diff options
| -rw-r--r-- | fs/locks.c | 18 | ||||
| -rw-r--r-- | include/linux/fs.h | 1 |
2 files changed, 17 insertions, 2 deletions
diff --git a/fs/locks.c b/fs/locks.c index 1ad29c9b625..50cb0a2b74d 100644 --- a/fs/locks.c +++ b/fs/locks.c @@ -725,6 +725,10 @@ next_task: /* Try to create a FLOCK lock on filp. We always insert new FLOCK locks * at the head of the list, but that's secret knowledge known only to * flock_lock_file and posix_lock_file. + * + * 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_file(struct file *filp, struct file_lock *request) { @@ -750,8 +754,11 @@ static int flock_lock_file(struct file *filp, struct file_lock *request) break; } - if (request->fl_type == F_UNLCK) + if (request->fl_type == F_UNLCK) { + if ((request->fl_flags & FL_EXISTS) && !found) + error = -ENOENT; goto out; + } error = -ENOMEM; new_fl = locks_alloc_lock(); @@ -948,8 +955,11 @@ static int __posix_lock_file_conf(struct inode *inode, struct file_lock *request error = 0; if (!added) { - if (request->fl_type == F_UNLCK) + if (request->fl_type == F_UNLCK) { + if (request->fl_flags & FL_EXISTS) + error = -ENOENT; goto out; + } if (!new_fl) { error = -ENOLCK; @@ -996,6 +1006,10 @@ static int __posix_lock_file_conf(struct inode *inode, struct file_lock *request * 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) { diff --git a/include/linux/fs.h b/include/linux/fs.h index 134b3206824..43aef9b230f 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -716,6 +716,7 @@ extern spinlock_t files_lock; #define FL_POSIX 1 #define FL_FLOCK 2 #define FL_ACCESS 8 /* not trying to lock, just looking */ +#define FL_EXISTS 16 /* when unlocking, test for existence */ #define FL_LEASE 32 /* lease held on this file */ #define FL_CLOSE 64 /* unlock on close */ #define FL_SLEEP 128 /* A blocking lock */ |