1 files changed, 65 insertions, 78 deletions

diff --git a/fs/dcache.c b/fs/dcache.c
index 89509b5a090e..16a53cc2cc02 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -38,6 +38,7 @@
 #include <linux/prefetch.h>
 #include <linux/ratelimit.h>
 #include "internal.h"
+#include "mount.h"
 
 /*
  * Usage:
@@ -242,6 +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--;
 }
@@ -275,15 +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);
 }
@@ -769,14 +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);
@@ -795,18 +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;
@@ -821,23 +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
  *
@@ -1091,7 +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;
@@ -1113,17 +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
@@ -1180,14 +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);
 
@@ -1460,6 +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;
@@ -1471,7 +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;
 
@@ -1480,7 +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
@@ -2451,6 +2462,7 @@ static int prepend_path(const struct path *path,
 {
 	struct dentry *dentry = path->dentry;
 	struct vfsmount *vfsmnt = path->mnt;
+	struct mount *mnt = real_mount(vfsmnt);
 	bool slash = false;
 	int error = 0;
 
@@ -2460,11 +2472,11 @@ static int prepend_path(const struct path *path,
 
 		if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) {
 			/* Global root? */
-			if (vfsmnt->mnt_parent == vfsmnt) {
+			if (!mnt_has_parent(mnt))
 				goto global_root;
-			}
-			dentry = vfsmnt->mnt_mountpoint;
-			vfsmnt = vfsmnt->mnt_parent;
+			dentry = mnt->mnt_mountpoint;
+			mnt = mnt->mnt_parent;
+			vfsmnt = &mnt->mnt;
 			continue;
 		}
 		parent = dentry->d_parent;
@@ -2501,7 +2513,7 @@ global_root:
 	if (!slash)
 		error = prepend(buffer, buflen, "/", 1);
 	if (!error)
-		error = vfsmnt->mnt_ns ? 1 : 2;
+		error = real_mount(vfsmnt)->mnt_ns ? 1 : 2;
 	goto out;
 }
 
@@ -2853,31 +2865,6 @@ int is_subdir(struct dentry *new_dentry, struct dentry *old_dentry)
 	return result;
 }
 
-int path_is_under(struct path *path1, struct path *path2)
-{
-	struct vfsmount *mnt = path1->mnt;
-	struct dentry *dentry = path1->dentry;
-	int res;
-
-	br_read_lock(vfsmount_lock);
-	if (mnt != path2->mnt) {
-		for (;;) {
-			if (mnt->mnt_parent == mnt) {
-				br_read_unlock(vfsmount_lock);
-				return 0;
-			}
-			if (mnt->mnt_parent == path2->mnt)
-				break;
-			mnt = mnt->mnt_parent;
-		}
-		dentry = mnt->mnt_mountpoint;
-	}
-	res = is_subdir(dentry, path2->dentry);
-	br_read_unlock(vfsmount_lock);
-	return res;
-}
-EXPORT_SYMBOL(path_is_under);
-
 void d_genocide(struct dentry *root)
 {
 	struct dentry *this_parent;