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Commit 3fd5d3ad authored by Andreas Gruenbacher's avatar Andreas Gruenbacher Committed by Bob Peterson
Browse files

gfs2: Stop using rhashtable_walk_peek 



Function rhashtable_walk_peek is problematic because there is no
guarantee that the glock previously returned still exists; when that key
is deleted, rhashtable_walk_peek can end up returning a different key,
which will cause an inconsistent glock dump.  Fix this by keeping track
of the current glock in the seq file iterator functions instead.

Signed-off-by: default avatarAndreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: default avatarBob Peterson <rpeterso@redhat.com>
parent 450b1f6f

fs/gfs2/glock.c

+28 −19
Original line number Diff line number Diff line
@@ -1923,28 +1923,37 @@ void gfs2_glock_exit(void) 


static void gfs2_glock_iter_next(struct gfs2_glock_iter *gi, loff_t n)

{

	struct gfs2_glock *gl = gi->gl;



	if (gl) {

		if (n == 0)

		gi->gl = rhashtable_walk_peek(&gi->hti);

	else {

		gi->gl = rhashtable_walk_next(&gi->hti);

		n--;

			return;

		if (!lockref_put_not_zero(&gl->gl_lockref))

			gfs2_glock_queue_put(gl);

	}

	for (;;) {

		if (IS_ERR_OR_NULL(gi->gl)) {

			if (!gi->gl)

				return;

			if (PTR_ERR(gi->gl) != -EAGAIN) {

				gi->gl = NULL;

				return;

		gl = rhashtable_walk_next(&gi->hti);

		if (IS_ERR_OR_NULL(gl)) {

			if (gl == ERR_PTR(-EAGAIN)) {

				n = 1;

				continue;

			}

			n = 0;

		} else if (gi->sdp == gi->gl->gl_name.ln_sbd &&

			   !__lockref_is_dead(&gi->gl->gl_lockref)) {

			if (!n--)

			gl = NULL;

			break;

		}

		gi->gl = rhashtable_walk_next(&gi->hti);

		if (gl->gl_name.ln_sbd != gi->sdp)

			continue;

		if (n <= 1) {

			if (!lockref_get_not_dead(&gl->gl_lockref))

				continue;

			break;

		} else {

			if (__lockref_is_dead(&gl->gl_lockref))

				continue;

			n--;

		}

	}

	gi->gl = gl;

}



static void *gfs2_glock_seq_start(struct seq_file *seq, loff_t *pos)
@@ -1988,7 +1997,6 @@ static void gfs2_glock_seq_stop(struct seq_file *seq, void *iter_ptr) 
{

	struct gfs2_glock_iter *gi = seq->private;



	gi->gl = NULL;

	rhashtable_walk_stop(&gi->hti);

}
@@ -2076,7 +2084,8 @@ static int gfs2_glocks_release(struct inode *inode, struct file *file) 
	struct seq_file *seq = file->private_data;

	struct gfs2_glock_iter *gi = seq->private;



	gi->gl = NULL;

	if (gi->gl)

		gfs2_glock_put(gi->gl);

	rhashtable_walk_exit(&gi->hti);

	return seq_release_private(inode, file);

}