On Wed, Dec 26, 2018 at 01:32:11PM +0100, Rafał Miłecki wrote:
From: Richard Weinberger richard@nod.at
commit e58725d51fa8da9133f3f1c54170aa2e43056b91 upstream.
UBIFS's recovery code strictly assumes that a deleted inode will never come back, therefore it removes all data which belongs to that inode as soon it faces an inode with link count 0 in the replay list. Before O_TMPFILE this assumption was perfectly fine. With O_TMPFILE it can lead to data loss upon a power-cut.
Consider a journal with entries like: 0: inode X (nlink = 0) /* O_TMPFILE was created */ 1: data for inode X /* Someone writes to the temp file */ 2: inode X (nlink = 0) /* inode was changed, xattr, chmod, … */ 3: inode X (nlink = 1) /* inode was re-linked via linkat() */
Upon replay of entry #2 UBIFS will drop all data that belongs to inode X, this will lead to an empty file after mounting.
As solution for this problem, scan the replay list for a re-link entry before dropping data.
Fixes: 474b93704f32 ("ubifs: Implement O_TMPFILE") Cc: stable@vger.kernel.org # 4.9-4.18 Cc: Russell Senior russell@personaltelco.net Cc: Rafał Miłecki zajec5@gmail.com Reported-by: Russell Senior russell@personaltelco.net Reported-by: Rafał Miłecki zajec5@gmail.com Tested-by: Rafał Miłecki rafal@milecki.pl Signed-off-by: Richard Weinberger richard@nod.at [rmilecki: update ubifs_assert() calls to compile with 4.18 and older] Signed-off-by: Rafał Miłecki rafal@milecki.pl (cherry picked from commit e58725d51fa8da9133f3f1c54170aa2e43056b91)
Queued for 4.14 and 4.9, thank you.
-- Thanks, Sasha