[PATCH AUTOSEL 6.14 199/642] gfs2: Check for empty queue in run_queue

Sasha Levin
2025-05-05T22:22:28Z

From: Andreas Gruenbacher <agruenba@redhat.com>

[ Upstream commit d838605fea6eabae3746a276fd448f6719eb3926 ]

In run_queue(), check if the queue of pending requests is empty instead
of blindly assuming that it won't be.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/gfs2/glock.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index 65c07aa957184..7f9cc7872214e 100644
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -843,12 +843,13 @@ static void run_queue(struct gfs2_glock *gl, const int nonblock)
__releases(&gl->gl_lockref.lock)
__acquires(&gl->gl_lockref.lock)
{
- struct gfs2_holder *gh = NULL;
+ struct gfs2_holder *gh;

if (test_bit(GLF_LOCK, &gl->gl_flags))
return;
set_bit(GLF_LOCK, &gl->gl_flags);

+ /* While a demote is in progress, the GLF_LOCK flag must be set. */
GLOCK_BUG_ON(gl, test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags));

if (test_bit(GLF_DEMOTE, &gl->gl_flags) &&
@@ -860,18 +861,22 @@ __acquires(&gl->gl_lockref.lock)
set_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags);
GLOCK_BUG_ON(gl, gl->gl_demote_state == LM_ST_EXCLUSIVE);
gl->gl_target = gl->gl_demote_state;
+ do_xmote(gl, NULL, gl->gl_target);
+ return;
} else {
if (test_bit(GLF_DEMOTE, &gl->gl_flags))
gfs2_demote_wake(gl);
if (do_promote(gl))
goto out_unlock;
gh = find_first_waiter(gl);
+ if (!gh)
+ goto out_unlock;
gl->gl_target = gh->gh_state;
if (!(gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)))
do_error(gl, 0); /* Fail queued try locks */
+ do_xmote(gl, gh, gl->gl_target);
+ return;
}
- do_xmote(gl, gh, gl->gl_target);
- return;

out_sched:
clear_bit(GLF_LOCK, &gl->gl_flags);
--
2.39.5