ext4: fix incorect journal credits reservation in ext4_zero_range

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>
Cc: stable@vger.kernel.org

1 files changed, 9 insertions, 2 deletions

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index f0e6934291dd..0e9de2328bd2 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -4731,6 +4731,7 @@ static long ext4_zero_range(struct file *file, loff_t offset,
         loff_t new_size = 0;
         int ret = 0;
         int flags;
+        int credits;
         int partial;
         loff_t start, end;
         ext4_lblk_t lblk;
@@ -4830,8 +4831,14 @@ static long ext4_zero_range(struct file *file, loff_t offset,
                 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);