ext4: start handle at the last possible moment in ext4_unlink()

Don't start the jbd2 transaction handle until after the directory
entry has been found, to minimize the amount of time that a handle is
held active.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>

1 files changed, 14 insertions, 10 deletions

diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 51841032ca03..4a27069d54ad 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -2787,7 +2787,7 @@ static int ext4_unlink(struct inode *dir, struct dentry *dentry)
         struct inode *inode;
         struct buffer_head *bh;
         struct ext4_dir_entry_2 *de;
-        handle_t *handle;
+        handle_t *handle = NULL;
 
         trace_ext4_unlink_enter(dir, dentry);
         /* Initialize quotas before so that eventual writes go
@@ -2795,14 +2795,6 @@ static int ext4_unlink(struct inode *dir, struct dentry *dentry)
         dquot_initialize(dir);
         dquot_initialize(dentry->d_inode);
 
-        handle = ext4_journal_start(dir, EXT4_HT_DIR,
-                                    EXT4_DELETE_TRANS_BLOCKS(dir->i_sb));
-        if (IS_ERR(handle))
-                return PTR_ERR(handle);
-
-        if (IS_DIRSYNC(dir))
-                ext4_handle_sync(handle);
-
         retval = -ENOENT;
         bh = ext4_find_entry(dir, &dentry->d_name, &de, NULL);
         if (!bh)
@@ -2814,6 +2806,17 @@ static int ext4_unlink(struct inode *dir, struct dentry *dentry)
         if (le32_to_cpu(de->inode) != inode->i_ino)
                 goto end_unlink;
 
+        handle = ext4_journal_start(dir, EXT4_HT_DIR,
+                                    EXT4_DELETE_TRANS_BLOCKS(dir->i_sb));
+        if (IS_ERR(handle)) {
+                retval = PTR_ERR(handle);
+                handle = NULL;
+                goto end_unlink;
+        }
+
+        if (IS_DIRSYNC(dir))
+                ext4_handle_sync(handle);
+
         if (!inode->i_nlink) {
                 ext4_warning(inode->i_sb,
                              "Deleting nonexistent file (%lu), %d",
@@ -2834,8 +2837,9 @@ static int ext4_unlink(struct inode *dir, struct dentry *dentry)
         retval = 0;
 
 end_unlink:
-        ext4_journal_stop(handle);
         brelse(bh);
+        if (handle)
+                ext4_journal_stop(handle);
         trace_ext4_unlink_exit(dentry, retval);
         return retval;
 }