/* * linux/fs/locks.c * * Provide support for fcntl()'s F_GETLK, F_SETLK, and F_SETLKW calls. * Doug Evans (dje@spiff.uucp), August 07, 1992 * * Deadlock detection added. * FIXME: one thing isn't handled yet: * - mandatory locks (requires lots of changes elsewhere) * Kelly Carmichael (kelly@[142.24.8.65]), September 17, 1994. * * Miscellaneous edits, and a total rewrite of posix_lock_file() code. * Kai Petzke (wpp@marie.physik.tu-berlin.de), 1994 * * Converted file_lock_table to a linked list from an array, which eliminates * the limits on how many active file locks are open. * Chad Page (pageone@netcom.com), November 27, 1994 * * Removed dependency on file descriptors. dup()'ed file descriptors now * get the same locks as the original file descriptors, and a close() on * any file descriptor removes ALL the locks on the file for the current * process. Since locks still depend on the process id, locks are inherited * after an exec() but not after a fork(). This agrees with POSIX, and both * BSD and SVR4 practice. * Andy Walker (andy@lysaker.kvaerner.no), February 14, 1995 * * Scrapped free list which is redundant now that we allocate locks * dynamically with kmalloc()/kfree(). * Andy Walker (andy@lysaker.kvaerner.no), February 21, 1995 * * Implemented two lock personalities - FL_FLOCK and FL_POSIX. * * FL_POSIX locks are created with calls to fcntl() and lockf() through the * fcntl() system call. They have the semantics described above. * * FL_FLOCK locks are created with calls to flock(), through the flock() * system call, which is new. Old C libraries implement flock() via fcntl() * and will continue to use the old, broken implementation. * * FL_FLOCK locks follow the 4.4 BSD flock() semantics. They are associated * with a file pointer (filp). As a result they can be shared by a parent * process and its children after a fork(). They are removed when the last * file descriptor referring to the file pointer is closed (unless explicitly * unlocked). * * FL_FLOCK locks never deadlock, an existing lock is always removed before * upgrading from shared to exclusive (or vice versa). When this happens * any processes blocked by the current lock are woken up and allowed to * run before the new lock is applied. * Andy Walker (andy@lysaker.kvaerner.no), June 09, 1995 * * Removed some race conditions in flock_lock_file(), marked other possible * races. Just grep for FIXME to see them. * Dmitry Gorodchanin (pgmdsg@ibi.com), February 09, 1996. * * Addressed Dmitry's concerns. Deadlock checking no longer recursive. * Lock allocation changed to GFP_ATOMIC as we can't afford to sleep * once we've checked for blocking and deadlocking. * Andy Walker (andy@lysaker.kvaerner.no), April 03, 1996. * * Initial implementation of mandatory locks. SunOS turned out to be * a rotten model, so I implemented the "obvious" semantics. * See 'Documentation/mandatory.txt' for details. * Andy Walker (andy@lysaker.kvaerner.no), April 06, 1996. * * Don't allow mandatory locks on mmap()'ed files. Added simple functions to * check if a file has mandatory locks, used by mmap(), open() and creat() to * see if system call should be rejected. Ref. HP-UX/SunOS/Solaris Reference * Manual, Section 2. * Andy Walker (andy@lysaker.kvaerner.no), April 09, 1996. * * Tidied up block list handling. Added '/proc/locks' interface. * Andy Walker (andy@lysaker.kvaerner.no), April 24, 1996. * * Fixed deadlock condition for pathological code that mixes calls to * flock() and fcntl(). * Andy Walker (andy@lysaker.kvaerner.no), April 29, 1996. * * Allow only one type of locking scheme (FL_POSIX or FL_FLOCK) to be in use * for a given file at a time. Changed the CONFIG_LOCK_MANDATORY scheme to * guarantee sensible