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ext4: fix e2fsprogs checksum failure for mounted filesystem

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Commit 81414b4dd4 ("ext4: remove redundant sb checksum
recomputation") removed checksum recalculation after updating
superblock free space / inode counters in ext4_fill_super() based on
the fact that we will recalculate the checksum on superblock
writeout.

That is correct assumption but until the writeout happens (which can
take a long time) the checksum is incorrect in the buffer cache and if
programs such as tune2fs or resize2fs is called shortly after a file
system is mounted can fail.  So return back the checksum recalculation
and add a comment explaining why.

Fixes: 81414b4dd4 ("ext4: remove redundant sb checksum recomputation")
Cc: stable@kernel.org
Reported-by: Boyang Xue <bxue@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Link: https://lore.kernel.org/r/20210812124737.21981-1-jack@suse.cz
This commit is contained in:
Jan Kara 2021-08-12 14:47:37 +02:00 committed by Theodore Ts'o
parent 308c57ccf4
commit b2bbb92f70
1 changed files with 8 additions and 0 deletions
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8
fs/ext4/super.c
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@ -5032,6 +5032,14 @@ no_journal:
err = percpu_counter_init(&sbi->s_freeinodes_counter, freei,
GFP_KERNEL);
}
/*
* Update the checksum after updating free space/inode
* counters. Otherwise the superblock can have an incorrect
* checksum in the buffer cache until it is written out and
* e2fsprogs programs trying to open a file system immediately
* after it is mounted can fail.
*/
ext4_superblock_csum_set(sb);
if (!err)
err = percpu_counter_init(&sbi->s_dirs_counter,
ext4_count_dirs(sb), GFP_KERNEL);