| /* |
| * 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/security.h> |
| #include <linux/slab.h> |
| #include <linux/syscalls.h> |
| #include <linux/time.h> |
| #include <linux/rcupdate.h> |
| #include <linux/pid_namespace.h> |
| #include <linux/hashtable.h> |
| #include <linux/percpu.h> |
| #include <linux/lglock.h> |
| |
| #define CREATE_TRACE_POINTS |
| #include <trace/events/filelock.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|FL_DELEG|FL_LAYOUT)) |
| #define IS_OFDLCK(fl) (fl->fl_flags & FL_OFDLCK) |
| |
| 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; |
| |
| /* |
| * The global file_lock_list is only used for displaying /proc/locks, so we |
| * keep a list on each CPU, with each list protected by its own spinlock via |
| * the file_lock_lglock. Note that alterations to the list also require that |
| * the relevant flc_lock is held. |
| */ |
| DEFINE_STATIC_LGLOCK(file_lock_lglock); |
| static DEFINE_PER_CPU(struct hlist_head, file_lock_list); |
| |
| /* |
| * The blocked_hash is used to find POSIX lock loops for deadlock detection. |
| * It is protected by blocked_lock_lock. |
| * |
| * We hash locks by lockowner in order to optimize searching for the lock a |
| * particular lockowner is waiting on. |
| * |
| * FIXME: make this value scale via some heuristic? We generally will want more |
| * buckets when we have more lockowners holding locks, but that's a little |
| * difficult to determine without knowing what the workload will look like. |
| */ |
| #define BLOCKED_HASH_BITS 7 |
| static DEFINE_HASHTABLE(blocked_hash, BLOCKED_HASH_BITS); |
| |
| /* |
| * This lock protects the blocked_hash. Generally, if you're accessing it, you |
| * want to be holding this lock. |
| * |
| * In addition, it also protects the fl->fl_block list, and the fl->fl_next |
| * pointer for file_lock structures that are acting as lock requests (in |
| * contrast to those that are acting as records of acquired locks). |
| * |
| * Note that when we acquire this lock in order to change the above fields, |
| * we often hold the flc_lock as well. In certain cases, when reading the fields |
| * protected by this lock, we can skip acquiring it iff we already hold the |
| * flc_lock. |
| * |
| * In particular, adding an entry to the fl_block list requires that you hold |
| * both the flc_lock and the blocked_lock_lock (acquired in that order). |
| * Deleting an entry from the list however only requires the file_lock_lock. |
| */ |
| static DEFINE_SPINLOCK(blocked_lock_lock); |
| |
| static struct kmem_cache *flctx_cache __read_mostly; |
| static struct kmem_cache *filelock_cache __read_mostly; |
| |
| static struct file_lock_context * |
| locks_get_lock_context(struct inode *inode, int type) |
| { |
| struct file_lock_context *ctx; |
| |
| /* paired with cmpxchg() below */ |
| ctx = smp_load_acquire(&inode->i_flctx); |
| if (likely(ctx) || type == F_UNLCK) |
| goto out; |
| |
| ctx = kmem_cache_alloc(flctx_cache, GFP_KERNEL); |
| if (!ctx) |
| goto out; |
| |
| spin_lock_init(&ctx->flc_lock); |
| INIT_LIST_HEAD(&ctx->flc_flock); |
| INIT_LIST_HEAD(&ctx->flc_posix); |
| INIT_LIST_HEAD(&ctx->flc_lease); |
| |
| /* |
| * Assign the pointer if it's not already assigned. If it is, then |
| * free the context we just allocated. |
| */ |
| if (cmpxchg(&inode->i_flctx, NULL, ctx)) { |
| kmem_cache_free(flctx_cache, ctx); |
| ctx = smp_load_acquire(&inode->i_flctx); |
| } |
| out: |
| trace_locks_get_lock_context(inode, type, ctx); |
| return ctx; |
| } |
| |
| static void |
| locks_dump_ctx_list(struct list_head *list, char *list_type) |
| { |
| struct file_lock *fl; |
| |
| list_for_each_entry(fl, list, fl_list) { |
| pr_warn("%s: fl_owner=%p fl_flags=0x%x fl_type=0x%x fl_pid=%u\n", list_type, fl->fl_owner, fl->fl_flags, fl->fl_type, fl->fl_pid); |
| } |
| } |
| |
| static void |
| locks_check_ctx_lists(struct inode *inode) |
| { |
| struct file_lock_context *ctx = inode->i_flctx; |
| |
| if (unlikely(!list_empty(&ctx->flc_flock) || |
| !list_empty(&ctx->flc_posix) || |
| !list_empty(&ctx->flc_lease))) { |
| pr_warn("Leaked locks on dev=0x%x:0x%x ino=0x%lx:\n", |
| MAJOR(inode->i_sb->s_dev), MINOR(inode->i_sb->s_dev), |
| inode->i_ino); |
| locks_dump_ctx_list(&ctx->flc_flock, "FLOCK"); |
| locks_dump_ctx_list(&ctx->flc_posix, "POSIX"); |
| locks_dump_ctx_list(&ctx->flc_lease, "LEASE"); |
| } |
| } |
| |
| void |
| locks_free_lock_context(struct inode *inode) |
| { |
| struct file_lock_context *ctx = inode->i_flctx; |
| |
| if (unlikely(ctx)) { |
| locks_check_ctx_lists(inode); |
| kmem_cache_free(flctx_cache, ctx); |
| } |
| } |
| |
| static void locks_init_lock_heads(struct file_lock *fl) |
| { |
| INIT_HLIST_NODE(&fl->fl_link); |
| INIT_LIST_HEAD(&fl->fl_list); |
| 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_put_owner) { |
| fl->fl_lmops->lm_put_owner(fl->fl_owner); |
| fl->fl_owner = NULL; |
| } |
| 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_list)); |
| BUG_ON(!list_empty(&fl->fl_block)); |
| BUG_ON(!hlist_unhashed(&fl->fl_link)); |
| |
| locks_release_private(fl); |
| kmem_cache_free(filelock_cache, fl); |
| } |
| EXPORT_SYMBOL(locks_free_lock); |
| |
| static void |
| locks_dispose_list(struct list_head *dispose) |
| { |
| struct file_lock *fl; |
| |
| while (!list_empty(dispose)) { |
| fl = list_first_entry(dispose, struct file_lock, fl_list); |
| list_del_init(&fl->fl_list); |
| locks_free_lock(fl); |
| } |
| } |
| |
| 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); |
| |
| /* |
| * Initialize a new lock from an existing file_lock structure. |
| */ |
| void locks_copy_conflock(struct file_lock *new, 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_lmops = fl->fl_lmops; |
| new->fl_ops = NULL; |
| |
| if (fl->fl_lmops) { |
| if (fl->fl_lmops->lm_get_owner) |
| fl->fl_lmops->lm_get_owner(fl->fl_owner); |
| } |
| } |
| EXPORT_SYMBOL(locks_copy_conflock); |
| |
| void locks_copy_lock(struct file_lock *new, struct file_lock *fl) |
| { |
| /* "new" must be a freshly-initialized lock */ |
