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authorDmitry Monakhov <dmonakhov@openvz.org>2013-03-04 00:34:34 -0500
committerTheodore Ts'o <tytso@mit.edu>2013-03-04 00:34:34 -0500
commit357b66fdc8ad4cea6e6336956a70742f961f0a4d (patch)
treebbb15a0d60de8c3ab70595484e72b3ef38515026 /fs/ext4
parent9b2ff35753c0512bc8c6adae9e9c87cbeee86f82 (diff)
ext4: ext4_split_extent should take care of extent zeroout
When ext4_split_extent_at() ends up doing zeroout & conversion to initialized instead of split & conversion, ext4_split_extent() gets confused and can wrongly mark the extent back as uninitialized resulting in end IO code getting confused from large unwritten extents and may result in data loss. The example of problematic behavior is: lblk len lblk len ext4_split_extent() (ex=[1000,30,uninit], map=[1010,10]) ext4_split_extent_at() (split [1000,30,uninit] at 1020) ext4_ext_insert_extent() -> ENOSPC ext4_ext_zeroout() -> extent [1000,30] is now initialized ext4_split_extent_at() (split [1000,30,init] at 1010, MARK_UNINIT1 | MARK_UNINIT2) -> extent is split and parts marked as uninitialized Fix the problem by rechecking extent type after the first ext4_split_extent_at() returns. None of split_flags can not be applied to initialized extent so this patch also add BUG_ON to prevent similar issues in future. TESTCASE: https://github.com/dmonakhov/xfstests/commit/b8a55eb5ce28c6ff29e620ab090902fcd5833597 Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Reviewed-by: Jan Kara <jack@suse.cz>
Diffstat (limited to 'fs/ext4')
-rw-r--r--fs/ext4/extents.c23
1 files changed, 17 insertions, 6 deletions
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 372b2cbee07..bef194a1443 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -2943,6 +2943,10 @@ static int ext4_split_extent_at(handle_t *handle,
newblock = split - ee_block + ext4_ext_pblock(ex);
BUG_ON(split < ee_block || split >= (ee_block + ee_len));
+ BUG_ON(!ext4_ext_is_uninitialized(ex) &&
+ split_flag & (EXT4_EXT_MAY_ZEROOUT |
+ EXT4_EXT_MARK_UNINIT1 |
+ EXT4_EXT_MARK_UNINIT2));
err = ext4_ext_get_access(handle, inode, path + depth);
if (err)
@@ -3061,19 +3065,26 @@ static int ext4_split_extent(handle_t *handle,
if (err)
goto out;
}
-
+ /*
+ * Update path is required because previous ext4_split_extent_at() may
+ * result in split of original leaf or extent zeroout.
+ */
ext4_ext_drop_refs(path);
path = ext4_ext_find_extent(inode, map->m_lblk, path);
if (IS_ERR(path))
return PTR_ERR(path);
+ depth = ext_depth(inode);
+ ex = path[depth].p_ext;
+ uninitialized = ext4_ext_is_uninitialized(ex);
+ split_flag1 = 0;
if (map->m_lblk >= ee_block) {
- split_flag1 = split_flag & (EXT4_EXT_MAY_ZEROOUT |
- EXT4_EXT_DATA_VALID2);
- if (uninitialized)
+ split_flag1 = split_flag & EXT4_EXT_DATA_VALID2;
+ if (uninitialized) {
split_flag1 |= EXT4_EXT_MARK_UNINIT1;
- if (split_flag & EXT4_EXT_MARK_UNINIT2)
- split_flag1 |= EXT4_EXT_MARK_UNINIT2;
+ split_flag1 |= split_flag & (EXT4_EXT_MAY_ZEROOUT |
+ EXT4_EXT_MARK_UNINIT2);
+ }
err = ext4_split_extent_at(handle, inode, path,
map->m_lblk, split_flag1, flags);
if (err)