[Patch 0/2] [F/I linux-azure] Xfstest failure with sparse_super2 mount option

[Tim Gardner]

BugLink: https://bugs.launchpad.net/bugs/1970223

SRU Justification

[Impact]

Microsoft has detected an Xfstest failure scenario. There might be fs corruption
when resizing ext4 filesystems mounted with sparse_super2 option enabled.

Fix: commit b1489186cc8391e0c1e342f9fbc3eedf6b944c61 ("ext4: add check to
prevent attempting to resize an fs with sparse_super2")

[Test Case]
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

[Where things could go wrong]

The file system may erroneously not mount.

[Other Info]

SF: #00334996