->fl_start > request->fl_end) break; if (request->fl_type == F_UNLCK) added = 1; if (fl->fl_start < request->fl_start) left = fl; /* If the next lock in the list has a higher end * address than the new one, insert the new one here. */ if (fl->fl_end > request->fl_end) { right = fl; break; } if (fl->fl_start >= request->fl_start) { /* The new lock completely replaces an old * one (This may happen several times). */ if (added) { locks_delete_lock(before); continue; } /* Replace the old lock with the new one. * Wake up anybody waiting for the old one, * as the change in lock type might satisfy * their needs. */ locks_wake_up_blocks(fl); fl->fl_start = request->fl_start; fl->fl_end = request->fl_end; fl->fl_type = request->fl_type; fl->fl_u = request->fl_u; request = fl; added = 1; } } /* Go on to next lock. */ next_lock: before = &fl->fl_next; } error = 0; if (!added) { if (request->fl_type == F_UNLCK) goto out; locks_copy_lock(new_fl, request); locks_insert_lock(before, new_fl); new_fl = NULL; } if (right) { if (left == right) { /* The new lock breaks the old one in two pieces, * so we have to use the second new lock. */ left = new_fl2; new_fl2 = NULL; locks_copy_lock(left, right); locks_insert_lock(before, left); } right->fl_start = request->fl_end + 1; locks_wake_up_blocks(right); } if (left) { left->fl_end = request->fl_start - 1; locks_wake_up_blocks(left); } out: unlock_kernel(); /* * Free any unused locks. */ if (new_fl) locks_free_lock(new_fl); if (new_fl2) locks_free_lock(new_fl2); return error; } /** * posix_lock_file - Apply a POSIX-style lock to a file * @filp: The file to apply the lock to * @fl: The lock to be applied * * Add a POSIX style lock to a file. * We merge adjacent & overlapping locks whenever possible. * POSIX locks are sorted by owner task, then by starting address */ int posix_lock_file(struct file *filp, struct file_lock *fl) { return __posix_lock_file(filp->f_dentry->d_inode, fl); } /** * posix_lock_file_wait - Apply a POSIX-style lock to a file * @filp: The file to apply the lock to * @fl: The lock to be applied * * Add a POSIX style lock to a file. * We merge adjacent & overlapping locks whenever possible. * POSIX locks are sorted by owner task, then by starting address */ int posix_lock_file_wait(struct file *filp, struct file_lock *fl) { int error; might_sleep (); for (;;) { error = __posix_lock_file(filp->f_dentry->d_inode, fl); if ((error != -EAGAIN) || !(fl->fl_flags & FL_SLEEP)) break; error = wait_event_interruptible(fl->fl_wait, !fl->fl_next); if (!error) continue; locks_delete_block(fl); break; } return error; } EXPORT_SYMBOL(posix_lock_file_wait); /** * locks_mandatory_locked - Check for an active lock * @inode: the file to check * * Searches the inode's list of locks to find any POSIX locks which conflict. * This function is called from locks_verify_locked() only. */ int locks_mandatory_locked(struct inode *inode) { fl_owner_t owner = current->files; struct file_lock *fl; /* * Search the lock list for this inode for any POSIX locks. */ lock_kernel(); for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) { if (!IS_POSIX(fl)) continue; if (fl->fl_owner != owner) break; } unlock_kernel(); return fl ? -EAGAIN : 0; } /** * locks_mandatory_area - Check for a conflicting lock * @read_write: %FLOCK_VERIFY_WRITE for exclusive access, %FLOCK_VERIFY_READ * for shared * @inode: the file to check * @filp: how the file was opened (if it was) * @offset: start of area to check * @count: length of area to check * * Searches the inode's list of locks to find any POSIX locks which conflict. * This function is called from rw_verify_area() and * locks_verify_truncate(). */ int locks_mandatory_area(int read_write, struct inode *inode, struct file *filp, loff_t offset, size_t count) { struct file_lock fl; int error; locks_init_lock(&fl); fl.fl_owner = current->files; fl.fl_pid = current->tgid; fl.fl_file = filp; fl.fl_flags = FL_POSIX | FL_ACCESS; if (filp && !