| WARN_ON_ONCE(new->fl_ops); |
| |
| locks_copy_conflock(new, fl); |
| |
| new->fl_file = fl->fl_file; |
| new->fl_ops = fl->fl_ops; |
| |
| if (fl->fl_ops) { |
| if (fl->fl_ops->fl_copy_lock) |
| fl->fl_ops->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 struct file_lock * |
| flock_make_lock(struct file *filp, unsigned int cmd) |
| { |
| struct file_lock *fl; |
| int type = flock_translate_cmd(cmd); |
| |
| if (type < 0) |
| return ERR_PTR(type); |
| |
| fl = locks_alloc_lock(); |
| if (fl == NULL) |
| return ERR_PTR(-ENOMEM); |
| |
| fl->fl_file = filp; |
| fl->fl_owner = filp; |
| fl->fl_pid = current->tgid; |
| fl->fl_flags = FL_FLOCK; |
| fl->fl_type = type; |
| fl->fl_end = OFFSET_MAX; |
| |
| return fl; |
| } |
| |
| 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; |
| } |
| |
| static int flock64_to_posix_lock(struct file *filp, struct file_lock *fl, |
| struct flock64 *l) |
| { |
| switch (l->l_whence) { |
| case SEEK_SET: |
| fl->fl_start = 0; |
| break; |
| case SEEK_CUR: |
| fl->fl_start = filp->f_pos; |
| break; |
| case SEEK_END: |
| fl->fl_start = i_size_read(file_inode(filp)); |
| break; |
| default: |
| return -EINVAL; |
| } |
| if (l->l_start > OFFSET_MAX - fl->fl_start) |
| return -EOVERFLOW; |
| fl->fl_start += l->l_start; |
| if (fl->fl_start < 0) |
| return -EINVAL; |
| |
| /* POSIX-1996 leaves the case l->l_len < 0 undefined; |
| POSIX-2001 defines it. */ |
| if (l->l_len > 0) { |
| if (l->l_len - 1 > OFFSET_MAX - fl->fl_start) |
| return -EOVERFLOW; |
| fl->fl_end = fl->fl_start + l->l_len - 1; |
| |
| } else if (l->l_len < 0) { |
| if (fl->fl_start + l->l_len < 0) |
| return -EINVAL; |
| fl->fl_end = fl->fl_start - 1; |
| fl->fl_start += l->l_len; |
| } else |
| 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); |
| } |
| |
| /* 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) |
| { |
| struct flock64 ll = { |
| .l_type = l->l_type, |
| .l_whence = l->l_whence, |
| .l_start = l->l_start, |
| .l_len = l->l_len, |
| }; |
| |
| return flock64_to_posix_lock(filp, fl, &ll); |
| } |
| |
| /* default lease lock manager operations */ |
| static bool |
| lease_break_callback(struct file_lock *fl) |
| { |
| kill_fasync(&fl->fl_fasync, SIGIO, POLL_MSG); |
| return false; |
| } |
| |
| static void |
| lease_setup(struct file_lock *fl, void **priv) |
| { |
| struct file *filp = fl->fl_file; |
| struct fasync_struct *fa = *priv; |
| |
| /* |
| * fasync_insert_entry() returns the old entry if any. If there was no |
| * old entry, then it used "priv" and inserted it into the fasync list. |
| * Clear the pointer to indicate that it shouldn't be freed. |
| */ |
| if (!fasync_insert_entry(fa->fa_fd, filp, &fl->fl_fasync, fa)) |
| *priv = NULL; |
| |
| __f_setown(filp, task_pid(current), PIDTYPE_PID, 0); |
| } |
| |
| static const struct lock_manager_operations lease_manager_ops = { |
| .lm_break = lease_break_callback, |
| .lm_change = lease_modify, |
| .lm_setup = lease_setup, |
| }; |
| |
| /* |
| * 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 = filp; |
| 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; |
| } |
| |
| /* Must be called with the flc_lock held! */ |
| static void locks_insert_global_locks(struct file_lock *fl) |
| { |
| lg_local_lock(&file_lock_lglock); |
| fl->fl_link_cpu = smp_processor_id(); |
| hlist_add_head(&fl->fl_link, this_cpu_ptr(&file_lock_list)); |
| lg_local_unlock(&file_lock_lglock); |
| } |
| |
| /* Must be called with the flc_lock held! */ |
| static void locks_delete_global_locks(struct file_lock *fl) |
| { |
| /* |
| * Avoid taking lock if already unhashed. This is safe since this check |
| * is done while holding the flc_lock, and new insertions into the list |
| * also require that it be held. |
| */ |
| if (hlist_unhashed(&fl->fl_link)) |
| return; |
| lg_local_lock_cpu(&file_lock_lglock, fl->fl_link_cpu); |
| hlist_del_init(&fl->fl_link); |
| lg_local_unlock_cpu(&file_lock_lglock, fl->fl_link_cpu); |
| } |
| |
| static unsigned long |
| posix_owner_key(struct file_lock *fl) |
| { |
| if (fl->fl_lmops && fl->fl_lmops->lm_owner_key) |
| return fl->fl_lmops->lm_owner_key(fl); |
| return (unsigned long)fl->fl_owner; |
| } |
| |
| static void locks_insert_global_blocked(struct file_lock *waiter) |
| { |
| lockdep_assert_held(&blocked_lock_lock); |
| |
| hash_add(blocked_hash, &waiter->fl_link, posix_owner_key(waiter)); |
| } |
| |
| static void locks_delete_global_blocked(struct file_lock *waiter) |
| { |
| lockdep_assert_held(&blocked_lock_lock); |
| |
| hash_del(&waiter->fl_link); |
| } |
| |
| /* Remove waiter from blocker's block list. |
| * When blocker ends up pointing to itself then the list is empty. |
| * |
| * Must be called with blocked_lock_lock held. |
| */ |
| static void __locks_delete_block(struct file_lock *waiter) |
| { |
| locks_delete_global_blocked(waiter); |
| list_del_init(&waiter->fl_block); |
| waiter->fl_next = NULL; |
| } |
| |
| static void locks_delete_block(struct file_lock *waiter) |
| { |
| spin_lock(&blocked_lock_lock); |
| __locks_delete_block(waiter); |
| spin_unlock(&blocked_lock_lock); |
| } |
| |
| /* 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. |
| * |
| * Must be called with both the flc_lock and blocked_lock_lock held. The |
| * fl_block list itself is protected by the blocked_lock_lock, but by ensuring |
| * that the flc_lock is also held on insertions we can avoid taking the |
| * blocked_lock_lock in some cases when we see that the fl_block list is empty. |
| */ |
| static void __locks_insert_block(struct file_lock *blocker, |
| struct file_lock *waiter) |
| { |
| BUG_ON(!list_empty(&waiter->fl_block)); |
| waiter->fl_next = blocker; |
| list_add_tail(&waiter->fl_block, &blocker->fl_block); |
| if (IS_POSIX(blocker) && !IS_OFDLCK(blocker)) |
| locks_insert_global_blocked(waiter); |
| } |
| |
| /* Must be called with flc_lock held. */ |
| static void locks_insert_block(struct file_lock *blocker, |
| struct file_lock *waiter) |
| { |
| spin_lock(&blocked_lock_lock); |
| __locks_insert_block(blocker, waiter); |