behaviour in the case where file system modules might * be compiled with different options than the kernel itself. * Andy Walker (andy@lysaker.kvaerner.no), May 15, 1996. * * Added a couple of missing wake_up() calls. Thanks to Thomas Meckel * (Thomas.Meckel@mni.fh-giessen.de) for spotting this. * Andy Walker (andy@lysaker.kvaerner.no), May 15, 1996. * * Changed FL_POSIX locks to use the block list in the same way as FL_FLOCK * locks. Changed process synchronisation to avoid dereferencing locks that * have already been freed. * Andy Walker (andy@lysaker.kvaerner.no), Sep 21, 1996. * * Made the block list a circular list to minimise searching in the list. * Andy Walker (andy@lysaker.kvaerner.no), Sep 25, 1996. * * Made mandatory locking a mount option. Default is not to allow mandatory * locking. * Andy Walker (andy@lysaker.kvaerner.no), Oct 04, 1996. * * Some adaptations for NFS support. * Olaf Kirch (okir@monad.swb.de), Dec 1996, * * Fixed /proc/locks interface so that we can't overrun the buffer we are handed. * Andy Walker (andy@lysaker.kvaerner.no), May 12, 1997. * * Use slab allocator instead of kmalloc/kfree. * Use generic list implementation from <linux/list.h>. * Sped up posix_locks_deadlock by only considering blocked locks. * Matthew Wilcox <willy@debian.org>, March, 2000. * * Leases and LOCK_MAND * Matthew Wilcox <willy@debian.org>, June, 2000. * Stephen Rothwell <sfr@canb.auug.org.au>, June, 2000. */ #include <linux/capability.h>#include <linux/file.h>#include <linux/fs.h>#include <linux/init.h>#include <linux/module.h>#include <linux/security.h>#include <linux/slab.h>#include <linux/smp_lock.h>#include <linux/syscalls.h>#include <linux/time.h>#include <linux/rcupdate.h> #include <asm/semaphore.h>#include <asm/uaccess.h> #define IS_POSIX(fl) (fl->fl_flags & FL_POSIX)#define IS_FLOCK(fl) (fl->fl_flags & FL_FLOCK)#define IS_LEASE(fl) (fl->fl_flags & FL_LEASE) int leases_enable = 1;int lease_break_time = 45; #define for_each_lock(inode, lockp) \ for (lockp = &inode->i_flock; *lockp != NULL; lockp = &(*lockp)->fl_next) static LIST_HEAD(file_lock_list);static LIST_HEAD(blocked_list); static struct kmem_cache *filelock_cache __read_mostly; /* Allocate an empty lock structure. */static struct file_lock *locks_alloc_lock(void){ return kmem_cache_alloc(filelock_cache, GFP_KERNEL);} static void locks_release_private(struct file_lock *fl){ if (fl->fl_ops) { if (fl->fl_ops->fl_release_private) fl->fl_ops->fl_release_private(fl); fl->fl_ops = NULL; } if (fl->fl_lmops) { if (fl->fl_lmops->fl_release_private) fl->fl_lmops->fl_release_private(fl); fl->fl_lmops = NULL; } } /* Free a lock which is not in use. */static void locks_free_lock(struct file_lock *fl){ BUG_ON(waitqueue_active(&fl->fl_wait)); BUG_ON(!list_empty(&fl->fl_block)); BUG_ON(!list_empty(&fl->fl_link)); locks_release_private(fl); kmem_cache_free(filelock_cache, fl);} void locks_init_lock(struct file_lock *fl){ INIT_LIST_HEAD(&fl->fl_link); INIT_LIST_HEAD(&fl->fl_block); init_waitqueue_head(&fl->fl_wait); fl->fl_next = NULL; fl->fl_fasync = NULL; fl->fl_owner = NULL; fl->fl_pid = 0; fl->fl_file = NULL; fl->fl_flags = 0; fl->fl_type = 0; fl->fl_start = fl->fl_end = 0; fl->fl_ops = NULL; fl->fl_lmops = NULL;} EXPORT_SYMBOL(locks_init_lock); /* * Initialises the fields of the file lock which are invariant for * free file_locks. */static void init_once(void *foo, struct kmem_cache *cache, unsigned long flags){ struct file_lock *lock = (struct file_lock *) foo; if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) != SLAB_CTOR_CONSTRUCTOR) return; locks_init_lock(lock);} static void locks_copy_private(struct file_lock *new, struct file_lock *fl){ if (fl->fl_ops) { if (fl->fl_ops->fl_copy_lock) fl->fl_ops->fl_copy_lock(new, fl); new->fl_ops = fl->fl_ops; } if (fl->fl_lmops) { if (fl->fl_lmops->fl_copy_lock) fl->fl_lmops->fl_copy_lock(new, fl); new->fl_lmops = fl->fl_lmops; }} /* * Initialize a new lock from an existing file_lock structure. */static void __locks_copy_lock(struct file_lock *new, const struct file_lock *fl){ new->fl_owner = fl->fl_owner; new->fl_pid = fl->fl_pid; new->fl_file = NULL; new->fl_flags = fl->fl_flags; new->fl_type = fl->fl_type; new->fl_start = fl->fl_start; new->fl_end = fl->fl_end; new->fl_ops = NULL; new->fl_lmops = NULL;} void locks_copy_lock(struct file_lock *new, struct file_lock *fl){ locks_release_private(new); __locks_copy_lock(new, fl); new->fl_file = fl->fl_file; new->fl_ops = fl->fl_ops; new->fl_lmops = fl->fl_lmops; locks_copy_private(new, fl);} EXPORT_SYMBOL(locks_copy_lock); static inline int flock_translate_cmd(int cmd) { if (cmd & LOCK_MAND) return cmd & (LOCK_MAND | LOCK_RW); switch (cmd) { case LOCK_SH: return F_RDLCK; case LOCK_EX: return F_WRLCK; case LOCK_UN: return F_UNLCK; } return -EINVAL;} /* Fill in a file_lock structure with an appropriate FLOCK lock. */static int flock_make_lock(struct file *filp, struct file_lock **lock, unsigned int cmd){ struct file_lock *fl; int type = flock_translate_cmd(cmd); if (type < 0) return type; fl = locks_alloc_lock(); if (fl == NULL) return -ENOMEM; fl->fl_file = filp; fl->fl_pid = current->tgid; fl->fl_flags = FL_FLOCK; fl->fl_type = type; fl->fl_end = OFFSET_MAX; *lock = fl; return 0;} static int assign_type(struct file_lock *fl, int type){ switch (type) { case F_RDLCK: case F_WRLCK: case F_UNLCK: fl->fl_type = type; break; default: return -EINVAL; } return 0;} /* Verify a "struct flock" and copy it to a "struct file_lock" as a POSIX * style lock. */static int flock_to_posix_lock(struct file *filp, struct file_lock *fl, struct flock *l){ off_t start, end; switch (l->l_whence) { case SEEK_SET: start = 0; break; case SEEK_CUR: start = filp->f_pos; break; case SEEK_END: start = i_size_read(filp->f_path.dentry->d_inode); break; default: return -EINVAL; } /* POSIX-1996 leaves the case l->l_len < 0 undefined; POSIX-2001 defines it. */ start += l->l_start; if (start < 0) return -EINVAL; fl->fl_end = OFFSET_MAX; if (l->l_len > 0) { end = start + l->l_len - 1; fl->fl_end = end; } else if (l->l_len < 0) { end = start - 1; fl->fl_end = end; start += l->l_len; if (start < 0) return -EINVAL; } fl->fl_start = start; /* we record the absolute position */ if (fl->fl_end < fl->fl_start) return -EOVERFLOW; fl->fl_owner = current->files; fl->fl_pid = current->tgid; fl->fl_file = filp; fl->fl_flags = FL_POSIX; fl->fl_ops = NULL; fl->fl_lmops = NULL; return assign_type(fl, l->l_type);} #if BITS_PER_LONG == 32static int flock64_to_posix_lock(struct file *filp, struct file_lock *fl, struct flock64 *l){ loff_t start; switch (l->l_whence) { case SEEK_SET: start = 0; break; case SEEK_CUR: start = filp->f_pos; break; case SEEK_END: start = i_size_read(filp->f_path.dentry->d_inode); break; default: return -EINVAL; } start += l->l_start; if (start < 0) return -EINVAL; fl->fl_end = OFFSET_MAX; if (l->l_len > 0) { fl->fl_end = start + l->l_len - 1; } else if (l->l_len < 0) { fl->fl_end = start - 1; start += l->l_len; if (start < 0) return -EINVAL; } fl->fl_start = start; /* we record the absolute position */ if (fl->fl_end < fl->fl_start) return -EOVERFLOW; fl->fl_owner = current->files; fl->fl_pid = current->tgid; fl->fl_file = filp; fl->fl_flags = FL_POSIX; fl->fl_ops = NULL; fl->fl_lmops = NULL; switch (l->l_type) { case F_RDLCK: case F_WRLCK: case F_UNLCK: fl->fl_type = l->l_type; break; default: return -EINVAL; } return (0);}#endif /* default lease lock manager operations */static void