Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 29723ade authored by Jeff Layton's avatar Jeff Layton
Browse files

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: default avatarTrond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: default avatarJeff Layton <jlayton@redhat.com>
parent d7a06983

fs/locks.c

+13 −2
Original line number Diff line number Diff line
@@ -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;