linux-yocto - Yocto Linux Embedded kernel

Age	Commit message (Expand)	Author
2013-09-07	lockref: add ability to mark lockrefs "dead"	Linus Torvalds
2013-09-07	lockref: fix docbook argument names	Linus Torvalds
2013-09-03	lockref: Relax in cmpxchg loop	Luck, Tony
2013-09-02	lockref: implement lockless reference count updates using cmpxchg()	Linus Torvalds
2013-09-02	lockref: uninline lockref helper functions	Linus Torvalds

/* * 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 <linux/list.h>. * Sped up posix_locks_deadlock by only considering blocked locks. * Matthew Wilcox <willy@debian.org>, March, 2000. * * Leases and LOCK_MAND * Matthew Wilcox <willy@debian.org>, June, 2000. * Stephen Rothwell <sfr@canb.auug.org.au>, June, 2000. */ #include <linux/capability.h> #include <linux/file.h> #include <linux/fdtable.h> #include <linux/fs.h> #include <linux/init.h> #include <linux/module.h> #include <linux/security.h> #include <linux/slab.h> #include <linux/smp_lock.h> #include <linux/syscalls.h> #include <linux/time.h> #include <linux/rcupdate.h> #include <linux/pid_namespace.h> #include <asm/uaccess.h> #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) static LIST_HEAD(file_lock_list); static LIST_HEAD(blocked_list); static struct kmem_cache *filelock_cache __read_mostly; /* Allocate an empty lock structure. */ static struct file_lock *locks_alloc_lock(void) { return kmem_cache_alloc(filelock_cache, GFP_KERNEL); } void locks_release_private(struct file_lock *fl) { 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; } } EXPORT_SYMBOL_GPL(locks_release_private); /* Free a lock which is not in use. */ static void locks_free_lock(struct file_lock *fl) { BUG_ON(waitqueue_active(&fl->fl_wait)); BUG_ON(!list_empty(&fl->fl_block)); BUG_ON(!list_empty(&fl->fl_link)); locks_release_private(fl); 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_nspid = NULL; 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) { struct file_lock *lock = (struct file_lock *) foo; locks_init_lock(lock); } static void locks_copy_private(struct file_lock *new, struct file_lock *fl) { if (fl->fl_ops) { if (fl->fl_ops->fl_copy_lock) fl->fl_ops->fl_copy_lock(new, fl); new->fl_ops = fl->fl_ops; } if (fl->fl_lmops) { if (fl->fl_lmops->fl_copy_lock) fl->fl_lmops->fl_copy_lock(new, fl); new->fl_lmops = fl->fl_lmops; } } /* * Initialize a new lock from an existing file_lock structure. */ void __locks_copy_lock(struct file_lock *new, const struct file_lock *fl) { new->fl_owner = fl->fl_owner; new->fl_pid = fl->fl_pid; new->fl_file = NULL; 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 = NULL; new->fl_lmops = NULL; } EXPORT_SYMBOL(__locks_copy_lock); void locks_copy_lock(struct file_lock *new, struct file_lock *fl) { locks_release_private(new); __locks_copy_lock(new, fl); new->fl_file = fl->fl_file; new->fl_ops = fl->fl_ops; new->fl_lmops = fl->fl_lmops; locks_copy_private(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 SEEK_SET: start = 0; break; case SEEK_CUR: start = filp->f_pos; break; case SEEK_END: start = i_size_read(filp->f_path.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 SEEK_SET: start = 0; break; case SEEK_CUR: start = filp->f_pos; break; case SEEK_END: start = i_size_read(filp->f_path.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 const 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 struct file_lock *lease_alloc(struct file *filp, int type) { struct file_lock *fl = locks_alloc_lock(); int error = -ENOMEM; if (fl == NULL) return ERR_PTR(error); error = lease_init(filp, type, fl); if (error) { locks_free_lock(fl); return ERR_PTR(error); } return fl; } /* 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) { BUG_ON(!list_empty(&waiter->fl_block)); 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; waiter = list_first_entry(&blocker->fl_block, 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); fl->fl_nspid = get_pid(task_tgid(current)); /* insert into file's list */ fl->fl_next = *pos; *pos = 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_nspid) { put_pid(fl->fl_nspid); fl->fl_nspid = NULL; } 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)); } void posix_test_lock(struct file *filp, struct file_lock *fl) { struct file_lock *cfl; lock_kernel(); for (cfl = filp->f_path.dentry->d_inode->i_flock; cfl; cfl = cfl->fl_next) { if (!IS_POSIX(cfl)) continue; if (posix_locks_conflict(fl, cfl)) break; } if (cfl) { __locks_copy_lock(fl, cfl); if (cfl->fl_nspid) fl->fl_pid = pid_vnr(cfl->fl_nspid); } else fl->fl_type = F_UNLCK; unlock_kernel(); return; } EXPORT_SYMBOL(posix_test_lock); /* * Deadlock detection: * * We attempt to detect deadlocks that are due purely to posix file * locks. * * We assume that a task can be waiting for at most one lock at a time. * So for any acquired lock, the process holding that lock may be * waiting on at most one other lock. That lock in turns may be held by * someone waiting for at most one other lock. Given a requested lock * caller_fl which is about to wait for a conflicting lock block_fl, we * follow this chain of waiters to ensure we are not about to create a * cycle. * * Since we do this before we ever put a process to sleep on a lock, we * are ensured that there is never a cycle; that is what guarantees that * the while() loop in posix_locks_deadlock() eventually completes. * * Note: the above assumption may not be true when handling lock * requests from a broken NFS client. It may also fail in the presence * of tasks (such as posix threads) sharing the same open file table. * * To handle those cases, we just bail out after a few iterations. */ #define MAX_DEADLK_ITERATIONS 10 /* Find a lock that the owner of the given block_fl is blocking on. */ static struct file_lock *what_owner_is_waiting_for(struct file_lock *block_fl) { struct file_lock *fl; list_for_each_entry(fl, &blocked_list, fl_link) { if (posix_same_owner(fl, block_fl)) return fl->fl_next; } return NULL; } static int posix_locks_deadlock(struct file_lock *caller_fl, struct file_lock *block_fl) { int i = 0; while ((block_fl = what_owner_is_waiting_for(block_fl))) { if (i++ > MAX_DEADLK_ITERATIONS) return 0; if (posix_same_owner(caller_fl, block_fl)) return 1; } return 0; } /* Try to create a FLOCK lock on filp. We always insert new FLOCK locks * after any leases, but before any posix locks. * * Note that if called with an FL_EXISTS argument, the caller may determine * whether or not a lock was successfully freed by testing the return * value for -ENOENT. */ 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_path.dentry->d_inode; int error = 0; int found = 0; lock_kernel(); if (request->fl_flags & FL_ACCESS) goto find_conflict; if (request->fl_type != F_UNLCK) { error = -ENOMEM; new_fl = locks_alloc_lock(); if (new_fl == NULL) goto out; error = 0; } 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) { if ((request->fl_flags & FL_EXISTS) && !found) error = -ENOENT; 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(); find_conflict: 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)) goto out; error = FILE_LOCK_DEFERRED; locks_insert_block(fl, request); goto out; } if (request->fl_flags & FL_ACCESS) goto out; locks_copy_lock(new_fl, request); locks_insert_lock(before, new_fl); new_fl = NULL; error = 0; out: unlock_kernel(); if (new_fl) locks_free_lock(new_fl); return error; } static int __posix_lock_file(struct inode *inode, struct file_lock *request, struct file_lock *conflock) { struct file_lock *fl; struct file_lock *new_fl = NULL; struct file_lock *new_fl2 = NULL; 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. * * In some cases we can be sure, that no new locks will be needed */ if (!(request->fl_flags & FL_ACCESS) && (request->fl_type != F_UNLCK || request->fl_start != 0 || request->fl_end != OFFSET_MAX)) { new_fl = locks_alloc_lock(); new_fl2 = locks_alloc_lock(); } lock_kernel(); if (request->fl_type != F_UNLCK) { for_each_lock(inode, before) { fl = *before; if (!IS_POSIX(fl)) continue; if (!posix_locks_conflict(request, fl)) continue; if (conflock) __locks_copy_lock(conflock, fl); error = -EAGAIN; if (!(request->fl_flags & FL_SLEEP)) goto out; error = -EDEADLK; if (posix_locks_deadlock(request, fl)) goto out; error = FILE_LOCK_DEFERRED; 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; /* * 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; locks_release_private(fl); locks_copy_private(fl, request); request = fl; added = 1; } } /* Go on to next lock. */ next_lock: before = &fl->fl_next; } /* * The above code only modifies existing locks in case of * merging or replacing. If new lock(s) need to be inserted * all modifications are done bellow this, so it's safe yet to * bail out. */ error = -ENOLCK; /* "no luck" */ if (right && left == right && !new_fl2) goto out; error = 0; if (!added) { if (request->fl_type == F_UNLCK) { if (request->fl_flags & FL_EXISTS) error = -ENOENT; goto out; } if (!new_fl) { error = -ENOLCK; 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 * @conflock: Place to return a copy of the conflicting lock, if found. * * 