From: Jan Kara Date: Fri, 30 Sep 2016 06:02:29 +0000 (-0400) Subject: ext4: unmap metadata when zeroing blocks X-Git-Tag: v4.14-rc1~2333^2~3 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=9b623df614576680cadeaa4d7e0b5884de8f7c17;p=platform%2Fkernel%2Flinux-rpi.git ext4: unmap metadata when zeroing blocks When zeroing blocks for DAX allocations, we also have to unmap aliases in the block device mappings. Otherwise writeback can overwrite zeros with stale data from block device page cache. Signed-off-by: Jan Kara Signed-off-by: Theodore Ts'o Cc: stable@kernel.org --- diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index d8a4afc..cd91882 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -647,11 +647,19 @@ found: /* * We have to zeroout blocks before inserting them into extent * status tree. Otherwise someone could look them up there and - * use them before they are really zeroed. + * use them before they are really zeroed. We also have to + * unmap metadata before zeroing as otherwise writeback can + * overwrite zeros with stale data from block device. */ if (flags & EXT4_GET_BLOCKS_ZERO && map->m_flags & EXT4_MAP_MAPPED && map->m_flags & EXT4_MAP_NEW) { + ext4_lblk_t i; + + for (i = 0; i < map->m_len; i++) { + unmap_underlying_metadata(inode->i_sb->s_bdev, + map->m_pblk + i); + } ret = ext4_issue_zeroout(inode, map->m_lblk, map->m_pblk, map->m_len); if (ret) {