diff options
Diffstat (limited to 'fs/locks.c')
| -rw-r--r-- | fs/locks.c | 2212 |
1 files changed, 2212 insertions, 0 deletions
diff --git a/fs/locks.c b/fs/locks.c new file mode 100644 index 0000000..1792ce5 --- /dev/null +++ b/fs/locks.c @@ -0,0 +1,2212 @@ +/* + * 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/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 <asm/semaphore.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) + +LIST_HEAD(file_lock_list); + +EXPORT_SYMBOL(file_lock_list); + +static LIST_HEAD(blocked_list); + +static kmem_cache_t *filelock_cache; + +/* Allocate an empty lock structure. */ +static struct file_lock *locks_alloc_lock(void) +{ + return kmem_cache_alloc(filelock_cache, SLAB_KERNEL); +} + +/* Free a lock which is not in use. */ +static inline void locks_free_lock(struct file_lock *fl) +{ + if (fl == NULL) { + BUG(); + return; + } + if (waitqueue_active(&fl->fl_wait)) + panic("Attempting to free lock with active wait queue"); + + if (!list_empty(&fl->fl_block)) + panic("Attempting to free lock with active block list"); + + if (!list_empty(&fl->fl_link)) + panic("Attempting to free lock on active lock list"); + + if (fl->fl_ops) { + if (fl->fl_ops->fl_release_private) + fl->fl_ops->fl_release_private(fl); + fl->fl_ops = NULL; + } + + if (fl->fl_lmops) { + if (fl->fl_lmops->fl_release_private) + fl->fl_lmops->fl_release_private(fl); + fl->fl_lmops = NULL; + } + + kmem_cache_free(filelock_cache, fl); +} + +void locks_init_lock(struct file_lock *fl) +{ + INIT_LIST_HEAD(&fl->fl_link); + INIT_LIST_HEAD(&fl->fl_block); + init_waitqueue_head(&fl->fl_wait); + fl->fl_next = NULL; + fl->fl_fasync = NULL; + fl->fl_owner = NULL; + fl->fl_pid = 0; + fl->fl_file = NULL; + fl->fl_flags = 0; + fl->fl_type = 0; + fl->fl_start = fl->fl_end = 0; + fl->fl_ops = NULL; + fl->fl_lmops = NULL; +} + +EXPORT_SYMBOL(locks_init_lock); + +/* + * Initialises the fields of the file lock which are invariant for + * free file_locks. + */ +static void init_once(void *foo, kmem_cache_t *cache, unsigned long flags) +{ + struct file_lock *lock = (struct file_lock *) foo; + + if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) != + SLAB_CTOR_CONSTRUCTOR) + return; + + locks_init_lock(lock); +} + +/* + * Initialize a new lock from an existing file_lock structure. + */ +void locks_copy_lock(struct file_lock *new, struct file_lock *fl) +{ + new->fl_owner = fl->fl_owner; + new->fl_pid = fl->fl_pid; + new->fl_file = fl->fl_file; + new->fl_flags = fl->fl_flags; + new->fl_type = fl->fl_type; + new->fl_start = fl->fl_start; + new->fl_end = fl->fl_end; + new->fl_ops = fl->fl_ops; + new->fl_lmops = fl->fl_lmops; + if (fl->fl_ops && fl->fl_ops->fl_copy_lock) + fl->fl_ops->fl_copy_lock(new, fl); + if (fl->fl_lmops && fl->fl_lmops->fl_copy_lock) + fl->fl_lmops->fl_copy_lock(new, fl); +} + +EXPORT_SYMBOL(locks_copy_lock); + +static inline int flock_translate_cmd(int cmd) { + if (cmd & LOCK_MAND) + return cmd & (LOCK_MAND | LOCK_RW); + switch (cmd) { + case LOCK_SH: + return F_RDLCK; + case LOCK_EX: + return F_WRLCK; + case LOCK_UN: + return F_UNLCK; + } + return -EINVAL; +} + +/* Fill in a file_lock structure with an appropriate FLOCK lock. */ +static int flock_make_lock(struct file *filp, struct file_lock **lock, + unsigned int cmd) +{ + struct file_lock *fl; + int type = flock_translate_cmd(cmd); + if (type < 0) + return type; + + fl = locks_alloc_lock(); + if (fl == NULL) + return -ENOMEM; + + fl->fl_file = filp; + fl->fl_pid = current->tgid; + fl->fl_flags = FL_FLOCK; + fl->fl_type = type; + fl->fl_end = OFFSET_MAX; + + *lock = fl; + return 0; +} + +static int assign_type(struct file_lock *fl, int type) +{ + switch (type) { + case F_RDLCK: + case F_WRLCK: + case F_UNLCK: + fl->fl_type = type; + break; + default: + return -EINVAL; + } + return 0; +} + +/* Verify a "struct flock" and copy it to a "struct file_lock" as a POSIX + * style lock. + */ +static int flock_to_posix_lock(struct file *filp, struct file_lock *fl, + struct flock *l) +{ + off_t start, end; + + switch (l->l_whence) { + case 0: /*SEEK_SET*/ + start = 0; + break; + case 1: /*SEEK_CUR*/ + start = filp->f_pos; + break; + case 2: /*SEEK_END*/ + start = i_size_read(filp->f_dentry->d_inode); + break; + default: + return -EINVAL; + } + + /* POSIX-1996 leaves the case l->l_len < 0 undefined; + POSIX-2001 defines it. */ + start += l->l_start; + end = start + l->l_len - 1; + if (l->l_len < 0) { + end = start - 1; + start += l->l_len; + } + + if (start < 0) + return -EINVAL; + if (l->l_len > 0 && end < 0) + return -EOVERFLOW; + + fl->fl_start = start; /* we record the absolute position */ + fl->fl_end = end; + if (l->l_len == 0) + fl->fl_end = OFFSET_MAX; + + fl->fl_owner = current->files; + fl->fl_pid = current->tgid; + fl->fl_file = filp; + fl->fl_flags = FL_POSIX; + fl->fl_ops = NULL; + fl->fl_lmops = NULL; + + return assign_type(fl, l->l_type); +} + +#if BITS_PER_LONG == 32 +static int flock64_to_posix_lock(struct file *filp, struct file_lock *fl, + struct flock64 *l) +{ + loff_t start; + + switch (l->l_whence) { + case 0: /*SEEK_SET*/ + start = 0; + break; + case 1: /*SEEK_CUR*/ + start = filp->f_pos; + break; + case 2: /*SEEK_END*/ + start = i_size_read(filp->f_dentry->d_inode); + break; + default: + return -EINVAL; + } + + if (((start += l->l_start) < 0) || (l->l_len < 0)) + return -EINVAL; + fl->fl_end = start + l->l_len - 1; + if (l->l_len > 0 && fl->fl_end < 0) + return -EOVERFLOW; + fl->fl_start = start; /* we record the absolute position */ + if (l->l_len == 0) + fl->fl_end = OFFSET_MAX; + + 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; +} + +int lease_mylease_callback(struct file_lock *fl, struct file_lock *try) +{ + return fl->fl_file == try->fl_file; +} + +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) + { + fl->fl_owner = current->files; + fl->fl_pid = current->tgid; + + fl->fl_file = filp; + fl->fl_flags = FL_LEASE; + if (assign_type(fl, type) != 0) { + locks_free_lock(fl); + return -EINVAL; + } + fl->fl_start = 0; + fl->fl_end = OFFSET_MAX; + fl->fl_ops = NULL; + fl->fl_lmops = &lease_manager_ops; + return 0; +} + +/* Allocate a file_lock initialised to