| /* |
| * 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/filesystems/mandatory-locking.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/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) |
| #define IS_FILE_PVT(fl) (fl->fl_flags & FL_FILE_PVT) |
| |
| static bool lease_breaking(struct file_lock *fl) |
| { |
| return fl->fl_flags & (FL_UNLOCK_PENDING | FL_DOWNGRADE_PENDING); |
| } |
| |
| static int target_leasetype(struct file_lock *fl) |
| { |
| if (fl->fl_flags & FL_UNLOCK_PENDING) |
| return F_UNLCK; |
| if (fl->fl_flags & FL_DOWNGRADE_PENDING) |
| return F_RDLCK; |
| return fl->fl_type; |
| } |
| |
| 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 DEFINE_SPINLOCK(file_lock_lock); |
| |
| /* |
| * Protects the two list heads above, plus the inode->i_flock list |
| */ |
| void lock_flocks(void) |
| { |
| spin_lock(&file_lock_lock); |
| } |
| EXPORT_SYMBOL_GPL(lock_flocks); |
| |
| void unlock_flocks(void) |
| { |
| spin_unlock(&file_lock_lock); |
| } |
| EXPORT_SYMBOL_GPL(unlock_flocks); |
| |
| static struct kmem_cache *filelock_cache __read_mostly; |
| |
| static void locks_init_lock_heads(struct file_lock *fl) |
| { |
| INIT_LIST_HEAD(&fl->fl_link); |
| INIT_LIST_HEAD(&fl->fl_block); |
| init_waitqueue_head(&fl->fl_wait); |
| } |
| |
| /* Allocate an empty lock structure. */ |
| struct file_lock *locks_alloc_lock(void) |
| { |
| struct file_lock *fl = kmem_cache_zalloc(filelock_cache, GFP_KERNEL); |
| |
| if (fl) |
| locks_init_lock_heads(fl); |
| |
| return fl; |
| } |
| EXPORT_SYMBOL_GPL(locks_alloc_lock); |
| |
| 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->lm_release_private) |
| fl->fl_lmops->lm_release_private(fl); |
| fl->fl_lmops = NULL; |
| } |
| |
| } |
| EXPORT_SYMBOL_GPL(locks_release_private); |
| |
| /* Free a lock which is not in use. */ |
| 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); |
| } |
| EXPORT_SYMBOL(locks_free_lock); |
| |
| void locks_init_lock(struct file_lock *fl) |
| { |
| memset(fl, 0, sizeof(struct file_lock)); |
| locks_init_lock_heads(fl); |
| } |
| |
| EXPORT_SYMBOL(locks_init_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) |
| 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, long 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; |
| |
| return assign_type(fl, l->l_type); |
| } |
| #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 const struct lock_manager_operations lease_manager_ops = { |
| .lm_break = lease_break_callback, |
| .lm_release_private = lease_release_private_callback, |
| .lm_change = lease_modify, |
| }; |
| |
| /* |
| * Initialize a lease, use the default lock manager operations |
| */ |
| static int lease_init(struct file *filp, long 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, long 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->lm_compare_owner) |
| return fl2->fl_lmops == fl1->fl_lmops && |
| fl1->fl_lmops->lm_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; |
| } |
| |
| /* |
| */ |
| void locks_delete_block(struct file_lock *waiter) |
| { |
| lock_flocks(); |
| __locks_delete_block(waiter); |
| unlock_flocks(); |
| } |
| EXPORT_SYMBOL(locks_delete_block); |
| |
| /* 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->lm_notify) |
| waiter->fl_lmops->lm_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_flocks(); |
| 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_flocks(); |
| 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; |
| |
| if (!(request->fl_flags & FL_ACCESS) && (request->fl_type != F_UNLCK)) { |
| new_fl = locks_alloc_lock(); |
| if (!new_fl) |
| return -ENOMEM; |
| } |
| |
| lock_flocks(); |
| if (request->fl_flags & FL_ACCESS) |
| goto find_conflict; |
| |
| 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) { |
| unlock_flocks(); |
| cond_resched(); |
| lock_flocks(); |
| } |
| |
| 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_flocks(); |
| 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_flocks(); |
