The in-kernel ext4 resize code doesn't support filesystem with the
sparse_super2 feature. It fails with errors like this and doesn't finish
the resize:
EXT4-fs (loop0): resizing filesystem from 16640 to 7864320 blocks
EXT4-fs warning (device loop0): verify_reserved_gdb:760: reserved GDT 2 missing grp 1 (32770)
EXT4-fs warning (device loop0): ext4_resize_fs:2111: error (-22) occurred during file system resize
EXT4-fs (loop0): resized filesystem to 2097152
To reproduce:
mkfs.ext4 -b 4096 -I 256 -J size=32 -E resize=$((256*1024*1024)) -O sparse_super2 ext4.img 65M
truncate -s 30G ext4.img
mount ext4.img /mnt
python3 -c 'import fcntl, os, struct ; fd = os.open("/mnt", os.O_RDONLY | os.O_DIRECTORY) ; fcntl.ioctl(fd, 0x40086610, struct.pack("Q", 30 * 1024 * 1024 * 1024 // 4096), False) ; os.close(fd)'
dmesg | tail
e2fsck ext4.img
The userspace resize2fs tool has a check for this case: it checks if the
filesystem has sparse_super2 set and if the kernel provides
/sys/fs/ext4/features/sparse_super2. However, the former check requires
manually reading and parsing the filesystem superblock.
Detect this case in ext4_resize_begin and error out early with a clear
error message.
Signed-off-by: Josh Triplett <josh@xxxxxxxxxxxxxxxx>
---
fs/ext4/resize.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
index d13bb9e76482..fc885914c88a 100644
--- a/fs/ext4/resize.c
+++ b/fs/ext4/resize.c
@@ -78,6 +78,10 @@ int ext4_resize_begin(struct super_block *sb)
ext4_msg(sb, KERN_ERR, "Online resizing not supported with bigalloc");
return -EOPNOTSUPP;
}
+ if (ext4_has_feature_sparse_super2(sb)) {
+ ext4_msg(sb, KERN_ERR, "Online resizing not supported with sparse_super2");
+ return -EOPNOTSUPP;
+ }
if (test_and_set_bit_lock(EXT4_FLAGS_RESIZING,
&EXT4_SB(sb)->s_ext4_flags))
--
2.32.0.rc2
