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: Josef Bacik <josef@redhat.com>
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@ -89,13 +89,8 @@ int btrfs_insert_xattr_item(struct btrfs_trans_handle *trans,
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data_size = sizeof(*dir_item) + name_len + data_len;
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dir_item = insert_with_overflow(trans, root, path, &key, data_size,
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name, name_len);
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/*
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* FIXME: at some point we should handle xattr's that are larger than
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* what we can fit in our leaf. We set location to NULL b/c we arent
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* pointing at anything else, that will change if we store the xattr
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* data in a separate inode.
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*/
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BUG_ON(IS_ERR(dir_item));
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if (IS_ERR(dir_item))
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return PTR_ERR(dir_item);
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memset(&location, 0, sizeof(location));
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leaf = path->nodes[0];
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@ -102,43 +102,57 @@ static int do_setxattr(struct btrfs_trans_handle *trans,
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if (!path)
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return -ENOMEM;
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/* first lets see if we already have this xattr */
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di = btrfs_lookup_xattr(trans, root, path, btrfs_ino(inode), name,
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strlen(name), -1);
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if (IS_ERR(di)) {
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ret = PTR_ERR(di);
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goto out;
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}
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/* ok we already have this xattr, lets remove it */
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if (di) {
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/* if we want create only exit */
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if (flags & XATTR_CREATE) {
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ret = -EEXIST;
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if (flags & XATTR_REPLACE) {
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di = btrfs_lookup_xattr(trans, root, path, btrfs_ino(inode), name,
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name_len, -1);
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if (IS_ERR(di)) {
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ret = PTR_ERR(di);
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goto out;
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}
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ret = btrfs_delete_one_dir_name(trans, root, path, di);
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BUG_ON(ret);
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btrfs_release_path(path);
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/* if we don't have a value then we are removing the xattr */
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if (!value)
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goto out;
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} else {
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btrfs_release_path(path);
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if (flags & XATTR_REPLACE) {
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/* we couldn't find the attr to replace */
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} else if (!di) {
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ret = -ENODATA;
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goto out;
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}
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ret = btrfs_delete_one_dir_name(trans, root, path, di);
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if (ret)
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goto out;
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btrfs_release_path(path);
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}
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/* ok we have to create a completely new xattr */
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again:
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ret = btrfs_insert_xattr_item(trans, root, path, btrfs_ino(inode),
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name, name_len, value, size);
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BUG_ON(ret);
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if (ret == -EEXIST) {
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if (flags & XATTR_CREATE)
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goto out;
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/*
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* We can't use the path we already have since we won't have the
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* proper locking for a delete, so release the path and
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* re-lookup to delete the thing.
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*/
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btrfs_release_path(path);
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di = btrfs_lookup_xattr(trans, root, path, btrfs_ino(inode),
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name, name_len, -1);
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if (IS_ERR(di)) {
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ret = PTR_ERR(di);
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goto out;
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} else if (!di) {
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/* Shouldn't happen but just in case... */
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btrfs_release_path(path);
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goto again;
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}
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ret = btrfs_delete_one_dir_name(trans, root, path, di);
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if (ret)
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goto out;
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/*
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* We have a value to set, so go back and try to insert it now.
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*/
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if (value) {
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btrfs_release_path(path);
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goto again;
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}
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}
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out:
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btrfs_free_path(path);
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return ret;
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