// SPDX-License-Identifier: GPL-2.0-only /* * linux/fs/locks.c * * We implement four types of file locks: BSD locks, posix locks, open * file description locks, and leases. For details about BSD locks, * see the flock(2) man page; for details about the other three, see * fcntl(2). * * * Locking conflicts and dependencies: * If multiple threads attempt to lock the same byte (or flock the same file) * only one can be granted the lock, and other must wait their turn. * The first lock has been "applied" or "granted", the others are "waiting" * and are "blocked" by the "applied" lock.. * * Waiting and applied locks are all kept in trees whose properties are: * * - the root of a tree may be an applied or waiting lock. * - every other node in the tree is a waiting lock that * conflicts with every ancestor of that node. * * Every such tree begins life as a waiting singleton which obviously * satisfies the above properties. * * The only ways we modify trees preserve these properties: * * 1. We may add a new leaf node, but only after first verifying that it * conflicts with all of its ancestors. * 2. We may remove the root of a tree, creating a new singleton * tree from the root and N new trees rooted in the immediate * children. * 3. If the root of a tree is not currently an applied lock, we may * apply it (if possible). * 4. We may upgrade the root of the tree (either extend its range, * or upgrade its entire range from read to write). * * When an applied lock is modified in a way that reduces or downgrades any * part of its range, we remove all its children (2 above). This particularly * happens when a lock is unlocked. * * For each of those child trees we "wake up" the thread which is * waiting for the lock so it can continue handling as follows: if the * root of the tree applies, we do so (3). If it doesn't, it must * conflict with some applied lock. We remove (wake up) all of its children * (2), and add it is a new leaf to the tree rooted in the applied * lock (1). We then repeat the process recursively with those * children. * */ #include <linux/capability.h> #include <linux/file.h> #include <linux/fdtable.h> #include <linux/filelock.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/sysctl.h> #define CREATE_TRACE_POINTS #include <trace/events/filelock.h> #include <linux/uaccess.h> static struct file_lock *file_lock(struct file_lock_core *flc) { … } static struct file_lease *file_lease(struct file_lock_core *flc) { … } static bool lease_breaking(struct file_lease *fl) { … } static int target_leasetype(struct file_lease *fl) { … } static int leases_enable = …; static int lease_break_time = …; #ifdef CONFIG_SYSCTL static struct ctl_table locks_sysctls[] = …; static int __init init_fs_locks_sysctls(void) { … } early_initcall(init_fs_locks_sysctls); #endif /* CONFIG_SYSCTL */ /* * 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. * Global serialization is done using file_rwsem. * * Note that alterations to the list also require that the relevant flc_lock is * held. */ struct file_lock_list_struct { … }; static DEFINE_PER_CPU(struct file_lock_list_struct, file_lock_list); DEFINE_STATIC_PERCPU_RWSEM(…); /* * 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 … 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_blocked_requests list, and the * fl->fl_blocker 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. */ static DEFINE_SPINLOCK(blocked_lock_lock); static struct kmem_cache *flctx_cache __ro_after_init; static struct kmem_cache *filelock_cache __ro_after_init; static struct kmem_cache *filelease_cache __ro_after_init; static struct file_lock_context * locks_get_lock_context(struct inode *inode, int type) { … } static void locks_dump_ctx_list(struct list_head *list, char *list_type) { … } static void locks_check_ctx_lists(struct inode *inode) { … } static void locks_check_ctx_file_list(struct file *filp, struct list_head *list, char *list_type) { … } void locks_free_lock_context(struct inode *inode) { … } static void locks_init_lock_heads(struct file_lock_core *flc) { … } /* Allocate an empty lock structure. */ struct file_lock *locks_alloc_lock(void) { … } EXPORT_SYMBOL_GPL(…); /* Allocate an empty lock structure. */ struct file_lease *locks_alloc_lease(void) { … } EXPORT_SYMBOL_GPL(…); void locks_release_private(struct file_lock *fl) { … } EXPORT_SYMBOL_GPL(…); /** * locks_owner_has_blockers - Check for blocking lock requests * @flctx: file lock context * @owner: lock owner * * Return values: * %true: @owner has at least one blocker * %false: @owner has no blockers */ bool