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 * * Note that if called with an FL_EXISTS argument, the caller may determine * whether or not a lock was successfully freed by testing the return * value for -ENOENT. */ int posix_lock_file(struct file *filp, struct file_lock *fl, struct file_lock *conflock) { return __posix_lock_file(filp->f_path.dentry->d_inode, fl, conflock); } EXPORT_SYMBOL(posix_lock_file); /** * 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, fl, NULL); if (error != FILE_LOCK_DEFERRED) 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, NULL); if (error != FILE_LOCK_DEFERRED) 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 (__mandatory_lock(inode)) 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 at least * some kind of lock (maybe 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; unsigned long break_time; int i_have_this_lease = 0; int want_write = (mode & O_ACCMODE) != O_RDONLY; new_fl = lease_alloc(NULL, want_write ? F_WRLCK : F_RDLCK); 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 (want_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 (IS_ERR(new_fl) && !i_have_this_lease && ((mode & O_NONBLOCK) == 0)) { error = PTR_ERR(new_fl); 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++; } locks_insert_block(flock, new_fl); error = wait_event_interruptible_timeout(new_fl->fl_wait, !new_fl->fl_next, break_time); __locks_delete_block(new_fl); 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 (!IS_ERR(new_fl)) locks_free_lock(new_fl); return error; } EXPORT_SYMBOL(__break_lease); /** * lease_get_mtime - get the last modified time of an inode * @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 modifying 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_path.dentry->d_inode); for (fl = filp->f_path.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; } /** * generic_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. */ int generic_setlease(struct file *filp, long arg, struct file_lock **flp) { struct file_lock *fl, **before, **my_before = NULL, *lease; struct file_lock *new_fl = NULL; struct dentry *dentry = filp->f_path.dentry; struct inode *inode = dentry->d_inode; int error, rdlease_count = 0, wrlease_count = 0; 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; time_out_leases(inode); BUG_ON(!(*flp)->fl_lmops->fl_break); lease = *flp; if (arg != F_UNLCK) { error = -ENOMEM; new_fl = locks_alloc_lock(); if (new_fl == NULL) goto out; 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++; } error = -EAGAIN; 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; locks_copy_lock(new_fl, lease); locks_insert_lock(before, new_fl); *flp = new_fl; return 0; out: if (new_fl != NULL) locks_free_lock(new_fl); return error; } EXPORT_SYMBOL(generic_setlease); /** * vfs_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 (*lease)->fl_lmops->fl_break operation must be set; if not, * break_lease will oops! * * This will call the filesystem's setlease file method, if * defined. Note that there is no getlease method; instead, the * filesystem setlease method should call back to setlease() to * add a lease to the inode's lease list, where fcntl_getlease() can * find it. Since fcntl_getlease() only reports whether the current * task holds a lease, a cluster filesystem need only do this for * leases held by processes on this node. * * There is also no break_lease method; filesystems that * handle their own leases should break leases themselves from the * filesystem's open, create, and (on truncate) setattr methods. * * Warning: the only current setlease methods exist only to disable * leases in certain cases. More vfs changes may be required to * allow a full filesystem lease implementation. */ int vfs_setlease(struct file *filp, long arg, struct file_lock **lease) { int error; lock_kernel(); if (filp->f_op && filp->f_op->setlease) error = filp->f_op->setlease(filp, arg, lease); else error = generic_setlease(filp, arg, lease); unlock_kernel(); return error; } EXPORT_SYMBOL_GPL(vfs_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 inode *inode = filp->f_path.dentry->d_inode; int error; locks_init_lock(&fl); error = lease_init(filp, arg, &fl); if (error) return error; lock_kernel(); error = vfs_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, task_pid(current), PIDTYPE_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 != FILE_LOCK_DEFERRED) 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. */ SYSCALL_DEFINE2(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 & (FMODE_READ|FMODE_WRITE))) 