| spin_unlock(&blocked_lock_lock); |
| } |
| |
| /* |
| * Wake up processes blocked waiting for blocker. |
| * |
| * Must be called with the inode->flc_lock held! |
| */ |
| static void locks_wake_up_blocks(struct file_lock *blocker) |
| { |
| /* |
| * Avoid taking global lock if list is empty. This is safe since new |
| * blocked requests are only added to the list under the flc_lock, and |
| * the flc_lock is always held here. Note that removal from the fl_block |
| * list does not require the flc_lock, so we must recheck list_empty() |
| * after acquiring the blocked_lock_lock. |
| */ |
| if (list_empty(&blocker->fl_block)) |
| return; |
| |
| spin_lock(&blocked_lock_lock); |
| 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); |
| } |
| spin_unlock(&blocked_lock_lock); |
| } |
| |
| static void |
| locks_insert_lock_ctx(struct file_lock *fl, struct list_head *before) |
| { |
| fl->fl_nspid = get_pid(task_tgid(current)); |
| list_add_tail(&fl->fl_list, before); |
| locks_insert_global_locks(fl); |
| } |
| |
| static void |
| locks_unlink_lock_ctx(struct file_lock *fl) |
| { |
| locks_delete_global_locks(fl); |
| list_del_init(&fl->fl_list); |
| if (fl->fl_nspid) { |
| put_pid(fl->fl_nspid); |
| fl->fl_nspid = NULL; |
| } |
| locks_wake_up_blocks(fl); |
| } |
| |
| static void |
| locks_delete_lock_ctx(struct file_lock *fl, struct list_head *dispose) |
| { |
| locks_unlink_lock_ctx(fl); |
| if (dispose) |
| list_add(&fl->fl_list, dispose); |
| else |
| 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 (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 (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; |
| struct file_lock_context *ctx; |
| struct inode *inode = file_inode(filp); |
| |
| ctx = smp_load_acquire(&inode->i_flctx); |
| if (!ctx || list_empty_careful(&ctx->flc_posix)) { |
| fl->fl_type = F_UNLCK; |
| return; |
| } |
| |
| spin_lock(&ctx->flc_lock); |
| list_for_each_entry(cfl, &ctx->flc_posix, fl_list) { |
| if (posix_locks_conflict(fl, cfl)) { |
| locks_copy_conflock(fl, cfl); |
| if (cfl->fl_nspid) |
| fl->fl_pid = pid_vnr(cfl->fl_nspid); |
| goto out; |
| } |
| } |
| fl->fl_type = F_UNLCK; |
| out: |
| spin_unlock(&ctx->flc_lock); |
| 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. |
| * |
| * For FL_OFDLCK locks, the owner is the filp, not the files_struct. |
| * Because the owner is not even nominally tied to a thread of |
| * execution, the deadlock detection below can't reasonably work well. Just |
| * skip it for those. |
| * |
| * In principle, we could do a more limited deadlock detection on FL_OFDLCK |
| * locks that just checks for the case where two tasks are attempting to |
| * upgrade from read to write locks on the same inode. |
| */ |
| |
| #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; |
| |
| hash_for_each_possible(blocked_hash, fl, fl_link, posix_owner_key(block_fl)) { |
| if (posix_same_owner(fl, block_fl)) |
| return fl->fl_next; |
| } |
| return NULL; |
| } |
| |
| /* Must be called with the blocked_lock_lock held! */ |
| static int posix_locks_deadlock(struct file_lock *caller_fl, |
| struct file_lock *block_fl) |
| { |
| int i = 0; |
| |
| lockdep_assert_held(&blocked_lock_lock); |
| |
| /* |
| * This deadlock detector can't reasonably detect deadlocks with |
| * FL_OFDLCK locks, since they aren't owned by a process, per-se. |
| */ |
| if (IS_OFDLCK(caller_fl)) |
| return 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_inode(struct inode *inode, struct file_lock *request) |
| { |
| struct file_lock *new_fl = NULL; |
| struct file_lock *fl; |
| struct file_lock_context *ctx; |
| int error = 0; |
| bool found = false; |
| LIST_HEAD(dispose); |
| |
| ctx = locks_get_lock_context(inode, request->fl_type); |
| if (!ctx) { |
| if (request->fl_type != F_UNLCK) |
| return -ENOMEM; |
| return (request->fl_flags & FL_EXISTS) ? -ENOENT : 0; |
| } |
| |
| if (!(request->fl_flags & FL_ACCESS) && (request->fl_type != F_UNLCK)) { |
| new_fl = locks_alloc_lock(); |
| if (!new_fl) |
| return -ENOMEM; |
| } |
| |
| spin_lock(&ctx->flc_lock); |
| if (request->fl_flags & FL_ACCESS) |
| goto find_conflict; |
| |
| list_for_each_entry(fl, &ctx->flc_flock, fl_list) { |
| if (request->fl_file != fl->fl_file) |
| continue; |
| if (request->fl_type == fl->fl_type) |
| goto out; |
| found = true; |
| locks_delete_lock_ctx(fl, &dispose); |
| break; |
| } |
| |
| if (request->fl_type == F_UNLCK) { |
| if ((request->fl_flags & FL_EXISTS) && !found) |
| error = -ENOENT; |
| goto out; |
| } |
| |
| find_conflict: |
| list_for_each_entry(fl, &ctx->flc_flock, fl_list) { |
| 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_ctx(new_fl, &ctx->flc_flock); |
| new_fl = NULL; |
| error = 0; |
| |
| out: |
| spin_unlock(&ctx->flc_lock); |
| if (new_fl) |
| locks_free_lock(new_fl); |
| locks_dispose_list(&dispose); |
| return error; |
| } |
| |
| static int posix_lock_inode(struct inode *inode, struct file_lock *request, |
| struct file_lock *conflock) |
| { |
| struct file_lock *fl, *tmp; |
| 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_context *ctx; |
| int error; |
| bool added = false; |
| LIST_HEAD(dispose); |
| |
| ctx = locks_get_lock_context(inode, request->fl_type); |
| if (!ctx) |
| return (request->fl_type == F_UNLCK) ? 0 : -ENOMEM; |
| |
| /* |
| * 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(); |
| } |
| |
| spin_lock(&ctx->flc_lock); |
| /* |
| * New lock request. Walk all POSIX locks and look for conflicts. If |
| * there are any, either return error or put the request on the |
| * blocker's list of waiters and the global blocked_hash. |
| */ |
| if (request->fl_type != F_UNLCK) { |
| list_for_each_entry(fl, &ctx->flc_posix, fl_list) { |
| if (!posix_locks_conflict(request, fl)) |
| continue; |
| if (conflock) |
| locks_copy_conflock(conflock, fl); |
| error = -EAGAIN; |
| if (!(request->fl_flags & FL_SLEEP)) |
| goto out; |
| /* |
| * Deadlock detection and insertion into the blocked |
| * locks list must be done while holding the same lock! |
