get rid of useless dget_parent() in fs/btrfs/ioctl.c

both callers there have dentry->d_parent stabilized by the fact that
their caller had obtained dentry from lookup_one_len() and had not
dropped ->i_mutex on parent since then.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index a3c4751..6225433 100644 (file)
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -323,7 +323,7 @@ static noinline int create_subvol(struct btrfs_root *root,
        struct btrfs_inode_item *inode_item;
        struct extent_buffer *leaf;
        struct btrfs_root *new_root;
-       struct dentry *parent = dget_parent(dentry);
+       struct dentry *parent = dentry->d_parent;
        struct inode *dir;
        int ret;
        int err;
@@ -332,10 +332,8 @@ static noinline int create_subvol(struct btrfs_root *root,
        u64 index = 0;
 
        ret = btrfs_find_free_objectid(root->fs_info->tree_root, &objectid);
-       if (ret) {
-               dput(parent);
+       if (ret)
                return ret;
-       }
 
        dir = parent->d_inode;
 
@@ -346,10 +344,8 @@ static noinline int create_subvol(struct btrfs_root *root,
         * 2 - dir items
         */
        trans = btrfs_start_transaction(root, 6);
-       if (IS_ERR(trans)) {
-               dput(parent);
+       if (IS_ERR(trans))
                return PTR_ERR(trans);
-       }
 
        leaf = btrfs_alloc_free_block(trans, root, root->leafsize,
                                      0, objectid, NULL, 0, 0, 0);
@@ -439,7 +435,6 @@ static noinline int create_subvol(struct btrfs_root *root,
 
        d_instantiate(dentry, btrfs_lookup_dentry(dir, dentry));
 fail:
-       dput(parent);
        if (async_transid) {
                *async_transid = trans->transid;
                err = btrfs_commit_transaction_async(trans, root, 1);
@@ -456,7 +451,6 @@ static int create_snapshot(struct btrfs_root *root, struct dentry *dentry,
                           bool readonly)
 {
        struct inode *inode;
-       struct dentry *parent;
        struct btrfs_pending_snapshot *pending_snapshot;
        struct btrfs_trans_handle *trans;
        int ret;
@@ -504,9 +498,7 @@ static int create_snapshot(struct btrfs_root *root, struct dentry *dentry,
        if (ret)
                goto fail;
 
-       parent = dget_parent(dentry);
-       inode = btrfs_lookup_dentry(parent->d_inode, dentry);
-       dput(parent);
+       inode = btrfs_lookup_dentry(dentry->d_parent->d_inode, dentry);
        if (IS_ERR(inode)) {
                ret = PTR_ERR(inode);
                goto fail;