| 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_flocks(); |
| /* |
| * 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_flocks(); |
| for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) { |
| if (!IS_POSIX(fl)) |
| continue; |
| if (fl->fl_owner != owner) |
| break; |
| } |
| unlock_flocks(); |
| 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); |
| |
| static void lease_clear_pending(struct file_lock *fl, int arg) |
| { |
| switch (arg) { |
| case F_UNLCK: |
| fl->fl_flags &= ~FL_UNLOCK_PENDING; |
| /* fall through: */ |
| case F_RDLCK: |
| fl->fl_flags &= ~FL_DOWNGRADE_PENDING; |
| } |
| } |
| |
| /* 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; |
| lease_clear_pending(fl, arg); |
| locks_wake_up_blocks(fl); |
| if (arg == F_UNLCK) |
| locks_delete_lock(before); |
| return 0; |
| } |
| |
| EXPORT_SYMBOL(lease_modify); |
| |
| static bool past_time(unsigned long then) |
| { |
| if (!then) |
| /* 0 is a special value meaning "this never expires": */ |
| return false; |
| return time_after(jiffies, then); |
| } |
| |
| 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) && lease_breaking(fl)) { |
| if (past_time(fl->fl_downgrade_time)) |
| lease_modify(before, F_RDLCK); |
| if (past_time(fl->fl_break_time)) |
| lease_modify(before, F_UNLCK); |
| 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; |
| 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); |
| if (IS_ERR(new_fl)) |
| return PTR_ERR(new_fl); |
| |
| lock_flocks(); |
| |
| time_out_leases(inode); |
| |
| flock = inode->i_flock; |
| if ((flock == NULL) || !IS_LEASE(flock)) |
| goto out; |
| |
| if (!locks_conflict(flock, new_fl)) |
| goto out; |
| |
| for (fl = flock; fl && IS_LEASE(fl); fl = fl->fl_next) |
| if (fl->fl_owner == current->files) |
| i_have_this_lease = 1; |
| |
| 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 (want_write) { |
| if (fl->fl_flags & FL_UNLOCK_PENDING) |
| continue; |
| fl->fl_flags |= FL_UNLOCK_PENDING; |
| fl->fl_break_time = break_time; |
| } else { |
| if (lease_breaking(flock)) |
| continue; |
| fl->fl_flags |= FL_DOWNGRADE_PENDING; |
| fl->fl_downgrade_time = break_time; |
| } |
| fl->fl_lmops->lm_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); |
| unlock_flocks(); |
| error = wait_event_interruptible_timeout(new_fl->fl_wait, |
| !new_fl->fl_next, break_time); |
| lock_flocks(); |
| __locks_delete_block(new_fl); |
| if (error >= 0) { |
| if (error == 0) |
| time_out_leases(inode); |
| /* |
| * Wait for the next conflicting lease that has not been |
| * broken yet |
| */ |
| for (flock = inode->i_flock; flock && IS_LEASE(flock); |
| flock = flock->fl_next) { |
| if (locks_conflict(new_fl, flock)) |
| goto restart; |
| } |
| error = 0; |
| } |
| |
| out: |
| unlock_flocks(); |
| 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_flocks(); |
| 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 = target_leasetype(fl); |
| break; |
| } |
| } |
| unlock_flocks(); |
| return type; |
| } |
| |
| int generic_add_lease(struct file *filp, long arg, struct file_lock **flp) |
| { |
| struct file_lock *fl, **before, **my_before = NULL, *lease; |
| struct dentry *dentry = filp->f_path.dentry; |
| struct inode *inode = dentry->d_inode; |
| int error; |
| |
| lease = *flp; |
| |
| error = -EAGAIN; |
| if ((arg == F_RDLCK) && (atomic_read(&inode->i_writecount) > 0)) |
| goto out; |
| if ((arg == F_WRLCK) |
| && ((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. |
| */ |
| error = -EAGAIN; |
| for (before = &inode->i_flock; |
| ((fl = *before) != NULL) && IS_LEASE(fl); |
| before = &fl->fl_next) { |
| if (fl->fl_file == filp) { |
| my_before = before; |
| continue; |
| } |
| /* |
| * No exclusive leases if someone else has a lease on |
| * this file: |
| */ |
| if (arg == F_WRLCK) |
| goto out; |
| /* |
| * Modifying our existing lease is OK, but no getting a |
| * new lease if someone else is opening for write: |
| */ |
| if (fl->fl_flags & FL_UNLOCK_PENDING) |
