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If we log a new inode (not persisted in a past transaction) that has 0 links and extents, then log another inode with an higher inode number, we end up with failing to replay the log tree with -EINVAL. The steps for this are: 1) create new file A 2) write some data to file A 3) open an fd on file A 4) unlink file A 5) fsync file A using the previously open fd 6) create file B (has higher inode number than file A) 7) fsync file B 8) power fail before current transaction commits Now when attempting to mount the fs, the log replay will fail with -ENOENT at replay_one_extent() when attempting to replay the first extent of file A. The failure comes when trying to open the inode for file A in the subvolume tree, since it doesn't exist. Before commit5f61b96159("btrfs: fix inode lookup error handling during log replay"), the returned error was -EIO instead of -ENOENT, since we converted any errors when attempting to read an inode during log replay to -EIO. The reason for this is that the log replay procedure fails to ignore the current inode when we are at the stage LOG_WALK_REPLAY_ALL, our current inode has 0 links and last inode we processed in the previous stage has a non 0 link count. In other words, the issue is that at replay_one_extent() we only update wc->ignore_cur_inode if the current replay stage is LOG_WALK_REPLAY_INODES. Fix this by updating wc->ignore_cur_inode whenever we find an inode item regardless of the current replay stage. This is a simple solution and easy to backport, but later we can do other alternatives like avoid logging extents or inode items other than the inode item for inodes with a link count of 0. The problem with the wc->ignore_cur_inode logic has been around since commitf2d72f42d5("Btrfs: fix warning when replaying log after fsync of a tmpfile") but it only became frequent to hit since the more recent commit5e85262e54("btrfs: fix fsync of files with no hard links not persisting deletion"), because we stopped skipping inodes with a link count of 0 when logging, while before the problem would only be triggered if trying to replay a log tree created with an older kernel which has a logged inode with 0 links. A test case for fstests will be submitted soon. Reported-by: Peter Jung <ptr1337@cachyos.org> Link: https://lore.kernel.org/linux-btrfs/fce139db-4458-4788-bb97-c29acf6cb1df@cachyos.org/ Reported-by: burneddi <burneddi@protonmail.com> Link: https://lore.kernel.org/linux-btrfs/lh4W-Lwc0Mbk-QvBhhQyZxf6VbM3E8VtIvU3fPIQgweP_Q1n7wtlUZQc33sYlCKYd-o6rryJQfhHaNAOWWRKxpAXhM8NZPojzsJPyHMf2qY=@protonmail.com/#t Reported-by: Russell Haley <yumpusamongus@gmail.com> Link: https://lore.kernel.org/linux-btrfs/598ecc75-eb80-41b3-83c2-f2317fbb9864@gmail.com/ Fixes:f2d72f42d5("Btrfs: fix warning when replaying log after fsync of a tmpfile") CC: stable@vger.kernel.org # 5.4+ Reviewed-by: Boris Burkov <boris@bur.io> Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.