(filp->f_flags & O_NONBLOCK)) fl.fl_flags |= FL_SLEEP; fl.fl_type = (read_write == FLOCK_VERIFY_WRITE) ? F_WRLCK : F_RDLCK; fl.fl_start = offset; fl.fl_end = offset + count - 1; for (;;) { error = __posix_lock_file(inode, &fl); if (error != -EAGAIN) break; if (!(fl.fl_flags & FL_SLEEP)) break; error = wait_event_interruptible(fl.fl_wait, !fl.fl_next); if (!error) { /* * If we've been sleeping someone might have * changed the permissions behind our back. */ if ((inode->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID) continue; } locks_delete_block(&fl); break; } return error; } EXPORT_SYMBOL(locks_mandatory_area); /* We already had a lease on this file; just change its type */ int lease_modify(struct file_lock **before, int arg) { struct file_lock *fl = *before; int error = assign_type(fl, arg); if (error) return error; locks_wake_up_blocks(fl); if (arg == F_UNLCK) locks_delete_lock(before); return 0; } EXPORT_SYMBOL(lease_modify); static void time_out_leases(struct inode *inode) { struct file_lock **before; struct file_lock *fl; before = &inode->i_flock; while ((fl = *before) && IS_LEASE(fl) && (fl->fl_type & F_INPROGRESS)) { if ((fl->fl_break_time == 0) || time_before(jiffies, fl->fl_break_time)) { before = &fl->fl_next; continue; } lease_modify(before, fl->fl_type & ~F_INPROGRESS); if (fl == *before) /* lease_modify may have freed fl */ before = &fl->fl_next; } } /** * __break_lease - revoke all outstanding leases on file * @inode: the inode of the file to return * @mode: the open mode (read or write) * * break_lease (inlined for speed) has checked there already * is a lease on this file. Leases are broken on a call to open() * or truncate(). This function can sleep unless you * specified %O_NONBLOCK to your open(). */ int __break_lease(struct inode *inode, unsigned int mode) { int error = 0, future; struct file_lock *new_fl, *flock; struct file_lock *fl; int alloc_err; unsigned long break_time; int i_have_this_lease = 0; alloc_err = lease_alloc(NULL, mode & FMODE_WRITE ? F_WRLCK : F_RDLCK, &new_fl); lock_kernel(); time_out_leases(inode); flock = inode->i_flock; if ((flock == NULL) || !IS_LEASE(flock)) goto out; for (fl = flock; fl && IS_LEASE(fl); fl = fl->fl_next) if (fl->fl_owner == current->files) i_have_this_lease = 1; if (mode & FMODE_WRITE) { /* If we want write access, we have to revoke any lease. */ future = F_UNLCK | F_INPROGRESS; } else if (flock->fl_type & F_INPROGRESS) { /* If the lease is already being broken, we just leave it */ future = flock->fl_type; } else if (flock->fl_type & F_WRLCK) { /* Downgrade the exclusive lease to a read-only lease. */ future = F_RDLCK | F_INPROGRESS; } else { /* the existing lease was read-only, so we can read too. */ goto out; } if (alloc_err && !i_have_this_lease && ((mode & O_NONBLOCK) == 0)) { error = alloc_err; goto out; } break_time = 0; if (lease_break_time > 0) { break_time = jiffies + lease_break_time * HZ; if (break_time == 0) break_time++; /* so that 0 means no break time */ } for (fl = flock; fl && IS_LEASE(fl); fl = fl->fl_next) { if (fl->fl_type != future) { fl->fl_type = future; fl->fl_break_time = break_time; /* lease must have lmops break callback */ fl->fl_lmops->fl_break(fl); } } if (i_have_this_lease || (mode & O_NONBLOCK)) { error = -EWOULDBLOCK; goto out; } restart: break_time = flock->fl_break_time; if (break_time != 0) { break_time -= jiffies; if (break_time == 0) break_time++; } error = locks_block_on_timeout(flock, new_fl, break_time); if (error >= 0) { if (error == 0) time_out_leases(inode); /* Wait for the next lease that has not been broken yet */ for (flock = inode->i_flock; flock && IS_LEASE(flock); flock = flock->fl_next) { if (flock->fl_type & F_INPROGRESS) goto restart; } error = 0; } out: unlock_kernel(); if (!alloc_err) locks_free_lock(new_fl); return error; } EXPORT_SYMBOL(__break_lease); /** * lease_get_mtime * @inode: the inode * @time: pointer to a timespec which will contain the last modified time * * This is to force NFS clients to flush their caches for files with * exclusive leases. The justification is that if someone has an * exclusive lease, then they could be modifiying it. */ void lease_get_mtime(struct inode *inode, struct timespec *time) { struct file_lock *flock = inode->i_flock; if (flock && IS_LEASE(flock) && (flock->fl_type & F_WRLCK)) *time = current_fs_time(inode->i_sb); else *time = inode->i_mtime; } EXPORT_SYMBOL(lease_get_mtime); /** * fcntl_getlease - Enquire what lease is currently active * @filp: the file * * The value returned by this function will be one of * (if no lease break is pending): * * %F_RDLCK to indicate a shared lease is held. * * %F_WRLCK to indicate an exclusive lease is held. * * %F_UNLCK to indicate no lease is held. * * (if a lease break is pending): * * %F_RDLCK to indicate an exclusive lease needs to be * changed to a shared lease (or removed). * * %F_UNLCK to indicate the lease needs to be removed. * * XXX: sfr & willy disagree over whether F_INPROGRESS * should be returned to userspace. */ int fcntl_getlease(struct file *filp) { struct file_lock *fl; int type = F_UNLCK; lock_kernel(); time_out_leases(filp->f_dentry->d_inode); for (fl = filp->f_dentry->d_inode->i_flock; fl && IS_LEASE(fl); fl = fl->fl_next) { if (fl->fl_file == filp) { type = fl->fl_type & ~F_INPROGRESS; break; } } unlock_kernel(); return type; } /** * __setlease - sets a lease on an open file * @filp: file pointer * @arg: type of lease to obtain * @flp: input - file_lock to use, output - file_lock inserted * * The (input) flp->fl_lmops->fl_break function is required * by break_lease(). * * Called with kernel lock held. */ static int __setlease(struct file *filp, long arg, struct file_lock **flp) { struct file_lock *fl, **before, **my_before = NULL, *lease; struct dentry *dentry = filp->f_dentry; struct inode *inode = dentry->d_inode; int error, rdlease_count = 0, wrlease_count = 0; time_out_leases(inode); error = -EINVAL; if (!flp || !(*flp) || !(*flp)->fl_lmops || !(*flp)->fl_lmops->fl_break) goto out; lease = *flp; error = -EAGAIN; if ((arg == F_RDLCK) && (atomic_read(&inode->i_writecount) > 0)) goto out; if ((arg == F_WRLCK) && ((atomic_read(&dentry->d_count) > 1) || (atomic_read(&inode->i_count) > 1))) goto out; /* * At this point, we know that if there is an exclusive * lease on this file, then we hold it on this filp * (otherwise our open of this file would have blocked). * And if we are trying to acquire an exclusive lease, * then the file is not open by anyone (including us) * except for this filp. */ for (before = &inode->i_flock; ((fl = *before) != NULL) && IS_LEASE(fl); before = &fl->fl_next) { if (lease->fl_lmops->fl_mylease(fl, lease)) my_before = before; else if (fl->fl_type == (F_INPROGRESS | F_UNLCK)) /* * Someone is in the process of opening this * file for writing so we may not take an * exclusive lease on it. */ wrlease_count++; else rdlease_count++; } if ((arg == F_RDLCK && (wrlease_count > 0)) || (arg == F_WRLCK && ((rdlease_count + wrlease_count) > 0))) goto out; if (my_before != NULL) { *flp = *my_before; error = lease->fl_lmops->fl_change(my_before, arg); goto out; } error = 0; if (arg == F_UNLCK) goto out; error = -EINVAL; if (!leases_enable) goto out; error = -ENOMEM; fl = locks_alloc_lock(); if (fl == NULL) goto out; locks_copy_lock(fl, lease); locks_insert_lock(before, fl); *flp = fl; error = 0; out: return error; } /** * setlease - sets a lease on an open file * @filp: file pointer * @arg: type of lease to obtain * @lease: file_lock to use * * Call this to establish a lease on the file. * The fl_lmops fl_break function is required by break_lease */ int setlease(struct file *filp, long arg, struct file_lock **lease) { struct dentry *dentry = filp->f_dentry; struct inode *inode = dentry->d_inode; int error; if ((current->fsuid != inode->i_uid) && !capable(CAP_LEASE)) return -EACCES; if (!S_ISREG(inode->i_mode)) return -EINVAL; error = security_file_lock(filp, arg); if (error) return error; lock_kernel(); error = __setlease(filp, arg, lease); unlock_kernel(); return error; } EXPORT_SYMBOL(setlease); /** * fcntl_setlease - sets a lease on an open file * @fd: open file descriptor * @filp: file pointer * @arg: type of lease to obtain * * Call this fcntl to establish a lease on the file. * Note that you also need to call %F_SETSIG to * receive a signal when the lease is broken. */ int fcntl_setlease(unsigned int fd, struct file *filp, long arg) { struct file_lock fl, *flp = &fl; struct dentry *dentry = filp->f_dentry; struct inode *inode = dentry->d_inode; int error; if ((current->fsuid != inode->i_uid) && !capable(CAP_LEASE)) return -EACCES; if (!S_ISREG(inode->i_mode)) return -EINVAL; error = security_file_lock(filp, arg); if (error) return error; locks_init_lock(&fl); error = lease_init(filp, arg, &fl); if (error) return error; lock_kernel(); error = __setlease(filp, arg, &flp); if (error || arg == F_UNLCK) goto out_unlock; error = fasync_helper(fd, filp, 1, &flp->fl_fasync); if (error < 0) { /* remove lease just inserted by __setlease */ flp->fl_type = F_UNLCK | F_INPROGRESS; flp->fl_break_time = jiffies- 10; time_out_leases(inode); goto out_unlock; } error = f_setown(filp, current->pid, 0); out_unlock: unlock_kernel(); return error; } /** * flock_lock_file_wait - Apply a FLOCK-style lock to a file * @filp: The file to apply the lock to * @fl: The lock to be applied * * Add a FLOCK style lock to a file. */ int flock_lock_file_wait(struct file *filp, struct file_lock *fl) { int error; might_sleep(); for (;;) { error = flock_lock_file(filp, fl); if ((error != -EAGAIN) || !(fl->fl_flags & FL_SLEEP)) break; error = wait_event_interruptible(fl->fl_wait, !fl->fl_next); if (!error) continue; locks_delete_block(fl); break; } return error; } EXPORT_SYMBOL(flock_lock_file_wait); /** * sys_flock: - flock() system call. * @fd: the file descriptor to lock. * @cmd: the type of lock to apply. * * Apply a %FL_FLOCK style lock to an open file descriptor. * The @cmd can be one of * * %LOCK_SH -- a shared lock. * * %LOCK_EX -- an exclusive lock. * * %LOCK_UN -- remove an existing lock. * * %LOCK_MAND -- a `mandatory' flock. This exists to emulate Windows Share Modes. * * %LOCK_MAND can be combined with %LOCK_READ or %LOCK_WRITE to allow other * processes read and write access respectively. */ asmlinkage long sys_flock(unsigned int fd, unsigned int cmd) { struct file *filp; struct file_lock *lock; int can_sleep, unlock; int error; error = -EBADF; filp = fget(fd); if (!filp) goto out; can_sleep = !(cmd & LOCK_NB); cmd &= ~LOCK_NB; unlock = (cmd == LOCK_UN); if (!unlock && !(cmd & LOCK_MAND) && !(filp->f_mode & 3)) goto out_putf; error = flock_make_lock(filp, &lock, cmd); if (error) goto out_putf; if (can_sleep) lock->fl_flags |= FL_SLEEP; error = security_file_lock(filp, cmd); if (error) goto out_free; if (filp->f_op && filp->f_op->flock) error = filp->f_op->flock(filp, (can_sleep) ? F_SETLKW : F_SETLK, lock); else error = flock_lock_file_wait(filp, lock); out_free: locks_free_lock(lock); out_putf: fput(filp); out: return error; } /* Report the first existing lock that would conflict with l. * This implements the F_GETLK command of fcntl(). */ int fcntl_getlk(struct file *filp, struct flock __user *l) { struct file_lock *fl, file_lock; struct flock flock; int error; error = -EFAULT; if (copy_from_user(&flock, l, sizeof(flock))) goto out; error = -EINVAL; if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK)) goto out; error = flock_to_posix_lock(filp, &file_lock, &flock); if (error) goto out; if (filp->f_op && filp->f_op->lock) { error = filp->f_op->lock(filp, F_GETLK, &file_lock); if (file_lock.fl_ops && file_lock.fl_ops->fl_release_private) file_lock.fl_ops->fl_release_private(&file_lock); if (error < 0) goto out; else fl = (file_lock.fl_type == F_UNLCK ? NULL : &file_lock); } else { fl = posix_test_lock(filp, &file_lock); } flock.l_type = F_UNLCK; if (fl != NULL) { flock.l_pid = fl->fl_pid; #if BITS_PER_LONG == 32 /* * Make sure we can represent the posix lock via * legacy 32bit flock. */ error = -EOVERFLOW; if (fl->fl_start > OFFT_OFFSET_MAX) goto out; if ((fl->fl_end != OFFSET_MAX) && (fl->fl_end > OFFT_OFFSET_MAX)) goto out; #endif flock.l_start = fl->fl_start; flock.l_len = fl->fl_end == OFFSET_MAX ? 0 : fl->fl_end - fl->fl_start + 1; flock.l_whence = 0; flock.l_type = fl->fl_type; } error = -EFAULT; if (!copy_to_user(l, &flock, sizeof(flock))) error = 0; out: return error; } /* Apply the lock described by l to an open file descriptor. * This implements both the F_SETLK and F_SETLKW commands of fcntl(). */ int fcntl_setlk(unsigned int fd, struct file *filp, unsigned int cmd, struct flock __user *l) { struct file_lock *file_lock = locks_alloc_lock(); struct flock flock; struct inode *inode; struct file *f; int error; if (file_lock == NULL) return -ENOLCK; /* * This might block, so we do it before checking the inode. */ error = -EFAULT; if (copy_from_user(&flock, l, sizeof(flock))) goto out; inode = filp->f_dentry->d_inode; /* Don't allow mandatory locks on files that may be memory mapped * and shared. */ if (IS_MANDLOCK(inode) && (inode->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID && mapping_writably_mapped(filp->f_mapping)) { error = -EAGAIN; goto out; } again: error = flock_to_posix_lock(filp, file_lock, &flock); if (error) goto out; if (cmd == F_SETLKW) { file_lock->fl_flags |= FL_SLEEP; } error = -EBADF; switch (flock.l_type) { case F_RDLCK: if (!(filp->f_mode & FMODE_READ)) goto out; break; case F_WRLCK: if (!(filp->f_mode & FMODE_WRITE)) goto out; break; case F_UNLCK: break; default: error = -EINVAL; goto out; } error = security_file_lock(filp, file_lock->fl_type); if (error) goto out; if (filp->f_op && filp->f_op->lock != NULL) error = filp->f_op->lock(filp, cmd, file_lock); else { for (;;) { error = __posix_lock_file(inode, file_lock); if ((error != -EAGAIN) || (cmd == F_SETLK)) break; error = wait_event_interruptible(file_lock->fl_wait, !file_lock->fl_next); if (!error) continue; locks_delete_block(file_lock); break; } } /* * Attempt to detect a close/fcntl race and recover by * releasing the lock that was just acquired. */ /* * we need that spin_lock here - it prevents reordering between * update of inode->i_flock and check for it done in close(). * rcu_read_lock() wouldn't do. */ spin_lock(¤t->files->file_lock); f = fcheck(fd); spin_unlock(¤t->files->file_lock); if (!error && f != filp && flock.l_type != F_UNLCK) { flock.l_type = F_UNLCK; goto again; } out: locks_free_lock(file_lock); return error; } #if BITS_PER_LONG == 32 /* Report the first existing lock that would conflict with l. * This implements the F_GETLK command of fcntl(). */ int fcntl_getlk64(struct file *filp, struct flock64 __user *l) { struct file_lock *fl, file_lock; struct flock64 flock; int error; error = -EFAULT; if (copy_from_user(&flock, l, sizeof(flock))) goto out; error = -EINVAL; if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK)) goto out; error = flock64_to_posix_lock(filp, &file_lock, &flock); if (error) goto out; if (filp->f_op && filp->f_op->lock) { error = filp->f_op->lock(filp, F_GETLK, &file_lock); if (file_lock.fl_ops && file_lock.fl_ops->fl_release_private) file_lock.fl_ops->fl_release_private(&file_lock); if (error < 0) goto out; else fl = (file_lock.fl_type == F_UNLCK ? NULL : &file_lock); } else { fl = posix_test_lock(filp, &file_lock); } flock.l_type = F_UNLCK; if (fl != NULL) { flock.l_pid = fl->fl_pid; flock.l_start = fl->fl_start; flock.l_len = fl->fl_end == OFFSET_MAX ? 