this type of lease */ +static int lease_alloc(struct file *filp, int type, struct file_lock **flp) +{ + struct file_lock *fl = locks_alloc_lock(); + int error; + + if (fl == NULL) + return -ENOMEM; + + error = lease_init(filp, type, fl); + if (error) + return error; + *flp = fl; + return 0; +} + +/* 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 inline 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 inline void __locks_delete_block(struct file_lock *waiter) +{ + list_del_init(&waiter->fl_block); + list_del_init(&waiter->fl_link); + waiter->fl_next = NULL; +} + +/* + */ +static void locks_delete_block(struct file_lock *waiter) +{ + lock_kernel(); + __locks_delete_block(waiter); + unlock_kernel(); +} + +/* Insert waiter into blocker's block list. + * We use a circular list so that processes can be easily woken up in + * the order they blocked. The documentation doesn't require this but + * it seems like the reasonable thing to do. + */ +static void locks_insert_block(struct file_lock *blocker, + struct file_lock *waiter) +{ + if (!list_empty(&waiter->fl_block)) { + printk(KERN_ERR "locks_insert_block: removing duplicated lock " + "(pid=%d %Ld-%Ld type=%d)\n", waiter->fl_pid, + waiter->fl_start, waiter->fl_end, waiter->fl_type); + __locks_delete_block(waiter); + } + list_add_tail(&waiter->fl_block, &blocker->fl_block); + waiter->fl_next = blocker; + if (IS_POSIX(blocker)) + list_add(&waiter->fl_link, &blocked_list); +} + +/* Wake up processes blocked waiting for blocker. + * If told to wait then schedule the processes until the block list + * is empty, otherwise empty the block list ourselves. + */ +static void locks_wake_up_blocks(struct file_lock *blocker) +{ + while (!list_empty(&blocker->fl_block)) { + struct file_lock *waiter = list_entry(blocker->fl_block.next, + struct file_lock, fl_block); + __locks_delete_block(waiter); + if (waiter->fl_lmops && waiter->fl_lmops->fl_notify) + waiter->fl_lmops->fl_notify(waiter); + else + wake_up(&waiter->fl_wait); + } +} + +/* Insert file lock fl into an inode's lock list at the position indicated + * by pos. At the same time add the lock to the global file lock list. + */ +static void locks_insert_lock(struct file_lock **pos, struct file_lock *fl) +{ + list_add(&fl->fl_link, &file_lock_list); + + /* insert into file's list */ + fl->fl_next = *pos; + *pos = fl; + + if (fl->fl_ops && fl->fl_ops->fl_insert) + fl->fl_ops->fl_insert(fl); +} + +/* + * Delete a lock and then free it. + * Wake up processes that are blocked waiting for this lock, + * notify the FS that the lock has been cleared and + * finally free the lock. + */ +static void locks_delete_lock(struct file_lock **thisfl_p) +{ + struct file_lock *fl = *thisfl_p; + + *thisfl_p = fl->fl_next; + fl->fl_next = NULL; + list_del_init(&fl->fl_link); + + fasync_helper(0, fl->fl_file, 0, &fl->fl_fasync); + if (fl->fl_fasync != NULL) { + printk(KERN_ERR "locks_delete_lock: fasync == %p\n", fl->fl_fasync); + fl->fl_fasync = NULL; + } + + if (fl->fl_ops && fl->fl_ops->fl_remove) + fl->fl_ops->fl_remove(fl); + + locks_wake_up_blocks(fl); + locks_free_lock(fl); +} + +/* Determine if lock sys_fl blocks lock caller_fl. Common functionality + * checks for shared/exclusive status of overlapping locks. + */ +static int locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl) +{ + if (sys_fl->fl_type == F_WRLCK) + return 1; + if (caller_fl->fl_type == F_WRLCK) + return 1; + return 0; +} + +/* Determine if lock sys_fl blocks lock caller_fl. POSIX specific + * checking before calling the locks_conflict(). + */ +static int posix_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl) +{ + /* POSIX locks owned by the same process do not conflict with + * each other. + */ + if (!IS_POSIX(sys_fl) || posix_same_owner(caller_fl, sys_fl)) + return (0); + + /* Check whether they overlap */ + if (!locks_overlap(caller_fl, sys_fl)) + return 0; + + return (locks_conflict(caller_fl, sys_fl)); +} + +/* Determine if lock sys_fl blocks lock caller_fl. FLOCK specific + * checking before calling the locks_conflict(). + */ +static int flock_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl) +{ + /* FLOCK locks referring to the same filp do not conflict with + * each other. + */ + if (!IS_FLOCK(sys_fl) || (caller_fl->fl_file == sys_fl->fl_file)) + return (0); + if ((caller_fl->fl_type & LOCK_MAND) || (sys_fl->fl_type & LOCK_MAND)) + return 0; + + return (locks_conflict(caller_fl, sys_fl)); +} + +static int interruptible_sleep_on_locked(wait_queue_head_t *fl_wait, int timeout) +{ + int result = 0; + DECLARE_WAITQUEUE(wait, current); + + __set_current_state(TASK_INTERRUPTIBLE); + add_wait_queue(fl_wait, &wait); + if (timeout == 0) + schedule(); + else + result = schedule_timeout(timeout); + if (signal_pending(current)) + result = -ERESTARTSYS; + remove_wait_queue(fl_wait, &wait); + __set_current_state(TASK_RUNNING); + return result; +} + +static int locks_block_on_timeout(struct file_lock *blocker, struct file_lock *waiter, int time) +{ + int result; + locks_insert_block(blocker, waiter); + result = interruptible_sleep_on_locked(&waiter->fl_wait, time); + __locks_delete_block(waiter); + return result; +} + +struct file_lock * +posix_test_lock(struct file *filp, struct file_lock *fl) +{ + struct file_lock *cfl; + + lock_kernel(); + for (cfl = filp->f_dentry->d_inode->i_flock; cfl; cfl = cfl->fl_next) { + if (!IS_POSIX(cfl)) + continue; + if (posix_locks_conflict(cfl, fl)) + break; + } + unlock_kernel(); + + return (cfl); +} + +EXPORT_SYMBOL(posix_test_lock); + +/* This function tests for deadlock condition before putting a process to + * sleep. The detection scheme is no longer recursive. Recursive was neat, + * but dangerous - we risked stack corruption if the lock data was bad, or + * if the recursion was too deep for any other reason. + * + * We rely on the fact that a task can only be on one lock's wait queue + * at a time. When we find blocked_task on a wait queue we can re-search + * with blocked_task equal to that queue's owner, until either blocked_task + * isn't found, or blocked_task is found on a queue owned by my_task. + * + * Note: the above assumption may not