1 files changed, 58 insertions, 48 deletions

diff --git a/fs/dcache.c b/fs/dcache.c
index 9791b1e7eee4..16a53cc2cc02 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -243,6 +243,7 @@ static void dentry_lru_add(struct dentry *dentry)
 static void __dentry_lru_del(struct dentry *dentry)
 {
         list_del_init(&dentry->d_lru);
+        dentry->d_flags &= ~DCACHE_SHRINK_LIST;
         dentry->d_sb->s_nr_dentry_unused--;
         dentry_stat.nr_unused--;
 }
@@ -276,15 +277,15 @@ static void dentry_lru_prune(struct dentry *dentry)
         }
 }
 
-static void dentry_lru_move_tail(struct dentry *dentry)
+static void dentry_lru_move_list(struct dentry *dentry, struct list_head *list)
 {
         spin_lock(&dcache_lru_lock);
         if (list_empty(&dentry->d_lru)) {
-                list_add_tail(&dentry->d_lru, &dentry->d_sb->s_dentry_lru);
+                list_add_tail(&dentry->d_lru, list);
                 dentry->d_sb->s_nr_dentry_unused++;
                 dentry_stat.nr_unused++;
         } else {
-                list_move_tail(&dentry->d_lru, &dentry->d_sb->s_dentry_lru);
+                list_move_tail(&dentry->d_lru, list);
         }
         spin_unlock(&dcache_lru_lock);
 }
@@ -770,14 +771,18 @@ static void shrink_dentry_list(struct list_head *list)
 }
 
 /**
- * __shrink_dcache_sb - shrink the dentry LRU on a given superblock
- * @sb:         superblock to shrink dentry LRU.
- * @count:      number of entries to prune
- * @flags:      flags to control the dentry processing
+ * prune_dcache_sb - shrink the dcache
+ * @sb: superblock
+ * @count: number of entries to try to free
+ *
+ * Attempt to shrink the superblock dcache LRU by @count entries. This is
+ * done when we need more memory an called from the superblock shrinker
+ * function.
  *
- * If flags contains DCACHE_REFERENCED reference dentries will not be pruned.
+ * This function may fail to free any resources if all the dentries are in
+ * use.
  */
-static void __shrink_dcache_sb(struct super_block *sb, int count, int flags)
+void prune_dcache_sb(struct super_block *sb, int count)
 {
         struct dentry *dentry;
         LIST_HEAD(referenced);
@@ -796,18 +801,13 @@ relock:
                         goto relock;
                 }
 
-                /*
-                 * If we are honouring the DCACHE_REFERENCED flag and the
-                 * dentry has this flag set, don't free it.  Clear the flag
-                 * and put it back on the LRU.
-                 */
-                if (flags & DCACHE_REFERENCED &&
-                                dentry->d_flags & DCACHE_REFERENCED) {
+                if (dentry->d_flags & DCACHE_REFERENCED) {
                         dentry->d_flags &= ~DCACHE_REFERENCED;
                         list_move(&dentry->d_lru, &referenced);
                         spin_unlock(&dentry->d_lock);
                 } else {
                         list_move_tail(&dentry->d_lru, &tmp);
+                        dentry->d_flags |= DCACHE_SHRINK_LIST;
                         spin_unlock(&dentry->d_lock);
                         if (!--count)
                                 break;
@@ -822,23 +822,6 @@ relock:
 }
 
 /**
- * prune_dcache_sb - shrink the dcache
- * @sb: superblock
- * @nr_to_scan: number of entries to try to free
- *
- * Attempt to shrink the superblock dcache LRU by @nr_to_scan entries. This is
- * done when we need more memory an called from the superblock shrinker
- * function.
- *
- * This function may fail to free any resources if all the dentries are in
- * use.
- */
-void prune_dcache_sb(struct super_block *sb, int nr_to_scan)
-{
-        __shrink_dcache_sb(sb, nr_to_scan, DCACHE_REFERENCED);
-}
-
-/**
  * shrink_dcache_sb - shrink dcache for a superblock
  * @sb: superblock
  *
@@ -1092,7 +1075,7 @@ EXPORT_SYMBOL(have_submounts);
  * drop the lock and return early due to latency
  * constraints.
  */
-static int select_parent(struct dentry * parent)
+static int select_parent(struct dentry *parent, struct list_head *dispose)
 {
         struct dentry *this_parent;
         struct list_head *next;
@@ -1114,17 +1097,21 @@ resume:
 
                 spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
 
-                /* 
-                 * move only zero ref count dentries to the end 
-                 * of the unused list for prune_dcache
+                /*
+                 * move only zero ref count dentries to the dispose list.
+                 *
+                 * Those which are presently on the shrink list, being processed
+                 * by shrink_dentry_list(), shouldn't be moved.  Otherwise the
+                 * loop in shrink_dcache_parent() might not make any progress
+                 * and loop forever.
                  */
-                if (!dentry->d_count) {
-                        dentry_lru_move_tail(dentry);
-                        found++;
-                } else {
+                if (dentry->d_count) {
                         dentry_lru_del(dentry);
+                } else if (!(dentry->d_flags & DCACHE_SHRINK_LIST)) {
+                        dentry_lru_move_list(dentry, dispose);
+                        dentry->d_flags |= DCACHE_SHRINK_LIST;
+                        found++;
                 }
-
                 /*
                  * We can return to the caller if we have found some (this
                  * ensures forward progress). We'll be coming back to find
@@ -1181,14 +1168,13 @@ rename_retry:
  *
  * Prune the dcache to remove unused children of the parent dentry.
  */
- 
 void shrink_dcache_parent(struct dentry * parent)
 {
-        struct super_block *sb = parent->d_sb;
+        LIST_HEAD(dispose);
         int found;
 
-        while ((found = select_parent(parent)) != 0)
-                __shrink_dcache_sb(sb, found, 0);
+        while ((found = select_parent(parent, &dispose)) != 0)
+                shrink_dentry_list(&dispose);
 }
 EXPORT_SYMBOL(shrink_dcache_parent);
 
@@ -1461,6 +1447,23 @@ struct dentry * d_alloc_root(struct inode * root_inode)
 }
 EXPORT_SYMBOL(d_alloc_root);
 
+struct dentry *d_make_root(struct inode *root_inode)
+{
+        struct dentry *res = NULL;
+
+        if (root_inode) {
+                static const struct qstr name = { .name = "/", .len = 1 };
+
+                res = __d_alloc(root_inode->i_sb, &name);
+                if (res)
+                        d_instantiate(res, root_inode);
+                else
+                        iput(root_inode);
+        }
+        return res;
+}
+EXPORT_SYMBOL(d_make_root);
+
 static struct dentry * __d_find_any_alias(struct inode *inode)
 {
         struct dentry *alias;
@@ -1472,7 +1475,14 @@ static struct dentry * __d_find_any_alias(struct inode *inode)
         return alias;
 }
 
-static struct dentry * d_find_any_alias(struct inode *inode)
+/**
+ * d_find_any_alias - find any alias for a given inode
+ * @inode: inode to find an alias for
+ *
+ * If any aliases exist for the given inode, take and return a
+ * reference for one of them.  If no aliases exist, return %NULL.
+ */
+struct dentry *d_find_any_alias(struct inode *inode)
 {
         struct dentry *de;
 
@@ -1481,7 +1491,7 @@ static struct dentry * d_find_any_alias(struct inode *inode)
         spin_unlock(&inode->i_lock);
         return de;
 }
-
+EXPORT_SYMBOL(d_find_any_alias);
 
 /**
  * d_obtain_alias - find or allocate a dentry for a given inode