From: "Kiselev, Oleg" okiselev@amazon.com
[ 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 --- fs/ext4/resize.c | 10 ++++++++++ 1 file changed, 10 insertions(+)
diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c index c367129dcdc1..c16bcd3f2e6d 100644 --- a/fs/ext4/resize.c +++ b/fs/ext4/resize.c @@ -1940,6 +1940,16 @@ 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);