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

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index f0e6934291dd2ff592644aa5d4fe1c8c866e37f7..0e9de2328bd20d373024eef6aead582805b0c6c6 100644 (file)
--- 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);