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Date:   Wed, 11 Dec 2019 10:34:59 -0500
From:   Sasha Levin <>
Cc:     Theodore Ts'o <>,,
        Andreas Dilger <>,
        Sasha Levin <>,
Subject: [PATCH AUTOSEL 4.9 31/42] ext4: work around deleting a file with i_nlink == 0 safely

From: Theodore Ts'o <>

[ Upstream commit c7df4a1ecb8579838ec8c56b2bb6a6716e974f37 ]

If the file system is corrupted such that a file's i_links_count is
too small, then it's possible that when unlinking that file, i_nlink
will already be zero.  Previously we were working around this kind of
corruption by forcing i_nlink to one; but we were doing this before
trying to delete the directory entry --- and if the file system is
corrupted enough that ext4_delete_entry() fails, then we exit with
i_nlink elevated, and this causes the orphan inode list handling to be
FUBAR'ed, such that when we unmount the file system, the orphan inode
list can get corrupted.

A better way to fix this is to simply skip trying to call drop_nlink()
if i_nlink is already zero, thus moving the check to the place where
it makes the most sense.

Signed-off-by: Theodore Ts'o <>
Reviewed-by: Andreas Dilger <>
Signed-off-by: Sasha Levin <>
 fs/ext4/namei.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 29dc02758a52b..b8082ca9e3bac 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -3078,18 +3078,17 @@ static int ext4_unlink(struct inode *dir, struct dentry *dentry)
 	if (IS_DIRSYNC(dir))
-	if (inode->i_nlink == 0) {
-		ext4_warning_inode(inode, "Deleting file '%.*s' with no links",
-				   dentry->d_name.len, dentry->;
-		set_nlink(inode, 1);
-	}
 	retval = ext4_delete_entry(handle, dir, de, bh);
 	if (retval)
 		goto end_unlink;
 	dir->i_ctime = dir->i_mtime = ext4_current_time(dir);
 	ext4_mark_inode_dirty(handle, dir);
-	drop_nlink(inode);
+	if (inode->i_nlink == 0)
+		ext4_warning_inode(inode, "Deleting file '%.*s' with no links",
+				   dentry->d_name.len, dentry->;
+	else
+		drop_nlink(inode);
 	if (!inode->i_nlink)
 		ext4_orphan_add(handle, inode);
 	inode->i_ctime = ext4_current_time(inode);

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