be true when handling lock requests + * from a broken NFS client. But broken NFS clients have a lot more to + * worry about than proper deadlock detection anyway... --okir + */ +int posix_locks_deadlock(struct file_lock *caller_fl, + struct file_lock *block_fl) +{ + struct list_head *tmp; + +next_task: + if (posix_same_owner(caller_fl, block_fl)) + return 1; + list_for_each(tmp, &blocked_list) { + struct file_lock *fl = list_entry(tmp, struct file_lock, fl_link); + if (posix_same_owner(fl, block_fl)) { + fl = fl->fl_next; + block_fl = fl; + goto next_task; + } + } + return 0; +} + +EXPORT_SYMBOL(posix_locks_deadlock); + +/* Try to create a FLOCK lock on filp. We always insert new FLOCK locks + * at the head of the list, but that's secret knowledge known only to + * flock_lock_file and posix_lock_file. + */ +static int flock_lock_file(struct file *filp, struct file_lock *new_fl) +{ + struct file_lock **before; + struct inode * inode = filp->f_dentry->d_inode; + int error = 0; + int found = 0; + + lock_kernel(); + for_each_lock(inode, before) { + struct file_lock *fl = *before; + if (IS_POSIX(fl)) + break; + if (IS_LEASE(fl)) + continue; + if (filp != fl->fl_file) + continue; + if (new_fl->fl_type == fl->fl_type) + goto out; + found = 1; + locks_delete_lock(before); + break; + } + unlock_kernel(); + + if (new_fl->fl_type == F_UNLCK) + return 0; + + /* + * If a higher-priority process was blocked on the old file lock, + * give it the opportunity to lock the file. + */ + if (found) + cond_resched(); + + lock_kernel(); + for_each_lock(inode, before) { + struct file_lock *fl = *before; + if (IS_POSIX(fl)) + break; + if (IS_LEASE(fl)) + continue; + if (!flock_locks_conflict(new_fl, fl)) + continue; + error = -EAGAIN; + if (new_fl->fl_flags & FL_SLEEP) { + locks_insert_block(fl, new_fl); + } + goto out; + } + locks_insert_lock(&inode->i_flock, new_fl); + error = 0; + +out: + unlock_kernel(); + return error; +} + +EXPORT_SYMBOL(posix_lock_file); + +static int __posix_lock_file(struct inode *inode, struct file_lock *request) +{ + struct file_lock *fl; + struct file_lock *new_fl, *new_fl2; + struct file_lock *left = NULL; + struct file_lock *right = NULL; + struct file_lock **before; + int error, added = 0; + + /* + * We may need two file_lock structures for this operation, + * so we get them in advance to avoid races. + */ + new_fl = locks_alloc_lock(); + new_fl2 = locks_alloc_lock(); + + lock_kernel(); + if (request->fl_type != F_UNLCK) { + for_each_lock(inode, before) { + struct file_lock *fl = *before; + if (!IS_POSIX(fl)) + continue; + if (!posix_locks_conflict(request, fl)) + continue; + error = -EAGAIN; + if (!(request->fl_flags & FL_SLEEP)) + goto out; + error = -EDEADLK; + if (posix_locks_deadlock(request, fl)) + goto out; + error = -EAGAIN; + locks_insert_block(fl, request); + goto out; + } + } + + /* If we're just looking for a conflict, we're done. */ + error = 0; + if (request->fl_flags & FL_ACCESS) + goto out; + + error = -ENOLCK; /* "no luck" */ + if (!(new_fl && new_fl2)) + goto out; + + /* + * We've allocated the new locks in advance, so there are no + * errors possible (and no blocking operations) from here on. + * + * Find the first old lock with the same owner as the new lock. + */ + + before = &inode->i_flock; + + /* First skip locks owned by other processes. */ + while ((fl = *before) && (!IS_POSIX(fl) || + !posix_same_owner(request, fl))) { + before = &fl->fl_next; + } + + /* Process locks with this owner. */ + while ((fl = *before) && posix_same_owner(request, fl)) { + /* Detect adjacent or overlapping regions (if same lock type) + */ + if (request->fl_type == fl->fl_type) { + 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 > request->fl_end + 1) + break; + + /* If we come here, the new and old lock are of the + * same type and adjacent or overlapping. Make one + * lock yielding from the lower start address of both + * locks to the higher end address. + */ + if (fl->fl_start > request->fl_start) + fl->fl_start = request->fl_start; + else + request->fl_start = fl->fl_start; + if (fl->fl_end < request->fl_end) + fl->fl_end = request->fl_end; + else + request->fl_end = fl->fl_end; + if (added) { + locks_delete_lock(before); + continue; + } + request = fl; + added = 1; + } + else { + /* Processing for different lock types is a bit + * more complex. + */ + if (fl->fl_end < request->fl_start) + goto next_lock; + if (fl->fl_start > request->fl_end) + break; + if (request->fl_type == F_UNLCK) + added = 1; + if (fl->fl_start < request->fl_start) + left = fl; + /* If the next lock in the list has a higher end + * address than the new one, insert the new one here. + */ + if (fl->fl_end > request->fl_end) { + right = fl; + break; + } + if (fl->fl_start >= request->fl_start) { + /* The new lock completely replaces an old + * one (This may happen several times). + */ + if (added) { + locks_delete_lock(before); + continue; + } + /* Replace the old lock with the new one. + * Wake up anybody waiting for the old one, + * as the change in lock type might satisfy + * their needs. + */ + locks_wake_up_blocks(fl); + fl->fl_start = request->fl_start; + fl->fl_end = request->fl_end; + fl->fl_type = request->fl_type; + fl->fl_u = request->fl_u; + request = fl; + added = 1; + } + } + /* Go on to next lock. + */ + next_lock: + before = &fl->fl_next; + } + + error = 0; + if (!added) { + if (request->fl_type == F_UNLCK) + goto out; + locks_copy_lock(new_fl, request); + locks_insert_lock(before, new_fl); + new_fl = NULL; + } + if (right) { + if (left == right) { + /* The new lock breaks the old one in two pieces, + * so we have to use the second new lock. + */ + left = new_fl2; + new_fl2 = NULL; + locks_copy_lock(left, right); + locks_insert_lock(before, left); + } + right->fl_start = request->fl_end + 1; + locks_wake_up_blocks(right); + } + if (left) { + left->fl_end = request->fl_start - 1; + locks_wake_up_blocks(left); + } + out: + unlock_kernel(); + /* + * Free any unused locks. + */ + if (new_fl) + locks_free_lock(new_fl); + if (new_fl2) + locks_free_lock(new_fl2); + return error; +} + +/** + * posix_lock_file - Apply a POSIX-style lock to a file + * @filp: The file to apply the lock to + * @fl: The lock to be applied + * + * Add a POSIX style lock to a file. + * We merge adjacent & overlapping locks whenever possible. + * POSIX locks are sorted by owner task, then by starting address + */ +int posix_lock_file(struct file *filp, struct file_lock *fl) +{ + return __posix_lock_file(filp->f_dentry->d_inode, fl); +} + +/** + * posix_lock_file_wait - Apply a POSIX-style lock to a file + * @filp: The file to apply the lock to + * @fl: The lock to be applied + * + * Add a POSIX style lock to a file. + * We merge adjacent & overlapping locks whenever possible. + * POSIX locks are sorted by owner task, then by starting address + */ +int posix_lock_file_wait(struct file *filp, struct file_lock *fl) +{ + int error; + might_sleep (); + for (;;) { + error = __posix_lock_file(filp->f_dentry->d_inode, fl); + if ((error != -EAGAIN) || !