New: Corruption on a small loopback ext4 file system with Linux 3.4
https://bugzilla.kernel.org/show_bug.cgi?id=43354
Summary: Corruption on a small loopback ext4 file system with
Linux 3.4
Product: File System
Version: 2.5
Kernel Version: 3.4.1
Platform: All
OS/Version: Linux
Tree: Mainline
Status: NEW
Severity: high
Priority: P1
Component: ext4
AssignedTo: [email protected]
ReportedBy: [email protected]
Regression: YesWith Linux 3.4, I am getting major corruption on a loopback ext4 filesystem:
parts of files are randomly inserted into other files.
Below are steps to reproduce - I've been able to reproduce this on two different systems. Both have ext4 root, using a plain kernel.org 3.4.1 kernel. The problem does not reproduce when switching back to Linux 3.3.6.
If you need any additional info, I'll be happy to provide it.
# uname -r
3.4.1
# dd if=/dev/zero of=tree.ext4 bs=1M count=512
512+0 records in
512+0 records out
536870912 bytes (537 MB) copied, 0.589387 s, 911 MB/s
# mkfs.ext4 -T small -N 200000 tree.ext4
mke2fs 1.42.3 (14-May-2012)
tree.ext4 is not a block special device.
Proceed anyway? (y,n) y
Discarding device blocks: done
Filesystem label=
OS type: Linux
Block size=1024 (log=0)
Fragment size=1024 (log=0)
Stride=0 blocks, Stripe width=0 blocks
200192 inodes, 524288 blocks
26214 blocks (5.00%) reserved for the super user
First data block=1
Maximum filesystem blocks=67633152
64 block groups
8192 blocks per group, 8192 fragments per group
3128 inodes per group
Superblock backups stored on blocks:
8193, 24577, 40961, 57345, 73729, 204801, 221185, 401409Allocating group tables: done
Writing inode tables: done
Creating journal (16384 blocks): done
Writing superblocks and filesystem accounting information: done
# mkdir tree
# mount -o loop tree.ext4 tree
# tar xaf portage-20120607.tar.xz -C tree
# find tree -type f -exec sha1sum {} \; > checksums
# umount tree
# sync
# echo 3 > /proc/sys/vm/drop_caches # important! everything will seem fine
otherwise
# fsck.ext4 -f tree.ext4
e2fsck 1.42.3 (14-May-2012)
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
tree.ext4: 183722/200192 files (0.0% non-contiguous), 402575/524288 blocks
# mount -o loop tree.ext4 tree
# sha1sum --check --quiet checksums
tree/portage/net-firewall/conntrack-tools/ChangeLog: FAILED
tree/portage/net-firewall/conntrack-tools/files/conntrackd.initd-r1: FAILED
tree/portage/net-firewall/nufw/ChangeLog: FAILED
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[Bug 43354] Corruption on a small loopback ext4 file system with Linux 3.4
https://bugzilla.kernel.org/show_bug.cgi?id=43354
--- Comment #1 from Alec Moskvin <[email protected]> 2012-06-08 04:18:27 --- Created an attachment (id=73536)
--> (https://bugzilla.kernel.org/attachment.cgi?id=73536)
tree.ext4.xz - resulting fs image
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[Bug 43354] Corruption on a small loopback ext4 file system with Linux 3.4
In reply to [email protected]https://bugzilla.kernel.org/show_bug.cgi?id=43354
Eric Sandeen <[email protected]> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |[email protected]
--- Comment #2 from Eric Sandeen <[email protected]> 2012-06-08 04:58:37 --- Does it go any better w/ a 4k fs block size? (-b 4096?)
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[Bug 43354] Corruption on a small loopback ext4 file system with Linux 3.4
In reply to [email protected]https://bugzilla.kernel.org/show_bug.cgi?id=43354
--- Comment #3 from Alec Moskvin <[email protected]> 2012-06-08 13:44:13 --- Yes, it seems to work fine with the 4k block size.
mkfs.ext4 -T small -N 200000 -b 4096 tree.ext4
(Of course, I had to also double the image size because otherwise the data won't fit, but the size does not have an effect - the above is reproducible with a 1G image as well.)
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[Bug 43354] Corruption on a small loopback ext4 file system with Linux 3.4
In reply to [email protected]https://bugzilla.kernel.org/show_bug.cgi?id=43354
--- Comment #4 from Eric Sandeen <[email protected]> 2012-06-08 17:46:39 --- Hm, wait - drop caches _after_ unmount is required? Ok that's even weirder (and scarier - especially since it's after a sync)
And - on further testing, ext2 & ext3 fail too. Yikes.
It also seems to happen only on loopback; a real device is fine.
And, loopback fails whether it's hosted on ext4 or xfs. So something generic broke here...
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[Bug 43354] Corruption on a small loopback ext4 file system with Linux 3.4
In reply to [email protected]https://bugzilla.kernel.org/show_bug.cgi?id=43354
Jan Kara <[email protected]> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |[email protected]
--- Comment #5 from Jan Kara <[email protected]> 2012-06-14 21:48:41 --- Hmm, I'm not able to reproduce with 3.5-rc1. Can you?
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[Bug 43354] Corruption on a small loopback ext4 file system with Linux 3.4
In reply to [email protected]https://bugzilla.kernel.org/show_bug.cgi?id=43354
--- Comment #6 from Alec Moskvin <[email protected]> 2012-07-28 14:33:19 --- I can't reproduce with 3.5 either.
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[Bug 43354] Corruption on a small loopback ext4 file system with Linux 3.4
In reply to [email protected]https://bugzilla.kernel.org/show_bug.cgi?id=43354
Jan Kara <[email protected]> changed:
What |Removed |Added
----------------------------------------------------------------------------
AssignedTo|[email protected] |[email protected] |g |
--- Comment #7 from Jan Kara <[email protected]> 2012-08-14 15:28:24 --- Ok, thanks for verification. I'll close this bug then.
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