Btrfs: Add back pointers from the inode to the directory that references it

Signed-off-by: Chris Mason <chris.mason@oracle.com>

3 files changed, 272 insertions, 143 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index cb1b156d954e..035fa1550343 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -53,7 +53,7 @@ extern struct kmem_cache *btrfs_path_cachep;
 #define BTRFS_CSUM_SIZE 32
 /* four bytes for CRC32 */
 #define BTRFS_CRC32_SIZE 4
-#define BTRFS_EMPTY_DIR_SIZE 6
+#define BTRFS_EMPTY_DIR_SIZE 0
 
 #define BTRFS_FT_UNKNOWN        0
 #define BTRFS_FT_REG_FILE       1
@@ -206,6 +206,11 @@ struct btrfs_extent_ref {
         __le64 offset;
 } __attribute__ ((__packed__));
 
+struct btrfs_inode_ref {
+        __le16 name_len;
+        /* name goes here */
+} __attribute__ ((__packed__));
+
 struct btrfs_inode_timespec {
         __le64 sec;
         __le32 nsec;
@@ -379,7 +384,8 @@ struct btrfs_root {
  * the FS
  */
 #define BTRFS_INODE_ITEM_KEY            1
-#define BTRFS_XATTR_ITEM_KEY            2
+#define BTRFS_INODE_REF_KEY             2
+#define BTRFS_XATTR_ITEM_KEY            8
 /* reserve 2-15 close to the inode for later flexibility */
 
 /*
@@ -486,6 +492,9 @@ BTRFS_SETGET_STACK_FUNCS(block_group_used, struct btrfs_block_group_item,
 BTRFS_SETGET_FUNCS(disk_block_group_used, struct btrfs_block_group_item,
                          used, 64);
 
+/* struct btrfs_inode_ref */
+BTRFS_SETGET_FUNCS(inode_ref_name_len, struct btrfs_inode_ref, name_len, 16);
+
 /* struct btrfs_inode_item */
 BTRFS_SETGET_FUNCS(inode_generation, struct btrfs_inode_item, generation, 64);
 BTRFS_SETGET_FUNCS(inode_size, struct btrfs_inode_item, size, 64);
@@ -1043,6 +1052,14 @@ int btrfs_find_free_objectid(struct btrfs_trans_handle *trans,
 int btrfs_find_highest_inode(struct btrfs_root *fs_root, u64 *objectid);
 
 /* inode-item.c */
+int btrfs_insert_inode_ref(struct btrfs_trans_handle *trans,
+                           struct btrfs_root *root,
+                           const char *name, int name_len,
+                           u64 inode_objectid, u64 ref_objectid);
+int btrfs_del_inode_ref(struct btrfs_trans_handle *trans,
+                           struct btrfs_root *root,
+                           const char *name, int name_len,
+                           u64 inode_objectid, u64 ref_objectid);
 int btrfs_insert_empty_inode(struct btrfs_trans_handle *trans,
                              struct btrfs_root *root,
                              struct btrfs_path *path, u64 objectid);
diff --git a/fs/btrfs/inode-item.c b/fs/btrfs/inode-item.c
index 35d2608f8918..cba30b6cc6fe 100644
--- a/fs/btrfs/inode-item.c
+++ b/fs/btrfs/inode-item.c
@@ -20,6 +20,142 @@
 #include "disk-io.h"
 #include "transaction.h"
 
