From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eryu Guan Subject: [PATCH 1/2] ext4: be more strict when migrating to non-extent based file Date: Sat, 4 Jul 2015 00:51:50 +0800 Message-ID: <1435942311-2337-2-git-send-email-guaneryu@gmail.com> References: <1435942311-2337-1-git-send-email-guaneryu@gmail.com> Cc: Eryu Guan To: linux-ext4@vger.kernel.org Return-path: Received: from mail-wi0-f170.google.com ([209.85.212.170]:36674 "EHLO mail-wi0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755061AbbGCQzf (ORCPT ); Fri, 3 Jul 2015 12:55:35 -0400 Received: by widjy10 with SMTP id jy10so114364462wid.1 for ; Fri, 03 Jul 2015 09:55:34 -0700 (PDT) In-Reply-To: <1435942311-2337-1-git-send-email-guaneryu@gmail.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: Currently the check in ext4_ind_migrate() is not enough before doing the real conversion: a) delayed allocated extents could bypass the check on eh->eh_entries and eh->eh_depth This can be demonstrated by this script xfs_io -fc "pwrite 0 4k" -c "pwrite 8k 4k" /mnt/ext4/testfile chattr -e /mnt/ext4/testfile where testfile has two extents but still be converted to non-extent based file format. b) only extent length is checked but not the offset, which would result in data lose (delalloc) or fs corruption (nodelalloc), because non-extent based file only supports at most (12 + 2^10 + 2^20 + 2^30) blocks This can be demostrated by xfs_io -fc "pwrite 5T 4k" /mnt/ext4/testfile chattr -e /mnt/ext4/testfile sync If delalloc is enabled, dmesg prints EXT4-fs warning (device dm-4): ext4_block_to_path:105: block 1342177280 > max in inode 53 EXT4-fs (dm-4): Delayed block allocation failed for inode 53 at logical offset 1342177280 with max blocks 1 with error 5 EXT4-fs (dm-4): This should not happen!! Data will be lost If delalloc is disabled, e2fsck -nf shows corruption Inode 53, i_size is 5497558142976, should be 4096. Fix? no Fix the two issues by a) forcing all delayed allocation blocks to be allocated before checking eh->eh_depth and eh->eh_entries b) limiting the last logical block of the extent is within direct map Signed-off-by: Eryu Guan --- fs/ext4/migrate.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/fs/ext4/migrate.c b/fs/ext4/migrate.c index b52374e..3651141 100644 --- a/fs/ext4/migrate.c +++ b/fs/ext4/migrate.c @@ -620,6 +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_fsblk_t blk; handle_t *handle; int ret; @@ -633,6 +634,14 @@ int ext4_ind_migrate(struct inode *inode) EXT4_FEATURE_RO_COMPAT_BIGALLOC)) return -EOPNOTSUPP; + /* + * In order to get correct extent info, force all delayed allocation + * blocks to be allocated, otherwise delayed allocation blocks may not + * be reflected and bypass the checks on extent header. + */ + if (test_opt(inode->i_sb, DELALLOC)) + ext4_alloc_da_blocks(inode); + handle = ext4_journal_start(inode, EXT4_HT_MIGRATE, 1); if (IS_ERR(handle)) return PTR_ERR(handle); @@ -654,7 +663,8 @@ int ext4_ind_migrate(struct inode *inode) else { len = le16_to_cpu(ex->ee_len); blk = ext4_ext_pblock(ex); - if (len > EXT4_NDIR_BLOCKS) { + end = le32_to_cpu(ex->ee_block) + len - 1; + if (end >= EXT4_NDIR_BLOCKS) { ret = -EOPNOTSUPP; goto errout; } -- 1.8.3.1