https://bugzilla.kernel.org/show_bug.cgi?id=219136 Bug ID: 219136 Summary: ext4: dax: overflowing extents beyond inode size when partially writing Product: File System Version: 2.5 Hardware: All OS: Linux Status: NEW Severity: normal Priority: P3 Component: ext4 Assignee: fs_ext4@xxxxxxxxxxxxxxxxxxxx Reporter: chengzhihao1@xxxxxxxxxx Regression: No The dax_iomap_rw() does two things in each iteration: map written blocks and copy user data to blocks. If the process is killed by user(See signal handling in dax_iomap_iter()), the copied data will be returned and added on inode size, which means that the length of written extents may exceed the inode size, then fsck will fail. An example is given as: dd if=/dev/urandom of=file bs=4M count=1 dax_iomap_rw iomap_iter // round 1 ext4_iomap_begin ext4_iomap_alloc // allocate 0~2M extents(written flag) dax_iomap_iter // copy 2M data iomap_iter // round 2 iomap_iter_advance iter->pos += iter->processed // iter->pos = 2M ext4_iomap_begin ext4_iomap_alloc // allocate 2~4M extents(written flag) dax_iomap_iter fatal_signal_pending done = iter->pos - iocb->ki_pos // done = 2M ext4_handle_inode_extension ext4_update_inode_size // inode size = 2M fsck reports: Inode 13, i_size is 2097152, should be 4194304. Fix? Reproducer: 1. Apply diff and compile kernel 2. ./test.sh mke2fs 1.47.0 (5-Feb-2023) Creating filesystem with 524288 4k blocks and 131072 inodes Filesystem UUID: e2c71b4e-3315-4463-8613-ea3f40bf1efb Superblock backups stored on blocks: 32768, 98304, 163840, 229376, 294912 Allocating group tables: done Writing inode tables: done Creating journal (16384 blocks): done Writing superblocks and filesystem accounting information: done ./test.sh: line 18: 1559 Terminated dd if=/dev/urandom of=$MNT/file bs=4M count=1 e2fsck 1.47.0 (5-Feb-2023) Pass 1: Checking inodes, blocks, and sizes Inode 13, i_size is 2097152, should be 4194304. Fix? no Pass 2: Checking directory structure Pass 3: Checking directory connectivity Pass 4: Checking reference counts Pass 5: Checking group summary information /dev/pmem2: ********** WARNING: Filesystem still has errors ********** /dev/pmem2: 13/131072 files (0.0% non-contiguous), 27308/524288 blocks -- You may reply to this email to add a comment. You are receiving this mail because: You are watching the assignee of the bug.