+int find_name_in_backref(struct btrfs_path *path, const char * name,
+                         int name_len, struct btrfs_inode_ref **ref_ret)
+{
+        struct extent_buffer *leaf;
+        struct btrfs_inode_ref *ref;
+        unsigned long ptr;
+        unsigned long name_ptr;
+        u32 item_size;
+        u32 cur_offset = 0;
+        int len;
+
+        leaf = path->nodes[0];
+        item_size = btrfs_item_size_nr(leaf, path->slots[0]);
+        ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
+        while (cur_offset < item_size) {
+                ref = (struct btrfs_inode_ref *)(ptr + cur_offset);
+                len = btrfs_inode_ref_name_len(leaf, ref);
+                name_ptr = (unsigned long)(ref + 1);
+                cur_offset += len + sizeof(*ref);
+                if (len != name_len)
+                        continue;
+                if (memcmp_extent_buffer(leaf, name, name_ptr, name_len) == 0) {
+                        *ref_ret = ref;
+                        return 1;
+                }
+        }
+        return 0;
+}
+
+int btrfs_del_inode_ref(struct btrfs_trans_handle *trans,
+                           struct btrfs_root *root,
+                           const char *name, int name_len,
+                           u64 inode_objectid, u64 ref_objectid)
+{
+        struct btrfs_path *path;
+        struct btrfs_key key;
+        struct btrfs_inode_ref *ref;
+        struct extent_buffer *leaf;
+        unsigned long ptr;
+        unsigned long item_start;
+        u32 item_size;
+        u32 sub_item_len;
+        int ret;
+        int del_len = name_len + sizeof(*ref);
+
+        key.objectid = inode_objectid;
+        key.offset = ref_objectid;
+        btrfs_set_key_type(&key, BTRFS_INODE_REF_KEY);
+
+        path = btrfs_alloc_path();
+        if (!path)
+                return -ENOMEM;
+
+        ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
+        if (ret > 0) {
+                ret = -ENOENT;
+                goto out;
+        } else if (ret < 0) {
+                goto out;
+        }
+        if (!find_name_in_backref(path, name, name_len, &ref)) {
+                ret = -ENOENT;
+                goto out;
+        }
+        leaf = path->nodes[0];
+        item_size = btrfs_item_size_nr(leaf, path->slots[0]);
+        if (del_len == item_size) {
+                ret = btrfs_del_item(trans, root, path);
+                goto out;
+        }
+        ptr = (unsigned long)ref;
+        sub_item_len = name_len + sizeof(*ref);
+        item_start = btrfs_item_ptr_offset(leaf, path->slots[0]);
+        memmove_extent_buffer(leaf, ptr, ptr + sub_item_len,
+                              item_size - (ptr + sub_item_len - item_start));
+        ret = btrfs_truncate_item(trans, root, path,
+                                  item_size - sub_item_len, 1);
+        BUG_ON(ret);
+out:
+        btrfs_free_path(path);
+        return ret;
+}
+
+int btrfs_insert_inode_ref(struct btrfs_trans_handle *trans,
+                           struct btrfs_root *root,
+                           const char *name, int name_len,
+                           u64 inode_objectid, u64 ref_objectid)
+{
+        struct btrfs_path *path;
+        struct btrfs_key key;
+        struct btrfs_inode_ref *ref;
+        unsigned long ptr;
+        int ret;
+        int ins_len = name_len + sizeof(*ref);
+
+        key.objectid = inode_objectid;
+        key.offset = ref_objectid;
+        btrfs_set_key_type(&key, BTRFS_INODE_REF_KEY);
+
+        path = btrfs_alloc_path();
+        if (!path)
+                return -ENOMEM;
+
+        ret = btrfs_insert_empty_item(trans, root, path, &key,
+                                      ins_len);
+        if (ret == -EEXIST) {
+                u32 old_size;
+
+                if (find_name_in_backref(path, name, name_len, &ref))
+                        goto out;
+
+                old_size = btrfs_item_size_nr(path->nodes[0], path->slots[0]);
+                ret = btrfs_extend_item(trans, root, path, ins_len);
+                BUG_ON(ret);
+                ref = btrfs_item_ptr(path->nodes[0], path->slots[0],
+                                     struct btrfs_inode_ref);
+                ref = (struct btrfs_inode_ref *)((unsigned long)ref + old_size);
+                btrfs_set_inode_ref_name_len(path->nodes[0], ref, name_len);
+                ptr = (unsigned long)(ref + 1);
+                ret = 0;
+        } else if (ret < 0) {
+                goto out;
+        } else {
+                ref = btrfs_item_ptr(path->nodes[0], path->slots[0],
+                                     struct btrfs_inode_ref);
+                btrfs_set_inode_ref_name_len(path->nodes[0], ref, name_len);
+                ptr = (unsigned long)(ref + 1);
+        }
+        write_extent_buffer(path->nodes[0], name, ptr, name_len);
+        btrfs_mark_buffer_dirty(path->nodes[0]);
+
+out:
+        btrfs_free_path(path);
+        return ret;
+}
+
 int btrfs_insert_empty_inode(struct btrfs_trans_handle *trans,
                              struct btrfs_root *root,
                              struct btrfs_path *path, u64 objectid)
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 03fea037667e..cefe740b6c79 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -404,6 +404,17 @@ static int btrfs_unlink_trans(struct btrfs_trans_handle *trans,
         ret = btrfs_delete_one_dir_name(trans, root, path, di);
 
