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btrfs: hold a ref on the root in btrfs_ioctl_get_subvol_info 

We look up whatever root userspace has given us, we need to hold a ref
throughout this operation. Use 'root' only for the on fs root and not as
a temporary variable elsewhere.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Josef Bacik 2020-01-24 09:32:36 -05:00 committed by David Sterba
parent b8a49ae191
commit 04734e8448
1 changed files with 8 additions and 4 deletions
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12
fs/btrfs/ioctl.c
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@ -2681,6 +2681,10 @@ static int btrfs_ioctl_get_subvol_info(struct file *file, void __user *argp)
root = btrfs_get_fs_root(fs_info, &key, true); root = btrfs_get_fs_root(fs_info, &key, true);
if (IS_ERR(root)) { if (IS_ERR(root)) {
ret = PTR_ERR(root); ret = PTR_ERR(root);
goto out_free;
}
if (!btrfs_grab_fs_root(root)) {
ret = -ENOENT;
goto out; goto out;
} }
root_item = &root->root_item; root_item = &root->root_item;
@ -2714,16 +2718,14 @@ static int btrfs_ioctl_get_subvol_info(struct file *file, void __user *argp)
if (key.objectid != BTRFS_FS_TREE_OBJECTID) { if (key.objectid != BTRFS_FS_TREE_OBJECTID) {
/* Search root tree for ROOT_BACKREF of this subvolume */ /* Search root tree for ROOT_BACKREF of this subvolume */
root = fs_info->tree_root;
key.type = BTRFS_ROOT_BACKREF_KEY; key.type = BTRFS_ROOT_BACKREF_KEY;
key.offset = 0; key.offset = 0;
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) { if (ret < 0) {
goto out; goto out;
} else if (path->slots[0] >= } else if (path->slots[0] >=
btrfs_header_nritems(path->nodes[0])) { btrfs_header_nritems(path->nodes[0])) {
ret = btrfs_next_leaf(root, path); ret = btrfs_next_leaf(fs_info->tree_root, path);
if (ret < 0) { if (ret < 0) {
goto out; goto out;
} else if (ret > 0) { } else if (ret > 0) {
@ -2758,6 +2760,8 @@ static int btrfs_ioctl_get_subvol_info(struct file *file, void __user *argp)
ret = -EFAULT; ret = -EFAULT;
out: out:
btrfs_put_fs_root(root);
out_free:
btrfs_free_path(path); btrfs_free_path(path);
kzfree(subvol_info); kzfree(subvol_info);
return ret; return ret;