ext4: avoid resizing to a partial cluster size

[ Upstream commit 69cb8e9d8cd97cdf5e293b26d70a9dee3e35e6bd ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Kiselev, Oleg 2022-07-20 04:27:48 +00:00 committed by Greg Kroah-Hartman
parent 5bebfd6077
commit a6805b3dcf

View File

@ -1979,6 +1979,16 @@ int ext4_resize_fs(struct super_block *sb, ext4_fsblk_t n_blocks_count)
} }
brelse(bh); 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: retry:
o_blocks_count = ext4_blocks_count(es); o_blocks_count = ext4_blocks_count(es);