(fl->fl_flags & FL_SLEEP)) + break; + error = wait_event_interruptible(fl->fl_wait, !fl->fl_next); + if (!error) + continue; + + locks_delete_block(fl); + break; + } + return error; +} +EXPORT_SYMBOL(posix_lock_file_wait); + +/** + * locks_mandatory_locked - Check for an active lock + * @inode: the file to check + * + * Searches the inode's list of locks to find any POSIX locks which conflict. + * This function is called from locks_verify_locked() only. + */ +int locks_mandatory_locked(struct inode *inode) +{ + fl_owner_t owner = current->files; + struct file_lock *fl; + + /* + * Search the lock list for this inode for any POSIX locks. + */ + lock_kernel(); + for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) { + if (!IS_POSIX(fl)) + continue; + if (fl->fl_owner != owner) + break; + } + unlock_kernel(); + return fl ? -EAGAIN : 0; +} + +/** + * locks_mandatory_area - Check for a conflicting lock + * @read_write: %FLOCK_VERIFY_WRITE for exclusive access, %FLOCK_VERIFY_READ + * for shared + * @inode: the file to check + * @filp: how the file was opened (if it was) + * @offset: start of area to check + * @count: length of area to check + * + * Searches the inode's list of locks to find any POSIX locks which conflict. + * This function is called from rw_verify_area() and + * locks_verify_truncate(). + */ +int locks_mandatory_area(int read_write, struct inode *inode, + struct file *filp, loff_t offset, + size_t count) +{ + struct file_lock fl; + int error; + + locks_init_lock(&fl); + fl.fl_owner = current->files; + fl.fl_pid = current->tgid; + fl.fl_file = filp; + fl.fl_flags = FL_POSIX | FL_ACCESS; + if (filp && !(filp->f_flags & O_NONBLOCK)) + fl.fl_flags |= FL_SLEEP; + fl.fl_type = (read_write == FLOCK_VERIFY_WRITE) ? F_WRLCK : F_RDLCK; + fl.fl_start = offset; + fl.fl_end = offset + count - 1; + + for (;;) { + error = __posix_lock_file(inode, &fl); + if (error != -EAGAIN) + break; + if (!(fl.fl_flags & FL_SLEEP)) + break; + error = wait_event_interruptible(fl.fl_wait, !fl.fl_next); + if (!error) { + /* + * If we've been sleeping someone might have + * changed the permissions behind our back. + */ + if ((inode->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID) + continue; + } + + locks_delete_block(&fl); + break; + } + + return error; +} + +EXPORT_SYMBOL(locks_mandatory_area); + +/* We already had a lease on this file; just change its type */ +int lease_modify(struct file_lock **before, int arg) +{ + struct file_lock *fl = *before; + int error = assign_type(fl, arg); + + if (error) + return error; + locks_wake_up_blocks(fl); + if (arg == F_UNLCK) + locks_delete_lock(before); + return 0; +} + +EXPORT_SYMBOL(lease_modify); + +static void time_out_leases(struct inode *inode) +{ + struct file_lock **before; + struct file_lock *fl; + + before = &inode->i_flock; + while ((fl = *before) && IS_LEASE(fl) && (fl->fl_type & F_INPROGRESS)) { + if ((fl->fl_break_time == 0) + || time_before(jiffies, fl->fl_break_time)) { + before = &fl->fl_next; + continue; + } + printk(KERN_INFO "lease broken - owner pid = %d\n", fl->fl_pid); + lease_modify(before, fl->fl_type & ~F_INPROGRESS); + if (fl == *before) /* lease_modify may have freed fl */ + before = &fl->fl_next; + } +} + +/** + * __break_lease - revoke all outstanding leases on file + * @inode: the inode of the file to return + * @mode: the open mode (read or write) + * + * break_lease (inlined for speed) has checked there already + * is a lease on this file. Leases are broken on a call to open() + * or truncate(). This function can sleep unless you + * specified %O_NONBLOCK to your open(). + */ +int __break_lease(struct inode *inode, unsigned int mode) +{ + int error = 0, future; + struct file_lock *new_fl, *flock; + struct file_lock *fl; + int alloc_err; + unsigned long break_time; + int i_have_this_lease = 0; + + alloc_err = lease_alloc(NULL, mode & FMODE_WRITE ? F_WRLCK : F_RDLCK, + &new_fl); + + lock_kernel(); + + time_out_leases(inode); + + flock = inode->i_flock; + if ((flock == NULL) || !IS_LEASE(flock)) + goto out; + + for (fl = flock; fl && IS_LEASE(fl); fl = fl->fl_next) + if (fl->fl_owner == current->files) + i_have_this_lease = 1; + + if (mode & FMODE_WRITE) { + /* If we want write access, we have to revoke any lease. */ + future = F_UNLCK | F_INPROGRESS; + } else if (flock->fl_type & F_INPROGRESS) { + /* If the lease is already being broken, we just leave it */ + future = flock->fl_type; + } else if (flock->fl_type & F_WRLCK) { + /* Downgrade the exclusive lease to a read-only lease. */ + future = F_RDLCK | F_INPROGRESS; + } else { + /* the existing lease was read-only, so we can read too. */ + goto out; + } + + if (alloc_err && !i_have_this_lease && ((mode & O_NONBLOCK) == 0)) { + error = alloc_err; + goto out; + } + + break_time = 0; + if (lease_break_time > 0) { + break_time = jiffies + lease_break_time * HZ; + if (break_time == 0) + break_time++; /* so that 0 means no break time */ + } + + for (fl = flock; fl && IS_LEASE(fl); fl = fl->fl_next) { + if (fl->fl_type != future) { + fl->fl_type = future; + fl->fl_break_time = break_time; + /* lease must have lmops break callback */ + fl->fl_lmops->fl_break(fl); + } + } + + if (i_have_this_lease || (mode & O_NONBLOCK)) { + error = -EWOULDBLOCK; + goto out; + } + +restart: + break_time = flock->fl_break_time; + if (break_time != 0) { + break_time -= jiffies; + if (break_time == 0) + break_time++; + } + error = locks_block_on_timeout(flock, new_fl, break_time); + if (error >= 0) { + if (error == 0) + time_out_leases(inode); + /* Wait for the next lease that has not been broken yet */ + for (flock = inode->i_flock; flock && IS_LEASE(flock); + flock = flock->fl_next) { + if (flock->fl_type & F_INPROGRESS) + goto restart; + } + error = 0; + } + +out: + unlock_kernel(); + if (!alloc_err) + locks_free_lock(new_fl); + return error; +} + +EXPORT_SYMBOL(__break_lease); + +/** + * lease_get_mtime + * @inode: the inode + * @time: pointer to a timespec which will contain the last modified time + * + * This is to force NFS clients to flush their caches for files with + * exclusive leases. The justification is that if someone has an + * exclusive lease, then they could be modifiying it. + */ +void lease_get_mtime(struct inode *inode, struct timespec *time) +{ + struct file_lock *flock = inode->i_flock; + if (flock && IS_LEASE(flock) && (flock->fl_type & F_WRLCK)) + *time = current_fs_time(inode->i_sb); + else + *time = inode->i_mtime; +} + +EXPORT_SYMBOL(lease_get_mtime); + +/** + * fcntl_getlease - Enquire what lease is currently active + * @filp: the file + * + * The value returned by this function will be one of + * (if no lease break is pending): + * + * %F_RDLCK to indicate a shared lease is held. + * + * %F_WRLCK to indicate an exclusive lease is held. + * + * %F_UNLCK to indicate no lease is held. + * + * (if a lease break is pending): + * + * %F_RDLCK to indicate an exclusive lease needs to be + * changed to a shared lease (or removed). + * + * %F_UNLCK to indicate the lease needs to be removed. + * + * XXX: sfr & willy disagree over whether F_INPROGRESS + * should be returned to userspace. + */ +int fcntl_getlease(struct file *filp) +{ + struct file_lock *fl; + int type = F_UNLCK; + + lock_kernel(); + time_out_leases(filp->f_dentry->d_inode); + for (fl = filp->f_dentry->d_inode->i_flock; fl && IS_LEASE(fl); + fl = fl->fl_next) { + if (fl->fl_file == filp) { + type = fl->fl_type & ~F_INPROGRESS; + break; + } + } + unlock_kernel(); + return type; +} + +/** + * __setlease - sets a lease on an open file + * @filp: file pointer + * @arg: type of lease to obtain + * @flp: input - file_lock to use, output - file_lock inserted + * + * The (input) flp->fl_lmops->fl_break function is required + * by break_lease(). + * + * Called with kernel lock held. + */ +int __setlease(struct file *filp, long arg, struct file_lock **flp) +{ + struct file_lock *fl, **before, **my_before = NULL, *lease = *flp; + struct dentry *dentry = filp->f_dentry; + struct inode *inode = dentry->d_inode; + int error, rdlease_count = 0, wrlease_count = 0; + + time_out_leases(inode); + + error = -EINVAL; + if (!flp || !(*flp) || !(*flp)->fl_lmops || !(*flp)->fl_lmops->fl_break) + goto out; + + error = -EAGAIN; + if ((arg == F_RDLCK) && (atomic_read(&inode->i_writecount) > 0)) + goto out; + if ((arg == F_WRLCK) + && ((atomic_read(&dentry->d_count) > 1) + || (atomic_read(&inode->i_count) > 1))) + goto out; + + /* + * At this point, we know that if there is an exclusive + * lease on this file, then we hold it on this filp + * (otherwise our open of this file would have blocked). + * And if we are trying to acquire an exclusive lease, + * then the file is not open by anyone (including us) + * except for this filp. + */ + for (before = &inode->i_flock; + ((fl = *before) != NULL) && IS_LEASE(fl); + before = &fl->fl_next) { + if (lease->fl_lmops->fl_mylease(fl, lease)) + my_before = before; + else if (fl->fl_type == (F_INPROGRESS | F_UNLCK)) + /* + * Someone is in the process of opening this + * file for writing so we may not take an + * exclusive lease on it. + */ + wrlease_count++; + else + rdlease_count++; + } + + if ((arg == F_RDLCK && (wrlease_count > 0)) || + (arg == F_WRLCK && ((rdlease_count + wrlease_count) > 0))) + goto out; + + if (my_before != NULL) { + error = lease->fl_lmops->fl_change(my_before, arg); + goto out; + } + + error = 0; + if (arg == F_UNLCK) + goto out; + + error = -EINVAL; + if (!leases_enable) + goto out; + + error = lease_alloc(filp, arg, &fl); + if (error) + goto out; + + locks_copy_lock(fl, lease); + + locks_insert_lock(before, fl); + + *flp = fl; +out: + return error; +} + + /** + * setlease - sets a lease on an open file + * @filp: file pointer + * @arg: type of lease to obtain + * @lease: file_lock to use + * + * Call this to establish a lease on the file. + * The fl_lmops fl_break function is required by break_lease + */ + +int setlease(struct file *filp, long arg, struct file_lock **lease) +{ + struct dentry *dentry = filp->f_dentry; + struct inode *inode = dentry->d_inode; + int error; + + if ((current->fsuid != inode->i_uid) && !capable(CAP_LEASE)) + return -EACCES; + if (!S_ISREG(inode->i_mode)) + return -EINVAL; + error = security_file_lock(filp, arg); + if (error) + return error; + + lock_kernel(); + error = __setlease(filp, arg, lease); + unlock_kernel(); + + return error; +} + +EXPORT_SYMBOL(setlease); + +/** + * fcntl_setlease - sets a lease on an open file + * @fd: open file descriptor + * @filp: file pointer + * @arg: type of lease to obtain + * + * Call this fcntl to establish a lease on the file. + * Note that you also need to call %F_SETSIG to + * receive a signal when the lease is broken. + */ +int fcntl_setlease(unsigned int fd, struct file *filp, long arg) +{ + struct file_lock fl, *flp = &fl; + struct dentry *dentry = filp->f_dentry; + struct inode *inode = dentry->d_inode; + int error; + + if ((current->fsuid != inode->i_uid) && !capable(CAP_LEASE)) + return -EACCES; + if (!S_ISREG(inode->i_mode)) + return -EINVAL; + error = security_file_lock(filp, arg); + if (error) + return error; + + locks_init_lock(&fl); + error = lease_init(filp, arg, &fl); + if (error) + return error; + + lock_kernel(); + + error = __setlease(filp, arg, &flp); + if (error) + goto out_unlock; + + error = fasync_helper(fd, filp, 1, &flp->fl_fasync); + if (error < 0) { + /* remove lease just inserted by __setlease */ + flp->fl_type = F_UNLCK | F_INPROGRESS; + flp->fl_break_time = jiffies- 10; + time_out_leases(inode); + goto out_unlock; + } + + error = f_setown(filp, current->pid, 0); +out_unlock: + unlock_kernel(); + return error; +} + +/** + * flock_lock_file_wait - Apply a FLOCK-style lock to a file + * @filp: The file to apply the lock to + * @fl: The lock to be applied + * + * Add a FLOCK style lock to a file. + */ +int flock_lock_file_wait(struct file *filp, struct file_lock *fl) +{ + int error; + might_sleep(); + for (;;) { + error = flock_lock_file(filp, fl); + if ((error != -EAGAIN) || !