| goto out; |
| } |
| |
| if (my_before != NULL) { |
| error = lease->fl_lmops->lm_change(my_before, arg); |
| if (!error) |
| *flp = *my_before; |
| goto out; |
| } |
| |
| error = -EINVAL; |
| if (!leases_enable) |
| goto out; |
| |
| locks_insert_lock(before, lease); |
| return 0; |
| |
| out: |
| return error; |
| } |
| |
| int generic_delete_lease(struct file *filp, struct file_lock **flp) |
| { |
| struct file_lock *fl, **before; |
| struct dentry *dentry = filp->f_path.dentry; |
| struct inode *inode = dentry->d_inode; |
| |
| for (before = &inode->i_flock; |
| ((fl = *before) != NULL) && IS_LEASE(fl); |
| before = &fl->fl_next) { |
| if (fl->fl_file != filp) |
| continue; |
| return (*flp)->fl_lmops->lm_change(before, F_UNLCK); |
| } |
| return -EAGAIN; |
| } |
| |
| /** |
| * 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->lm_break function is required |
| * by break_lease(). |
| * |
| * Called with file_lock_lock held. |
| */ |
| int generic_setlease(struct file *filp, long arg, struct file_lock **flp) |
| { |
| struct dentry *dentry = filp->f_path.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; |
| |
| time_out_leases(inode); |
| |
| BUG_ON(!(*flp)->fl_lmops->lm_break); |
| |
| switch (arg) { |
| case F_UNLCK: |
| return generic_delete_lease(filp, flp); |
| case F_RDLCK: |
| case F_WRLCK: |
| return generic_add_lease(filp, arg, flp); |
| default: |
| return -EINVAL; |
| } |
| } |
| EXPORT_SYMBOL(generic_setlease); |
| |
| static int __vfs_setlease(struct file *filp, long arg, struct file_lock **lease) |
| { |
| if (filp->f_op && filp->f_op->setlease) |
| return filp->f_op->setlease(filp, arg, lease); |
| else |
| return generic_setlease(filp, arg, lease); |
| } |
| |
| /** |
| * 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->lm_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_flocks(); |
| error = __vfs_setlease(filp, arg, lease); |
| unlock_flocks(); |
| |
| return error; |
| } |
| EXPORT_SYMBOL_GPL(vfs_setlease); |
| |
| static int do_fcntl_delete_lease(struct file *filp) |
| { |
| struct file_lock fl, *flp = &fl; |
| |
| lease_init(filp, F_UNLCK, flp); |
| |
| return vfs_setlease(filp, F_UNLCK, &flp); |
| } |
| |
| static int do_fcntl_add_lease(unsigned int fd, struct file *filp, long arg) |
| { |
| struct file_lock *fl, *ret; |
| struct fasync_struct *new; |
| int error; |
| |
| fl = lease_alloc(filp, arg); |
| if (IS_ERR(fl)) |
| return PTR_ERR(fl); |
| |
| new = fasync_alloc(); |
| if (!new) { |
| locks_free_lock(fl); |
| return -ENOMEM; |
| } |
| ret = fl; |
| lock_flocks(); |
| error = __vfs_setlease(filp, arg, &ret); |
| if (error) { |
| unlock_flocks(); |
| locks_free_lock(fl); |
| goto out_free_fasync; |
| } |
| if (ret != fl) |
| locks_free_lock(fl); |
| |
| /* |
| * fasync_insert_entry() returns the old entry if any. |
| * If there was no old entry, then it used 'new' and |
| * inserted it into the fasync list. Clear new so that |
| * we don't release it here. |
| */ |
| if (!fasync_insert_entry(fd, filp, &ret->fl_fasync, new)) |
| new = NULL; |
| |
| error = __f_setown(filp, task_pid(current), PIDTYPE_PID, 0); |
| unlock_flocks(); |
| |
| out_free_fasync: |
| if (new) |
| fasync_free(new); |
| return error; |
| } |
| |
| /** |
| * 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) |
| { |
| if (arg == F_UNLCK) |
| return do_fcntl_delete_lease(filp); |
| return do_fcntl_add_lease(fd, filp, arg); |
| } |
| |
| /** |
| * 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 = IS_FILE_PVT(fl) ? -1 : 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 = IS_FILE_PVT(fl) ? -1 : 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, unsigned int cmd, 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; |
| |
| if (cmd == F_OFD_GETLK) { |
| cmd = F_GETLK; |
| file_lock.fl_flags |= FL_FILE_PVT; |
| file_lock.fl_owner = (fl_owner_t)filp; |
| } |
| |
| 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) |
