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ext4: avoid resizing to a partial cluster size

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This patch avoids an attempt to resize the filesystem to an
unaligned cluster boundary.  An online resize to a size that is not
integral to cluster size results in the last iteration attempting to
grow the fs by a negative amount, which trips a BUG_ON and leaves the fs
with a corrupted in-memory superblock.

Signed-off-by: Oleg Kiselev <okiselev@amazon.com>
Link: https://lore.kernel.org/r/0E92A0AB-4F16-4F1A-94B7-702CC6504FDE@amazon.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Kiselev, Oleg 2022-07-20 04:27:48 +00:00 committed by Theodore Ts'o
parent 026d0d27c4
commit 69cb8e9d8c
1 changed files with 10 additions and 0 deletions
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10
fs/ext4/resize.c
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@ -2011,6 +2011,16 @@ int ext4_resize_fs(struct super_block *sb, ext4_fsblk_t n_blocks_count)
}
brelse(bh);
/*
* For bigalloc, trim the requested size to the nearest cluster
* boundary to avoid creating an unusable filesystem. We do this
* silently, instead of returning an error, to avoid breaking
* callers that blindly resize the filesystem to the full size of
* the underlying block device.
*/
if (ext4_has_feature_bigalloc(sb))
n_blocks_count &= ~((1 << EXT4_CLUSTER_BITS(sb)) - 1);
retry:
o_blocks_count = ext4_blocks_count(es);