[PATCH 4.9 156/159] ext4: continue to expand file system when the target size doesnt reach

[Greg Kroah-Hartman]

From: Jerry Lee 李修賢 <jerrylee@xxxxxxxx>

commit df3cb754d13d2cd5490db9b8d536311f8413a92e upstream.

When expanding a file system from (16TiB-2MiB) to 18TiB, the operation
exits early which leads to result inconsistency between resize2fs and
Ext4 kernel driver.

=== before ===
○ → resize2fs /dev/mapper/thin
resize2fs 1.45.5 (07-Jan-2020)
Filesystem at /dev/mapper/thin is mounted on /mnt/test; on-line resizing required
old_desc_blocks = 2048, new_desc_blocks = 2304
The filesystem on /dev/mapper/thin is now 4831837696 (4k) blocks long.

[  865.186308] EXT4-fs (dm-5): mounted filesystem with ordered data mode. Opts: (null). Quota mode: none.
[  912.091502] dm-4: detected capacity change from 34359738368 to 38654705664
[  970.030550] dm-5: detected capacity change from 34359734272 to 38654701568
[ 1000.012751] EXT4-fs (dm-5): resizing filesystem from 4294966784 to 4831837696 blocks
[ 1000.012878] EXT4-fs (dm-5): resized filesystem to 4294967296

=== after ===
[  129.104898] EXT4-fs (dm-5): mounted filesystem with ordered data mode. Opts: (null). Quota mode: none.
[  143.773630] dm-4: detected capacity change from 34359738368 to 38654705664
[  198.203246] dm-5: detected capacity change from 34359734272 to 38654701568
[  207.918603] EXT4-fs (dm-5): resizing filesystem from 4294966784 to 4831837696 blocks
[  207.918754] EXT4-fs (dm-5): resizing filesystem from 4294967296 to 4831837696 blocks
[  207.918758] EXT4-fs (dm-5): Converting file system to meta_bg
[  207.918790] EXT4-fs (dm-5): resizing filesystem from 4294967296 to 4831837696 blocks
[  221.454050] EXT4-fs (dm-5): resized to 4658298880 blocks
[  227.634613] EXT4-fs (dm-5): resized filesystem to 4831837696

Signed-off-by: Jerry Lee <jerrylee@xxxxxxxx>
Link: https://lore.kernel.org/r/PU1PR04MB22635E739BD21150DC182AC6A18C9@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 fs/ext4/resize.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/ext4/resize.c
+++ b/fs/ext4/resize.c
@@ -2052,7 +2052,7 @@ retry:
 			goto out;
 	}
 
-	if (ext4_blocks_count(es) == n_blocks_count)
+	if (ext4_blocks_count(es) == n_blocks_count && n_blocks_count_retry == 0)
 		goto out;
 
 	err = ext4_alloc_flex_bg_array(sb, n_group + 1);