Btrfs: remove unnecessary dget_parent/dput when creating the pending snapshot

Since we have grabbed the parent inode at the beginning of the
snapshot creation, and both sync and async snapshot creation
release it after the pending snapshots are actually created,
it is safe to access the parent inode directly during the snapshot
creation, we needn't use dget_parent/dput to fix the parent dentry
and get the dir inode.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 059546aa8fdf963c46c9ff188237bdf947d0ea06..8dcd4ff0c3a58fc8be83cafeceb6cd925c1bbc52 100644 (file)
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -530,9 +530,10 @@ fail:
        return ret;
 }
 
-static int create_snapshot(struct btrfs_root *root, struct dentry *dentry,
-                          char *name, int namelen, u64 *async_transid,
-                          bool readonly, struct btrfs_qgroup_inherit *inherit)
+static int create_snapshot(struct btrfs_root *root, struct inode *dir,
+                          struct dentry *dentry, char *name, int namelen,
+                          u64 *async_transid, bool readonly,
+                          struct btrfs_qgroup_inherit *inherit)
 {
        struct inode *inode;
        struct btrfs_pending_snapshot *pending_snapshot;
@@ -551,6 +552,7 @@ static int create_snapshot(struct btrfs_root *root, struct dentry *dentry,
        pending_snapshot->dentry = dentry;
        pending_snapshot->root = root;
        pending_snapshot->readonly = readonly;
+       pending_snapshot->dir = dir;
        pending_snapshot->inherit = inherit;
 
        trans = btrfs_start_transaction(root->fs_info->extent_root, 6);
@@ -728,7 +730,7 @@ static noinline int btrfs_mksubvol(struct path *parent,
                goto out_up_read;
 
        if (snap_src) {
-               error = create_snapshot(snap_src, dentry, name, namelen,
+               error = create_snapshot(snap_src, dir, dentry, name, namelen,
                                        async_transid, readonly, inherit);
        } else {
                error = create_subvol(BTRFS_I(dir)->root, dentry,

diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 3733c4939a27a6c2dc1cc3dce41de7989fd7be58..71de435a291ebc974bdc931dfd8c2756cacdbfb8 100644 (file)
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -1068,7 +1068,6 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
        struct inode *parent_inode;
        struct btrfs_path *path;
        struct btrfs_dir_item *dir_item;
-       struct dentry *parent;
        struct dentry *dentry;
        struct extent_buffer *tmp;
        struct extent_buffer *old;
@@ -1126,8 +1125,7 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
        trans->bytes_reserved = trans->block_rsv->reserved;
 
        dentry = pending->dentry;
-       parent = dget_parent(dentry);
-       parent_inode = parent->d_inode;
+       parent_inode = pending->dir;
        parent_root = BTRFS_I(parent_inode)->root;
        record_root_in_trans(trans, parent_root);
 
@@ -1275,7 +1273,6 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
        if (ret)
                btrfs_abort_transaction(trans, root, ret);
 fail:
-       dput(parent);
        trans->block_rsv = rsv;
        trans->bytes_reserved = 0;
 no_free_objectid:

diff --git a/fs/btrfs/transaction.h b/fs/btrfs/transaction.h
index 5afd7b1dceacf27a92e2b026aa7d76432ee9f18a..5f67fba07ab4294bfadacc2c135573ab6fa2c7d7 100644 (file)
--- a/fs/btrfs/transaction.h
+++ b/fs/btrfs/transaction.h
@@ -84,6 +84,7 @@ struct btrfs_trans_handle {
 
 struct btrfs_pending_snapshot {
        struct dentry *dentry;
+       struct inode *dir;
        struct btrfs_root *root;
        struct btrfs_root *snap;
        struct btrfs_qgroup_inherit *inherit;