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authorJeff Layton <jlayton@redhat.com>2014-03-10 09:54:19 -0400
committerJeff Layton <jlayton@redhat.com>2014-03-31 08:24:43 -0400
commit29723adee11804b548903ddb1db666cf4a60f60e (patch)
tree15ffb52af6c920d52cb53b970c9d6a21fe6cc2b1
parentd7a06983a01a33605191c0766857b832ac32a2b6 (diff)
downloadlinux-linaro-stable-29723adee11804b548903ddb1db666cf4a60f60e.tar.gz
locks: make locks_mandatory_area check for file-private locks
Allow locks_mandatory_area() to handle file-private locks correctly. If there is a file-private lock set on an open file and we're doing I/O via the same, then that should not cause anything to block. Handle this by first doing a non-blocking FL_ACCESS check for a file-private lock, and then fall back to checking for a classic POSIX lock (and possibly blocking). Note that this approach is subject to the same races that have always plagued mandatory locking on Linux. Reported-by: Trond Myklebust <trond.myklebust@primarydata.com> Signed-off-by: Jeff Layton <jlayton@redhat.com>
-rw-r--r--fs/locks.c15
1 files changed, 13 insertions, 2 deletions
diff --git a/fs/locks.c b/fs/locks.c
index d82c51c4fcd2..13fc7a6d380a 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -1199,19 +1199,30 @@ int locks_mandatory_area(int read_write, struct inode *inode,
{
struct file_lock fl;
int error;
+ bool sleep = false;
locks_init_lock(&fl);
- fl.fl_owner = current->files;
fl.fl_pid = current->tgid;
fl.fl_file = filp;
fl.fl_flags = FL_POSIX | FL_ACCESS;
if (filp && !(filp->f_flags & O_NONBLOCK))
- fl.fl_flags |= FL_SLEEP;
+ sleep = true;
fl.fl_type = (read_write == FLOCK_VERIFY_WRITE) ? F_WRLCK : F_RDLCK;
fl.fl_start = offset;
fl.fl_end = offset + count - 1;
for (;;) {
+ if (filp) {
+ fl.fl_owner = (fl_owner_t)filp;
+ fl.fl_flags &= ~FL_SLEEP;
+ error = __posix_lock_file(inode, &fl, NULL);
+ if (!error)
+ break;
+ }
+
+ if (sleep)
+ fl.fl_flags |= FL_SLEEP;
+ fl.fl_owner = current->files;
error = __posix_lock_file(inode, &fl, NULL);
if (error != FILE_LOCK_DEFERRED)
break;