Linux-ext4 Archive on
 help / color / Atom feed
From: "Theodore Ts'o" <>
To: Ext4 Developers List <>
Cc: "Theodore Ts'o" <>,
Subject: [PATCH] ext4: work around deleting a file with i_nlink == 0 safely
Date: Mon, 11 Nov 2019 22:29:03 -0500
Message-ID: <> (raw)

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 <>
 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 a67cae3c8ff5..a856997d87b5 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -3196,18 +3196,17 @@ 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 = 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 = current_time(inode);

             reply index

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-12  3:29 Theodore Ts'o [this message]
2019-11-13 21:25 ` Andreas Dilger

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \ \ \ \ \

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-ext4 Archive on

Archives are clonable:
	git clone --mirror linux-ext4/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-ext4 linux-ext4/ \
	public-inbox-index linux-ext4

Example config snippet for mirrors

Newsgroup available over NNTP:

AGPL code for this site: git clone