lease_break_callback(struct file_lock *fl){ kill_fasync(&fl->fl_fasync, SIGIO, POLL_MSG);} static void lease_release_private_callback(struct file_lock *fl){ if (!fl->fl_file) return; f_delown(fl->fl_file); fl->fl_file->f_owner.signum = 0;} static int lease_mylease_callback(struct file_lock *fl, struct file_lock *try){ return fl->fl_file == try->fl_file;} static struct lock_manager_operations lease_manager_ops = { .fl_break = lease_break_callback, .fl_release_private = lease_release_private_callback, .fl_mylease = lease_mylease_callback, .fl_change = lease_modify,}; /* * Initialize a lease, use the default lock manager operations */static int lease_init(struct file *filp, int type, struct file_lock *fl) { if (assign_type(fl, type) != 0) return -EINVAL; fl->fl_owner = current->files; fl->fl_pid = current->tgid; fl->fl_file = filp; fl->fl_flags = FL_LEASE; fl->fl_start = 0; fl->fl_end = OFFSET_MAX; fl->fl_ops = NULL; fl->fl_lmops = &lease_manager_ops; return 0;} /* Allocate a file_lock initialised to this type of lease */static int lease_alloc(struct file *filp, int type, struct file_lock **flp){ struct file_lock *fl = locks_alloc_lock(); int error = -ENOMEM; if (fl == NULL) goto out; error = lease_init(filp, type, fl); if (error) { locks_free_lock(fl); fl = NULL; }out: *flp = fl; return error;} /* Check if two locks overlap each other. */static inline int locks_overlap(struct file_lock *fl1, struct file_lock *fl2){ return ((fl1->fl_end >= fl2->fl_start) && (fl2->fl_end >= fl1->fl_start));} /* * Check whether two locks have the same owner. */static int posix_same_owner(struct file_lock *fl1, struct file_lock *fl2){ if (fl1->fl_lmops && fl1->fl_lmops->fl_compare_owner) return fl2->fl_lmops == fl1->fl_lmops && fl1->fl_lmops->fl_compare_owner(fl1, fl2); return fl1->fl_owner == fl2->fl_owner;}Lines 1–500 of 2236. Load more
/* * linux/fs/locks.c * * Provide support for fcntl()'s F_GETLK, F_SETLK, and F_SETLKW calls. * Doug Evans (dje@spiff.uucp), August 07, 1992 * * Deadlock detection added. * FIXME: one thing isn't handled yet: * - mandatory locks (requires lots of changes elsewhere) * Kelly Carmichael (kelly@[142.24.8.65]), September 17, 1994. * * Miscellaneous edits, and a total rewrite of posix_lock_file() code. * Kai Petzke (wpp@marie.physik.tu-berlin.de), 1994 * * Converted file_lock_table to a linked list from an array, which eliminates * the limits on how many active file locks are open. * Chad Page (pageone@netcom.com), November 27, 1994 * * Removed dependency on file descriptors. dup()'ed file descriptors now * get the same locks as the original file descriptors, and a close() on * any file descriptor removes ALL the locks on the file for the current * process. Since locks still depend on the process id, locks are inherited * after an exec() but not after a fork(). This agrees with POSIX, and both * BSD and SVR4 practice. * Andy Walker (andy@lysaker.kvaerner.no), February 14, 1995 * * Scrapped free list which is redundant now that we allocate locks * dynamically with kmalloc()/kfree(). * Andy Walker (andy@lysaker.kvaerner.no), February 21, 1995 * * Implemented two lock personalities - FL_FLOCK and FL_POSIX. * * FL_POSIX locks are created with calls to fcntl() and lockf() through the * fcntl() system call. They have the semantics described above. * * FL_FLOCK locks are created with calls to flock(), through the flock() * system call, which is new. Old C libraries implement flock() via fcntl() * and will continue to use the old, broken implementation. * * FL_FLOCK locks follow the 4.4 BSD flock() semantics. They are associated * with a file pointer (filp). As a result they can be shared by a parent * process and its children after a fork(). They are removed