| */ |
| error = -EDEADLK; |
| spin_lock(&blocked_lock_lock); |
| if (likely(!posix_locks_deadlock(request, fl))) { |
| error = FILE_LOCK_DEFERRED; |
| __locks_insert_block(fl, request); |
| } |
| spin_unlock(&blocked_lock_lock); |
| 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 */ |
| list_for_each_entry(fl, &ctx->flc_posix, fl_list) { |
| if (posix_same_owner(request, fl)) |
| break; |
| } |
| |
| /* Process locks with this owner. */ |
| list_for_each_entry_safe_from(fl, tmp, &ctx->flc_posix, fl_list) { |
| if (!posix_same_owner(request, fl)) |
| break; |
| |
| /* 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) |
| continue; |
| /* 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_ctx(fl, &dispose); |
| continue; |
| } |
| request = fl; |
| added = true; |
| } else { |
| /* Processing for different lock types is a bit |
| * more complex. |
| */ |
| if (fl->fl_end < request->fl_start) |
| continue; |
| if (fl->fl_start > request->fl_end) |
| break; |
| if (request->fl_type == F_UNLCK) |
| added = true; |
| 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_ctx(fl, &dispose); |
| continue; |
| } |
| /* |
| * Replace the old lock with new_fl, and |
| * remove the old one. It's safe to do the |
| * insert here since we know that we won't be |
| * using new_fl later, and that the lock is |
| * just replacing an existing lock. |
| */ |
| error = -ENOLCK; |
| if (!new_fl) |
| goto out; |
| locks_copy_lock(new_fl, request); |
| request = new_fl; |
| new_fl = NULL; |
| locks_insert_lock_ctx(request, &fl->fl_list); |
| locks_delete_lock_ctx(fl, &dispose); |
| added = true; |
| } |
| } |
| } |
| |
| /* |
| * 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 below 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_ctx(new_fl, &fl->fl_list); |
| fl = 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_ctx(left, &fl->fl_list); |
| } |
| 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: |
| spin_unlock(&ctx->flc_lock); |
| /* |
| * Free any unused locks. |
| */ |
| if (new_fl) |
| locks_free_lock(new_fl); |
| if (new_fl2) |
| locks_free_lock(new_fl2); |
| locks_dispose_list(&dispose); |
| trace_posix_lock_inode(inode, request, error); |
| |
| 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_inode(file_inode(filp), fl, conflock); |
| } |
| EXPORT_SYMBOL(posix_lock_file); |
| |
| /** |
| * posix_lock_inode_wait - Apply a POSIX-style lock to a file |
| * @inode: inode of file to which lock request should be applied |
| * @fl: The lock to be applied |
| * |
| * Apply a POSIX style lock request to an inode. |
| */ |
| static int posix_lock_inode_wait(struct inode *inode, struct file_lock *fl) |
| { |
| int error; |
| might_sleep (); |
| for (;;) { |
| error = posix_lock_inode(inode, 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; |
| } |
| |
| #ifdef CONFIG_MANDATORY_FILE_LOCKING |
| /** |
| * locks_mandatory_locked - Check for an active lock |
| * @file: 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 file *file) |
| { |
| int ret; |
| struct inode *inode = file_inode(file); |
| struct file_lock_context *ctx; |
| struct file_lock *fl; |
| |
| ctx = smp_load_acquire(&inode->i_flctx); |
| if (!ctx || list_empty_careful(&ctx->flc_posix)) |
| return 0; |
| |
| /* |
| * Search the lock list for this inode for any POSIX locks. |
| */ |
| spin_lock(&ctx->flc_lock); |
| ret = 0; |
| list_for_each_entry(fl, &ctx->flc_posix, fl_list) { |
| if (fl->fl_owner != current->files && |
| fl->fl_owner != file) { |
| ret = -EAGAIN; |
| break; |
| } |
| } |
| spin_unlock(&ctx->flc_lock); |
| return ret; |
| } |
| |
| /** |
| * locks_mandatory_area - Check for a conflicting lock |
| * @inode: the file to check |
| * @filp: how the file was opened (if it was) |
| * @start: first byte in the file to check |
| * @end: lastbyte in the file to check |
| * @type: %F_WRLCK for a write lock, else %F_RDLCK |
| * |
| * Searches the inode's list of locks to find any POSIX locks which conflict. |
| */ |
| int locks_mandatory_area(struct inode *inode, struct file *filp, loff_t start, |
| loff_t end, unsigned char type) |
| { |
| struct file_lock fl; |
| int error; |
| bool sleep = false; |
| |
| locks_init_lock(&fl); |
| fl.fl_pid = current->tgid; |
| fl.fl_file = filp; |
| fl.fl_flags = FL_POSIX | FL_ACCESS; |
| if (filp && !(filp->f_flags & O_NONBLOCK)) |
| sleep = true; |
| fl.fl_type = type; |
| fl.fl_start = start; |
| fl.fl_end = end; |
| |
| for (;;) { |
| if (filp) { |
| fl.fl_owner = filp; |
| fl.fl_flags &= ~FL_SLEEP; |
| error = posix_lock_inode(inode, &fl, NULL); |
| if (!error) |
| break; |
| } |
| |
| if (sleep) |
| fl.fl_flags |= FL_SLEEP; |
| fl.fl_owner = current->files; |
| error = posix_lock_inode(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); |
| #endif /* CONFIG_MANDATORY_FILE_LOCKING */ |
| |
| 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 *fl, int arg, struct list_head *dispose) |
| { |
| int error = assign_type(fl, arg); |
| |
| if (error) |
| return error; |
| lease_clear_pending(fl, arg); |
| locks_wake_up_blocks(fl); |
| if (arg == F_UNLCK) { |
| struct file *filp = fl->fl_file; |
| |
| f_delown(filp); |
| filp->f_owner.signum = 0; |
| 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; |
| } |
| locks_delete_lock_ctx(fl, dispose); |
| } |
| 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 list_head *dispose) |
| { |
| struct file_lock_context *ctx = inode->i_flctx; |
| struct file_lock *fl, *tmp; |
| |
| lockdep_assert_held(&ctx->flc_lock); |
| |
| list_for_each_entry_safe(fl, tmp, &ctx->flc_lease, fl_list) { |
| trace_time_out_leases(inode, fl); |
| if (past_time(fl->fl_downgrade_time)) |
| lease_modify(fl, F_RDLCK, dispose); |
| if (past_time(fl->fl_break_time)) |
| lease_modify(fl, F_UNLCK, dispose); |
| } |
| } |
| |
| static bool leases_conflict(struct file_lock *lease, struct file_lock *breaker) |
| { |
| if ((breaker->fl_flags & FL_LAYOUT) != (lease->fl_flags & FL_LAYOUT)) |
| return false; |
| if ((breaker->fl_flags & FL_DELEG) && (lease->fl_flags & FL_LEASE)) |
