Btrfs: subvolumes

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

1 files changed, 152 insertions, 26 deletions

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index b93d790e7484..84abdde4e301 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -495,10 +495,6 @@ static struct dentry *btrfs_lookup(struct inode *dir, struct dentry *dentry,
                         return ERR_PTR(-EACCES);
                 if (inode->i_state & I_NEW) {
                         if (sub_root != root) {
-                                ret = radix_tree_insert(
-                                                &root->fs_info->fs_roots_radix,
-                                                (unsigned long)sub_root,
-                                                sub_root);
 printk("adding new root for inode %lu root %p (found %p)\n", inode->i_ino, sub_root, BTRFS_I(inode)->root);
                                 igrab(inode);
                                 sub_root->inode = inode;
@@ -723,22 +719,19 @@ static int btrfs_write_inode(struct inode *inode, int wait)
 }
 
 static struct inode *btrfs_new_inode(struct btrfs_trans_handle *trans,
-                                     struct inode *dir, int mode)
+                                     struct btrfs_root *root,
+                                     u64 objectid, int mode)
 {
         struct inode *inode;
         struct btrfs_inode_item inode_item;
-        struct btrfs_root *root = BTRFS_I(dir)->root;
         struct btrfs_key *location;
         int ret;
-        u64 objectid;
 
-        inode = new_inode(dir->i_sb);
+        inode = new_inode(root->fs_info->sb);
         if (!inode)
                 return ERR_PTR(-ENOMEM);
 
-        BTRFS_I(inode)->root = BTRFS_I(dir)->root;
-        ret = btrfs_find_free_objectid(trans, root, dir->i_ino, &objectid);
-        BUG_ON(ret);
+        BTRFS_I(inode)->root = root;
 
         inode->i_uid = current->fsuid;
         inode->i_gid = current->fsgid;
@@ -804,10 +797,18 @@ static int btrfs_create(struct inode *dir, struct dentry *dentry,
         struct inode *inode;
         int err;
         int drop_inode = 0;
+        u64 objectid;
 
         mutex_lock(&root->fs_info->fs_mutex);
         trans = btrfs_start_transaction(root, 1);
-        inode = btrfs_new_inode(trans, dir, mode);
+
+        err = btrfs_find_free_objectid(trans, root, dir->i_ino, &objectid);
+        if (err) {
+                err = -ENOSPC;
+                goto out_unlock;
+        }
+
+        inode = btrfs_new_inode(trans, root, objectid, mode);
         err = PTR_ERR(inode);
         if (IS_ERR(inode))
                 goto out_unlock;
@@ -833,9 +834,9 @@ out_unlock:
 }
 
 static int btrfs_make_empty_dir(struct btrfs_trans_handle *trans,
-                                struct inode *inode, struct inode *dir)
+                                struct btrfs_root *root,
+                                u64 objectid, u64 dirid)
 {
-        struct btrfs_root *root = BTRFS_I(dir)->root;
         int ret;
         char buf[2];
         struct btrfs_key key;
@@ -843,22 +844,20 @@ static int btrfs_make_empty_dir(struct btrfs_trans_handle *trans,
         buf[0] = '.';
         buf[1] = '.';
 
-        key.objectid = inode->i_ino;
+        key.objectid = objectid;
         key.offset = 0;
         key.flags = 0;
         btrfs_set_key_type(&key, BTRFS_INODE_ITEM_KEY);
 
-        ret = btrfs_insert_dir_item(trans, root, buf, 1, inode->i_ino,
+        ret = btrfs_insert_dir_item(trans, root, buf, 1, objectid,
                                     &key, 1);
         if (ret)
                 goto error;
-        key.objectid = dir->i_ino;
-        ret = btrfs_insert_dir_item(trans, root, buf, 2, inode->i_ino,
+        key.objectid = dirid;
+        ret = btrfs_insert_dir_item(trans, root, buf, 2, objectid,
                                     &key, 1);
         if (ret)
                 goto error;
-        inode->i_size = 6;
-        ret = btrfs_update_inode(trans, root, inode);
 error:
         return ret;
 }
@@ -870,6 +869,7 @@ static int btrfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
         struct btrfs_root *root = BTRFS_I(dir)->root;
         int err = 0;
         int drop_on_err = 0;
+        u64 objectid;
 
