reiserfs: Relax lock on xattr removing

When we remove an xattr, we call lookup_and_delete_xattr()
that takes some private xattr inodes mutexes. But we hold
the reiserfs lock at this time, which leads to dependency
inversions.

We can safely call lookup_and_delete_xattr() without the
reiserfs lock, where xattr inodes lookups only need the
xattr inodes mutexes.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Christian Kujau <lists@nerdbynature.de>
Cc: Alexander Beregalov <a.beregalov@gmail.com>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Ingo Molnar <mingo@elte.hu>

diff --git a/fs/reiserfs/xattr.c b/fs/reiserfs/xattr.c
index 75d3706..4899d78 100644 (file)
--- a/fs/reiserfs/xattr.c
+++ b/fs/reiserfs/xattr.c
@@ -451,7 +451,9 @@ static int lookup_and_delete_xattr(struct inode *inode, const char *name)
        }
 
        if (dentry->d_inode) {
+               reiserfs_write_lock(inode->i_sb);
                err = xattr_unlink(xadir->d_inode, dentry);
+               reiserfs_write_unlock(inode->i_sb);
                update_ctime(inode);
        }
 
@@ -485,10 +487,14 @@ reiserfs_xattr_set_handle(struct reiserfs_transaction_handle *th,
        if (get_inode_sd_version(inode) == STAT_DATA_V1)
                return -EOPNOTSUPP;
 
-       if (!buffer)
-               return lookup_and_delete_xattr(inode, name);
-
        reiserfs_write_unlock(inode->i_sb);
+
+       if (!buffer) {
+               err = lookup_and_delete_xattr(inode, name);
+               reiserfs_write_lock(inode->i_sb);
+               return err;
+       }
+
        dentry = xattr_lookup(inode, name, flags);
        if (IS_ERR(dentry)) {
                reiserfs_write_lock(inode->i_sb);