[PATCH] f2fs: correctly fix the parent inode number during fsync()

[Eric Biggers]

fsync() may be called on a deleted file that's still open.  So when
fsync() tries to set the parent inode number when the inode has
LOST_PINO and i_nlink == 1 (to avoid later checkpoints), it needs to
make sure to get the parent directory via a non-deleted alias.

Also remove the unnecessary igrab() and iput(), as the caller already
holds a reference to the inode.

Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
---
 fs/f2fs/file.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 6ab8f621a3c5a2..b3069188fd3478 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -165,9 +165,11 @@ static int get_parent_ino(struct inode *inode, nid_t *pino)
 {
 	struct dentry *dentry;
 
-	inode = igrab(inode);
-	dentry = d_find_any_alias(inode);
-	iput(inode);
+	/*
+	 * Make sure to get the non-deleted alias.  The alias associated with
+	 * the open file descriptor being fsync()'ed may be deleted already.
+	 */
+	dentry = d_find_alias(inode);
 	if (!dentry)
 		return 0;
 
-- 
2.26.2