0 : fl->fl_end - fl->fl_start + 1; flock.l_whence = 0; flock.l_type = fl->fl_type; } error = -EFAULT; if (!copy_to_user(l, &flock, sizeof(flock))) error = 0; out: return error; } /* Apply the lock described by l to an open file descriptor. * This implements both the F_SETLK and F_SETLKW commands of fcntl(). */ int fcntl_setlk64(unsigned int fd, struct file *filp, unsigned int cmd, struct flock64 __user *l) { struct file_lock *file_lock = locks_alloc_lock(); struct flock64 flock; struct inode *inode; struct file *f; int error; if (file_lock == NULL) return -ENOLCK; /* * This might block, so we do it before checking the inode. */ error = -EFAULT; if (copy_from_user(&flock, l, sizeof(flock))) goto out; inode = filp->f_dentry->d_inode; /* Don't allow mandatory locks on files that may be memory mapped * and shared. */ if (IS_MANDLOCK(inode) && (inode->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID && mapping_writably_mapped(filp->f_mapping)) { error = -EAGAIN; goto out; } again: error = flock64_to_posix_lock(filp, file_lock, &flock); if (error) goto out; if (cmd == F_SETLKW64) { file_lock->fl_flags |= FL_SLEEP; } error = -EBADF; switch (flock.l_type) { case F_RDLCK: if (!(filp->f_mode & FMODE_READ)) goto out; break; case F_WRLCK: if (!(filp->f_mode & FMODE_WRITE)) goto out; break; case F_UNLCK: break; default: error = -EINVAL; goto out; } error = security_file_lock(filp, file_lock->fl_type); if (error) goto out; if (filp->f_op && filp->f_op->lock != NULL) error = filp->f_op->lock(filp, cmd, file_lock); else { for (;;) { error = __posix_lock_file(inode, file_lock); if ((error != -EAGAIN) || (cmd == F_SETLK64)) break; error = wait_event_interruptible(file_lock->fl_wait, !file_lock->fl_next); if (!error) continue; locks_delete_block(file_lock); break; } } /* * Attempt to detect a close/fcntl race and recover by * releasing the lock that was just acquired. */ spin_lock(¤t->files->file_lock); f = fcheck(fd); spin_unlock(¤t->files->file_lock); if (!error && f != filp && flock.l_type != F_UNLCK) { flock.l_type = F_UNLCK; goto again; } out: locks_free_lock(file_lock); return error; } #endif /* BITS_PER_LONG == 32 */ /* * This function is called when the file is being removed * from the task's fd array. POSIX locks belonging to this task * are deleted at this time. */ void locks_remove_posix(struct file *filp, fl_owner_t owner) { struct file_lock lock, **before; /* * If there are no locks held on this file, we don't need to call * posix_lock_file(). Another process could be setting a lock on this * file at the same time, but we wouldn't remove that lock anyway. */ before = &filp->f_dentry->d_inode->i_flock; if (*before == NULL) return; lock.fl_type = F_UNLCK; lock.fl_flags = FL_POSIX; lock.fl_start = 0; lock.fl_end = OFFSET_MAX; lock.fl_owner = owner; lock.fl_pid = current->tgid; lock.fl_file = filp; lock.fl_ops = NULL; lock.fl_lmops = NULL; if (filp->f_op && filp->f_op->lock != NULL) { filp->f_op->lock(filp, F_SETLK, &lock); goto out; } /* Can't use posix_lock_file here; we need to remove it no matter * which pid we have. */ lock_kernel(); while (*before != NULL) { struct file_lock *fl = *before; if (IS_POSIX(fl) && posix_same_owner(fl, &lock)) { locks_delete_lock(before); continue; } before = &fl->fl_next; } unlock_kernel(); out: if (lock.fl_ops && lock.fl_ops->fl_release_private) lock.fl_ops->fl_release_private(&lock); } EXPORT_SYMBOL(locks_remove_posix); /* * This function is called on the last close of an open file. */ void locks_remove_flock(struct file *filp) { struct inode * inode = filp->f_dentry->d_inode; struct file_lock *fl; struct file_lock **before; if (!inode->i_flock) return; if (filp->f_op && filp->f_op->flock) { struct