This is a note to let you know that I've just added the patch titled ext4: correctly migrate a file with a hole at the beginning to the 4.1-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: ext4-correctly-migrate-a-file-with-a-hole-at-the-beginning.patch and it can be found in the queue-4.1 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 8974fec7d72e3e02752fe0f27b4c3719c78d9a15 Mon Sep 17 00:00:00 2001 From: Eryu Guan <guaneryu@xxxxxxxxx> 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@xxxxxxxxx> 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@xxxxxxxxx> Signed-off-by: Theodore Ts'o <tytso@xxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/ext4/migrate.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) --- a/fs/ext4/migrate.c +++ b/fs/ext4/migrate.c @@ -620,7 +620,7 @@ 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; @@ -659,11 +659,12 @@ 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; @@ -672,7 +673,7 @@ 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: Patches currently in stable-queue which might be from guaneryu@xxxxxxxxx are queue-4.1/ext4-correctly-migrate-a-file-with-a-hole-at-the-beginning.patch queue-4.1/ext4-be-more-strict-when-migrating-to-non-extent-based-file.patch -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html