         mutex_lock(&root->fs_info->fs_mutex);
         trans = btrfs_start_transaction(root, 1);
@@ -877,7 +877,14 @@ static int btrfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
                 err = PTR_ERR(trans);
                 goto out_unlock;
         }
-        inode = btrfs_new_inode(trans, dir, S_IFDIR | mode);
+
+        err = btrfs_find_free_objectid(trans, root, dir->i_ino, &objectid);
+        if (err) {
+                err = -ENOSPC;
+                goto out_unlock;
+        }
+
+        inode = btrfs_new_inode(trans, root, objectid, S_IFDIR | mode);
         if (IS_ERR(inode)) {
                 err = PTR_ERR(inode);
                 goto out_fail;
@@ -886,7 +893,12 @@ static int btrfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
         inode->i_op = &btrfs_dir_inode_operations;
         inode->i_fop = &btrfs_dir_file_operations;
 
-        err = btrfs_make_empty_dir(trans, inode, dir);
+        err = btrfs_make_empty_dir(trans, root, inode->i_ino, dir->i_ino);
+        if (err)
+                goto out_fail;
+
+        inode->i_size = 6;
+        err = btrfs_update_inode(trans, root, inode);
         if (err)
                 goto out_fail;
         err = btrfs_add_link(trans, dentry, inode);
@@ -1666,6 +1678,102 @@ static ssize_t btrfs_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
         return retval;
 }
 
+static int create_subvol(struct btrfs_root *root, char *name, int namelen)
+{
+        struct btrfs_trans_handle *trans;
+        struct btrfs_key key;
+        struct btrfs_root_item root_item;
+        struct btrfs_inode_item *inode_item;
+        struct buffer_head *subvol;
+        struct btrfs_leaf *leaf;
+        struct btrfs_root *new_root;
+        struct inode *inode;
+        int ret;
+        u64 objectid;
+        u64 new_dirid = BTRFS_FIRST_FREE_OBJECTID;
+
+        mutex_lock(&root->fs_info->fs_mutex);
+        trans = btrfs_start_transaction(root, 1);
+        BUG_ON(!trans);
+
+        subvol = btrfs_alloc_free_block(trans, root);
+        leaf = btrfs_buffer_leaf(subvol);
+        btrfs_set_header_nritems(&leaf->header, 0);
+        btrfs_set_header_level(&leaf->header, 0);
+        btrfs_set_header_blocknr(&leaf->header, subvol->b_blocknr);
+        btrfs_set_header_generation(&leaf->header, trans->transid);
+        memcpy(leaf->header.fsid, root->fs_info->disk_super->fsid,
+               sizeof(leaf->header.fsid));
+
+        inode_item = &root_item.inode;
+        memset(inode_item, 0, sizeof(*inode_item));
+        btrfs_set_inode_generation(inode_item, 1);
+        btrfs_set_inode_size(inode_item, 3);
+        btrfs_set_inode_nlink(inode_item, 1);
+        btrfs_set_inode_nblocks(inode_item, 1);
+        btrfs_set_inode_mode(inode_item, S_IFDIR | 0755);
+
+        btrfs_set_root_blocknr(&root_item, subvol->b_blocknr);
+        btrfs_set_root_refs(&root_item, 1);
+
+        mark_buffer_dirty(subvol);
+        brelse(subvol);
+        subvol = NULL;
+
+        ret = btrfs_find_free_objectid(trans, root->fs_info->tree_root,
+                                       0, &objectid);
+        BUG_ON(ret);
+
+        btrfs_set_root_dirid(&root_item, new_dirid);
+
+        key.objectid = objectid;
+        key.offset = 1;
+        key.flags = 0;
+        btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
+        ret = btrfs_insert_root(trans, root->fs_info->tree_root, &key,
+                                &root_item);
+        BUG_ON(ret);
+
+        /*
+         * insert the directory item
+         */
+        key.offset = (u64)-1;
+        ret = btrfs_insert_dir_item(trans, root->fs_info->tree_root,
+                                    name, namelen,
+                                    root->fs_info->sb->s_root->d_inode->i_ino,
+                                    &key, 0);
+        BUG_ON(ret);
+
+        ret = btrfs_commit_transaction(trans, root);
+        BUG_ON(ret);
+
+        new_root = btrfs_read_fs_root(root->fs_info, &key);
+        BUG_ON(!new_root);
+
+        trans = btrfs_start_transaction(new_root, 1);
+        BUG_ON(!trans);
+
+        inode = btrfs_new_inode(trans, new_root, new_dirid, S_IFDIR | 0700);
+        inode->i_op = &btrfs_dir_inode_operations;
+        inode->i_fop = &btrfs_dir_file_operations;
+
+        ret = btrfs_make_empty_dir(trans, new_root, new_dirid, new_dirid);
+        BUG_ON(ret);
+
+        inode->i_nlink = 1;
+        inode->i_size = 6;
+        ret = btrfs_update_inode(trans, new_root, inode);
+        BUG_ON(ret);
+
+        ret = btrfs_commit_transaction(trans, new_root);
+        BUG_ON(ret);
+
+        iput(inode);
+
+        mutex_unlock(&root->fs_info->fs_mutex);
+        return 0;
+}
+
 static int create_snapshot(struct btrfs_root *root, char *name, int namelen)
 {
         struct btrfs_trans_handle *trans;
@@ -1674,6 +1782,9 @@ static int create_snapshot(struct btrfs_root *root, char *name, int namelen)
         int ret;
         u64 objectid;
 