| return false; |
| return locks_conflict(breaker, lease); |
| } |
| |
| static bool |
| any_leases_conflict(struct inode *inode, struct file_lock *breaker) |
| { |
| struct file_lock_context *ctx = inode->i_flctx; |
| struct file_lock *fl; |
| |
| lockdep_assert_held(&ctx->flc_lock); |
| |
| list_for_each_entry(fl, &ctx->flc_lease, fl_list) { |
| if (leases_conflict(fl, breaker)) |
| return true; |
| } |
| return false; |
| } |
| |
| /** |
| * __break_lease - revoke all outstanding leases on file |
| * @inode: the inode of the file to return |
| * @mode: O_RDONLY: break only write leases; O_WRONLY or O_RDWR: |
| * break all leases |
| * @type: FL_LEASE: break leases and delegations; FL_DELEG: break |
| * only delegations |
| * |
| * 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, unsigned int type) |
| { |
| int error = 0; |
| struct file_lock_context *ctx; |
| struct file_lock *new_fl, *fl, *tmp; |
| unsigned long break_time; |
| int want_write = (mode & O_ACCMODE) != O_RDONLY; |
| LIST_HEAD(dispose); |
| |
| new_fl = lease_alloc(NULL, want_write ? F_WRLCK : F_RDLCK); |
| if (IS_ERR(new_fl)) |
| return PTR_ERR(new_fl); |
| new_fl->fl_flags = type; |
| |
| /* typically we will check that ctx is non-NULL before calling */ |
| ctx = smp_load_acquire(&inode->i_flctx); |
| if (!ctx) { |
| WARN_ON_ONCE(1); |
| return error; |
| } |
| |
| spin_lock(&ctx->flc_lock); |
| |
| time_out_leases(inode, &dispose); |
| |
| if (!any_leases_conflict(inode, new_fl)) |
| goto out; |
| |
| break_time = 0; |
| if (lease_break_time > 0) { |
| break_time = jiffies + lease_break_time * HZ; |
| if (break_time == 0) |
| break_time++; /* so that 0 means no break time */ |
| } |
| |
| list_for_each_entry_safe(fl, tmp, &ctx->flc_lease, fl_list) { |
| if (!leases_conflict(fl, new_fl)) |
| continue; |
| 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(fl)) |
| continue; |
| fl->fl_flags |= FL_DOWNGRADE_PENDING; |
| fl->fl_downgrade_time = break_time; |
| } |
| if (fl->fl_lmops->lm_break(fl)) |
| locks_delete_lock_ctx(fl, &dispose); |
| } |
| |
| if (list_empty(&ctx->flc_lease)) |
| goto out; |
| |
| if (mode & O_NONBLOCK) { |
| trace_break_lease_noblock(inode, new_fl); |
| error = -EWOULDBLOCK; |
| goto out; |
| } |
| |
| restart: |
| fl = list_first_entry(&ctx->flc_lease, struct file_lock, fl_list); |
| break_time = fl->fl_break_time; |
| if (break_time != 0) |
| break_time -= jiffies; |
| if (break_time == 0) |
| break_time++; |
| locks_insert_block(fl, new_fl); |
| trace_break_lease_block(inode, new_fl); |
| spin_unlock(&ctx->flc_lock); |
| locks_dispose_list(&dispose); |
| error = wait_event_interruptible_timeout(new_fl->fl_wait, |
| !new_fl->fl_next, break_time); |
| spin_lock(&ctx->flc_lock); |
| trace_break_lease_unblock(inode, new_fl); |
| locks_delete_block(new_fl); |
| if (error >= 0) { |
| /* |
| * Wait for the next conflicting lease that has not been |
| * broken yet |
| */ |
| if (error == 0) |
| time_out_leases(inode, &dispose); |
| if (any_leases_conflict(inode, new_fl)) |
| goto restart; |
| error = 0; |
| } |
| out: |
| spin_unlock(&ctx->flc_lock); |
| locks_dispose_list(&dispose); |
| 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) |
| { |
| bool has_lease = false; |
| struct file_lock_context *ctx; |
| struct file_lock *fl; |
| |
| ctx = smp_load_acquire(&inode->i_flctx); |
| if (ctx && !list_empty_careful(&ctx->flc_lease)) { |
| spin_lock(&ctx->flc_lock); |
| fl = list_first_entry_or_null(&ctx->flc_lease, |
| struct file_lock, fl_list); |
| if (fl && (fl->fl_type == F_WRLCK)) |
| has_lease = true; |
| spin_unlock(&ctx->flc_lock); |
| } |
| |
| if (has_lease) |
| *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; |
| struct inode *inode = file_inode(filp); |
| struct file_lock_context *ctx; |
| int type = F_UNLCK; |
| LIST_HEAD(dispose); |
| |
| ctx = smp_load_acquire(&inode->i_flctx); |
| if (ctx && !list_empty_careful(&ctx->flc_lease)) { |
| spin_lock(&ctx->flc_lock); |
| time_out_leases(file_inode(filp), &dispose); |
| list_for_each_entry(fl, &ctx->flc_lease, fl_list) { |
| if (fl->fl_file != filp) |
| continue; |
| type = target_leasetype(fl); |
| break; |
| } |
| spin_unlock(&ctx->flc_lock); |
| locks_dispose_list(&dispose); |
| } |
| return type; |
| } |
| |
| /** |
| * check_conflicting_open - see if the given dentry points to a file that has |
| * an existing open that would conflict with the |
| * desired lease. |
| * @dentry: dentry to check |
| * @arg: type of lease that we're trying to acquire |
| * @flags: current lock flags |
| * |
| * Check to see if there's an existing open fd on this file that would |
| * conflict with the lease we're trying to set. |
| */ |
| static int |
| check_conflicting_open(const struct dentry *dentry, const long arg, int flags) |
| { |
| int ret = 0; |
| struct inode *inode = dentry->d_inode; |
| |
| if (flags & FL_LAYOUT) |
| return 0; |
| |
| if ((arg == F_RDLCK) && (atomic_read(&inode->i_writecount) > 0)) |
| return -EAGAIN; |
| |
| if ((arg == F_WRLCK) && ((d_count(dentry) > 1) || |
| (atomic_read(&inode->i_count) > 1))) |
| ret = -EAGAIN; |
| |
| return ret; |
| } |
| |
| static int |
| generic_add_lease(struct file *filp, long arg, struct file_lock **flp, void **priv) |
| { |
| struct file_lock *fl, *my_fl = NULL, *lease; |
| struct dentry *dentry = filp->f_path.dentry; |
| struct inode *inode = file_inode(filp); |
| struct file_lock_context *ctx; |
| bool is_deleg = (*flp)->fl_flags & FL_DELEG; |
| int error; |
| LIST_HEAD(dispose); |
| |
| lease = *flp; |
| trace_generic_add_lease(inode, lease); |
| |
| /* Note that arg is never F_UNLCK here */ |
| ctx = locks_get_lock_context(inode, arg); |
| if (!ctx) |
| return -ENOMEM; |
| |
| /* |
| * In the delegation case we need mutual exclusion with |
| * a number of operations that take the i_mutex. We trylock |
| * because delegations are an optional optimization, and if |
| * there's some chance of a conflict--we'd rather not |
| * bother, maybe that's a sign this just isn't a good file to |
