[PATCH] exportfs: add find_acceptable_alias helper

find_exported_dentry contains two duplicate loops to find an alias that the
acceptable callback likes.  Split this out to a new helper and switch from
list_for_each to list_for_each_entry to make it more readable.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: NeilBrown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/fs/exportfs/expfs.c b/fs/exportfs/expfs.c
index 5bfe400..b06b54f 100644 (file)
--- a/fs/exportfs/expfs.c
+++ b/fs/exportfs/expfs.c
@@ -11,6 +11,33 @@ struct export_operations export_op_default;
 
 #define dprintk(fmt, args...) do{}while(0)
 
+static struct dentry *
+find_acceptable_alias(struct dentry *result,
+               int (*acceptable)(void *context, struct dentry *dentry),
+               void *context)
+{
+       struct dentry *dentry, *toput = NULL;
+
+       spin_lock(&dcache_lock);
+       list_for_each_entry(dentry, &result->d_inode->i_dentry, d_alias) {
+               dget_locked(dentry);
+               spin_unlock(&dcache_lock);
+               if (toput)
+                       dput(toput);
+               if (dentry != result && acceptable(context, dentry)) {
+                       dput(result);
+                       return dentry;
+               }
+               spin_lock(&dcache_lock);
+               toput = dentry;
+       }
+       spin_unlock(&dcache_lock);
+
+       if (toput)
+               dput(toput);
+       return NULL;
+}
+
 /**
  * find_exported_dentry - helper routine to implement export_operations->decode_fh
  * @sb:                The &super_block identifying the filesystem
@@ -52,8 +79,7 @@ find_exported_dentry(struct super_block *sb, void *obj, void *parent,
        struct dentry *target_dir;
        int err;
        struct export_operations *nops = sb->s_export_op;
-       struct list_head *le, *head;
-       struct dentry *toput = NULL;
+       struct dentry *alias;
        int noprogress;
        char nbuf[NAME_MAX+1];
 
@@ -79,27 +105,10 @@ find_exported_dentry(struct super_block *sb, void *obj, void *parent,
                        /* there is no other dentry, so fail */
                        goto err_result;
                }
-               /* try any other aliases */
-               spin_lock(&dcache_lock);
-               head = &result->d_inode->i_dentry;
-               list_for_each(le, head) {
-                       struct dentry *dentry = list_entry(le, struct dentry, d_alias);
-                       dget_locked(dentry);
-                       spin_unlock(&dcache_lock);
-                       if (toput)
-                               dput(toput);
-                       toput = NULL;
-                       if (dentry != result &&
-                           acceptable(context, dentry)) {
-                               dput(result);
-                               return dentry;
-                       }
-                       spin_lock(&dcache_lock);
-                       toput = dentry;
-               }
-               spin_unlock(&dcache_lock);
-               if (toput)
-                       dput(toput);
+
+               alias = find_acceptable_alias(result, acceptable, context);
+               if (alias)
+                       return alias;
        }                       
 
        /* It's a directory, or we are required to confirm the file's
@@ -258,26 +267,10 @@ find_exported_dentry(struct super_block *sb, void *obj, void *parent,
        /* now result is properly connected, it is our best bet */
        if (acceptable(context, result))
                return result;
-       /* one last try of the aliases.. */
-       spin_lock(&dcache_lock);
-       toput = NULL;
-       head = &result->d_inode->i_dentry;
-       list_for_each(le, head) {
-               struct dentry *dentry = list_entry(le, struct dentry, d_alias);
-               dget_locked(dentry);
-               spin_unlock(&dcache_lock);
-               if (toput) dput(toput);
-               if (dentry != result &&
-                   acceptable(context, dentry)) {
-                       dput(result);
-                       return dentry;
-               }
-               spin_lock(&dcache_lock);
-               toput = dentry;
-       }
-       spin_unlock(&dcache_lock);
-       if (toput)
-               dput(toput);
+
+       alias = find_acceptable_alias(result, acceptable, context);
+       if (alias)
+               return alias;
 
        /* drat - I just cannot find anything acceptable */
        dput(result);