         dentry->d_inode->i_ctime = dir->i_ctime;
+        if (!S_ISLNK(dentry->d_inode->i_mode)) {
+                ret = btrfs_del_inode_ref(trans, root, name, name_len,
+                                          dentry->d_inode->i_ino,
+                                          dentry->d_parent->d_inode->i_ino);
+                if (ret) {
+                        printk("failed to delete reference to %.*s, "
+                               "inode %lu parent %lu\n", name_len, name,
+                               dentry->d_inode->i_ino,
+                               dentry->d_parent->d_inode->i_ino);
+                }
+        }
 err:
         btrfs_free_path(path);
         if (!ret) {
@@ -445,75 +456,27 @@ static int btrfs_rmdir(struct inode *dir, struct dentry *dentry)
         int err;
         int ret;
         struct btrfs_root *root = BTRFS_I(dir)->root;
-        struct btrfs_path *path;
-        struct btrfs_key key;
         struct btrfs_trans_handle *trans;
-        struct btrfs_key found_key;
-        int found_type;
-        struct extent_buffer *leaf;
-        char *goodnames = "..";
         unsigned long nr;
 
         if (inode->i_size > BTRFS_EMPTY_DIR_SIZE)
                 return -ENOTEMPTY;
 
-        path = btrfs_alloc_path();
-        BUG_ON(!path);
         mutex_lock(&root->fs_info->fs_mutex);
         trans = btrfs_start_transaction(root, 1);
-
         btrfs_set_trans_block_group(trans, dir);
-        key.objectid = inode->i_ino;
-        key.offset = (u64)-1;
-        key.type = (u8)-1;
-        while(1) {
-                ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
-                if (ret < 0) {
-                        err = ret;
-                        goto out;
-                }
-                BUG_ON(ret == 0);
-                if (path->slots[0] == 0) {
-                        err = -ENOENT;
-                        goto out;
-                }
-                path->slots[0]--;
-                leaf = path->nodes[0];
-                btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
-                found_type = btrfs_key_type(&found_key);
-                if (found_key.objectid != inode->i_ino) {
-                        err = -ENOENT;
-                        goto out;
-                }
-                if ((found_type != BTRFS_DIR_ITEM_KEY &&
-                     found_type != BTRFS_DIR_INDEX_KEY) ||
-                    (!btrfs_match_dir_item_name(root, path, goodnames, 2) &&
-                    !btrfs_match_dir_item_name(root, path, goodnames, 1))) {
-                        err = -ENOTEMPTY;
-                        goto out;
-                }
-                ret = btrfs_del_item(trans, root, path);
-                BUG_ON(ret);
-
-                if (found_type == BTRFS_DIR_ITEM_KEY && found_key.offset == 1)
-                        break;
-                btrfs_release_path(root, path);
-        }
-        ret = 0;
-        btrfs_release_path(root, path);
 
         /* now the directory is empty */
         err = btrfs_unlink_trans(trans, root, dir, dentry);
         if (!err) {
                 inode->i_size = 0;
         }
-out:
-        btrfs_release_path(root, path);
-        btrfs_free_path(path);
+
         nr = trans->blocks_used;
         ret = btrfs_end_transaction(trans, root);
         mutex_unlock(&root->fs_info->fs_mutex);
         btrfs_btree_balance_dirty(root, nr);
+
         if (ret && !err)
                 err = ret;
         return err;
@@ -887,21 +850,59 @@ static int btrfs_inode_by_name(struct inode *dir, struct dentry *dentry,
         struct btrfs_root *root = BTRFS_I(dir)->root;
         int ret = 0;
 
+        if (namelen == 1 && strcmp(name, ".") == 0) {
+                location->objectid = dir->i_ino;
+                location->type = BTRFS_INODE_ITEM_KEY;
+                location->offset = 0;
+                return 0;
+        }
         path = btrfs_alloc_path();
         BUG_ON(!path);
+
+        if (namelen == 1 && strcmp(name, "..") == 0) {
+                struct btrfs_key key;
+                struct extent_buffer *leaf;
+                u32 nritems;
+                int slot;
+
+                key.objectid = dir->i_ino;
+                btrfs_set_key_type(&key, BTRFS_INODE_REF_KEY);
+                key.offset = 0;
+                ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+                BUG_ON(ret == 0);
+                ret = 0;
+
+                leaf = path->nodes[0];
+                slot = path->slots[0];
+                nritems = btrfs_header_nritems(leaf);
+                if (slot >= nritems)
+                        goto out_err;
+
+                btrfs_item_key_to_cpu(leaf, &key, slot);
+                if (key.objectid != dir->i_ino ||
+                    key.type != BTRFS_INODE_REF_KEY) {
+                        goto out_err;
+                }
+                location->objectid = key.offset;
+                location->type = BTRFS_INODE_ITEM_KEY;
+                location->offset = 0;
+                goto out;
+        }
+
         di = btrfs_lookup_dir_item(NULL, root, path, dir->i_ino, name,
                                     namelen, 0);
         if (IS_ERR(di))
                 ret = PTR_ERR(di);
         if (!di || IS_ERR(di)) {
-                location->objectid = 0;
-                goto out;
+                goto out_err;
         }
         btrfs_dir_item_key_to_cpu(path->nodes[0], di, location);
 out:
-        btrfs_release_path(root, path);
         btrfs_free_path(path);
         return ret;
+out_err:
+        location->objectid = 0;
+        goto out;
 }
 