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, lock->fl_type); 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; } /** * vfs_test_lock - test file byte range lock * @filp: The file to test lock for * @fl: The lock to test; also used to hold result * * Returns -ERRNO on failure. Indicates presence of conflicting lock by * setting conf->fl_type to something other than F_UNLCK. */ int vfs_test_lock(struct file *filp, struct file_lock *fl) { if (filp->f_op && filp->f_op->lock) return filp->f_op->lock(filp, F_GETLK, fl); posix_test_lock(filp, fl); return 0; } EXPORT_SYMBOL_GPL(vfs_test_lock); static int posix_lock_to_flock(struct flock *flock, struct file_lock *fl) { flock->l_pid = fl->fl_pid; #if BITS_PER_LONG == 32 /* * Make sure we can represent the posix lock via * legacy 32bit flock. */ if (fl->fl_start > OFFT_OFFSET_MAX) return -EOVERFLOW; if (fl->fl_end != OFFSET_MAX && fl->fl_end > OFFT_OFFSET_MAX) return -EOVERFLOW; #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; return 0; } #if BITS_PER_LONG == 32 static void posix_lock_to_flock64(struct flock64 *flock, struct file_lock *fl) { 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; } #endif /* 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 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; error = vfs_test_lock(filp, &file_lock); if (error) goto out; flock.l_type = file_lock.fl_type; if (file_lock.fl_type != F_UNLCK) { error = posix_lock_to_flock(&flock, &file_lock); if (error) goto out; } error = -EFAULT; if (!copy_to_user(l, &flock, sizeof(flock))) error = 0; out: return error; } /** * vfs_lock_file - file byte range lock * @filp: The file to apply the lock to * @cmd: type of locking operation (F_SETLK, F_GETLK, etc.) * @fl: The lock to be applied * @conf: Place to return a copy of the conflicting lock, if found. * * A caller that doesn't care about the conflicting lock may pass NULL * as the final argument. * * If the filesystem defines a private ->lock() method, then @conf will * be left unchanged; so a caller that cares should initialize it to * some acceptable default. * * To avoid blocking kernel daemons, such as lockd, that need to acquire POSIX * locks, the ->lock() interface may return asynchronously, before the lock has * been granted or denied by the underlying filesystem, if (and only if) * fl_grant is set. Callers expecting ->lock() to return asynchronously * will only use F_SETLK, not F_SETLKW; they will set FL_SLEEP if (and only if) * the request is for a blocking lock. When ->lock() does return asynchronously, * it must return FILE_LOCK_DEFERRED, and call ->fl_grant() when the lock * request completes. * If the request is for non-blocking lock the file system should return * FILE_LOCK_DEFERRED then try to get the lock and call the callback routine * with the result. If the request timed out the callback routine will return a * nonzero return code and the file system should release the lock. The file * system is also responsible to keep a corresponding posix lock when it * grants a lock so the VFS can find out which locks are locally held and do * the correct lock cleanup when required. * The underlying filesystem must not drop the kernel lock or call * ->fl_grant() before returning to the caller with a FILE_LOCK_DEFERRED * return code. */ int vfs_lock_file(struct file *filp, unsigned int cmd, struct file_lock *fl, struct file_lock *conf) { if (filp->f_op && filp->f_op->lock) return filp->f_op->lock(filp, cmd, fl); else return posix_lock_file(filp, fl, conf); } EXPORT_SYMBOL_GPL(vfs_lock_file); static int do_lock_file_wait(struct file *filp, unsigned int cmd, struct file_lock *fl) { int error; error = security_file_lock(filp, fl->fl_type); if (error) return error; for (;;) { error = vfs_lock_file(filp, cmd, fl, NULL); if (error != FILE_LOCK_DEFERRED) break; error = wait_event_interruptible(fl->fl_wait, !fl->fl_next); if (!error) continue; locks_delete_block(fl); break; } 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_path.dentry->d_inode; /* Don't allow mandatory locks on files that may be memory mapped * and shared. */ if (mandatory_lock(inode) && 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 = do_lock_file_wait(filp, cmd, file_lock); /* * 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(&current->files->file_lock); f = fcheck(fd); spin_unlock(&current->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 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; error = vfs_test_lock(filp, &file_lock); if (error) goto out; flock.l_type = file_lock.fl_type; if (file_lock.fl_type != F_UNLCK) posix_lock_to_flock64(&flock, &file_lock); 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_path.dentry->d_inode; /* Don't allow mandatory locks on files that may be memory mapped * and shared. */ if (mandatory_lock(inode) && 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 = do_lock_file_wait(filp, cmd, file_lock); /* * Attempt to detect a close/fcntl race and recover by * releasing the lock that was just acquired. */ spin_lock(&current->files->file_lock); f = fcheck(fd); spin_unlock(&current->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; /* * 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. */ if (!filp->f_path.dentry->d_inode->i_flock) return; lock.fl_type = F_UNLCK; lock.fl_flags = FL_POSIX | FL_CLOSE; 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; vfs_lock_file(filp, F_SETLK, &lock, NULL); 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_path.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_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); /** * vfs_cancel_lock - file byte range unblock lock * @filp: The file to apply the unblock to * @fl: The lock to be unblocked * * Used by lock managers to cancel blocked requests */ int vfs_cancel_lock(struct file *filp, struct file_lock *fl) { if (filp->f_op && filp->f_op->lock) return filp->f_op->lock(filp, F_CANCELLK, fl); return 0; } EXPORT_SYMBOL_GPL(vfs_cancel_lock); #ifdef CONFIG_PROC_FS #include <linux/proc_fs.h> #include <linux/seq_file.h> static void lock_get_status(struct seq_file *f, struct file_lock *fl, int id, char *pfx) { struct inode *inode = NULL; unsigned int fl_pid; if (fl->fl_nspid) fl_pid = pid_vnr(fl->fl_nspid); else fl_pid = fl->fl_pid; if (fl->fl_file != NULL) inode = fl->fl_file->f_path.dentry->d_inode; seq_printf(f, "%d:%s ", id, pfx); if (IS_POSIX(fl)) { seq_printf(f, "%6s %s ", (fl->fl_flags & FL_ACCESS) ? "ACCESS" : "POSIX ", (inode == NULL) ? "*NOINODE*" : mandatory_lock(inode) ? "MANDATORY" : "ADVISORY "); } else if (IS_FLOCK(fl)) { if (fl->fl_type & LOCK_MAND) { seq_printf(f, "FLOCK MSNFS "); } else { seq_printf(f, "FLOCK ADVISORY "); } } else if (IS_LEASE(fl)) { seq_printf(f, "LEASE "); if (fl->fl_type & F_INPROGRESS) seq_printf(f, "BREAKING "); else if (fl->fl_file) seq_printf(f, "ACTIVE "); else seq_printf(f, "BREAKER "); } else { seq_printf(f, "UNKNOWN UNKNOWN "); } if (fl->fl_type & LOCK_MAND) { seq_printf(f, "%s ", (fl->fl_type & LOCK_READ) ? (fl->fl_type & LOCK_WRITE) ? "RW " : "READ " : (fl->fl_type & LOCK_WRITE) ? "WRITE" : "NONE "); } else { seq_printf(f, "%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 seq_printf(f, "%d %s:%ld ", fl_pid, inode->i_sb->s_id, inode->i_ino); #else /* userspace relies on this representation of dev_t ;-( */ seq_printf(f, "%d %02x:%02x:%ld ", fl_pid, MAJOR(inode->i_sb->s_dev), MINOR(inode->i_sb->s_dev), inode->i_ino); #endif } else { seq_printf(f, "%d <none>:0 ", fl_pid); } if (IS_POSIX(fl)) { if (fl->fl_end == OFFSET_MAX) seq_printf(f, "%Ld EOF\n", fl->fl_start); else seq_printf(f, "%Ld %Ld\n", fl->fl_start, fl->fl_end); } else { seq_printf(f, "0 EOF\n"); } } static int locks_show(struct seq_file *f, void *v) { struct file_lock *fl, *bfl; fl = list_entry(v, struct file_lock, fl_link); lock_get_status(f, fl, (long)f->private, ""); list_for_each_entry(bfl, &fl->fl_block, fl_block) lock_get_status(f, bfl, (long)f->private, " ->"); f->private++; return 0; } static void *locks_start(struct seq_file *f, loff_t *pos) { lock_kernel(); f->private = (void *)1; return seq_list_start(&file_lock_list, *pos); } static void *locks_next(struct seq_file *f, void *v, loff_t *pos) { return seq_list_next(v, &file_lock_list, pos); } static void locks_stop(struct seq_file *f, void *v) { unlock_kernel(); } static const struct seq_operations locks_seq_operations = { .start = locks_start, .next = locks_next, .stop = locks_stop, .show = locks_show, }; static int locks_open(struct inode *inode, struct file *filp) { return seq_open(filp, &locks_seq_operations); } static const struct file_operations proc_locks_operations = { .open = locks_open, .read = seq_read, .llseek = seq_lseek, .release = seq_release, }; static int __init proc_locks_init(void) { proc_create("locks", 0, NULL, &proc_locks_operations); return 0; } module_init(proc_locks_init); #endif /** * 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 int __init filelock_init(void) { filelock_cache = kmem_cache_create("file_lock_cache", sizeof(struct file_lock), 0, SLAB_PANIC, init_once); return 0; } core_initcall(filelock_init);