Commit 69cb8e9d authored by Kiselev, Oleg's avatar Kiselev, Oleg Committed by Theodore Ts'o
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ext4: avoid resizing to a partial cluster size 



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: default avatarOleg Kiselev <okiselev@amazon.com>
Link: https://lore.kernel.org/r/0E92A0AB-4F16-4F1A-94B7-702CC6504FDE@amazon.com


Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
parent 026d0d27

fs/ext4/resize.c

+10 −0
Original line number Original line Diff line number Diff line
@@ -2011,6 +2011,16 @@ 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);