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);