3 files changed, 39 insertions, 1 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 7b73a9c3d868..ad4eacca7f59 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -1544,6 +1544,9 @@ int btrfs_csum_truncate(struct btrfs_trans_handle *trans,
                         struct btrfs_root *root, struct btrfs_path *path,
                         u64 isize);
 /* inode.c */
+void btrfs_invalidate_dcache_root(struct btrfs_root *root, char *name,
+                                  int namelen);
+
 int btrfs_merge_bio_hook(struct page *page, unsigned long offset,
                          size_t size, struct bio *bio);
 
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 1569fb864515..31aa4ba06fce 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -2642,6 +2642,31 @@ static void btrfs_truncate(struct inode *inode)
         btrfs_throttle(root);
 }
 
+/*
+ * Invalidate a single dcache entry at the root of the filesystem.
+ * Needed after creation of snapshot or subvolume.
+ */
+void btrfs_invalidate_dcache_root(struct btrfs_root *root, char *name,
+                                  int namelen)
+{
+        struct dentry *alias, *entry;
+        struct qstr qstr;
+
+        alias = d_find_alias(root->fs_info->sb->s_root->d_inode);
+        if (alias) {
+                qstr.name = name;
+                qstr.len = namelen;
+                /* change me if btrfs ever gets a d_hash operation */
+                qstr.hash = full_name_hash(qstr.name, qstr.len);
+                entry = d_lookup(alias, &qstr);
+                dput(alias);
+                if (entry) {
+                        d_invalidate(entry);
+                        dput(entry);
+                }
+        }
+}
+
 static int noinline create_subvol(struct btrfs_root *root, char *name,
                                   int namelen)
 {
@@ -2761,6 +2786,10 @@ static int noinline create_subvol(struct btrfs_root *root, char *name,
         ret = btrfs_update_inode(trans, new_root, inode);
         if (ret)
                 goto fail;
+
+        /* Invalidate existing dcache entry for new subvolume. */
+        btrfs_invalidate_dcache_root(root, name, namelen);
+
 fail:
         nr = trans->blocks_used;
         err = btrfs_commit_transaction(trans, new_root);
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 1cb084efd6ed..f04684f7fea3 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -560,6 +560,7 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
         struct btrfs_root *root = pending->root;
         struct extent_buffer *tmp;
         int ret;
+        int namelen;
         u64 objectid;
 
         new_root_item = kmalloc(sizeof(*new_root_item), GFP_NOFS);
@@ -595,8 +596,9 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
          * insert the directory item
          */
         key.offset = (u64)-1;
+        namelen = strlen(pending->name);
         ret = btrfs_insert_dir_item(trans, root->fs_info->tree_root,
-                                    pending->name, strlen(pending->name),
+                                    pending->name, namelen,
                                     root->fs_info->sb->s_root->d_inode->i_ino,
                                     &key, BTRFS_FT_DIR);
 
@@ -606,6 +608,10 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
         ret = btrfs_insert_inode_ref(trans, root->fs_info->tree_root,
                              pending->name, strlen(pending->name), objectid,
                              root->fs_info->sb->s_root->d_inode->i_ino);
+
+        /* Invalidate existing dcache entry for new snapshot. */
+        btrfs_invalidate_dcache_root(root, pending->name, namelen);
+
 fail:
         kfree(new_root_item);
         return ret;