| * hand out a delegation on. |
| */ |
| if (is_deleg && !inode_trylock(inode)) |
| return -EAGAIN; |
| |
| if (is_deleg && arg == F_WRLCK) { |
| /* Write delegations are not currently supported: */ |
| inode_unlock(inode); |
| WARN_ON_ONCE(1); |
| return -EINVAL; |
| } |
| |
| spin_lock(&ctx->flc_lock); |
| time_out_leases(inode, &dispose); |
| error = check_conflicting_open(dentry, arg, lease->fl_flags); |
| if (error) |
| 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; |
| list_for_each_entry(fl, &ctx->flc_lease, fl_list) { |
| if (fl->fl_file == filp && |
| fl->fl_owner == lease->fl_owner) { |
| my_fl = fl; |
| 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_fl != NULL) { |
| lease = my_fl; |
| error = lease->fl_lmops->lm_change(lease, arg, &dispose); |
| if (error) |
| goto out; |
| goto out_setup; |
| } |
| |
| error = -EINVAL; |
| if (!leases_enable) |
| goto out; |
| |
| locks_insert_lock_ctx(lease, &ctx->flc_lease); |
| /* |
| * The check in break_lease() is lockless. It's possible for another |
| * open to race in after we did the earlier check for a conflicting |
| * open but before the lease was inserted. Check again for a |
| * conflicting open and cancel the lease if there is one. |
| * |
| * We also add a barrier here to ensure that the insertion of the lock |
| * precedes these checks. |
| */ |
| smp_mb(); |
| error = check_conflicting_open(dentry, arg, lease->fl_flags); |
| if (error) { |
| locks_unlink_lock_ctx(lease); |
| goto out; |
| } |
| |
| out_setup: |
| if (lease->fl_lmops->lm_setup) |
| lease->fl_lmops->lm_setup(lease, priv); |
| out: |
| spin_unlock(&ctx->flc_lock); |
| locks_dispose_list(&dispose); |
| if (is_deleg) |
| inode_unlock(inode); |
| if (!error && !my_fl) |
| *flp = NULL; |
| return error; |
| } |
| |
| static int generic_delete_lease(struct file *filp, void *owner) |
| { |
| int error = -EAGAIN; |
| struct file_lock *fl, *victim = NULL; |
| struct inode *inode = file_inode(filp); |
| struct file_lock_context *ctx; |
| LIST_HEAD(dispose); |
| |
| ctx = smp_load_acquire(&inode->i_flctx); |
| if (!ctx) { |
| trace_generic_delete_lease(inode, NULL); |
| return error; |
| } |
| |
| spin_lock(&ctx->flc_lock); |
| list_for_each_entry(fl, &ctx->flc_lease, fl_list) { |
| if (fl->fl_file == filp && |
| fl->fl_owner == owner) { |
| victim = fl; |
| break; |
| } |
| } |
| trace_generic_delete_lease(inode, victim); |
| if (victim) |
| error = fl->fl_lmops->lm_change(victim, F_UNLCK, &dispose); |
| spin_unlock(&ctx->flc_lock); |
| locks_dispose_list(&dispose); |
| return error; |
| } |
| |
| /** |
| * 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 |
| * @priv: private data for lm_setup (may be NULL if lm_setup |
| * doesn't require it) |
| * |
| * The (input) flp->fl_lmops->lm_break function is required |
| * by break_lease(). |
| */ |
| int generic_setlease(struct file *filp, long arg, struct file_lock **flp, |
| void **priv) |
| { |
| struct inode *inode = file_inode(filp); |
| int error; |
| |
| if ((!uid_eq(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; |
| |
| switch (arg) { |
| case F_UNLCK: |
| return generic_delete_lease(filp, *priv); |
| case F_RDLCK: |
| case F_WRLCK: |
| if (!(*flp)->fl_lmops->lm_break) { |
| WARN_ON_ONCE(1); |
| return -ENOLCK; |
| } |
| |
| return generic_add_lease(filp, arg, flp, priv); |
| default: |
| return -EINVAL; |
| } |
| } |
| EXPORT_SYMBOL(generic_setlease); |
| |
| /** |
| * vfs_setlease - sets a lease on an open file |
| * @filp: file pointer |
| * @arg: type of lease to obtain |
| * @lease: file_lock to use when adding a lease |
| * @priv: private info for lm_setup when adding a lease (may be |
| * NULL if lm_setup doesn't require it) |
| * |
| * Call this to establish a lease on the file. The "lease" argument is not |
| * used for F_UNLCK requests and may be NULL. For commands that set or alter |
| * an existing lease, the (*lease)->fl_lmops->lm_break operation must be set; |
| * if not, this function will return -ENOLCK (and generate a scary-looking |
| * stack trace). |
| * |
| * The "priv" pointer is passed directly to the lm_setup function as-is. It |
| * may be NULL if the lm_setup operation doesn't require it. |
| */ |
| int |
| vfs_setlease(struct file *filp, long arg, struct file_lock **lease, void **priv) |
| { |
| if (filp->f_op->setlease) |
| return filp->f_op->setlease(filp, arg, lease, priv); |
| else |
| return generic_setlease(filp, arg, lease, priv); |
| } |
| EXPORT_SYMBOL_GPL(vfs_setlease); |
| |
| static int do_fcntl_add_lease(unsigned int fd, struct file *filp, long arg) |
| { |
| struct file_lock *fl; |
| 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; |
| } |
| new->fa_fd = fd; |
| |
| error = vfs_setlease(filp, arg, &fl, (void **)&new); |
| if (fl) |
| locks_free_lock(fl); |
| 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 vfs_setlease(filp, F_UNLCK, NULL, (void **)&filp); |
| return do_fcntl_add_lease(fd, filp, arg); |
| } |
| |
| /** |
| * flock_lock_inode_wait - Apply a FLOCK-style lock to a file |
| * @inode: inode of the file to apply to |
| * @fl: The lock to be applied |
| * |
| * Apply a FLOCK style lock request to an inode. |
| */ |
| static int flock_lock_inode_wait(struct inode *inode, struct file_lock *fl) |
| { |
| int error; |
| might_sleep(); |
| for (;;) { |
| error = flock_lock_inode(inode, 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; |
| } |
| |
| /** |
| * locks_lock_inode_wait - Apply a lock to an inode |
| * @inode: inode of the file to apply to |
| * @fl: The lock to be applied |
| * |
| * Apply a POSIX or FLOCK style lock request to an inode. |
| */ |
| int locks_lock_inode_wait(struct inode *inode, struct file_lock *fl) |
| { |
| int res = 0; |
| switch (fl->fl_flags & (FL_POSIX|FL_FLOCK)) { |
| case FL_POSIX: |
| res = posix_lock_inode_wait(inode, fl); |
| break; |
| case FL_FLOCK: |
| res = flock_lock_inode_wait(inode, fl); |
| break; |
| default: |
| BUG(); |
| } |
| return res; |
| } |
| EXPORT_SYMBOL(locks_lock_inode_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 fd f = fdget(fd); |