locks_owner_has_blockers(struct file_lock_context *flctx, fl_owner_t owner) { … } EXPORT_SYMBOL_GPL(…); /* Free a lock which is not in use. */ void locks_free_lock(struct file_lock *fl) { … } EXPORT_SYMBOL(…); /* Free a lease which is not in use. */ void locks_free_lease(struct file_lease *fl) { … } EXPORT_SYMBOL(…); static void locks_dispose_list(struct list_head *dispose) { … } void locks_init_lock(struct file_lock *fl) { … } EXPORT_SYMBOL(…); void locks_init_lease(struct file_lease *fl) { … } EXPORT_SYMBOL(…); /* * Initialize a new lock from an existing file_lock structure. */ void locks_copy_conflock(struct file_lock *new, struct file_lock *fl) { … } EXPORT_SYMBOL(…); void locks_copy_lock(struct file_lock *new, struct file_lock *fl) { … } EXPORT_SYMBOL(…); static void locks_move_blocks(struct file_lock *new, struct file_lock *fl) { … } static inline int flock_translate_cmd(int cmd) { … } /* Fill in a file_lock structure with an appropriate FLOCK lock. */ static void flock_make_lock(struct file *filp, struct file_lock *fl, int type) { … } static int assign_type(struct file_lock_core *flc, int type) { … } static int flock64_to_posix_lock(struct file *filp, struct file_lock *fl, struct flock64 *l) { … } /* 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) { … } /* default lease lock manager operations */ static bool lease_break_callback(struct file_lease *fl) { … } static void lease_setup(struct file_lease *fl, void **priv) { … } static const struct lease_manager_operations lease_manager_ops = …; /* * Initialize a lease, use the default lock manager operations */ static int lease_init(struct file *filp, int type, struct file_lease *fl) { … } /* Allocate a file_lock initialised to this type of lease */ static struct file_lease *lease_alloc(struct file *filp, int type) { … } /* Check if two locks overlap each other. */ static inline int locks_overlap(struct file_lock *fl1, struct file_lock *fl2) { … } /* * Check whether two locks have the same owner. */ static int posix_same_owner(struct file_lock_core *fl1, struct file_lock_core *fl2) { … } /* Must be called with the flc_lock held! */ static void locks_insert_global_locks(struct file_lock_core *flc) { … } /* Must be called with the flc_lock held! */ static void locks_delete_global_locks(struct file_lock_core *flc) { … } static unsigned long posix_owner_key(struct file_lock_core *flc) { … } static void locks_insert_global_blocked(struct file_lock_core *waiter) { … } static void locks_delete_global_blocked(struct file_lock_core *waiter) { … } /* 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_unlink_block(struct file_lock_core *waiter) { … } static void __locks_wake_up_blocks(struct file_lock_core *blocker) { … } static int __locks_delete_block(struct file_lock_core *waiter) { … } /** * locks_delete_block - stop waiting for a file lock * @waiter: the lock which was waiting * * lockd/nfsd need to disconnect the lock while working on it. */ int locks_delete_block(struct file_lock *waiter) { … } EXPORT_SYMBOL(…); /* 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_blocked_requests 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_blocked_requests list is empty. * * Rather than just adding to the list, we check for conflicts with any existing * waiters, and add beneath any waiter that blocks the new waiter. * Thus wakeups don't happen until needed. */ static void __locks_insert_block(struct file_lock_core *blocker, struct file_lock_core *waiter, bool conflict(struct file_lock_core *, struct file_lock_core *)) { … } /* Must be called with flc_lock held. */ static void locks_insert_block(struct file_lock_core *blocker, struct file_lock_core *waiter, bool conflict(struct file_lock_core *, struct file_lock_core *)) { … } /* * 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_core *blocker) { … } static void locks_insert_lock_ctx(struct file_lock_core *fl, struct list_head *before) { … } static void locks_unlink_lock_ctx(struct file_lock_core *fl) { … } static void locks_delete_lock_ctx(struct file_lock_core *fl, struct list_head *dispose) { … } /* Determine if lock sys_fl blocks lock caller_fl. Common functionality * checks for shared/exclusive status of overlapping locks. */ static bool locks_conflict(struct file_lock_core *caller_flc, struct file_lock_core *sys_flc) { … } /* Determine if lock sys_fl blocks lock caller_fl. POSIX specific * checking before calling the locks_conflict(). */ static bool posix_locks_conflict(struct file_lock_core *caller_flc, struct file_lock_core *sys_flc) { … } /* Determine if lock sys_fl