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Date: Sun, 14 Aug 2022 11:36:52 -0400 From: Sasha Levin <sashal@...nel.org> To: linux-kernel@...r.kernel.org, stable@...r.kernel.org Cc: "Kiselev, Oleg" <okiselev@...zon.com>, Theodore Ts'o <tytso@....edu>, Sasha Levin <sashal@...nel.org>, adilger.kernel@...ger.ca, linux-ext4@...r.kernel.org Subject: [PATCH AUTOSEL 4.9 7/7] ext4: avoid resizing to a partial cluster size From: "Kiselev, Oleg" <okiselev@...zon.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@...zon.com> Link: https://lore.kernel.org/r/0E92A0AB-4F16-4F1A-94B7-702CC6504FDE@amazon.com Signed-off-by: Theodore Ts'o <tytso@....edu> Signed-off-by: Sasha Levin <sashal@...nel.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); -- 2.35.1
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