Btrfs: symlinks and hard links

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

1 files changed, 147 insertions, 16 deletions

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index f49cad603ee8..c1a0adde9b1c 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -26,11 +26,13 @@ struct btrfs_iget_args {
 #define BTRFS_SUPER_MAGIC 0x9123682E
 
 static struct inode_operations btrfs_dir_inode_operations;
+static struct inode_operations btrfs_symlink_inode_operations;
 static struct inode_operations btrfs_dir_ro_inode_operations;
 static struct super_operations btrfs_super_ops;
 static struct file_operations btrfs_dir_file_operations;
 static struct inode_operations btrfs_file_inode_operations;
 static struct address_space_operations btrfs_aops;
+static struct address_space_operations btrfs_symlink_aops;
 static struct file_operations btrfs_file_operations;
 
 static void btrfs_read_locked_inode(struct inode *inode)
@@ -103,7 +105,8 @@ static void btrfs_read_locked_inode(struct inode *inode)
                         inode->i_op = &btrfs_dir_inode_operations;
                 break;
         case S_IFLNK:
-                // inode->i_op = &page_symlink_inode_operations;
+                inode->i_op = &btrfs_symlink_inode_operations;
+                inode->i_mapping->a_ops = &btrfs_symlink_aops;
                 break;
         }
         return;
@@ -940,6 +943,41 @@ out_unlock:
         return err;
 }
 
+static int btrfs_link(struct dentry *old_dentry, struct inode *dir,
+                      struct dentry *dentry)
+{
+        struct btrfs_trans_handle *trans;
+        struct btrfs_root *root = BTRFS_I(dir)->root;
+        struct inode *inode = old_dentry->d_inode;
+        int err;
+        int drop_inode = 0;
+
+        if (inode->i_nlink == 0)
+                return -ENOENT;
+
+        inc_nlink(inode);
+        mutex_lock(&root->fs_info->fs_mutex);
+        trans = btrfs_start_transaction(root, 1);
+        btrfs_set_trans_block_group(trans, dir);
+        atomic_inc(&inode->i_count);
+        err = btrfs_add_nondir(trans, dentry, inode);
+        if (err)
+                drop_inode = 1;
+        dir->i_sb->s_dirt = 1;
+        btrfs_update_inode_block_group(trans, dir);
+        btrfs_update_inode(trans, root, inode);
+
+        btrfs_end_transaction(trans, root);
+        mutex_unlock(&root->fs_info->fs_mutex);
+
+        if (drop_inode) {
+                inode_dec_link_count(inode);
+                iput(inode);
+        }
+        btrfs_btree_balance_dirty(root);
+        return err;
+}
+
 static int btrfs_make_empty_dir(struct btrfs_trans_handle *trans,
                                 struct btrfs_root *root,
                                 u64 objectid, u64 dirid)
@@ -2577,33 +2615,25 @@ static int btrfs_rename(struct inode * old_dir, struct dentry *old_dentry,
         }
 
 
-        ret = btrfs_add_link(trans, new_dentry, old_inode);
-        if (ret == -EEXIST && new_inode)
-                ret = 0;
-        else if (ret)
-                goto out_fail;
-
         ret = btrfs_unlink_trans(trans, root, old_dir, old_dentry);
         if (ret)
                 goto out_fail;
 
         if (new_inode) {
                 new_inode->i_ctime = CURRENT_TIME;
-                di = btrfs_lookup_dir_index_item(trans, root, path,
-                                                 new_dir->i_ino,
-                                                 new_inode->i_ino,
-                                                 new_dentry->d_name.name,
-                                                 new_dentry->d_name.len, -1);
-                if (di && !IS_ERR(di)) {
-                        btrfs_del_item(trans, root, path);
-                        btrfs_release_path(root, path);
-                }
+                ret = btrfs_unlink_trans(trans, root, new_dir, new_dentry);
+                if (ret)
+                        goto out_fail;
                 if (S_ISDIR(new_inode->i_mode))
                         clear_nlink(new_inode);
                 else
                         drop_nlink(new_inode);
                 btrfs_update_inode(trans, root, new_inode);
         }
+        ret = btrfs_add_link(trans, new_dentry, old_inode);
+        if (ret)
+                goto out_fail;
+
 out_fail:
         btrfs_free_path(path);
         btrfs_end_transaction(trans, root);
@@ -2611,6 +2641,94 @@ out_fail:
         return ret;
 }
 
