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@xxxxxxxxxx>
---
v2:
- Moved the code higher up in the call stack, changed the
implementation to trim the request size
---
fs/ext4/resize.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
index a69113b4ce4e..b69fda478e9d 100644
--- a/fs/ext4/resize.c
+++ b/fs/ext4/resize.c
@@ -2007,6 +2007,16 @@ int ext4_resize_fs(struct super_block *sb, ext4_fsblk_t )
}
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);
--
2.34.3