(fl->fl_flags & FL_SLEEP)) + break; + error = wait_event_interruptible(fl->fl_wait, !fl->fl_next); + if (!error) + continue; + + locks_delete_block(fl); + break; + } + return error; +} + +EXPORT_SYMBOL(flock_lock_file_wait); + +/** + * sys_flock: - flock() system call. + * @fd: the file descriptor to lock. + * @cmd: the type of lock to apply. + * + * Apply a %FL_FLOCK style lock to an open file descriptor. + * The @cmd can be one of + * + * %LOCK_SH -- a shared lock. + * + * %LOCK_EX -- an exclusive lock. + * + * %LOCK_UN -- remove an existing lock. + * + * %LOCK_MAND -- a `mandatory' flock. This exists to emulate Windows Share Modes. + * + * %LOCK_MAND can be combined with %LOCK_READ or %LOCK_WRITE to allow other + * processes read and write access respectively. + */ +asmlinkage long sys_flock(unsigned int fd, unsigned int cmd) +{ + struct file *filp; + struct file_lock *lock; + int can_sleep, unlock; + int error; + + error = -EBADF; + filp = fget(fd); + if (!filp) + goto out; + + can_sleep = !(cmd & LOCK_NB); + cmd &= ~LOCK_NB; + unlock = (cmd == LOCK_UN); + + if (!unlock && !(cmd & LOCK_MAND) && !(filp->f_mode & 3)) + goto out_putf; + + error = flock_make_lock(filp, &lock, cmd); + if (error) + goto out_putf; + if (can_sleep) + lock->fl_flags |= FL_SLEEP; + + error = security_file_lock(filp, cmd); + if (error) + goto out_free; + + if (filp->f_op && filp->f_op->flock) + error = filp->f_op->flock(filp, + (can_sleep) ? F_SETLKW : F_SETLK, + lock); + else + error = flock_lock_file_wait(filp, lock); + + out_free: + if (list_empty(&lock->fl_link)) { + locks_free_lock(lock); + } + + out_putf: + fput(filp); + out: + return error; +} + +/* Report the first existing lock that would conflict with l. + * This implements the F_GETLK command of fcntl(). + */ +int fcntl_getlk(struct file *filp, struct flock __user *l) +{ + struct file_lock *fl, file_lock; + struct flock flock; + int error; + + error = -EFAULT; + if (copy_from_user(&flock, l, sizeof(flock))) + goto out; + error = -EINVAL; + if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK)) + goto out; + + error = flock_to_posix_lock(filp, &file_lock, &flock); + if (error) + goto out; + + if (filp->f_op && filp->f_op->lock) { + error = filp->f_op->lock(filp, F_GETLK, &file_lock); + if (error < 0) + goto out; + else + fl = (file_lock.fl_type == F_UNLCK ? NULL : &file_lock); + } else { + fl = posix_test_lock(filp, &file_lock); + } + + flock.l_type = F_UNLCK; + if (fl != NULL) { + flock.l_pid = fl->fl_pid; +#if BITS_PER_LONG == 32 + /* + * Make sure we can represent the posix lock via + * legacy 32bit flock. + */ + error = -EOVERFLOW; + if (fl->fl_start > OFFT_OFFSET_MAX) + goto out; + if ((fl->fl_end != OFFSET_MAX) + && (fl->fl_end > OFFT_OFFSET_MAX)) + goto out; +#endif + flock.l_start = fl->fl_start; + flock.l_len = fl->fl_end == OFFSET_MAX ? 0 : + fl->fl_end - fl->fl_start + 1; + flock.l_whence = 0; + flock.l_type = fl->fl_type; + } + error = -EFAULT; + if (!copy_to_user(l, &flock, sizeof(flock))) + error = 0; +out: + return error; +} + +/* Apply the lock described by l to an open file descriptor. + * This implements both the F_SETLK and F_SETLKW commands of fcntl(). + */ +int fcntl_setlk(struct file *filp, unsigned int cmd, struct flock __user *l) +{ + struct file_lock *file_lock = locks_alloc_lock(); + struct flock flock; + struct inode *inode; + int error; + + if (file_lock == NULL) + return -ENOLCK; + + /* + * This might block, so we do it before checking the inode. + */ + error = -EFAULT; + if (copy_from_user(&flock, l, sizeof(flock))) + goto out; + + inode = filp->f_dentry->d_inode; + + /* Don't allow mandatory locks on files that may be memory mapped + * and shared. + */ + if (IS_MANDLOCK(inode) && + (inode->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID && + mapping_writably_mapped(filp->f_mapping)) { + error = -EAGAIN; + goto out; + } + + error = flock_to_posix_lock(filp, file_lock, &flock); + if (error) + goto out; + if (cmd == F_SETLKW) { + file_lock->fl_flags |= FL_SLEEP; + } + + error = -EBADF; + switch (flock.l_type) { + case F_RDLCK: + if (!(filp->f_mode & FMODE_READ)) + goto out; + break; + case F_WRLCK: + if (!(filp->f_mode & FMODE_WRITE)) + goto out; + break; + case F_UNLCK: + break; + default: + error = -EINVAL; + goto out; + } + + error = security_file_lock(filp, file_lock->fl_type); + if (error) + goto out; + + if (filp->f_op && filp->f_op->lock != NULL) { + error = filp->f_op->lock(filp, cmd, file_lock); + goto out; + } + + for (;;) { + error = __posix_lock_file(inode, file_lock); + if ((error != -EAGAIN) || (cmd == F_SETLK)) + break; + error = wait_event_interruptible(file_lock->fl_wait, + !file_lock->fl_next); + if (!error) + continue; + + locks_delete_block(file_lock); + break; + } + + out: + locks_free_lock(file_lock); + return error; +} + +#if BITS_PER_LONG == 32 +/* Report the first existing lock that would conflict with l. + * This implements the F_GETLK command of fcntl(). + */ +int fcntl_getlk64(struct file *filp, struct flock64 __user *l) +{ + struct file_lock *fl, file_lock; + struct flock64 flock; + int error; + + error = -EFAULT; + if (copy_from_user(&flock, l, sizeof(flock))) + goto out; + error = -EINVAL; + if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK)) + goto out; + + error = flock64_to_posix_lock(filp, &file_lock, &flock); + if (error) + goto out; + + if (filp->f_op && filp->f_op->lock) { + error = filp->f_op->lock(filp, F_GETLK, &file_lock); + if (error < 0) + goto out; + else + fl = (file_lock.fl_type == F_UNLCK ? NULL : &file_lock); + } else { + fl = posix_test_lock(filp, &file_lock); + } + + flock.l_type = F_UNLCK; + if (fl != NULL) { + flock.l_pid = fl->fl_pid; + flock.l_start = fl->fl_start; + flock.l_len = fl->fl_end == OFFSET_MAX ? 