when the last * file descriptor referring to the file pointer is closed (unless explicitly * unlocked). * * FL_FLOCK locks never deadlock, an existing lock is always removed before * upgrading from shared to exclusive (or vice versa). When this happens * any processes blocked by the current lock are woken up and allowed to * run before the new lock is applied. * Andy Walker (andy@lysaker.kvaerner.no), June 09, 1995 * * Removed some race conditions in flock_lock_file(), marked other possible * races. Just grep for FIXME to see them. * Dmitry Gorodchanin (pgmdsg@ibi.com), February 09, 1996. * * Addressed Dmitry's concerns. Deadlock checking no longer recursive. * Lock allocation changed to GFP_ATOMIC as we can't afford to sleep * once we've checked for blocking and deadlocking. * Andy Walker (andy@lysaker.kvaerner.no), April 03, 1996. * * Initial implementation of mandatory locks. SunOS turned out to be * a rotten model, so I implemented the "obvious" semantics. * See 'Documentation/mandatory.txt' for details. * Andy Walker (andy@lysaker.kvaerner.no), April 06, 1996. * * Don't allow mandatory locks on mmap()'ed files. Added simple functions to * check if a file has mandatory locks, used by mmap(), open() and creat() to * see if system call should be rejected. Ref. HP-UX/SunOS/Solaris Reference * Manual, Section 2. * Andy Walker (andy@lysaker.kvaerner.no), April 09, 1996. * * Tidied up block list handling. Added '/proc/locks' interface. * Andy Walker (andy@lysaker.kvaerner.no), April 24, 1996. * * Fixed deadlock condition for pathological code that mixes calls to * flock() and fcntl(). * Andy Walker (andy@lysaker.kvaerner.no), April 29, 1996. * * Allow only one type of locking scheme (FL_POSIX or FL_FLOCK) to be in use * for a given file at a time. Changed the CONFIG_LOCK_MANDATORY scheme to * guarantee sensible behaviour in the case where file system modules might * be compiled with different options than the kernel itself. * Andy Walker (andy@lysaker.kvaerner.no), May 15, 1996. * * Added a couple of missing wake_up() calls. Thanks to Thomas Meckel * (Thomas.Meckel@mni.fh-giessen.de) for spotting this. * Andy Walker (andy@lysaker.kvaerner.no), May 15, 1996. * * Changed FL_POSIX locks to use the block list in the same way as FL_FLOCK * locks. Changed process synchronisation to avoid dereferencing locks that * have already been freed. * Andy Walker (andy@lysaker.kvaerner.no), Sep 21, 1996. * * Made the block list a circular list to minimise searching in the list. * Andy Walker (andy@lysaker.kvaerner.no), Sep 25, 1996. * * Made mandatory locking a mount option. Default is not to allow mandatory * locking. * Andy Walker (andy@lysaker.kvaerner.no), Oct 04, 1996. * * Some adaptations for NFS support. * Olaf Kirch (okir@monad.swb.de), Dec 1996, * * Fixed /proc/locks interface so that we can't overrun the buffer we are handed. * Andy Walker (andy@lysaker.kvaerner.no), May 12, 1997. * * Use slab allocator instead of kmalloc/kfree. * Use generic list implementation from <linux/list.h>. * Sped up posix_locks_deadlock by only considering blocked locks. * Matthew Wilcox <willy@debian.org>, March, 2000. * * Leases and LOCK_MAND * Matthew Wilcox <willy@debian.org>, June, 2000. * Stephen Rothwell <sfr@canb.auug.org.au>, June, 2000. */ #include <linux/capability.h> #include <linux/file.h> #include <linux/fs.h> #include <linux/init.h> #include <linux/module.h> #include <linux/security.h> #include <linux/slab.h> #include <linux/smp_lock.h> #include <linux/syscalls.h> #include <linux/time.h> #include <linux/rcupdate.h> #include <asm/semaphore.h> #include <asm/uaccess.h> #define IS_POSIX(fl) (fl->fl_flags & FL_POSIX) #define IS_FLOCK(fl) (fl->fl_flags & FL_FLOCK) #define