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authorJan Kara <jack@suse.cz>2016-09-30 09:02:29 +0300
committerTheodore Ts'o <tytso@mit.edu>2016-09-30 09:02:29 +0300
commit9b623df614576680cadeaa4d7e0b5884de8f7c17 (patch)
tree06860f5d4dac697ceb441b2ad0305610470d387a /fs/ext4
parent51e8137b82622d8ea22e993d613db568f11c1523 (diff)
downloadlinux-9b623df614576680cadeaa4d7e0b5884de8f7c17.tar.xz
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 <jack@suse.cz> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Cc: stable@kernel.org
Diffstat (limited to 'fs/ext4')
-rw-r--r--fs/ext4/inode.c10
1 files changed, 9 insertions, 1 deletions
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index d8a4afc5eedb..cd918823b352 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) {