0 : + fl->fl_end - fl->fl_start + 1; + flock.l_whence = 0; + flock.l_type = fl->fl_type; + } + error = -EFAULT; + if (!copy_to_user(l, &flock, sizeof(flock))) + error = 0; + +out: + return error; +} + +/* Apply the lock described by l to an open file descriptor. + * This implements both the F_SETLK and F_SETLKW commands of fcntl(). + */ +int fcntl_setlk64(struct file *filp, unsigned int cmd, struct flock64 __user *l) +{ + struct file_lock *file_lock = locks_alloc_lock(); + struct flock64 flock; + struct inode *inode; + int error; + + if (file_lock == NULL) + return -ENOLCK; + + /* + * This might block, so we do it before checking the inode. + */ + error = -EFAULT; + if (copy_from_user(&flock, l, sizeof(flock))) + goto out; + + inode = filp->f_dentry->d_inode; + + /* Don't allow mandatory locks on files that may be memory mapped + * and shared. + */ + if (IS_MANDLOCK(inode) && + (inode->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID && + mapping_writably_mapped(filp->f_mapping)) { + error = -EAGAIN; + goto out; + } + + error = flock64_to_posix_lock(filp, file_lock, &flock); + if (error) + goto out; + if (cmd == F_SETLKW64) { + file_lock->fl_flags |= FL_SLEEP; + } + + error = -EBADF; + switch (flock.l_type) { + case F_RDLCK: + if (!(filp->f_mode & FMODE_READ)) + goto out; + break; + case F_WRLCK: + if (!(filp->f_mode & FMODE_WRITE)) + goto out; + break; + case F_UNLCK: + break; + default: + error = -EINVAL; + goto out; + } + + error = security_file_lock(filp, file_lock->fl_type); + if (error) + goto out; + + if (filp->f_op && filp->f_op->lock != NULL) { + error = filp->f_op->lock(filp, cmd, file_lock); + goto out; + } + + for (;;) { + error = __posix_lock_file(inode, file_lock); + if ((error != -EAGAIN) || (cmd == F_SETLK64)) + break; + error = wait_event_interruptible(file_lock->fl_wait, + !file_lock->fl_next); + if (!error) + continue; + + locks_delete_block(file_lock); + break; + } + +out: + locks_free_lock(file_lock); + return error; +} +#endif /* BITS_PER_LONG == 32 */ + +/* + * This function is called when the file is being removed + * from the task's fd array. POSIX locks belonging to this task + * are deleted at this time. + */ +void locks_remove_posix(struct file *filp, fl_owner_t owner) +{ + struct file_lock lock, **before; + + /* + * If there are no locks held on this file, we don't need to call + * posix_lock_file(). Another process could be setting a lock on this + * file at the same time, but we wouldn't remove that lock anyway. + */ + before = &filp->f_dentry->d_inode->i_flock; + if (*before == NULL) + return; + + lock.fl_type = F_UNLCK; + lock.fl_flags = FL_POSIX; + lock.fl_start = 0; + lock.fl_end = OFFSET_MAX; + lock.fl_owner = owner; + lock.fl_pid = current->tgid; + lock.fl_file = filp; + lock.fl_ops = NULL; + lock.fl_lmops = NULL; + + if (filp->f_op && filp->f_op->lock != NULL) { + filp->f_op->lock(filp, F_SETLK, &lock); + goto out; + } + + /* Can't use posix_lock_file here; we need to remove it no matter + * which pid we have. + */ + lock_kernel(); + while (*before != NULL) { + struct file_lock *fl = *before; + if (IS_POSIX(fl) && posix_same_owner(fl, &lock)) { + locks_delete_lock(before); + continue; + } + before = &fl->fl_next; + } + unlock_kernel(); +out: + if (lock.fl_ops && lock.fl_ops->fl_release_private) + lock.fl_ops->fl_release_private(&lock); +} + +EXPORT_SYMBOL(locks_remove_posix); + +/* + * This function is called on the last close of an open file. + */ +void locks_remove_flock(struct file *filp) +{ + struct inode * inode = filp->f_dentry->d_inode; + struct file_lock *fl; + struct file_lock **before; + + if (!inode->i_flock) + return; + + if (filp->f_op && filp->f_op->flock) { + struct file_lock fl = { + .fl_pid = current->tgid, + .fl_file = filp, + .fl_flags = FL_FLOCK, + .fl_type = F_UNLCK, + .fl_end = OFFSET_MAX, + }; + filp->f_op->flock(filp, F_SETLKW, &fl); + } + + lock_kernel(); + before = &inode->i_flock; + + while ((fl = *before) != NULL) { + if (fl->fl_file == filp) { + /* + * We might have a POSIX lock that was created at the same time + * the filp was closed for the last time. Just remove that too, + * regardless of ownership, since nobody can own it. + */ + if (IS_FLOCK(fl) || IS_POSIX(fl)) { + locks_delete_lock(before); + continue; + } + if (IS_LEASE(fl)) { + lease_modify(before, F_UNLCK); + continue; + } + /* What? */ + BUG(); + } + before = &fl->fl_next; + } + unlock_kernel(); +} + +/** + * posix_block_lock - blocks waiting for a file lock + * @blocker: the lock which is blocking + * @waiter: the lock which conflicts and has to wait + * + * lockd needs to block waiting for locks. + */ +void +posix_block_lock(struct file_lock *blocker, struct file_lock *waiter) +{ + locks_insert_block(blocker, waiter); +} + +EXPORT_SYMBOL(posix_block_lock); + +/** + * posix_unblock_lock - stop waiting for a file lock + * @filp: how the file was opened + * @waiter: the lock which was waiting + * + * lockd needs to block waiting for locks. + */ +void +posix_unblock_lock(struct file *filp, struct file_lock *waiter) +{ + /* + * A remote machine may cancel the lock request after it's been + * granted locally. If that happens, we need to delete the lock. + */ + lock_kernel(); + if (waiter->fl_next) { + __locks_delete_block(waiter); + unlock_kernel(); + } else { + unlock_kernel(); + waiter->fl_type = F_UNLCK; + posix_lock_file(filp, waiter); + } +} + +EXPORT_SYMBOL(posix_unblock_lock); + +static void lock_get_status(char* out, struct file_lock *fl, int id, char *pfx) +{ + struct inode *inode = NULL; + + if (fl->fl_file != NULL) + inode = fl->fl_file->f_dentry->d_inode; + + out += sprintf(out, "%d:%s ", id, pfx); + if (IS_POSIX(fl)) { + out += sprintf(out, "%6s %s ", + (fl->fl_flags & FL_ACCESS) ? "ACCESS" : "POSIX ", + (inode == NULL) ? "*NOINODE*" : + (IS_MANDLOCK(inode) && + (inode->i_mode & (S_IXGRP | S_ISGID)) == S_ISGID) ? + "MANDATORY" : "ADVISORY "); + } else if (IS_FLOCK(fl)) { + if (fl->fl_type & LOCK_MAND) { + out += sprintf(out, "FLOCK