+        if (!root->ref_cows)
+                return -EINVAL;
+
         mutex_lock(&root->fs_info->fs_mutex);
         trans = btrfs_start_transaction(root, 1);
         BUG_ON(!trans);
@@ -1685,7 +1796,6 @@ static int create_snapshot(struct btrfs_root *root, char *name, int namelen)
                                        0, &objectid);
         BUG_ON(ret);
 
-        memset(&new_root_item, 0, sizeof(new_root_item));
         memcpy(&new_root_item, &root->root_item,
                sizeof(new_root_item));
 
@@ -1728,9 +1838,9 @@ static int btrfs_ioctl(struct inode *inode, struct file *filp, unsigned int
         struct btrfs_ioctl_vol_args vol_args;
         int ret;
         int namelen;
+        struct btrfs_path *path;
+        u64 root_dirid;
 
-        if (!root->ref_cows)
-                return -EINVAL;
         switch (cmd) {
         case BTRFS_IOC_SNAP_CREATE:
                 if (copy_from_user(&vol_args,
@@ -1740,7 +1850,23 @@ static int btrfs_ioctl(struct inode *inode, struct file *filp, unsigned int
                 namelen = strlen(vol_args.name);
                 if (namelen > BTRFS_VOL_NAME_MAX)
                         return -EINVAL;
-                ret = create_snapshot(root, vol_args.name, namelen);
+                path = btrfs_alloc_path();
+                if (!path)
+                        return -ENOMEM;
+                root_dirid = btrfs_root_dirid(
+                                      &root->fs_info->tree_root->root_item);
+                mutex_lock(&root->fs_info->fs_mutex);
+                ret = btrfs_lookup_dir_item(NULL, root->fs_info->tree_root,
+                                    path, root_dirid,
+                                    vol_args.name, namelen, 0);
+                mutex_unlock(&root->fs_info->fs_mutex);
+                if (ret == 0)
+                        return -EEXIST;
+
+                if (root == root->fs_info->tree_root)
+                        ret = create_subvol(root, vol_args.name, namelen);
+                else
+                        ret = create_snapshot(root, vol_args.name, namelen);
                 WARN_ON(ret);
                 break;
         default: