Commit fa09200b authored by Josef Bacik's avatar Josef Bacik
Browse files

Btrfs: try to only do one btrfs_search_slot in do_setxattr 



I've been watching how many btrfs_search_slot()'s we do and I noticed that when
we create a file with selinux enabled we were doing 2 each time we initialize
the security context.  That's because we lookup the xattr first so we can delete
it if we're setting a new value to an existing xattr.  But in the create case we
don't have any xattrs, so it is completely useless to have the extra lookup.  So
re-arrange things so that we only lookup first if we specifically have
XATTR_REPLACE.  That way in the basic case we only do 1 search, and in the more
complicated case we do the normal 2 lookups.  Thanks,

Signed-off-by: default avatarJosef Bacik <josef@redhat.com>
parent 149e2d76

fs/btrfs/dir-item.c

+2 −7
Original line number Diff line number Diff line
@@ -89,13 +89,8 @@ int btrfs_insert_xattr_item(struct btrfs_trans_handle *trans, 
	data_size = sizeof(*dir_item) + name_len + data_len;

	dir_item = insert_with_overflow(trans, root, path, &key, data_size,

					name, name_len);

	/*

	 * FIXME: at some point we should handle xattr's that are larger than

	 * what we can fit in our leaf.  We set location to NULL b/c we arent

	 * pointing at anything else, that will change if we store the xattr

	 * data in a separate inode.

	 */

	BUG_ON(IS_ERR(dir_item));

	if (IS_ERR(dir_item))

		return PTR_ERR(dir_item);

	memset(&location, 0, sizeof(location));



	leaf = path->nodes[0];

fs/btrfs/xattr.c

+40 −26
Original line number Diff line number Diff line
@@ -102,43 +102,57 @@ static int do_setxattr(struct btrfs_trans_handle *trans, 
	if (!path)

		return -ENOMEM;



	/* first lets see if we already have this xattr */

	if (flags & XATTR_REPLACE) {

		di = btrfs_lookup_xattr(trans, root, path, btrfs_ino(inode), name,

				strlen(name), -1);

					name_len, -1);

		if (IS_ERR(di)) {

			ret = PTR_ERR(di);

			goto out;

	}



	/* ok we already have this xattr, lets remove it */

	if (di) {

		/* if we want create only exit */

		if (flags & XATTR_CREATE) {

			ret = -EEXIST;

		} else if (!di) {

			ret = -ENODATA;

			goto out;

		}



		ret = btrfs_delete_one_dir_name(trans, root, path, di);

		BUG_ON(ret);

		if (ret)

			goto out;

		btrfs_release_path(path);

	}



		/* if we don't have a value then we are removing the xattr */

		if (!value)

again:

	ret = btrfs_insert_xattr_item(trans, root, path, btrfs_ino(inode),

				      name, name_len, value, size);

	if (ret == -EEXIST) {

		if (flags & XATTR_CREATE)

			goto out;

	} else {

		/*

		 * We can't use the path we already have since we won't have the

		 * proper locking for a delete, so release the path and

		 * re-lookup to delete the thing.

		 */

		btrfs_release_path(path);

		di = btrfs_lookup_xattr(trans, root, path, btrfs_ino(inode),

					name, name_len, -1);

		if (IS_ERR(di)) {

			ret = PTR_ERR(di);

			goto out;

		} else if (!di) {

			/* Shouldn't happen but just in case... */

			btrfs_release_path(path);

			goto again;

		}



		if (flags & XATTR_REPLACE) {

			/* we couldn't find the attr to replace */

			ret = -ENODATA;

		ret = btrfs_delete_one_dir_name(trans, root, path, di);

		if (ret)

			goto out;



		/*

		 * We have a value to set, so go back and try to insert it now.

		 */

		if (value) {

			btrfs_release_path(path);

			goto again;

		}

	}



	/* ok we have to create a completely new xattr */

	ret = btrfs_insert_xattr_item(trans, root, path, btrfs_ino(inode),

				      name, name_len, value, size);

	BUG_ON(ret);

out:

	btrfs_free_path(path);

	return ret;

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