knfsd: exportfs: add find_disconnected_root helper

Break the loop that finds the root of a disconnected subtree into a helper of
its own to make reading easier and document the intent.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 23 insertions, 16 deletions

diff --git a/fs/exportfs/expfs.c b/fs/exportfs/expfs.c
index 085d6c547f44..166d8ca9eaea 100644
--- a/fs/exportfs/expfs.c
+++ b/fs/exportfs/expfs.c
@@ -70,6 +70,27 @@ find_acceptable_alias(struct dentry *result,
         return NULL;
 }
 
+/*
+ * Find root of a disconnected subtree and return a reference to it.
+ */
+static struct dentry *
+find_disconnected_root(struct dentry *dentry)
+{
+        dget(dentry);
+        spin_lock(&dentry->d_lock);
+        while (!IS_ROOT(dentry) &&
+               (dentry->d_parent->d_flags & DCACHE_DISCONNECTED)) {
+                struct dentry *parent = dentry->d_parent;
+                dget(parent);
+                spin_unlock(&dentry->d_lock);
+                dput(dentry);
+                dentry = parent;
+                spin_lock(&dentry->d_lock);
+        }
+        spin_unlock(&dentry->d_lock);
+        return dentry;
+}
+
 /**
  * find_exported_dentry - helper routine to implement export_operations->decode_fh
  * @sb:         The &super_block identifying the filesystem
@@ -164,23 +185,9 @@ find_exported_dentry(struct super_block *sb, void *obj, void *parent,
          * the noprogress counter.  If we go through the loop 10 times (2 is
          * probably enough) without getting anywhere, we just give up
          */
-        noprogress= 0;
+        noprogress = 0;
         while (target_dir->d_flags & DCACHE_DISCONNECTED && noprogress++ < 10) {
-                struct dentry *pd = target_dir;
-
-                dget(pd);
-                spin_lock(&pd->d_lock);
-                while (!IS_ROOT(pd) &&
-                                (pd->d_parent->d_flags&DCACHE_DISCONNECTED)) {
-                        struct dentry *parent = pd->d_parent;
-
-                        dget(parent);
-                        spin_unlock(&pd->d_lock);
-                        dput(pd);
-                        pd = parent;
-                        spin_lock(&pd->d_lock);
-                }
-                spin_unlock(&pd->d_lock);
+                struct dentry *pd = find_disconnected_root(target_dir);
 
                 if (!IS_ROOT(pd)) {
                         /* must have found a connected parent - great */