f2fs: fix incorrect FI_NO_EXTENT handling in __destroy_extent_node()

commit 1f70ddb upstream.

When __destroy_extent_node() sets the inode flag FI_NO_EXTENT, it does
not reset the length of the largest extent to 0 and update the inode
folio. Since modifications to the extent tree are disallowed afterward,
the cached largest extent may become stale. This can trigger the
following error in xfstests generic/388:

F2FS-fs (dm-0): sanity_check_extent_cache: inode (ino=1761) extent info [220057, 57, 6] is incorrect, run fsck to fix

In the f2fs_drop_inode path, __destroy_extent_node() does not need to
guarantee that et->node_cnt is 0, because concurrency with writeback
is expected in this path, and writeback may update the extent cache.

This patch reverts commit ed78aee ("f2fs: fix node_cnt race between
extent node destroy and writeback"), and remove the unnecessary zero
check of et->node_cnt.

Fixes: ed78aee ("f2fs: fix node_cnt race between extent node destroy and writeback")
Cc: stable@vger.kernel.org
Reported-by: Chao Yu <chao@kernel.org>
Suggested-by: Chao Yu <chao@kernel.org>
Signed-off-by: Yongpeng Yang <yangyongpeng@xiaomi.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: Yongpeng Yang

fs/f2fs/extent_cache.c

@@ -119,10 +119,9 @@ static bool __may_extent_tree(struct inode *inode, enum extent_type type)
 	if (!__init_may_extent_tree(inode, type))
 		return false;
 
-	if (is_inode_flag_set(inode, FI_NO_EXTENT))
-		return false;
-
 	if (type == EX_READ) {
+		if (is_inode_flag_set(inode, FI_NO_EXTENT))
+			return false;
 		if (is_inode_flag_set(inode, FI_COMPRESSED_FILE) &&
 				 !f2fs_sb_has_readonly(F2FS_I_SB(inode)))
 			return false;
@@ -645,14 +644,10 @@ static unsigned int __destroy_extent_node(struct inode *inode,
 
 	while (atomic_read(&et->node_cnt)) {
 		write_lock(&et->lock);
-		if (!is_inode_flag_set(inode, FI_NO_EXTENT))
-			set_inode_flag(inode, FI_NO_EXTENT);
 		node_cnt += __free_extent_tree(sbi, et, nr_shrink);
 		write_unlock(&et->lock);
 	}
 
-	f2fs_bug_on(sbi, atomic_read(&et->node_cnt));
-
 	return node_cnt;
 }
 
@@ -691,12 +686,12 @@ static void __update_extent_tree_range(struct inode *inode,
 
 	write_lock(&et->lock);
 
-	if (is_inode_flag_set(inode, FI_NO_EXTENT)) {
-		write_unlock(&et->lock);
-		return;
-	}
-
 	if (type == EX_READ) {
+		if (is_inode_flag_set(inode, FI_NO_EXTENT)) {
+			write_unlock(&et->lock);
+			return;
+		}
+
 		prev = et->largest;
 		dei.len = 0;