| * lm_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 ->lm_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 |
| * ->lm_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 the cmd is requesting file-private locks, then set the |
| * FL_FILE_PVT flag and override the owner. |
| */ |
| switch (cmd) { |
| case F_OFD_SETLK: |
| cmd = F_SETLK; |
| file_lock->fl_flags |= FL_FILE_PVT; |
| file_lock->fl_owner = (fl_owner_t)filp; |
| break; |
| case F_OFD_SETLKW: |
| cmd = F_SETLKW; |
| file_lock->fl_flags |= FL_FILE_PVT; |
| file_lock->fl_owner = (fl_owner_t)filp; |
| /* Fallthrough */ |
| case 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(¤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, unsigned int cmd, 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; |
| |
| if (cmd == F_OFD_GETLK) { |
| cmd = F_GETLK64; |
| file_lock.fl_flags |= FL_FILE_PVT; |
| file_lock.fl_owner = (fl_owner_t)filp; |
| } |
| |
| 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 the cmd is requesting file-private locks, then set the |
| * FL_FILE_PVT flag and override the owner. |
| */ |
| switch (cmd) { |
| case F_OFD_SETLK: |
| cmd = F_SETLK64; |
| file_lock->fl_flags |= FL_FILE_PVT; |
| file_lock->fl_owner = (fl_owner_t)filp; |
| break; |
| case F_OFD_SETLKW: |
| cmd = F_SETLKW64; |
| file_lock->fl_flags |= FL_FILE_PVT; |
| file_lock->fl_owner = (fl_owner_t)filp; |
| /* Fallthrough */ |
| case 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(¤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; |
| |
| /* |
| * 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_file(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; |
| |
| locks_remove_posix(filp, (fl_owner_t)filp); |
| |
| 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_flocks(); |
| 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_flocks(); |
| } |
| |
| /** |
| * 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_flocks(); |
| if (waiter->fl_next) |
| __locks_delete_block(waiter); |
| else |
| status = -ENOENT; |
| unlock_flocks(); |
| 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, |
| loff_t 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, "%lld:%s ", id, pfx); |
| if (IS_POSIX(fl)) { |
| if (fl->fl_flags & FL_ACCESS) |
| seq_printf(f, "ACCESS"); |
| else if (IS_FILE_PVT(fl)) |
| seq_printf(f, "FLPVT "); |
| else |
| seq_printf(f, "POSIX "); |
| |
| seq_printf(f, " %s ", |
| (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 (lease_breaking(fl)) |
| 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 ", |
| (lease_breaking(fl)) |
| ? (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, *((loff_t *)f->private), ""); |
| |
| list_for_each_entry(bfl, &fl->fl_block, fl_block) |
| lock_get_status(f, bfl, *((loff_t *)f->private), " ->"); |
| |
| return 0; |
| } |
| |
| static void *locks_start(struct seq_file *f, loff_t *pos) |
| { |
| loff_t *p = f->private; |
| |
| lock_flocks(); |
| *p = (*pos + 1); |
| return seq_list_start(&file_lock_list, *pos); |
| } |
| |
| static void *locks_next(struct seq_file *f, void *v, loff_t *pos) |
| { |
| loff_t *p = f->private; |
| ++*p; |
| return seq_list_next(v, &file_lock_list, pos); |
| } |
| |
| static void locks_stop(struct seq_file *f, void *v) |
| { |
| unlock_flocks(); |
| } |
| |
| 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_private(filp, &locks_seq_operations, sizeof(loff_t)); |
| } |
| |
| static const struct file_operations proc_locks_operations = { |
| .open = locks_open, |
| .read = seq_read, |
| .llseek = seq_lseek, |
| .release = seq_release_private, |
| }; |
| |
| 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_flocks(); |
| 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_flocks(); |
| 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_flocks(); |
| 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_flocks(); |
| 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, NULL); |
| |
| return 0; |
| } |
| |
| core_initcall(filelock_init); |