ext4: check s_chksum_driver when looking for bg csum presence

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commit 813d32f913 upstream.

Convert the ext4_has_group_desc_csum predicate to look for a checksum
driver instead of the metadata_csum flag and change the bg checksum
calculation function to look for GDT_CSUM before taking the crc16
path.

Without this patch, if we mount with ^uninit_bg,^metadata_csum and
later metadata_csum gets turned on by accident, the block group
checksum functions will incorrectly assume that checksumming is
enabled (metadata_csum) but that crc16 should be used
(!s_chksum_driver).  This is totally wrong, so fix the predicate
and the checksum formula selection.

(Granted, if the metadata_csum feature bit gets enabled on a live FS
then something underhanded is going on, but we could at least avoid
writing garbage into the on-disk fields.)

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

...

This commit is contained in:

Darrick J. Wong 2014-10-14 02:35:49 -04:00 • committed by Luis Henriques

parent 1875434771

commit c6243bdb2f

2 changed files with 6 additions and 2 deletions

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4

fs/ext4/ext4.h

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4

fs/ext4/super.c

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