file_lock fl = { .fl_pid = current->tgid, .fl_file = filp, .fl_flags = FL_FLOCK, .fl_type = F_UNLCK, .fl_end = OFFSET_MAX, }; filp->f_op->flock(filp, F_SETLKW, &fl); if (fl.fl_ops && fl.fl_ops->fl_release_private) fl.fl_ops->fl_release_private(&fl); } lock_kernel(); before = &inode->i_flock; while ((fl = *before) != NULL) { if (fl->fl_file == filp) { if (IS_FLOCK(fl)) { locks_delete_lock(before); continue; } if (IS_LEASE(fl)) { lease_modify(before, F_UNLCK); continue; } /* What? */ BUG(); } before = &fl->fl_next; } unlock_kernel(); } /** * posix_block_lock - blocks waiting for a file lock * @blocker: the lock which is blocking * @waiter: the lock which conflicts and has to wait * * lockd needs to block waiting for locks. */ void posix_block_lock(struct file_lock *blocker, struct file_lock *waiter) { locks_insert_block(blocker, waiter); } EXPORT_SYMBOL(posix_block_lock); /** * posix_unblock_lock - stop waiting for a file lock * @filp: how the file was opened * @waiter: the lock which was waiting * * lockd needs to block waiting for locks. */ int posix_unblock_lock(struct file *filp, struct file_lock *waiter) { int status = 0; lock_kernel(); if (waiter->fl_next) __locks_delete_block(waiter); else status = -ENOENT; unlock_kernel(); return status; } EXPORT_SYMBOL(posix_unblock_lock); static void lock_get_status(char* out, struct file_lock *fl, int id, char *pfx) { struct inode *inode = NULL; if (fl->fl_file != NULL) inode = fl->fl_file->f_dentry->d_inode; out += sprintf(out, "%d:%s ", id, pfx); if (IS_POSIX(fl)) { out += sprintf(out, "%6s %s ", (fl->fl_flags & FL_ACCESS) ? "ACCESS" : "POSIX ", (inode == NULL) ? "*NOINODE*" : (IS_MANDLOCK(inode) && (inode->i_mode & (S_IXGRP | S_ISGID)) == S_ISGID) ? "MANDATORY" : "ADVISORY "); } else if (IS_FLOCK(fl)) { if (fl->fl_type & LOCK_MAND) { out += sprintf(out, "FLOCK MSNFS "); } else { out += sprintf(out, "FLOCK ADVISORY "); } } else if (IS_LEASE(fl)) { out += sprintf(out, "LEASE "); if (fl->fl_type & F_INPROGRESS) out += sprintf(out, "BREAKING "); else if (fl->fl_file) out += sprintf(out, "ACTIVE "); else out += sprintf(out, "BREAKER "); } else { out += sprintf(out, "UNKNOWN UNKNOWN "); } if (fl->fl_type & LOCK_MAND) { out += sprintf(out, "%s ", (fl->fl_type & LOCK_READ) ? (fl->fl_type & LOCK_WRITE) ? "RW " : "READ " : (fl->fl_type & LOCK_WRITE) ? "WRITE" : "NONE "); } else { out += sprintf(out, "%s ", (fl->fl_type & F_INPROGRESS) ? (fl->fl_type & F_UNLCK) ? "UNLCK" : "READ " : (fl->fl_type & F_WRLCK) ? "WRITE" : "READ "); } if (inode) { #ifdef WE_CAN_BREAK_LSLK_NOW out += sprintf(out, "%d %s:%ld ", fl->fl_pid, inode->i_sb->s_id, inode->i_ino); #else /* userspace relies on this representation of dev_t ;-( */ out += sprintf(out, "%d %02x:%02x:%ld ", fl->fl_pid, MAJOR(inode->i_sb->s_dev), MINOR(inode->i_sb->s_dev), inode->i_ino); #endif } else { out += sprintf(out, "%d :0 ", fl->fl_pid); } if (IS_POSIX(fl)) { if (fl->fl_end == OFFSET_MAX) out += sprintf(out, "%Ld EOF\n", fl->fl_start); else out += sprintf(out, "%Ld %Ld\n", fl->fl_start, fl->fl_end); } else { out += sprintf(out, "0 EOF\n"); } } static void move_lock_status(char **p, off_t* pos, off_t offset) { int len; len = strlen(*p); if(*pos >= offset) { /* the complete line is valid */ *p += len; *pos += len; return; } if(*pos+len > offset) { /* use the second part of the line */ int i = offset-*pos; memmove(*p,*p+i,len-i); *p += len-i; *pos += len; return; } /* discard the complete line */ *pos += len; } /** * get_locks_status - reports lock usage in /proc/locks * @buffer: address in userspace to write into * @start: ? * @offset: how far we are through the buffer * @length: how much to read */ int get_locks_status(char *buffer, char **start, off_t offset, int length) { struct list_head *tmp; char *q = buffer; off_t pos = 0; int i = 0; lock_kernel(); list_for_each(tmp, &file_lock_list) { struct