[Cluster-devel] [PATCH AUTOSEL 4.19 07/21] gfs2: Prevent direct-I/O write fallback errors from getting lost

[Cluster-devel] [PATCH AUTOSEL 4.19 07/21] gfs2: Prevent direct-I/O write fallback errors from getting lost

[Sasha Levin]

From: Andreas Gruenbacher <agruenba@redhat.com>

[ Upstream commit 43a511c44e58e357a687d61a20cf5ef1dc9e5a7c ]

When a direct I/O write falls entirely and falls back to buffered I/O and the
buffered I/O fails, the write failed with return value 0 instead of the error
number reported by the buffered I/O. Fix that.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/gfs2/file.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/fs/gfs2/file.c b/fs/gfs2/file.c
index 143e7d518c5d..7c69486d556f 100644
--- a/fs/gfs2/file.c
+++ b/fs/gfs2/file.c
@@ -822,8 +822,11 @@ static ssize_t gfs2_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 		current->backing_dev_info = inode_to_bdi(inode);
 		buffered = iomap_file_buffered_write(iocb, from, &gfs2_iomap_ops);
 		current->backing_dev_info = NULL;
-		if (unlikely(buffered <= 0))
+		if (unlikely(buffered <= 0)) {
+			if (!ret)
+				ret = buffered;
 			goto out_unlock;
+		}
 
 		/*
 		 * We need to ensure that the page cache pages are written to
-- 
2.30.2

[Cluster-devel] [PATCH AUTOSEL 4.19 09/21] gfs2: Fix use-after-free in gfs2_glock_shrink_scan

[Sasha Levin]

From: Hillf Danton <hdanton@sina.com>

[ Upstream commit 1ab19c5de4c537ec0d9b21020395a5b5a6c059b2 ]

The GLF_LRU flag is checked under lru_lock in gfs2_glock_remove_from_lru() to
remove the glock from the lru list in __gfs2_glock_put().

On the shrink scan path, the same flag is cleared under lru_lock but because
of cond_resched_lock(&lru_lock) in gfs2_dispose_glock_lru(), progress on the
put side can be made without deleting the glock from the lru list.

Keep GLF_LRU across the race window opened by cond_resched_lock(&lru_lock) to
ensure correct behavior on both sides - clear GLF_LRU after list_del under
lru_lock.

Reported-by: syzbot <syzbot+34ba7ddbf3021981a228@syzkaller.appspotmail.com>
Signed-off-by: Hillf Danton <hdanton@sina.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/gfs2/glock.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index c20d71d86812..14d11ccda868 100644
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -1457,6 +1457,7 @@ __acquires(&lru_lock)
 	while(!list_empty(list)) {
 		gl = list_entry(list->next, struct gfs2_glock, gl_lru);
 		list_del_init(&gl->gl_lru);
+		clear_bit(GLF_LRU, &gl->gl_flags);
 		if (!spin_trylock(&gl->gl_lockref.lock)) {
 add_back_to_lru:
 			list_add(&gl->gl_lru, &lru_list);
@@ -1502,7 +1503,6 @@ static long gfs2_scan_glock_lru(int nr)
 		if (!test_bit(GLF_LOCK, &gl->gl_flags)) {
 			list_move(&gl->gl_lru, &dispose);
 			atomic_dec(&lru_count);
-			clear_bit(GLF_LRU, &gl->gl_flags);
 			freed++;
 			continue;
 		}
-- 
2.30.2