| From 8974fec7d72e3e02752fe0f27b4c3719c78d9a15 Mon Sep 17 00:00:00 2001 |
| From: Eryu Guan <guaneryu@gmail.com> |
| Date: Sat, 4 Jul 2015 00:03:44 -0400 |
| Subject: ext4: correctly migrate a file with a hole at the beginning |
| |
| From: Eryu Guan <guaneryu@gmail.com> |
| |
| commit 8974fec7d72e3e02752fe0f27b4c3719c78d9a15 upstream. |
| |
| Currently ext4_ind_migrate() doesn't correctly handle a file which |
| contains a hole at the beginning of the file. This caused the migration |
| to be done incorrectly, and then if there is a subsequent following |
| delayed allocation write to the "hole", this would reclaim the same data |
| blocks again and results in fs corruption. |
| |
| # assmuing 4k block size ext4, with delalloc enabled |
| # skip the first block and write to the second block |
| xfs_io -fc "pwrite 4k 4k" -c "fsync" /mnt/ext4/testfile |
| |
| # converting to indirect-mapped file, which would move the data blocks |
| # to the beginning of the file, but extent status cache still marks |
| # that region as a hole |
| chattr -e /mnt/ext4/testfile |
| |
| # delayed allocation writes to the "hole", reclaim the same data block |
| # again, results in i_blocks corruption |
| xfs_io -c "pwrite 0 4k" /mnt/ext4/testfile |
| umount /mnt/ext4 |
| e2fsck -nf /dev/sda6 |
| ... |
| Inode 53, i_blocks is 16, should be 8. Fix? no |
| ... |
| |
| Signed-off-by: Eryu Guan <guaneryu@gmail.com> |
| Signed-off-by: Theodore Ts'o <tytso@mit.edu> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| fs/ext4/migrate.c | 9 +++++---- |
| 1 file changed, 5 insertions(+), 4 deletions(-) |
| |
| --- a/fs/ext4/migrate.c |
| +++ b/fs/ext4/migrate.c |
| @@ -616,7 +616,7 @@ int ext4_ind_migrate(struct inode *inode |
| struct ext4_inode_info *ei = EXT4_I(inode); |
| struct ext4_extent *ex; |
| unsigned int i, len; |
| - ext4_lblk_t end; |
| + ext4_lblk_t start, end; |
| ext4_fsblk_t blk; |
| handle_t *handle; |
| int ret; |
| @@ -655,11 +655,12 @@ int ext4_ind_migrate(struct inode *inode |
| goto errout; |
| } |
| if (eh->eh_entries == 0) |
| - blk = len = 0; |
| + blk = len = start = end = 0; |
| else { |
| len = le16_to_cpu(ex->ee_len); |
| blk = ext4_ext_pblock(ex); |
| - end = le32_to_cpu(ex->ee_block) + len - 1; |
| + start = le32_to_cpu(ex->ee_block); |
| + end = start + len - 1; |
| if (end >= EXT4_NDIR_BLOCKS) { |
| ret = -EOPNOTSUPP; |
| goto errout; |
| @@ -668,7 +669,7 @@ int ext4_ind_migrate(struct inode *inode |
| |
| ext4_clear_inode_flag(inode, EXT4_INODE_EXTENTS); |
| memset(ei->i_data, 0, sizeof(ei->i_data)); |
| - for (i=0; i < len; i++) |
| + for (i = start; i <= end; i++) |
| ei->i_data[i] = cpu_to_le32(blk++); |
| ext4_mark_inode_dirty(handle, inode); |
| errout: |