+static int btrfs_symlink(struct inode *dir, struct dentry *dentry,
+                         const char *symname)
+{
+        struct btrfs_trans_handle *trans;
+        struct btrfs_root *root = BTRFS_I(dir)->root;
+        struct btrfs_path *path;
+        struct btrfs_key key;
+        struct inode *inode;
+        int err;
+        int drop_inode = 0;
+        u64 objectid;
+        int name_len;
+        int datasize;
+        char *ptr;
+        struct btrfs_file_extent_item *ei;
+
+        name_len = strlen(symname) + 1;
+        if (name_len > BTRFS_MAX_INLINE_DATA_SIZE(root))
+                return -ENAMETOOLONG;
+        mutex_lock(&root->fs_info->fs_mutex);
+        trans = btrfs_start_transaction(root, 1);
+        btrfs_set_trans_block_group(trans, dir);
+
+        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,
+                                BTRFS_I(dir)->block_group, S_IFLNK|S_IRWXUGO);
+        err = PTR_ERR(inode);
+        if (IS_ERR(inode))
+                goto out_unlock;
+
+        btrfs_set_trans_block_group(trans, inode);
+        err = btrfs_add_nondir(trans, dentry, inode);
+        if (err)
+                drop_inode = 1;
+        else {
+                inode->i_mapping->a_ops = &btrfs_aops;
+                inode->i_fop = &btrfs_file_operations;
+                inode->i_op = &btrfs_file_inode_operations;
+        }
+        dir->i_sb->s_dirt = 1;
+        btrfs_update_inode_block_group(trans, inode);
+        btrfs_update_inode_block_group(trans, dir);
+        if (drop_inode)
+                goto out_unlock;
+
+        path = btrfs_alloc_path();
+        BUG_ON(!path);
+        key.objectid = inode->i_ino;
+        key.offset = 0;
+        key.flags = 0;
+        btrfs_set_key_type(&key, BTRFS_EXTENT_DATA_KEY);
+        datasize = btrfs_file_extent_calc_inline_size(name_len);
+        err = btrfs_insert_empty_item(trans, root, path, &key,
+                                      datasize);
+        BUG_ON(err);
+        ei = btrfs_item_ptr(btrfs_buffer_leaf(path->nodes[0]),
+               path->slots[0], struct btrfs_file_extent_item);
+        btrfs_set_file_extent_generation(ei, trans->transid);
+        btrfs_set_file_extent_type(ei,
+                                   BTRFS_FILE_EXTENT_INLINE);
+        ptr = btrfs_file_extent_inline_start(ei);
+        btrfs_memcpy(root, path->nodes[0]->b_data,
+                     ptr, symname, name_len);
+        mark_buffer_dirty(path->nodes[0]);
+        btrfs_free_path(path);
+        inode->i_op = &btrfs_symlink_inode_operations;
+        inode->i_mapping->a_ops = &btrfs_symlink_aops;
+        inode->i_size = name_len - 1;
+        btrfs_update_inode(trans, root, inode);
+        err = 0;
+
+out_unlock:
+        btrfs_end_transaction(trans, root);
+        mutex_unlock(&root->fs_info->fs_mutex);
+
+        if (drop_inode) {
+                inode_dec_link_count(inode);
+                iput(inode);
+        }
+        btrfs_btree_balance_dirty(root);
+        return err;
+}
+
 static struct file_system_type btrfs_fs_type = {
         .owner          = THIS_MODULE,
         .name           = "btrfs",
@@ -2636,9 +2754,11 @@ static struct inode_operations btrfs_dir_inode_operations = {
         .lookup         = btrfs_lookup,
         .create         = btrfs_create,
         .unlink         = btrfs_unlink,
+        .link           = btrfs_link,
         .mkdir          = btrfs_mkdir,
         .rmdir          = btrfs_rmdir,
         .rename         = btrfs_rename,
+        .symlink        = btrfs_symlink,
 };
 
 static struct inode_operations btrfs_dir_ro_inode_operations = {
@@ -2660,6 +2780,11 @@ static struct address_space_operations btrfs_aops = {
         .commit_write   = btrfs_commit_write,
 };
 
+static struct address_space_operations btrfs_symlink_aops = {
+        .readpage       = btrfs_readpage,
+        .writepage      = btrfs_writepage,
+};
+
 static struct inode_operations btrfs_file_inode_operations = {
         .truncate       = btrfs_truncate,
         .getattr        = btrfs_getattr,
@@ -2676,6 +2801,12 @@ static struct file_operations btrfs_file_operations = {
         .fsync          = btrfs_sync_file,
 };
 
+static struct inode_operations btrfs_symlink_inode_operations = {
+        .readlink       = generic_readlink,
+        .follow_link    = page_follow_link_light,
+        .put_link       = page_put_link,
+};
+
 static int __init init_btrfs_fs(void)
 {
         int err;