diff options
| -rw-r--r-- | fs/locks.c | 145 |
1 files changed, 67 insertions, 78 deletions
diff --git a/fs/locks.c b/fs/locks.c index cf256e9fd3b5..4e0220993f8f 100644 --- a/fs/locks.c +++ b/fs/locks.c @@ -132,6 +132,9 @@ int leases_enable = 1; int lease_break_time = 45; +#define for_each_lock(inode, lockp) \ + for (lockp = &inode->i_flock; *lockp != NULL; lockp = &(*lockp)->fl_next) + LIST_HEAD(file_lock_list); static LIST_HEAD(blocked_list); @@ -220,25 +223,41 @@ void locks_copy_lock(struct file_lock *new, struct file_lock *fl) new->fl_u = fl->fl_u; } +static inline int flock_translate_cmd(int cmd) { + if (cmd & LOCK_MAND) + return cmd & (LOCK_MAND | LOCK_RW); + switch (cmd &~ LOCK_NB) { + 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 type) +static int flock_make_lock(struct file *filp, + struct file_lock **lock, unsigned int cmd) { - struct file_lock *fl = locks_alloc_lock(1); + struct file_lock *fl; + int type = flock_translate_cmd(cmd); + if (type < 0) + return type; + + fl = locks_alloc_lock(1); if (fl == NULL) - return NULL; + return -ENOMEM; - fl->fl_owner = NULL; fl->fl_file = filp; fl->fl_pid = current->pid; fl->fl_flags = FL_FLOCK; fl->fl_type = type; - fl->fl_start = 0; fl->fl_end = OFFSET_MAX; - fl->fl_notify = NULL; - fl->fl_insert = NULL; - fl->fl_remove = NULL; - return fl; + *lock = fl; + return 0; } static int assign_type(struct file_lock *fl, int type) @@ -756,59 +775,45 @@ repeat: * at the head of the list, but that's secret knowledge known only to * flock_lock_file and posix_lock_file. */ -static int flock_lock_file(struct file *filp, unsigned int lock_type, +static int flock_lock_file(struct file *filp, struct file_lock *new_fl, unsigned int wait) { - struct file_lock *fl; - struct file_lock *new_fl = NULL; struct file_lock **before; struct inode * inode = filp->f_dentry->d_inode; - int error, change; - int unlock = (lock_type == F_UNLCK); - - /* - * If we need a new lock, get it in advance to avoid races. - */ - if (!unlock) { - error = -ENOLCK; - new_fl = flock_make_lock(filp, lock_type); - if (!new_fl) - return error; - } + int error = 0; + int found = 0; - error = 0; -search: - change = 0; - before = &inode->i_flock; - while (((fl = *before) != NULL) && IS_FLOCK(fl)) { - if (filp == fl->fl_file) { - if (lock_type == fl->fl_type) - goto out; - change = 1; + lock_kernel(); + for_each_lock(inode, before) { + struct file_lock *fl = *before; + if (IS_POSIX(fl)) break; - } - before = &fl->fl_next; - } - /* change means that we are changing the type of an existing lock, - * or else unlocking it. - */ - if (change) { - /* N.B. What if the wait argument is false? */ + if (IS_LEASE(fl)) + continue; + if (filp != fl->fl_file) + continue; + if (new_fl->fl_type == fl->fl_type) + goto out; + found = 1; locks_delete_lock(before); - if (!unlock) { - yield(); - /* - * If we waited, another lock may have been added ... - */ - goto search; - } + break; } - if (unlock) - goto out; + unlock_kernel(); + + if (found) + yield(); + + if (new_fl->fl_type == F_UNLCK) + return 0; + lock_kernel(); repeat: - for (fl = inode->i_flock; (fl != NULL) && IS_FLOCK(fl); - fl = fl->fl_next) { + for_each_lock(inode, before) { + struct file_lock *fl = *before; + if (IS_POSIX(fl)) + break; + if (IS_LEASE(fl)) + continue; if (!flock_locks_conflict(new_fl, fl)) continue; error = -EAGAIN; @@ -820,12 +825,10 @@ repeat: goto repeat; } locks_insert_lock(&inode->i_flock, new_fl); - new_fl = NULL; error = 0; out: - if (new_fl) - locks_free_lock(new_fl); + unlock_kernel(); return error; } @@ -1025,20 +1028,6 @@ out_nolock: return error; } -static inline int flock_translate_cmd(int cmd) { - if (cmd & LOCK_MAND) - return cmd & (LOCK_MAND | LOCK_RW); - switch (cmd &~ LOCK_NB) { - case LOCK_SH: - return F_RDLCK; - case LOCK_EX: - return F_WRLCK; - case LOCK_UN: - return F_UNLCK; - } - return -EINVAL; -} - /** * __get_lease - revoke all outstanding leases on file * @inode: the inode of the file to return @@ -1307,26 +1296,26 @@ out_unlock: asmlinkage long sys_flock(unsigned int fd, unsigned int cmd) { struct file *filp; - int error, type; + struct file_lock *lock; + int error; error = -EBADF; filp = fget(fd); if (!filp) goto out; - error = flock_translate_cmd(cmd); - if (error < 0) + if ((cmd != LOCK_UN) && !(cmd & LOCK_MAND) && !(filp->f_mode & 3)) goto out_putf; - type = error; - error = -EBADF; - if ((type != F_UNLCK) && !(type & LOCK_MAND) && !(filp->f_mode & 3)) + error = flock_make_lock(filp, &lock, cmd); + if (error < 0) goto out_putf; - lock_kernel(); - error = flock_lock_file(filp, type, + error = flock_lock_file(filp, lock, (cmd & (LOCK_UN | LOCK_NB)) ? 0 : 1); - unlock_kernel(); + + if (error) + locks_free_lock(lock); out_putf: fput(filp); |