blocks lock caller_fl. Used on xx_GETLK * path so checks for additional GETLK-specific things like F_UNLCK. */ static bool posix_test_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl) { … } /* Determine if lock sys_fl blocks lock caller_fl. FLOCK specific * checking before calling the locks_conflict(). */ static bool flock_locks_conflict(struct file_lock_core *caller_flc, struct file_lock_core *sys_flc) { … } void posix_test_lock(struct file *filp, struct file_lock *fl) { … } EXPORT_SYMBOL(…); /* * 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 … /* Find a lock that the owner of the given @blocker is blocking on. */ static struct file_lock_core *what_owner_is_waiting_for(struct file_lock_core *blocker) { … } /* Must be called with the blocked_lock_lock held! */ static bool posix_locks_deadlock(struct file_lock *caller_fl, struct file_lock *block_fl) { … } /* 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) { … } static int posix_lock_inode(struct inode *inode, struct file_lock *request, struct file_lock *conflock) { … } /** * 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) { … } EXPORT_SYMBOL(…); /** * 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) { … } static void lease_clear_pending(struct file_lease *fl, int arg) { … } /* We already had a lease on this file; just change its type */ int lease_modify(struct file_lease *fl, int arg, struct list_head *dispose) { … } EXPORT_SYMBOL(…); static bool past_time(unsigned long then) { … } static void time_out_leases(struct inode *inode, struct list_head *dispose) { … } static bool leases_conflict(struct file_lock_core *lc, struct file_lock_core *bc) { … } static bool any_leases_conflict(struct inode *inode, struct file_lease *breaker) { … } /** * __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) { … } EXPORT_SYMBOL(…); /** * lease_get_mtime - update modified time of an inode with exclusive lease * @inode: the inode * @time: pointer to a timespec which contains 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 timespec64 *time) { … } EXPORT_SYMBOL(…); /** * 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) { … } /** * check_conflicting_open - see if the given file points to an inode that has * an existing open that would conflict with the * desired lease. * @filp: file 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(struct file *filp, const int arg, int flags) { … } static int generic_add_lease(struct file *filp, int arg, struct file_lease **flp, void **priv) { … } static int generic_delete_lease(struct file *filp, void *owner) { … } /** * 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, int arg, struct file_lease **flp, void **priv) { … } EXPORT_SYMBOL(…); /* * Kernel subsystems can register to be notified on any attempt to set * a new lease with the lease_notifier_chain. This is used by (e.g.) nfsd * to close files that it may have cached when there is an attempt to set a * conflicting lease. */ static struct srcu_notifier_head lease_notifier_chain; static inline void lease_notifier_chain_init(void) { … } static inline void setlease_notifier(int arg, struct file_lease *lease) { … } int lease_register_notifier(struct notifier_block *nb) { … } EXPORT_SYMBOL_GPL(…); void lease_unregister_notifier(struct notifier_block *nb) { … } EXPORT_SYMBOL_GPL(…); int kernel_setlease(struct file *filp, int arg, struct file_lease **lease, void **priv) { … } EXPORT_SYMBOL_GPL(…); /** * 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, int arg, struct file_lease **lease, void **priv) { … } EXPORT_SYMBOL_GPL(…); static int do_fcntl_add_lease(unsigned int fd, struct file *filp, int arg) { … } /** * 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, int 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) { … } /** * 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) { … } EXPORT_SYMBOL(…); /** * 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. (DEPRECATED) * * %LOCK_MAND support has been removed from the kernel. */ SYSCALL_DEFINE2(flock, unsigned int, fd, unsigned int, cmd) { … } /** * 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) { … } EXPORT_SYMBOL_GPL(…); /** * locks_translate_pid - translate a file_lock's fl_pid number into a namespace * @fl: The file_lock who's fl_pid should be translated * @ns: The namespace into which the pid should be translated * * Used to translate a fl_pid into a namespace virtual pid number */ static pid_t locks_translate_pid(struct file_lock_core *fl, struct pid_namespace *ns) { … } static int posix_lock_to_flock(struct flock *flock, struct