 /*
@@ -1053,13 +1054,50 @@ static int btrfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
         if (root->fs_info->tree_root == root)
                 key_type = BTRFS_DIR_ITEM_KEY;
 
+        /* special case for "." */
+        if (filp->f_pos == 0) {
+                over = filldir(dirent, ".", 1,
+                               1, inode->i_ino,
+                               DT_DIR);
+                if (over)
+                        return 0;
+                filp->f_pos = 1;
+        }
+
         mutex_lock(&root->fs_info->fs_mutex);
         key.objectid = inode->i_ino;
+        path = btrfs_alloc_path();
+        path->reada = 2;
+
+        /* special case for .., just use the back ref */
+        if (filp->f_pos == 1) {
+                btrfs_set_key_type(&key, BTRFS_INODE_REF_KEY);
+                key.offset = 0;
+                ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+                BUG_ON(ret == 0);
+                leaf = path->nodes[0];
+                slot = path->slots[0];
+                nritems = btrfs_header_nritems(leaf);
+                if (slot >= nritems) {
+                        btrfs_release_path(root, path);
+                        goto read_dir_items;
+                }
+                btrfs_item_key_to_cpu(leaf, &found_key, slot);
+                btrfs_release_path(root, path);
+                if (found_key.objectid != key.objectid ||
+                    found_key.type != BTRFS_INODE_REF_KEY)
+                        goto read_dir_items;
+                over = filldir(dirent, "..", 2,
+                               2, found_key.offset, DT_DIR);
+                if (over)
+                        goto nopos;
+                filp->f_pos = 2;
+        }
+
+read_dir_items:
         btrfs_set_key_type(&key, key_type);
         key.offset = filp->f_pos;
 
-        path = btrfs_alloc_path();
-        path->reada = 2;
         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
         if (ret < 0)
                 goto err;
@@ -1255,6 +1293,13 @@ static int btrfs_add_link(struct btrfs_trans_handle *trans,
                                     dentry->d_parent->d_inode->i_ino,
                                     &key, btrfs_inode_type(inode));
         if (ret == 0) {
+                if (!S_ISLNK(inode->i_mode)) {
+                        ret = btrfs_insert_inode_ref(trans, root,
+                                             dentry->d_name.name,
+                                             dentry->d_name.len,
+                                             inode->i_ino,
+                                             dentry->d_parent->d_inode->i_ino);
+                }
                 parent_inode = dentry->d_parent->d_inode;
                 parent_inode->i_size += dentry->d_name.len * 2;
                 parent_inode->i_mtime = parent_inode->i_ctime = CURRENT_TIME;
@@ -1430,35 +1475,6 @@ static int btrfs_link(struct dentry *old_dentry, struct inode *dir,
         return err;
 }
 
-static int btrfs_make_empty_dir(struct btrfs_trans_handle *trans,
-                                struct btrfs_root *root,
-                                u64 objectid, u64 dirid)
-{
-        int ret;
-        char buf[2];
-        struct btrfs_key key;
-
-        buf[0] = '.';
-        buf[1] = '.';
-
-        key.objectid = objectid;
-        key.offset = 0;
-        btrfs_set_key_type(&key, BTRFS_INODE_ITEM_KEY);
-
-        ret = btrfs_insert_dir_item(trans, root, buf, 1, objectid,
-                                    &key, BTRFS_FT_DIR);
-        if (ret)
-                goto error;
-
-        key.objectid = dirid;
-        ret = btrfs_insert_dir_item(trans, root, buf, 2, objectid,
-                                    &key, BTRFS_FT_DIR);
-        if (ret)
-                goto error;
-error:
-        return ret;
-}
-
 static int btrfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
 {
         struct inode *inode;
@@ -1496,11 +1512,7 @@ static int btrfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
         inode->i_fop = &btrfs_dir_file_operations;
         btrfs_set_trans_block_group(trans, inode);
 