| struct file_lock *lock; |
| int can_sleep, unlock; |
| int error; |
| |
| error = -EBADF; |
| if (!f.file) |
| goto out; |
| |
| can_sleep = !(cmd & LOCK_NB); |
| cmd &= ~LOCK_NB; |
| unlock = (cmd == LOCK_UN); |
| |
| if (!unlock && !(cmd & LOCK_MAND) && |
| !(f.file->f_mode & (FMODE_READ|FMODE_WRITE))) |
| goto out_putf; |
| |
| lock = flock_make_lock(f.file, cmd); |
| if (IS_ERR(lock)) { |
| error = PTR_ERR(lock); |
| goto out_putf; |
| } |
| |
| if (can_sleep) |
| lock->fl_flags |= FL_SLEEP; |
| |
| error = security_file_lock(f.file, lock->fl_type); |
| if (error) |
| goto out_free; |
| |
| if (f.file->f_op->flock) |
| error = f.file->f_op->flock(f.file, |
| (can_sleep) ? F_SETLKW : F_SETLK, |
| lock); |
| else |
| error = locks_lock_file_wait(f.file, lock); |
| |
| out_free: |
| locks_free_lock(lock); |
| |
| out_putf: |
| fdput(f); |
| 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->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_OFDLCK(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_OFDLCK(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) { |
| error = -EINVAL; |
| if (flock.l_pid != 0) |
| goto out; |
| |
| cmd = F_GETLK; |
| file_lock.fl_flags |= FL_OFDLCK; |
| file_lock.fl_owner = 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 rel_priv; |
| } |
| error = -EFAULT; |
| if (!copy_to_user(l, &flock, sizeof(flock))) |
| error = 0; |
| rel_priv: |
| locks_release_private(&file_lock); |
| 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->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; |
| } |
| |
| /* Ensure that fl->fl_file has compatible f_mode for F_SETLK calls */ |
| static int |
| check_fmode_for_setlk(struct file_lock *fl) |
| { |
| switch (fl->fl_type) { |
| case F_RDLCK: |
| if (!(fl->fl_file->f_mode & FMODE_READ)) |
| return -EBADF; |
| break; |
| case F_WRLCK: |
| if (!(fl->fl_file->f_mode & FMODE_WRITE)) |
| return -EBADF; |
| } |
| return 0; |
| } |
| |
| /* 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; |
| |
| inode = file_inode(filp); |
| |
| /* |
| * This might block, so we do it before checking the inode. |
| */ |
| error = -EFAULT; |
| if (copy_from_user(&flock, l, sizeof(flock))) |
| goto out; |
| |
| /* 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; |
| } |
| |
| error = flock_to_posix_lock(filp, file_lock, &flock); |
| if (error) |
| goto out; |
| |
| error = check_fmode_for_setlk(file_lock); |
| if (error) |
| goto out; |
| |
| /* |
| * If the cmd is requesting file-private locks, then set the |
| * FL_OFDLCK flag and override the owner. |
| */ |
| switch (cmd) { |
| case F_OFD_SETLK: |
| error = -EINVAL; |
| if (flock.l_pid != 0) |
| goto out; |
| |
| cmd = F_SETLK; |
| file_lock->fl_flags |= FL_OFDLCK; |
| file_lock->fl_owner = filp; |
| break; |
| case F_OFD_SETLKW: |
| error = -EINVAL; |
| if (flock.l_pid != 0) |
| goto out; |
| |
| cmd = F_SETLKW; |
| file_lock->fl_flags |= FL_OFDLCK; |
| file_lock->fl_owner = filp; |
| /* Fallthrough */ |
| case F_SETLKW: |
| file_lock->fl_flags |= FL_SLEEP; |
| } |
| |
| 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. There is no need to do that when we're |
| * unlocking though, or for OFD locks. |
| */ |
| if (!error && file_lock->fl_type != F_UNLCK && |
| !(file_lock->fl_flags & FL_OFDLCK)) { |
| /* |
| * We need that spin_lock here - it prevents reordering between |
| * update of i_flctx->flc_posix 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 (f != filp) { |
| file_lock->fl_type = F_UNLCK; |
| error = do_lock_file_wait(filp, cmd, file_lock); |
| WARN_ON_ONCE(error); |
| error = -EBADF; |
| } |
| } |
| out: |
| trace_fcntl_setlk(inode, file_lock, error); |
| 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) { |
| error = -EINVAL; |
| if (flock.l_pid != 0) |
| goto out; |
| |
| cmd = F_GETLK64; |
| file_lock.fl_flags |= FL_OFDLCK; |
| file_lock.fl_owner = 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; |
| |
| locks_release_private(&file_lock); |
| 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 = file_inode(filp); |
| |
| /* 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; |
| } |
| |
| error = flock64_to_posix_lock(filp, file_lock, &flock); |
| if (error) |
| goto out; |
| |
| error = check_fmode_for_setlk(file_lock); |
| if (error) |
| goto out; |
| |
| /* |
| * If the cmd is requesting file-private locks, then set the |
| * FL_OFDLCK flag and override the owner. |
| */ |
| switch (cmd) { |
| case F_OFD_SETLK: |
| error = -EINVAL; |
| if (flock.l_pid != 0) |
| goto out; |
| |
| cmd = F_SETLK64; |
| file_lock->fl_flags |= FL_OFDLCK; |
| file_lock->fl_owner = filp; |
| break; |
| case F_OFD_SETLKW: |
| error = -EINVAL; |
| if (flock.l_pid != 0) |
| goto out; |
| |
| cmd = F_SETLKW64; |
| file_lock->fl_flags |= FL_OFDLCK; |
| file_lock->fl_owner = filp; |
| /* Fallthrough */ |
| case F_SETLKW64: |
| file_lock->fl_flags |= FL_SLEEP; |
| } |
| |
| 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. There is no need to do that when we're |
| * unlocking though, or for OFD locks. |
| */ |
| if (!error && file_lock->fl_type != F_UNLCK && |
| !(file_lock->fl_flags & FL_OFDLCK)) { |
| /* |
| * We need that spin_lock here - it prevents reordering between |
| * update of i_flctx->flc_posix 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 (f != filp) { |
| file_lock->fl_type = F_UNLCK; |
| error = do_lock_file_wait(filp, cmd, file_lock); |
| WARN_ON_ONCE(error); |
| error = -EBADF; |
| } |
| } |
| 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) |
| { |
| int error; |
| struct file_lock lock; |
| struct file_lock_context *ctx; |
| |
| /* |
| * 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. |
| */ |
| ctx = smp_load_acquire(&file_inode(filp)->i_flctx); |
| if (!ctx || list_empty(&ctx->flc_posix)) |
| 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; |
| |
| error = 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); |
| trace_locks_remove_posix(file_inode(filp), &lock, error); |
| } |
| |
