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| author | Jeff Layton <jlayton@redhat.com> | 2014-03-10 09:54:19 -0400 |
|---|---|---|
| committer | Jeff Layton <jlayton@redhat.com> | 2014-03-31 08:24:43 -0400 |
| commit | 29723adee11804b548903ddb1db666cf4a60f60e (patch) | |
| tree | 15ffb52af6c920d52cb53b970c9d6a21fe6cc2b1 | |
| parent | d7a06983a01a33605191c0766857b832ac32a2b6 (diff) | |
| download | linux-29723adee11804b548903ddb1db666cf4a60f60e.tar.gz linux-29723adee11804b548903ddb1db666cf4a60f60e.tar.bz2 linux-29723adee11804b548903ddb1db666cf4a60f60e.zip | |
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.c | 15 |
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; |