btrfs: extended inode refs

This patch adds basic support for extended inode refs. This includes support
for link and unlink of the refs, which basically gets us support for rename
as well.

Inode creation does not need changing - extended refs are only added after
the ref array is full.

Signed-off-by: Mark Fasheh <mfasheh@suse.de>

1 files changed, 14 insertions, 9 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 1c50f7c4f5ac..596305e4d75b 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -2903,7 +2903,6 @@ static struct btrfs_trans_handle *__unlink_start_trans(struct inode *dir,
         struct btrfs_trans_handle *trans;
         struct btrfs_root *root = BTRFS_I(dir)->root;
         struct btrfs_path *path;
-        struct btrfs_inode_ref *ref;
         struct btrfs_dir_item *di;
         struct inode *inode = dentry->d_inode;
         u64 index;
@@ -3017,17 +3016,17 @@ static struct btrfs_trans_handle *__unlink_start_trans(struct inode *dir,
         }
         btrfs_release_path(path);
 
-        ref = btrfs_lookup_inode_ref(trans, root, path,
-                                dentry->d_name.name, dentry->d_name.len,
-                                ino, dir_ino, 0);
-        if (IS_ERR(ref)) {
-                err = PTR_ERR(ref);
+        ret = btrfs_get_inode_ref_index(trans, root, path, dentry->d_name.name,
+                                        dentry->d_name.len, ino, dir_ino, 0,
+                                        &index);
+        if (ret) {
+                err = ret;
                 goto out;
         }
-        BUG_ON(!ref); /* Logic error */
+
         if (check_path_shared(root, path))
                 goto out;
-        index = btrfs_inode_ref_index(path->nodes[0], ref);
+
         btrfs_release_path(path);
 
         /*
@@ -4743,6 +4742,12 @@ static struct inode *btrfs_new_inode(struct btrfs_trans_handle *trans,
         btrfs_set_key_type(&key[0], BTRFS_INODE_ITEM_KEY);
         key[0].offset = 0;
 
+        /*
+         * Start new inodes with an inode_ref. This is slightly more
+         * efficient for small numbers of hard links since they will
+         * be packed into one item. Extended refs will kick in if we
+         * add more hard links than can fit in the ref item.
+         */
         key[1].objectid = objectid;
         btrfs_set_key_type(&key[1], BTRFS_INODE_REF_KEY);
         key[1].offset = ref_objectid;
@@ -5049,7 +5054,7 @@ static int btrfs_link(struct dentry *old_dentry, struct inode *dir,
         if (root->objectid != BTRFS_I(inode)->root->objectid)
                 return -EXDEV;
 
-        if (inode->i_nlink == ~0U)
+        if (inode->i_nlink >= BTRFS_LINK_MAX)
                 return -EMLINK;
 
         err = btrfs_set_inode_index(dir, &index);