On Fri, Jan 24, 2020 at 09:32:35AM -0500, Josef Bacik wrote:
> We can wander into a different root, so grab a ref on the root we look
> up. Later on we make root = fs_info->tree_root so we need this separate
> out label to make sure we do the right cleanup only in the case we're
> looking up a different root.
>
> Signed-off-by: Josef Bacik <josef@xxxxxxxxxxxxxx>
> ---
> fs/btrfs/ioctl.c | 28 ++++++++++++++++++----------
> 1 file changed, 18 insertions(+), 10 deletions(-)
>
> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
> index c721b4fce1c0..5fffa1b6f685 100644
> --- a/fs/btrfs/ioctl.c
> +++ b/fs/btrfs/ioctl.c
> @@ -2432,6 +2432,10 @@ static int btrfs_search_path_in_tree_user(struct inode *inode,
> ret = PTR_ERR(root);
> goto out;
> }
> + if (!btrfs_grab_fs_root(root)) {
> + ret = -ENOENT;
> + goto out;
> + }
>
> key.objectid = dirid;
> key.type = BTRFS_INODE_REF_KEY;
> @@ -2439,15 +2443,15 @@ static int btrfs_search_path_in_tree_user(struct inode *inode,
> while (1) {
> ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
> if (ret < 0) {
> - goto out;
> + goto out_put;
> } else if (ret > 0) {
> ret = btrfs_previous_item(root, path, dirid,
> BTRFS_INODE_REF_KEY);
> if (ret < 0) {
> - goto out;
> + goto out_put;
> } else if (ret > 0) {
> ret = -ENOENT;
> - goto out;
> + goto out_put;
> }
> }
>
> @@ -2461,7 +2465,7 @@ static int btrfs_search_path_in_tree_user(struct inode *inode,
> total_len += len + 1;
> if (ptr < args->path) {
> ret = -ENAMETOOLONG;
> - goto out;
> + goto out_put;
> }
>
> *(ptr + len) = '/';
> @@ -2472,10 +2476,10 @@ static int btrfs_search_path_in_tree_user(struct inode *inode,
> ret = btrfs_previous_item(root, path, dirid,
> BTRFS_INODE_ITEM_KEY);
> if (ret < 0) {
> - goto out;
> + goto out_put;
> } else if (ret > 0) {
> ret = -ENOENT;
> - goto out;
> + goto out_put;
> }
>
> leaf = path->nodes[0];
> @@ -2483,26 +2487,26 @@ static int btrfs_search_path_in_tree_user(struct inode *inode,
> btrfs_item_key_to_cpu(leaf, &key2, slot);
> if (key2.objectid != dirid) {
> ret = -ENOENT;
> - goto out;
> + goto out_put;
> }
>
> temp_inode = btrfs_iget(sb, &key2, root);
> if (IS_ERR(temp_inode)) {
> ret = PTR_ERR(temp_inode);
> - goto out;
> + goto out_put;
> }
> ret = inode_permission(temp_inode, MAY_READ | MAY_EXEC);
> iput(temp_inode);
> if (ret) {
> ret = -EACCES;
> - goto out;
> + goto out_put;
> }
>
> if (key.offset == upper_limit.objectid)
> break;
> if (key.objectid == BTRFS_FIRST_FREE_OBJECTID) {
> ret = -EACCES;
> - goto out;
> + goto out_put;
> }
>
> btrfs_release_path(path);
> @@ -2513,6 +2517,7 @@ static int btrfs_search_path_in_tree_user(struct inode *inode,
>
> memmove(args->path, ptr, total_len);
> args->path[total_len] = '\0';
> + btrfs_put_fs_root(root);
> btrfs_release_path(path);
> }
>
> @@ -2551,6 +2556,9 @@ static int btrfs_search_path_in_tree_user(struct inode *inode,
> out:
> btrfs_free_path(path);
> return ret;
> +out_put:
> + btrfs_put_fs_root(root);
> + goto out;
That's the ugly goto pattern we'd rather not use
I see a simple way to merge the gotos to one: set root to NULL after the
proper btrfs_put_fs_root (next to the memmove call above), and do the
error btrfs_put_fs_root before free path.
There's one catch, 'root' is used to hold tree_root that's only passed
to search slot, but that can be simplified so 'root' is always the
referenced root.
Incremental diff:
---
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -2518,15 +2518,15 @@ static int btrfs_search_path_in_tree_user(struct inode *inode,
memmove(args->path, ptr, total_len);
args->path[total_len] = '\0';
btrfs_put_fs_root(root);
+ root = NULL;
btrfs_release_path(path);
}
/* Get the bottom subvolume's name from ROOT_REF */
- root = fs_info->tree_root;
key.objectid = treeid;
key.type = BTRFS_ROOT_REF_KEY;
key.offset = args->treeid;
- ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+ ret = btrfs_search_slot(NULL, fs_info->tree_root, &key, path, 0, 0);
if (ret < 0) {
goto out;
} else if (ret > 0) {
@@ -2553,12 +2553,11 @@ static int btrfs_search_path_in_tree_user(struct inode *inode,
read_extent_buffer(leaf, args->name, item_off, item_len);
args->name[item_len] = 0;
+out_put:
+ btrfs_put_fs_root(root);
out:
btrfs_free_path(path);
return ret;
-out_put:
- btrfs_put_fs_root(root);
- goto out;
}
---