file_lock *fl) { … } #if BITS_PER_LONG == 32 static void posix_lock_to_flock64(struct flock64 *flock, struct file_lock *fl) { flock->l_pid = locks_translate_pid(&fl->c, task_active_pid_ns(current)); 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->c.flc_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 *flock) { … } /** * 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. Additionally EXPORT_OP_ASYNC_LOCK in export_operations * flags need to be 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) { … } EXPORT_SYMBOL_GPL(…); static int do_lock_file_wait(struct file *filp, unsigned int cmd, struct file_lock *fl) { … } /* Ensure that fl->fl_file has compatible f_mode for F_SETLK calls */ static int check_fmode_for_setlk(struct file_lock *fl) { … } /* 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 *flock) { … } #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 *flock) { struct file_lock *fl; int error; fl = locks_alloc_lock(); if (fl == NULL) return -ENOMEM; error = -EINVAL; if (cmd != F_OFD_GETLK && flock->l_type != F_RDLCK && flock->l_type != F_WRLCK) goto out; error = flock64_to_posix_lock(filp, fl, flock); if (error) goto out; if (cmd == F_OFD_GETLK) { error = -EINVAL; if (flock->l_pid != 0) goto out; fl->c.flc_flags |= FL_OFDLCK; fl->c.flc_owner = filp; } error = vfs_test_lock(filp, fl); if (error) goto out; flock->l_type = fl->c.flc_type; if (fl->c.flc_type != F_UNLCK) posix_lock_to_flock64(flock, fl); out: locks_free_lock(fl); 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 *flock) { struct file_lock *file_lock = locks_alloc_lock(); struct file *f; int error; if (file_lock == NULL) return -ENOLCK; 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->c.flc_flags |= FL_OFDLCK; file_lock->c.flc_owner = filp; break; case F_OFD_SETLKW: error = -EINVAL; if (flock->l_pid != 0) goto out; cmd = F_SETLKW64; file_lock->c.flc_flags |= FL_OFDLCK; file_lock->c.flc_owner = filp; fallthrough; case F_SETLKW64: file_lock->c.flc_flags |= FL_SLEEP; } error = do_lock_file_wait(filp, cmd, file_lock); /* * Detect close/fcntl races and recover by zapping all POSIX locks * associated with this file and our files_struct, just like on * filp_flush(). There is no need to do that when we're * unlocking though, or for OFD locks. */ if (!error && file_lock->c.flc_type != F_UNLCK && !(file_lock->c.flc_flags & FL_OFDLCK)) { struct files_struct *files = current->files; /* * 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(&files->file_lock); f = files_lookup_fd_locked(files, fd); spin_unlock(&files->file_lock); if (f != filp) { locks_remove_posix(filp, files); 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) { … } EXPORT_SYMBOL(…); /* The i_flctx must be valid when calling into here */ static void locks_remove_flock(struct file *filp, struct file_lock_context *flctx) { … } /* The i_flctx must be valid when calling into here */ static void locks_remove_lease(struct file *filp, struct file_lock_context *ctx) { … } /* * This function is called on the last close of an open file. */ void locks_remove_file(struct file *filp) { … } /** * 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) { … } EXPORT_SYMBOL_GPL(…); /** * vfs_inode_has_locks - are any file locks held on @inode? * @inode: inode to check for locks * * Return true if there are any FL_POSIX or FL_FLOCK locks currently * set on @inode. */ bool vfs_inode_has_locks(struct inode *inode) { … } EXPORT_SYMBOL_GPL(…); #ifdef CONFIG_PROC_FS #include <linux/proc_fs.h> #include <linux/seq_file.h> struct locks_iterator { … }; static void lock_get_status(struct seq_file *f, struct file_lock_core *flc, loff_t id, char *pfx, int repeat) { … } static struct file_lock_core *get_next_blocked_member(struct file_lock_core *node) { … } static int locks_show(struct seq_file *f, void *v) { … } static void __show_fd_locks(struct seq_file *f, struct list_head *head, int *id, struct file *filp, struct files_struct *files) { … } void show_fd_locks(struct seq_file *f, struct file *filp, struct files_struct *files) { … } static void *locks_start(struct seq_file *f, loff_t *pos) __acquires(&blocked_lock_lock) { … } static void *locks_next(struct seq_file *f, void *v, loff_t *pos) { … } static void locks_stop(struct seq_file *f, void *v) __releases(&blocked_lock_lock) { … } static const struct seq_operations locks_seq_operations = …; static int __init proc_locks_init(void) { … } fs_initcall(proc_locks_init); #endif static int __init filelock_init(void) { … } core_initcall(filelock_init);
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