From: Theodore Ts'o <tytso@mit.edu>
To: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: linux-ext4@vger.kernel.org
Subject: Re: [PATCH 10/24] e2fsck: don't clobber critical metadata during check_blocks
Date: Thu, 24 Jul 2014 21:03:22 -0400 [thread overview]
Message-ID: <20140725010322.GA1865@thunk.org> (raw)
In-Reply-To: <20140718225328.31374.71677.stgit@birch.djwong.org>
On Fri, Jul 18, 2014 at 03:53:28PM -0700, Darrick J. Wong wrote:
> If we encounter an inode with IND/DIND/TIND blocks or internal extent
> tree blocks that point into critical FS metadata such as the
> superblock, the group descriptors, the bitmaps, or the inode table,
> it's quite possible that the validation code for those blocks is not
> going to like what it finds, and it'll ask to try to fix the block.
> Unfortunately, this happens before duplicate block processing (pass
> 1b), which means that we can end up doing stupid things like writing
> extent blocks into the inode table, which multiplies e2fsck'
> destructive effect and can render a filesystem unfixable.
>
> To solve this, create a bitmap of all the critical FS metadata. If
> before pass1b runs (basically check_blocks) we find a metadata block
> that points into these critical regions, continue processing that
> block, but avoid making any modifications, because we could be
> misinterpreting inodes as block maps. Pass 1b will find the
> multiply-owned blocks and fix that situation, which means that we can
> then restart e2fsck from the beginning and actually fix whatever
> problems we find.
>
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Thanks, applied.
- Ted
next prev parent reply other threads:[~2014-07-25 1:03 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-18 22:52 [PATCH 00/24] e2fsprogs patchbomb 7/14, part 1 Darrick J. Wong
2014-07-18 22:52 ` [PATCH 01/24] e4defrag: backwards-allocated files should be defragmented too Darrick J. Wong
2014-07-21 23:44 ` Akira Fujita
2014-07-22 16:32 ` Theodore Ts'o
2014-07-18 22:52 ` [PATCH 02/24] debugfs: Only print the first 60 bytes from i_block on a fast symlink Darrick J. Wong
2014-07-19 16:49 ` Andreas Dilger
2014-07-22 16:43 ` Theodore Ts'o
2014-07-22 20:39 ` Darrick J. Wong
2014-07-22 20:34 ` Darrick J. Wong
2014-07-18 22:52 ` [PATCH 03/24] debugfs: create idump command to dump an inode in hex Darrick J. Wong
2014-07-22 17:47 ` Theodore Ts'o
2014-07-18 22:52 ` [PATCH 04/24] debugfs: allow bmap to allocate blocks Darrick J. Wong
2014-07-22 17:52 ` Theodore Ts'o
2014-07-18 22:52 ` [PATCH 05/24] e2fsck: report correct inode number in pass1b Darrick J. Wong
2014-07-22 17:47 ` Theodore Ts'o
2014-07-18 22:52 ` [PATCH 06/24] e2fsck: don't offer to recreate the journal if fsck is aborting due to bad block bitmaps Darrick J. Wong
2014-07-22 17:58 ` Theodore Ts'o
2014-07-18 22:53 ` [PATCH 07/24] e2fsck: skip clearing bad extents if bitmaps are unreadable Darrick J. Wong
2014-07-22 17:58 ` Theodore Ts'o
2014-07-18 22:53 ` [PATCH 08/24] e2fsck: fix inode coherency issue when iterating an inode's blocks Darrick J. Wong
2014-07-22 18:58 ` Theodore Ts'o
2014-07-18 22:53 ` [PATCH 09/24] e2fsck: clear i_block if there are too many bad block mappings Darrick J. Wong
2014-07-22 18:59 ` Theodore Ts'o
2014-07-22 22:14 ` Darrick J. Wong
2014-07-22 22:48 ` Theodore Ts'o
2014-07-18 22:53 ` [PATCH 10/24] e2fsck: don't clobber critical metadata during check_blocks Darrick J. Wong
2014-07-25 1:03 ` Theodore Ts'o [this message]
2014-07-18 22:53 ` [PATCH 11/24] e2fsck: free ctx->fs, not fs, at the end of fsck Darrick J. Wong
2014-07-25 1:14 ` Theodore Ts'o
2014-07-18 22:53 ` [PATCH 12/24] e2fsck: force all block allocations to use block_found_map Darrick J. Wong
2014-07-25 2:18 ` Theodore Ts'o
2014-07-18 22:53 ` [PATCH 13/24] e2fsck: fix off-by-one bounds check on group number Darrick J. Wong
2014-07-25 2:20 ` Theodore Ts'o
2014-07-18 22:53 ` [PATCH 14/24] libext2fs: fix bounds check of the bitmap test range in get_free_blocks2 Darrick J. Wong
2014-07-25 11:13 ` Theodore Ts'o
2014-07-18 22:54 ` [PATCH 15/24] misc: fix problems with strncat Darrick J. Wong
2014-07-25 11:22 ` Theodore Ts'o
2014-07-18 22:54 ` [PATCH 16/24] e2fsck: don't crash during rehash Darrick J. Wong
2014-07-25 11:22 ` Theodore Ts'o
2014-07-18 22:54 ` [PATCH 17/24] e2fsck: reserve blocks for root/lost+found directory repair Darrick J. Wong
2014-07-25 12:12 ` Theodore Ts'o
2014-07-25 20:19 ` Darrick J. Wong
2014-07-18 22:54 ` [PATCH 18/24] e2fsck: collapse holes in extent-based directories Darrick J. Wong
2014-07-25 12:33 ` Theodore Ts'o
2014-07-18 22:54 ` [PATCH 19/24] e2fsck: always submit logical block 0 of a directory for pass 2 Darrick J. Wong
2014-07-25 12:40 ` Theodore Ts'o
2014-07-18 22:54 ` [PATCH 20/24] e2fsck: pass2 should not process directory blocks that are impossibly large Darrick J. Wong
2014-07-25 12:42 ` Theodore Ts'o
2014-07-18 22:55 ` [PATCH 21/24] e2fsck: clear uninit flag on directory extents Darrick J. Wong
2014-07-25 13:00 ` Theodore Ts'o
2014-07-18 22:55 ` [PATCH 22/24] e2fsck: check return value of ext2fs_extent_fix_parents() Darrick J. Wong
2014-07-25 12:51 ` Theodore Ts'o
2014-07-18 22:55 ` [PATCH 23/24] mke2fs: set error behavior at initialization time Darrick J. Wong
2014-07-25 13:00 ` Theodore Ts'o
2014-07-18 22:55 ` [PATCH 24/24] e2fuzz: Create a tool to fuzz ext* filesystems Darrick J. Wong
2014-07-25 13:16 ` Theodore Ts'o
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