| EXPORT_SYMBOL(locks_remove_posix); |
| |
| /* The i_flctx must be valid when calling into here */ |
| static void |
| locks_remove_flock(struct file *filp, struct file_lock_context *flctx) |
| { |
| struct file_lock fl = { |
| .fl_owner = filp, |
| .fl_pid = current->tgid, |
| .fl_file = filp, |
| .fl_flags = FL_FLOCK, |
| .fl_type = F_UNLCK, |
| .fl_end = OFFSET_MAX, |
| }; |
| struct inode *inode = file_inode(filp); |
| |
| if (list_empty(&flctx->flc_flock)) |
| return; |
| |
| if (filp->f_op->flock) |
| filp->f_op->flock(filp, F_SETLKW, &fl); |
| else |
| flock_lock_inode(inode, &fl); |
| |
| if (fl.fl_ops && fl.fl_ops->fl_release_private) |
| fl.fl_ops->fl_release_private(&fl); |
| } |
| |
| /* The i_flctx must be valid when calling into here */ |
| static void |
| locks_remove_lease(struct file *filp, struct file_lock_context *ctx) |
| { |
| struct file_lock *fl, *tmp; |
| LIST_HEAD(dispose); |
| |
| if (list_empty(&ctx->flc_lease)) |
| return; |
| |
| spin_lock(&ctx->flc_lock); |
| list_for_each_entry_safe(fl, tmp, &ctx->flc_lease, fl_list) |
| if (filp == fl->fl_file) |
| lease_modify(fl, F_UNLCK, &dispose); |
| spin_unlock(&ctx->flc_lock); |
| locks_dispose_list(&dispose); |
| } |
| |
| /* |
| * This function is called on the last close of an open file. |
| */ |
| void locks_remove_file(struct file *filp) |
| { |
| struct file_lock_context *ctx; |
| |
| ctx = smp_load_acquire(&file_inode(filp)->i_flctx); |
| if (!ctx) |
| return; |
| |
| /* remove any OFD locks */ |
| locks_remove_posix(filp, filp); |
| |
| /* remove flock locks */ |
| locks_remove_flock(filp, ctx); |
| |
| /* remove any leases */ |
| locks_remove_lease(filp, ctx); |
| } |
| |
| /** |
| * posix_unblock_lock - stop waiting for a file lock |
| * @waiter: the lock which was waiting |
| * |
| * lockd needs to block waiting for locks. |
| */ |
| int |
| posix_unblock_lock(struct file_lock *waiter) |
| { |
| int status = 0; |
| |
| spin_lock(&blocked_lock_lock); |
| if (waiter->fl_next) |
| __locks_delete_block(waiter); |
| else |
| status = -ENOENT; |
| spin_unlock(&blocked_lock_lock); |
| 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->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> |
| |
| struct locks_iterator { |
| int li_cpu; |
| loff_t li_pos; |
| }; |
| |
| 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 = file_inode(fl->fl_file); |
| |
| seq_printf(f, "%lld:%s ", id, pfx); |
| if (IS_POSIX(fl)) { |
| if (fl->fl_flags & FL_ACCESS) |
| seq_puts(f, "ACCESS"); |
| else if (IS_OFDLCK(fl)) |
| seq_puts(f, "OFDLCK"); |
| else |
| seq_puts(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_puts(f, "FLOCK MSNFS "); |
| } else { |
| seq_puts(f, "FLOCK ADVISORY "); |
| } |
| } else if (IS_LEASE(fl)) { |
| if (fl->fl_flags & FL_DELEG) |
| seq_puts(f, "DELEG "); |
| else |
| seq_puts(f, "LEASE "); |
| |
| if (lease_breaking(fl)) |
| seq_puts(f, "BREAKING "); |
| else if (fl->fl_file) |
| seq_puts(f, "ACTIVE "); |
| else |
| seq_puts(f, "BREAKER "); |
| } else { |
| seq_puts(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) { |
| /* 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); |
| } 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_puts(f, "0 EOF\n"); |
| } |
| } |
| |
| static int locks_show(struct seq_file *f, void *v) |
| { |
| struct locks_iterator *iter = f->private; |
| struct file_lock *fl, *bfl; |
| |
| fl = hlist_entry(v, struct file_lock, fl_link); |
| |
| lock_get_status(f, fl, iter->li_pos, ""); |
| |
| list_for_each_entry(bfl, &fl->fl_block, fl_block) |
| lock_get_status(f, bfl, iter->li_pos, " ->"); |
| |
| return 0; |
| } |
| |
| static void __show_fd_locks(struct seq_file *f, |
| struct list_head *head, int *id, |
| struct file *filp, struct files_struct *files) |
| { |
| struct file_lock *fl; |
| |
| list_for_each_entry(fl, head, fl_list) { |
| |
| if (filp != fl->fl_file) |
| continue; |
| if (fl->fl_owner != files && |
| fl->fl_owner != filp) |
| continue; |
| |
| (*id)++; |
| seq_puts(f, "lock:\t"); |
| lock_get_status(f, fl, *id, ""); |
| } |
| } |
| |
| void show_fd_locks(struct seq_file *f, |
| struct file *filp, struct files_struct *files) |
| { |
| struct inode *inode = file_inode(filp); |
| struct file_lock_context *ctx; |
| int id = 0; |
| |
| ctx = smp_load_acquire(&inode->i_flctx); |
| if (!ctx) |
| return; |
| |
| spin_lock(&ctx->flc_lock); |
| __show_fd_locks(f, &ctx->flc_flock, &id, filp, files); |
| __show_fd_locks(f, &ctx->flc_posix, &id, filp, files); |
| __show_fd_locks(f, &ctx->flc_lease, &id, filp, files); |
| spin_unlock(&ctx->flc_lock); |
| } |
| |
| static void *locks_start(struct seq_file *f, loff_t *pos) |
| __acquires(&blocked_lock_lock) |
| { |
| struct locks_iterator *iter = f->private; |
| |
| iter->li_pos = *pos + 1; |
| lg_global_lock(&file_lock_lglock); |
| spin_lock(&blocked_lock_lock); |
| return seq_hlist_start_percpu(&file_lock_list, &iter->li_cpu, *pos); |
| } |
| |
| static void *locks_next(struct seq_file *f, void *v, loff_t *pos) |
| { |
| struct locks_iterator *iter = f->private; |
| |
| ++iter->li_pos; |
| return seq_hlist_next_percpu(v, &file_lock_list, &iter->li_cpu, pos); |
| } |
| |
| static void locks_stop(struct seq_file *f, void *v) |
| __releases(&blocked_lock_lock) |
| { |
| spin_unlock(&blocked_lock_lock); |
| lg_global_unlock(&file_lock_lglock); |
| } |
| |
| 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(struct locks_iterator)); |
| } |
| |
| 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; |
| } |
| fs_initcall(proc_locks_init); |
| #endif |
| |
| static int __init filelock_init(void) |
| { |
| int i; |
| |
| flctx_cache = kmem_cache_create("file_lock_ctx", |
| sizeof(struct file_lock_context), 0, SLAB_PANIC, NULL); |
| |
| filelock_cache = kmem_cache_create("file_lock_cache", |
| sizeof(struct file_lock), 0, SLAB_PANIC, NULL); |
| |
| lg_lock_init(&file_lock_lglock, "file_lock_lglock"); |
| |
| for_each_possible_cpu(i) |
| INIT_HLIST_HEAD(per_cpu_ptr(&file_lock_list, i)); |
| |
| return 0; |
| } |
| |
| core_initcall(filelock_init); |