IS_LEASE(fl) (fl->fl_flags & FL_LEASE) int leases_enable = 1; int lease_break_time = 45; #define for_each_lock(inode, lockp) \ for (lockp = &inode->i_flock; *lockp != NULL; lockp = &(*lockp)->fl_next) static LIST_HEAD(file_lock_list); static LIST_HEAD(blocked_list); static struct kmem_cache *filelock_cache __read_mostly; /* Allocate an empty lock structure. */ static struct file_lock *locks_alloc_lock(void) { return kmem_cache_alloc(filelock_cache, GFP_KERNEL); } static void locks_release_private(struct file_lock *fl) { if (fl->fl_ops) { if (fl->fl_ops->fl_release_private) fl->fl_ops->fl_release_private(fl); fl->fl_ops = NULL; } if (fl->fl_lmops) { if (fl->fl_lmops->fl_release_private) fl->fl_lmops->fl_release_private(fl); fl->fl_lmops = NULL; } } /* Free a lock which is not in use. */ static void locks_free_lock(struct file_lock *fl) { BUG_ON(waitqueue_active(&fl->fl_wait)); BUG_ON(!list_empty(&fl->fl_block)); BUG_ON(!list_empty(&fl->fl_link)); locks_release_private(fl); kmem_cache_free(filelock_cache, fl); } void locks_init_lock(struct file_lock *fl) { INIT_LIST_HEAD(&fl->fl_link); INIT_LIST_HEAD(&fl->fl_block); init_waitqueue_head(&fl->fl_wait); fl->fl_next = NULL; fl->fl_fasync = NULL; fl->fl_owner = NULL; fl->fl_pid = 0; fl->fl_file = NULL; fl->fl_flags = 0; fl->fl_type = 0; fl->fl_start = fl->fl_end = 0; fl->fl_ops = NULL; fl->fl_lmops = NULL; } EXPORT_SYMBOL(locks_init_lock); /* * Initialises the fields of the file lock which are invariant for * free file_locks. */ static void init_once(void *foo, struct kmem_cache *cache, unsigned long flags) { struct file_lock *lock = (struct file_lock *) foo; if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) != SLAB_CTOR_CONSTRUCTOR) return; locks_init_lock(lock); } static void locks_copy_private(struct file_lock *new, struct file_lock *fl) { if (fl->fl_ops) { if (fl->fl_ops->fl_copy_lock) fl->fl_ops->fl_copy_lock(new, fl); new->fl_ops = fl->fl_ops; } if (fl->fl_lmops) { if (fl->fl_lmops->fl_copy_lock) fl->fl_lmops->fl_copy_lock(new, fl); new->fl_lmops = fl->fl_lmops; } } /* * Initialize a new lock from an existing file_lock structure. */ static void __locks_copy_lock(struct file_lock *new, const struct file_lock *fl) { new->fl_owner = fl->fl_owner; new->fl_pid = fl->fl_pid; new->fl_file = NULL; new->fl_flags = fl->fl_flags; new->fl_type = fl->fl_type; new->fl_start = fl->fl_start; new->fl_end = fl->fl_end; new->fl_ops = NULL; new->fl_lmops = NULL; } void locks_copy_lock(struct file_lock *new, struct file_lock *fl) { locks_release_private(new); __locks_copy_lock(new, fl); new->fl_file = fl->fl_file; new->fl_ops = fl->fl_ops; new->fl_lmops = fl->fl_lmops; locks_copy_private(new, fl); } EXPORT_SYMBOL(locks_copy_lock); static inline int flock_translate_cmd(int cmd) { if (cmd & LOCK_MAND) return cmd & (LOCK_MAND | LOCK_RW); switch (cmd) { case LOCK_SH: return F_RDLCK; case LOCK_EX: return F_WRLCK; case LOCK_UN: return F_UNLCK; } return -EINVAL; } /* Fill in a file_lock structure with an appropriate FLOCK lock. */ static int flock_make_lock(struct file *filp, struct file_lock **lock, unsigned int cmd) { struct file_lock *fl; int type = flock_translate_cmd(cmd); if (type < 0) return type; fl = locks_alloc_lock(); if (fl == NULL) return -ENOMEM; fl->fl_file = filp; fl->fl_pid = current->tgid; fl->fl_flags = FL_FLOCK; fl->fl_type = type; fl->fl_end = OFFSET_MAX; *lock = fl; return 0; } static int assign_type(struct file_lock *fl, int type) { switch (type) { case F_RDLCK: case F_WRLCK: case F_UNLCK: fl->fl_type = type; break; default: return -EINVAL; } return 0; } /* Verify a "struct flock" and copy it to a "struct file_lock" as a POSIX * style lock. */ static int flock_to_posix_lock(struct file *filp, struct file_lock *fl, struct flock *l) { off_t start, end; switch (l->l_whence) { case SEEK_SET: start = 0; break; case SEEK_CUR: start = filp->f_pos; break; case SEEK_END: start = i_size_read(filp->f_path.dentry->d_inode); break; default: return -EINVAL; } /* POSIX-1996 leaves the case l->l_len < 0 undefined; POSIX-2001 defines it. */ start += l->l_start; if (start < 0) return -EINVAL; fl->fl_end = OFFSET_MAX; if (l->l_len > 0) { end = start + l->l_len - 1; fl->fl_end = end; } else if (l->l_len < 0) { end = start - 1; fl->fl_end = end; start += l->l_len; if (start < 0) return -EINVAL; } fl->fl_start = start; /* we record the absolute position */ if (fl->fl_end < fl->fl_start) return -EOVERFLOW; fl->fl_owner = current->files; fl->fl_pid = current->tgid; fl->fl_file = filp; fl->fl_flags = FL_POSIX; fl->fl_ops = NULL; fl->fl_lmops = NULL; return assign_type(fl, l->l_type); } #if BITS_PER_LONG == 32 static int flock64_to_posix_lock(struct file *filp, struct file_lock *fl, struct flock64 *l) { loff_t start; switch (l->l_whence) { case SEEK_SET: start = 0; break; case SEEK_CUR: start = filp->f_pos; break; case SEEK_END: start = i_size_read(filp->f_path.dentry->d_inode); break; default: return -EINVAL; } start += l->l_start; if (start < 0) return -EINVAL; fl->fl_end = OFFSET_MAX; if (l->l_len > 0) { fl->fl_end = start + l->l_len - 1; } else if (l->l_len < 0) { fl->fl_end = start - 1; start += l->l_len; if (start < 0) return -EINVAL; } fl->fl_start = start; /* we record the absolute position */ if (fl->fl_end < fl->fl_start) return -EOVERFLOW; fl->fl_owner = current->files; fl->fl_pid = current->tgid; fl->fl_file = filp; fl->fl_flags = FL_POSIX; fl->fl_ops = NULL; fl->fl_lmops = NULL; switch (l->l_type) { case F_RDLCK: case F_WRLCK: case F_UNLCK: fl->fl_type = l->l_type; break; default: return -EINVAL; } return (0); } #endif /* default lease lock manager operations */ static void lease_break_callback(struct file_lock *fl) { kill_fasync(&fl->fl_fasync, SIGIO, POLL_MSG); } static void lease_release_private_callback(struct file_lock *fl) { if (!fl->fl_file) return; f_delown(fl->fl_file); fl->fl_file->f_owner.signum = 0; } static int lease_mylease_callback(struct file_lock *fl, struct file_lock *try) { return fl->fl_file == try->fl_file; } static struct lock_manager_operations lease_manager_ops = { .fl_break = lease_break_callback, .fl_release_private = lease_release_private_callback, .fl_mylease = lease_mylease_callback, .fl_change = lease_modify, }; /* * Initialize a lease, use the default lock manager operations */ static int lease_init(struct file *filp, int type, struct file_lock *fl) { if (assign_type(fl, type) != 0) return -EINVAL; fl->fl_owner = current->files; fl->fl_pid = current->tgid; fl->fl_file = filp; fl->fl_flags = FL_LEASE; fl->fl_start = 0; fl->fl_end = OFFSET_MAX; fl->fl_ops = NULL; fl->fl_lmops = &lease_manager_ops; return 0; } /* Allocate a file_lock initialised to this type of lease */ static int lease_alloc(struct file *filp, int type, struct file_lock **flp) { struct file_lock *fl = locks_alloc_lock(); int error = -ENOMEM; if (fl == NULL) goto out; error = lease_init(filp, type, fl); if (error) { locks_free_lock(fl); fl = NULL; } out: *flp = fl; return error; } /* Check if two locks overlap each other. */ static inline int locks_overlap(struct file_lock *fl1, struct file_lock *fl2) { return ((fl1->fl_end >= fl2->fl_start) && (fl2->fl_end >= fl1->fl_start)); } /* * Check whether two locks have the same owner. */ static int posix_same_owner(struct file_lock *fl1, struct file_lock *fl2) { if (fl1->fl_lmops && fl1->fl_lmops->fl_compare_owner) return fl2->fl_lmops == fl1->fl_lmops && fl1->fl_lmops->fl_compare_owner(fl1, fl2); return fl1->fl_owner == fl2->fl_owner; }