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From: "Darrick J. Wong" <darrick.wong@oracle.com>
To: sandeen@sandeen.net, darrick.wong@oracle.com
Cc: linux-xfs@vger.kernel.org, alex@zadara.com
Subject: [PATCH v4 0/7] xfs_repair: do not trash valid root dirs
Date: Tue, 04 Feb 2020 16:46:37 -0800	[thread overview]
Message-ID: <158086359783.2079685.9581209719946834913.stgit@magnolia> (raw)

Hi all,

Alex Lyakas observed that xfs_repair can accidentally trash the root
directory on a filesystem.  Specifically, if one formats a V4 filesystem
without sparse inodes but with sunit/swidth set and then mounts that
filesystem with a different sunit/swidth, the kernel will update the
values in the superblock.  This causes xfs_repair's sb_rootino
estimation to differ from the actual root directory, and it discards the
actual root directory even though there's nothing wrong with it.

Therefore, hoist the logic that computes the root inode location into
libxfs so that the kernel will avoid the sb update if the proposed
sunit/swidth changes would alter the sb_rootino estimation; and then
teach xfs_repair to retain the root directory even if the estimation
doesn't add up, as long as sb_rootino points to a directory whose '..'
entry points to itself.

v4 rebases on the latest for-next and adds in a few things that Eric
and I discussed during the review of v3.

If you're going to start using this mess, you probably ought to just
pull from my git trees, which are linked below.

This is an extraordinary way to destroy everything.  Enjoy!
Comments and questions are, as always, welcome.

--D

xfsprogs git tree:
https://git.kernel.org/cgit/linux/kernel/git/djwong/xfsprogs-dev.git/log/?h=repair-find-rootdir

fstests git tree:
https://git.kernel.org/cgit/linux/kernel/git/djwong/xfstests-dev.git/log/?h=repair-find-rootdir

             reply	other threads:[~2020-02-05  0:46 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-05  0:46 Darrick J. Wong [this message]
2020-02-05  0:46 ` [PATCH 1/7] xfs_repair: replace verify_inum with libxfs inode validators Darrick J. Wong
2020-02-05  0:50   ` Darrick J. Wong
2020-02-17 13:50   ` Christoph Hellwig
2020-02-19  4:32     ` Darrick J. Wong
2020-02-26 16:55   ` Eric Sandeen
2020-02-05  0:46 ` [PATCH 2/7] mkfs: check root inode location Darrick J. Wong
2020-02-17 13:50   ` Christoph Hellwig
2020-02-05  0:46 ` [PATCH 3/7] xfs_repair: enforce that inode btree chunks can't point to AG headers Darrick J. Wong
2020-02-17 13:51   ` Christoph Hellwig
2020-02-26 17:09   ` Eric Sandeen
2020-02-26 17:24     ` Darrick J. Wong
2020-02-26 17:34       ` Eric Sandeen
2020-02-26 17:19   ` Eric Sandeen
2020-02-26 17:32     ` Darrick J. Wong
2020-02-26 17:40       ` Eric Sandeen
2020-02-05  0:47 ` [PATCH 4/7] xfs_repair: refactor fixed inode location checks Darrick J. Wong
2020-02-17 13:51   ` Christoph Hellwig
2020-02-05  0:47 ` [PATCH 5/7] xfs_repair: use libxfs function to calculate root inode location Darrick J. Wong
2020-02-17 13:53   ` Christoph Hellwig
2020-02-05  0:47 ` [PATCH 6/7] xfs_repair: check plausibility of root dir pointer before trashing it Darrick J. Wong
2020-02-17 13:53   ` Christoph Hellwig
2020-02-05  0:47 ` [PATCH 7/7] xfs_repair: try to correct sb_unit value from secondaries Darrick J. Wong
2020-02-17 13:55   ` Christoph Hellwig
2020-02-26 17:42   ` Eric Sandeen
2020-02-26 17:55     ` Darrick J. Wong

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