ext4: cleanup ext4_sync_parent()

A condition !hlist_empty(&inode->i_dentry) is always true for open file.
Just remove it. Also ext4_sync_parent() could use some explanation why
races with rmdir() are not an issue - add a comment explaining that.

Reported-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

1 files changed, 8 insertions, 1 deletions

diff --git a/fs/ext4/fsync.c b/fs/ext4/fsync.c
index 5c4372512ef7..88effb1053c7 100644
--- a/fs/ext4/fsync.c
+++ b/fs/ext4/fsync.c
@@ -61,6 +61,13 @@ static int ext4_sync_parent(struct inode *inode)
                         break;
                 iput(inode);
                 inode = next;
+                /*
+                 * The directory inode may have gone through rmdir by now. But
+                 * the inode itself and its blocks are still allocated (we hold
+                 * a reference to the inode so it didn't go through
+                 * ext4_evict_inode()) and so we are safe to flush metadata
+                 * blocks and the inode.
+                 */
                 ret = sync_mapping_buffers(inode->i_mapping);
                 if (ret)
                         break;
@@ -107,7 +114,7 @@ int ext4_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
 
         if (!journal) {
                 ret = __generic_file_fsync(file, start, end, datasync);
-                if (!ret && !hlist_empty(&inode->i_dentry))
+                if (!ret)
                         ret = ext4_sync_parent(inode);
                 if (test_opt(inode->i_sb, BARRIER))
                         goto issue_flush;