[PATCH 3.16 096/125] ext4: fix incorect journal credits reservation in ext4_zero_range

Greg Kroah-Hartman
2014-09-03T22:28:56Z

From: Dmitry Monakhov <dmonakhov@openvz.org>

commit 69dc9536405213c1d545fcace1fc15c481d00aae upstream.

Currently we reserve only 4 blocks but in worst case scenario
ext4_zero_partial_blocks() may want to zeroout and convert two
non adjacent blocks.

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/ext4/extents.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)

--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -4730,6 +4730,7 @@ static long ext4_zero_range(struct file
loff_t new_size = 0;
int ret = 0;
int flags;
+ int credits;
int partial;
loff_t start, end;
ext4_lblk_t lblk;
@@ -4829,8 +4830,14 @@ static long ext4_zero_range(struct file
if (ret)
goto out_dio;
}
-
- handle = ext4_journal_start(inode, EXT4_HT_MISC, 4);
+ /*
+ * In worst case we have to writeout two nonadjacent unwritten
+ * blocks and update the inode
+ */
+ credits = (2 * ext4_ext_index_trans_blocks(inode, 2)) + 1;
+ if (ext4_should_journal_data(inode))
+ credits += 2;
+ handle = ext4_journal_start(inode, EXT4_HT_MISC, credits);
if (IS_ERR(handle)) {
ret = PTR_ERR(handle);
ext4_std_error(inode->i_sb, ret);