MSNFS "); + } else { + out += sprintf(out, "FLOCK ADVISORY "); + } + } else if (IS_LEASE(fl)) { + out += sprintf(out, "LEASE "); + if (fl->fl_type & F_INPROGRESS) + out += sprintf(out, "BREAKING "); + else if (fl->fl_file) + out += sprintf(out, "ACTIVE "); + else + out += sprintf(out, "BREAKER "); + } else { + out += sprintf(out, "UNKNOWN UNKNOWN "); + } + if (fl->fl_type & LOCK_MAND) { + out += sprintf(out, "%s ", + (fl->fl_type & LOCK_READ) + ? (fl->fl_type & LOCK_WRITE) ? "RW " : "READ " + : (fl->fl_type & LOCK_WRITE) ? "WRITE" : "NONE "); + } else { + out += sprintf(out, "%s ", + (fl->fl_type & F_INPROGRESS) + ? (fl->fl_type & F_UNLCK) ? "UNLCK" : "READ " + : (fl->fl_type & F_WRLCK) ? "WRITE" : "READ "); + } + if (inode) { +#ifdef WE_CAN_BREAK_LSLK_NOW + out += sprintf(out, "%d %s:%ld ", fl->fl_pid, + inode->i_sb->s_id, inode->i_ino); +#else + /* userspace relies on this representation of dev_t ;-( */ + out += sprintf(out, "%d %02x:%02x:%ld ", fl->fl_pid, + MAJOR(inode->i_sb->s_dev), + MINOR(inode->i_sb->s_dev), inode->i_ino); +#endif + } else { + out += sprintf(out, "%d <none>:0 ", fl->fl_pid); + } + if (IS_POSIX(fl)) { + if (fl->fl_end == OFFSET_MAX) + out += sprintf(out, "%Ld EOF\n", fl->fl_start); + else + out += sprintf(out, "%Ld %Ld\n", fl->fl_start, + fl->fl_end); + } else { + out += sprintf(out, "0 EOF\n"); + } +} + +static void move_lock_status(char **p, off_t* pos, off_t offset) +{ + int len; + len = strlen(*p); + if(*pos >= offset) { + /* the complete line is valid */ + *p += len; + *pos += len; + return; + } + if(*pos+len > offset) { + /* use the second part of the line */ + int i = offset-*pos; + memmove(*p,*p+i,len-i); + *p += len-i; + *pos += len; + return; + } + /* discard the complete line */ + *pos += len; +} + +/** + * get_locks_status - reports lock usage in /proc/locks + * @buffer: address in userspace to write into + * @start: ? + * @offset: how far we are through the buffer + * @length: how much to read + */ + +int get_locks_status(char *buffer, char **start, off_t offset, int length) +{ + struct list_head *tmp; + char *q = buffer; + off_t pos = 0; + int i = 0; + + lock_kernel(); + list_for_each(tmp, &file_lock_list) { + struct list_head *btmp; + struct file_lock *fl = list_entry(tmp, struct file_lock, fl_link); + lock_get_status(q, fl, ++i, ""); + move_lock_status(&q, &pos, offset); + + if(pos >= offset+length) + goto done; + + list_for_each(btmp, &fl->fl_block) { + struct file_lock *bfl = list_entry(btmp, + struct file_lock, fl_block); + lock_get_status(q, bfl, i, " ->"); + move_lock_status(&q, &pos, offset); + + if(pos >= offset+length) + goto done; + } + } +done: + unlock_kernel(); + *start = buffer; + if(q-buffer < length) + return (q-buffer); + return length; +} + +/** + * lock_may_read - checks that the region is free of locks + * @inode: the inode that is being read + * @start: the first byte to read + * @len: the number of bytes to read + * + * Emulates Windows locking requirements. Whole-file + * mandatory locks (share modes) can prohibit a read and + * byte-range POSIX locks can prohibit a read if they overlap. + * + * N.B. this function is only ever called + * from knfsd and ownership of locks is never checked. + */ +int lock_may_read(struct inode *inode, loff_t start, unsigned long len) +{ + struct file_lock *fl; + int result = 1; + lock_kernel(); + for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) { + if (IS_POSIX(fl)) { + if (fl->fl_type == F_RDLCK) + continue; + if ((fl->fl_end < start) || (fl->fl_start > (start + len))) + continue; + } else if (IS_FLOCK(fl)) { + if (!(fl->fl_type & LOCK_MAND)) + continue; + if (fl->fl_type & LOCK_READ) + continue; + } else + continue; + result = 0; + break; + } + unlock_kernel(); + return result; +} + +EXPORT_SYMBOL(lock_may_read); + +/** + * lock_may_write - checks that the region is free of locks + * @inode: the inode that is being written + * @start: the first byte to write + * @len: the number of bytes to write + * + * Emulates Windows locking requirements. Whole-file + * mandatory locks (share modes) can prohibit a write and + * byte-range POSIX locks can prohibit a write if they overlap. + * + * N.B. this function is only ever called + * from knfsd and ownership of locks is never checked. + */ +int lock_may_write(struct inode *inode, loff_t start, unsigned long len) +{ + struct file_lock *fl; + int result = 1; + lock_kernel(); + for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) { + if (IS_POSIX(fl)) { + if ((fl->fl_end < start) || (fl->fl_start > (start + len))) + continue; + } else if (IS_FLOCK(fl)) { + if (!(fl->fl_type & LOCK_MAND)) + continue; + if (fl->fl_type & LOCK_WRITE) + continue; + } else + continue; + result = 0; + break; + } + unlock_kernel(); + return result; +} + +EXPORT_SYMBOL(lock_may_write); + +static inline void __steal_locks(struct file *file, fl_owner_t from) +{ + struct inode *inode = file->f_dentry->d_inode; + struct file_lock *fl = inode->i_flock; + + while (fl) { + if (fl->fl_file == file && fl->fl_owner == from) + fl->fl_owner = current->files; + fl = fl->fl_next; + } +} + +/* When getting ready for executing a binary, we make sure that current + * has a files_struct on its own. Before dropping the old files_struct, + * we take over ownership of all locks for all file descriptors we own. + * Note that we may accidentally steal a lock for a file that a sibling + * has created since the unshare_files() call. + */ +void steal_locks(fl_owner_t from) +{ + struct files_struct *files = current->files; + int i, j; + + if (from == files) + return; + + lock_kernel(); + j = 0; + for (;;) { + unsigned long set; + i = j * __NFDBITS; + if (i >= files->max_fdset || i >= files->max_fds) + break; + set = files->open_fds->fds_bits[j++]; + while (set) { + if (set & 1) { + struct file *file = files->fd[i]; + if (file) + __steal_locks(file, from); + } + i++; + set >>= 1; + } + } + unlock_kernel(); +} +EXPORT_SYMBOL(steal_locks); + +static int __init filelock_init(void) +{ + filelock_cache = kmem_cache_create("file_lock_cache", + sizeof(struct file_lock), 0, SLAB_PANIC, + init_once, NULL); + return 0; +} + +core_initcall(filelock_init); |
