From: Andreas Gruenbacher agruenba@redhat.com
stable inclusion from stable-5.10.80 commit b870d8a76c04bb6875c68c261f266a1fac2241a9 bugzilla: 185821 https://gitee.com/openeuler/kernel/issues/I4L7CG
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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[ Upstream commit 7427f3bb49d81525b7dd1d0f7c5f6bbc752e6f0e ]
So far, glock_hash_walk took a reference on each glock it iterated over, and it was the examiner's responsibility to drop those references. Dropping the final reference to a glock can sleep and the examiners are called in a RCU critical section with spin locks held, so examiners that didn't need the extra reference had to drop it asynchronously via gfs2_glock_queue_put or similar. This wasn't done correctly in thaw_glock which did call gfs2_glock_put, and not at all in dump_glock_func.
Change glock_hash_walk to not take glock references at all. That way, the examiners that don't need them won't have to bother with slow asynchronous puts, and the examiners that do need references can take them themselves.
Reported-by: Alexander Aring aahringo@redhat.com Signed-off-by: Andreas Gruenbacher agruenba@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Chen Jun chenjun102@huawei.com Reviewed-by: Weilong Chen chenweilong@huawei.com Acked-by: Weilong Chen chenweilong@huawei.com
Signed-off-by: Chen Jun chenjun102@huawei.com Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com --- fs/gfs2/glock.c | 22 ++++++++++++---------- 1 file changed, 12 insertions(+), 10 deletions(-)
diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c index 538608730796..ee5cca5926ed 100644 --- a/fs/gfs2/glock.c +++ b/fs/gfs2/glock.c @@ -1884,10 +1884,10 @@ static void glock_hash_walk(glock_examiner examiner, const struct gfs2_sbd *sdp) do { rhashtable_walk_start(&iter);
- while ((gl = rhashtable_walk_next(&iter)) && !IS_ERR(gl)) - if (gl->gl_name.ln_sbd == sdp && - lockref_get_not_dead(&gl->gl_lockref)) + while ((gl = rhashtable_walk_next(&iter)) && !IS_ERR(gl)) { + if (gl->gl_name.ln_sbd == sdp) examiner(gl); + }
rhashtable_walk_stop(&iter); } while (cond_resched(), gl == ERR_PTR(-EAGAIN)); @@ -1929,7 +1929,6 @@ static void flush_delete_work(struct gfs2_glock *gl) &gl->gl_delete, 0); } } - gfs2_glock_queue_work(gl, 0); }
void gfs2_flush_delete_work(struct gfs2_sbd *sdp) @@ -1946,10 +1945,10 @@ void gfs2_flush_delete_work(struct gfs2_sbd *sdp)
static void thaw_glock(struct gfs2_glock *gl) { - if (!test_and_clear_bit(GLF_FROZEN, &gl->gl_flags)) { - gfs2_glock_put(gl); + if (!test_and_clear_bit(GLF_FROZEN, &gl->gl_flags)) + return; + if (!lockref_get_not_dead(&gl->gl_lockref)) return; - } set_bit(GLF_REPLY_PENDING, &gl->gl_flags); gfs2_glock_queue_work(gl, 0); } @@ -1965,9 +1964,12 @@ static void clear_glock(struct gfs2_glock *gl) gfs2_glock_remove_from_lru(gl);
spin_lock(&gl->gl_lockref.lock); - if (gl->gl_state != LM_ST_UNLOCKED) - handle_callback(gl, LM_ST_UNLOCKED, 0, false); - __gfs2_glock_queue_work(gl, 0); + if (!__lockref_is_dead(&gl->gl_lockref)) { + gl->gl_lockref.count++; + if (gl->gl_state != LM_ST_UNLOCKED) + handle_callback(gl, LM_ST_UNLOCKED, 0, false); + __gfs2_glock_queue_work(gl, 0); + } spin_unlock(&gl->gl_lockref.lock); }