list_head *btmp; struct file_lock *fl = list_entry(tmp, struct file_lock, fl_link); lock_get_status(q, fl, ++i, ""); move_lock_status(&q, &pos, offset); if(pos >= offset+length) goto done; list_for_each(btmp, &fl->fl_block) { struct file_lock *bfl = list_entry(btmp, struct file_lock, fl_block); lock_get_status(q, bfl, i, " ->"); move_lock_status(&q, &pos, offset); if(pos >= offset+length) goto done; } } done: unlock_kernel(); *start = buffer; if(q-buffer < length) return (q-buffer); return length; } /** * lock_may_read - checks that the region is free of locks * @inode: the inode that is being read * @start: the first byte to read * @len: the number of bytes to read * * Emulates Windows locking requirements. Whole-file * mandatory locks (share modes) can prohibit a read and * byte-range POSIX locks can prohibit a read if they overlap. * * N.B. this function is only ever called * from knfsd and ownership of locks is never checked. */ int lock_may_read(struct inode *inode, loff_t start, unsigned long len) { struct file_lock *fl; int result = 1; lock_kernel(); for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) { if (IS_POSIX(fl)) { if (fl->fl_type == F_RDLCK) continue; if ((fl->fl_end < start) || (fl->fl_start > (start + len))) continue; } else if (IS_FLOCK(fl)) { if (!(fl->fl_type & LOCK_MAND)) continue; if (fl->fl_type & LOCK_READ) continue; } else continue; result = 0; break; } unlock_kernel(); return result; } EXPORT_SYMBOL(lock_may_read); /** * lock_may_write - checks that the region is free of locks * @inode: the inode that is being written * @start: the first byte to write * @len: the number of bytes to write * * Emulates Windows locking requirements. Whole-file * mandatory locks (share modes) can prohibit a write and * byte-range POSIX locks can prohibit a write if they overlap. * * N.B. this function is only ever called * from knfsd and ownership of locks is never checked. */ int lock_may_write(struct inode *inode, loff_t start, unsigned long len) { struct file_lock *fl; int result = 1; lock_kernel(); for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) { if (IS_POSIX(fl)) { if ((fl->fl_end < start) || (fl->fl_start > (start + len))) continue; } else if (IS_FLOCK(fl)) { if (!(fl->fl_type & LOCK_MAND)) continue; if (fl->fl_type & LOCK_WRITE) continue; } else continue; result = 0; break; } unlock_kernel(); return result; } EXPORT_SYMBOL(lock_may_write); static inline void __steal_locks(struct file *file, fl_owner_t from) { struct inode *inode = file->f_dentry->d_inode; struct file_lock *fl = inode->i_flock; while (fl) { if (fl->fl_file == file && fl->fl_owner == from) fl->fl_owner = current->files; fl = fl->fl_next; } } /* When getting ready for executing a binary, we make sure that current * has a files_struct on its own. Before dropping the old files_struct, * we take over ownership of all locks for all file descriptors we own. * Note that we may accidentally steal a lock for a file that a sibling * has created since the unshare_files() call. */ void steal_locks(fl_owner_t from) { struct files_struct *files = current->files; int i, j; struct fdtable *fdt; if (from == files) return; lock_kernel(); j = 0; /* * We are not taking a ref to the file structures, so * we need to acquire ->file_lock. */ spin_lock(&files->file_lock); fdt = files_fdtable(files); for (;;) { unsigned long set; i = j * __NFDBITS; if (i >= fdt->max_fdset || i >= fdt->max_fds) break; set = fdt->open_fds->fds_bits[j++]; while (set) { if (set & 1) { struct file *file = fdt->fd[i]; if (file) __steal_locks(file, from); } i++; set >>= 1; } } spin_unlock(&files->file_lock); unlock_kernel(); } EXPORT_SYMBOL(steal_locks); static int __init filelock_init(void) { filelock_cache = kmem_cache_create("file_lock_cache", sizeof(struct file_lock), 0, SLAB_PANIC, init_once, NULL); return 0; } core_initcall(filelock_init);