linux-ext4 - [PATCH] ext4: fix RENAME_WHITEOUT handling for inline directories

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Date:   Fri, 10 Feb 2023 12:32:44 -0500
From:   Eric Whitney <enwlinux@...il.com>
To:     linux-ext4@...r.kernel.org
Cc:     tytso@....edu, Eric Whitney <enwlinux@...il.com>
Subject: [PATCH] ext4: fix RENAME_WHITEOUT handling for inline directories

A significant number of xfstests can cause ext4 to log one or more
warning messages when they are run on a test file system where the
inline_data feature has been enabled.  An example:

"EXT4-fs warning (device vdc): ext4_dirblock_csum_set:425: inode
 #16385: comm fsstress: No space for directory leaf checksum. Please
run e2fsck -D."

The xfstests include: ext4/057, 058, and 307; generic/013, 051, 068,
070, 076, 078, 083, 232, 269, 270, 390, 461, 475, 476, 482, 579, 585,
589, 626, 631, and 650.

In this situation, the warning message indicates a bug in the code that
performs the RENAME_WHITEOUT operation on a directory entry that has
been stored inline.  It doesn't detect that the directory is stored
inline, and incorrectly attempts to compute a dirent block checksum on
the whiteout inode when creating it.  This attempt fails as a result
of the integrity checking in get_dirent_tail (usually due to a failure
to match the EXT4_FT_DIR_CSUM magic cookie), and the warning message
is then emitted.

Fix this by simply collecting the inlined data state at the time the
search for the source directory entry is performed.  Existing code
handles the rest, and this is sufficient to eliminate all spurious
warning messages produced by the tests above.  Go one step further
and do the same in the code that resets the source directory entry in
the event of failure.  The inlined state should be present in the
"old" struct, but given the possibility of a race there's no harm
in taking a conservative approach and getting that information again
since the directory entry is being reread anyway.

Fixes: b7ff91fd030d ("ext4: find old entry again if failed to rename whiteout")

Signed-off-by: Eric Whitney <enwlinux@...il.com>
---
 fs/ext4/namei.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index dd28453d6ea3..924e16b239e0 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -1595,11 +1595,10 @@ static struct buffer_head *__ext4_find_entry(struct inode *dir,
 		int has_inline_data = 1;
 		ret = ext4_find_inline_entry(dir, fname, res_dir,
 					     &has_inline_data);
-		if (has_inline_data) {
-			if (inlined)
-				*inlined = 1;
+		if (inlined)
+			*inlined = has_inline_data;
+		if (has_inline_data)
 			goto cleanup_and_exit;
-		}
 	}

 	if ((namelen <= 2) && (name[0] == '.') &&
@@ -3646,7 +3645,8 @@ static void ext4_resetent(handle_t *handle, struct ext4_renament *ent,
 	 * so the old->de may no longer valid and need to find it again
 	 * before reset old inode info.
 	 */
-	old.bh = ext4_find_entry(old.dir, &old.dentry->d_name, &old.de, NULL);
+	old.bh = ext4_find_entry(old.dir, &old.dentry->d_name, &old.de,
+				 &old.inlined);
 	if (IS_ERR(old.bh))
 		retval = PTR_ERR(old.bh);
 	if (!old.bh)
@@ -3813,7 +3813,8 @@ static int ext4_rename(struct user_namespace *mnt_userns, struct inode *old_dir,
 			return retval;
 	}

-	old.bh = ext4_find_entry(old.dir, &old.dentry->d_name, &old.de, NULL);
+	old.bh = ext4_find_entry(old.dir, &old.dentry->d_name, &old.de,
+				 &old.inlined);
 	if (IS_ERR(old.bh))
 		return PTR_ERR(old.bh);
 	/*
-- 
2.30.2