-        err = btrfs_make_empty_dir(trans, root, inode->i_ino, dir->i_ino);
-        if (err)
-                goto out_fail;
-
-        inode->i_size = 6;
+        inode->i_size = 0;
         err = btrfs_update_inode(trans, root, inode);
         if (err)
                 goto out_fail;
@@ -1971,6 +1983,12 @@ static int create_subvol(struct btrfs_root *root, char *name, int namelen)
         if (ret)
                 goto fail;
 
+        ret = btrfs_insert_inode_ref(trans, root->fs_info->tree_root,
+                             name, namelen, objectid,
+                             root->fs_info->sb->s_root->d_inode->i_ino);
+        if (ret)
+                goto fail;
+
         ret = btrfs_commit_transaction(trans, root);
         if (ret)
                 goto fail_commit;
@@ -1989,12 +2007,10 @@ static int create_subvol(struct btrfs_root *root, char *name, int namelen)
         inode->i_fop = &btrfs_dir_file_operations;
         new_root->inode = inode;
 
-        ret = btrfs_make_empty_dir(trans, new_root, new_dirid, new_dirid);
-        if (ret)
-                goto fail;
-
+        ret = btrfs_insert_inode_ref(trans, new_root, "..", 2, new_dirid,
+                                     new_dirid);
         inode->i_nlink = 1;
-        inode->i_size = 6;
+        inode->i_size = 0;
         ret = btrfs_update_inode(trans, new_root, inode);
         if (ret)
                 goto fail;
@@ -2068,6 +2084,13 @@ static int create_snapshot(struct btrfs_root *root, char *name, int namelen)
         if (ret)
                 goto fail;
 
+        ret = btrfs_insert_inode_ref(trans, root->fs_info->tree_root,
+                             name, namelen, objectid,
+                             root->fs_info->sb->s_root->d_inode->i_ino);
+
+        if (ret)
+                goto fail;
+
         ret = btrfs_inc_root_ref(trans, root, objectid);
         if (ret)
                 goto fail;
@@ -2338,7 +2361,6 @@ static int btrfs_rename(struct inode * old_dir, struct dentry *old_dentry,
         struct inode *old_inode = old_dentry->d_inode;
         struct timespec ctime = CURRENT_TIME;
         struct btrfs_path *path;
-        struct btrfs_dir_item *di;
         int ret;
 
         if (S_ISDIR(old_inode->i_mode) && new_inode &&
@@ -2361,52 +2383,6 @@ static int btrfs_rename(struct inode * old_dir, struct dentry *old_dentry,
         new_dir->i_ctime = new_dir->i_mtime = ctime;
         old_inode->i_ctime = ctime;
 
-        if (S_ISDIR(old_inode->i_mode) && old_dir != new_dir) {
-                struct btrfs_key *location = &BTRFS_I(new_dir)->location;
-                struct btrfs_key old_parent_key;
-                di = btrfs_lookup_dir_item(trans, root, path, old_inode->i_ino,
-                                           "..", 2, -1);
-                if (IS_ERR(di)) {
-                        ret = PTR_ERR(di);
-                        goto out_fail;
-                }
-                if (!di) {
-                        ret = -ENOENT;
-                        goto out_fail;
-                }
-                btrfs_dir_item_key_to_cpu(path->nodes[0], di, &old_parent_key);
-                ret = btrfs_del_item(trans, root, path);
-                if (ret) {
-                        goto out_fail;
-                }
-                btrfs_release_path(root, path);
-
-                di = btrfs_lookup_dir_index_item(trans, root, path,
-                                                 old_inode->i_ino,
-                                                 old_parent_key.objectid,
-                                                 "..", 2, -1);
-                if (IS_ERR(di)) {
-                        ret = PTR_ERR(di);
-                        goto out_fail;
-                }
-                if (!di) {
-                        ret = -ENOENT;
-                        goto out_fail;
-                }
-                ret = btrfs_del_item(trans, root, path);
-                if (ret) {
-                        goto out_fail;
-                }
-                btrfs_release_path(root, path);
-
-                ret = btrfs_insert_dir_item(trans, root, "..", 2,
-                                            old_inode->i_ino, location,
-                                            BTRFS_FT_DIR);
-                if (ret)
-                        goto out_fail;
-        }
-
-
         ret = btrfs_unlink_trans(trans, root, old_dir, old_dentry);
         if (ret)
                 goto out_fail;