This ioctl will provide user the ability to recover the subvolume of the
given id to the given directory.
Note: It will lock fs_info->cleaner_mutex to keep the cleaner kthread
from deleting the subvolume which we want to recover.
Signed-off-by: Lu Fengqi <lufq.f...@cn.fujitsu.com>
---
fs/btrfs/ioctl.c | 64 ++++++++++++++++++++++++++++++++++++++
include/uapi/linux/btrfs.h | 7 +++++
2 files changed, 71 insertions(+)
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index f088dea53c16..3ddf6e1c117b 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1993,6 +1993,68 @@ static int btrfs_undelete_subvolume(struct btrfs_root
*root,
return ret;
}
+static int btrfs_ioctl_undelete(struct file *file, void __user *argp)
+{
+ struct btrfs_ioctl_subvol_undelete_args *args;
+ struct inode *inode = file_inode(file);
+ struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+ struct btrfs_root *root;
+ int ret = 0;
+
+ if (!S_ISDIR(inode->i_mode))
+ return -ENOTDIR;
+
+ args = memdup_user(argp, sizeof(*args));
+ if (IS_ERR(args))
+ return PTR_ERR(args);
+
+ args->name[BTRFS_PATH_NAME_MAX] = '\0';
+
+ if (!capable(CAP_SYS_ADMIN)) {
+ ret = -EPERM;
+ goto free;
+ }
+
+ ret = mnt_want_write_file(file);
+ if (ret)
+ goto free;
+
+ ret = -ENOENT;
+ spin_lock(&fs_info->trans_lock);
+ list_for_each_entry(root, &fs_info->dead_roots, root_list) {
+ if (root->root_key.objectid == args->subvol_id) {
+ list_del_init(&root->root_list);
+ ret = 0;
+ break;
+ }
+ }
+ spin_unlock(&fs_info->trans_lock);
+ if (ret)
+ goto drop_write;
+
+ /*
+ * Lock cleaner_mutex to prevent the cleaner kthread from deleting the
+ * subvolume we want to recover so that we can perform the next rescue
+ * in a relaxed manner.
+ */
+ mutex_lock(&fs_info->cleaner_mutex);
+
+ ret = btrfs_undelete_subvolume(root, file->f_path.dentry, args->name,
+ strlen(args->name));
+ if (ret) {
+ btrfs_add_dead_root(root);
+ goto unlock;
+ }
+
+unlock:
+ mutex_unlock(&fs_info->cleaner_mutex);
+drop_write:
+ mnt_drop_write_file(file);
+free:
+ kfree(args);
+ return ret;
+}
+
static noinline int btrfs_ioctl_subvol_getflags(struct file *file,
void __user *arg)
{
@@ -6118,6 +6180,8 @@ long btrfs_ioctl(struct file *file, unsigned int
return btrfs_ioctl_get_subvol_rootref(file, argp);
case BTRFS_IOC_INO_LOOKUP_USER:
return btrfs_ioctl_ino_lookup_user(file, argp);
+ case BTRFS_IOC_SUBVOL_UNDELETE:
+ return btrfs_ioctl_undelete(file, argp);
}
return -ENOTTY;
diff --git a/include/uapi/linux/btrfs.h b/include/uapi/linux/btrfs.h
index 5ca1d21fc4a7..e6d3c8e24bb8 100644
--- a/include/uapi/linux/btrfs.h
+++ b/include/uapi/linux/btrfs.h
@@ -816,6 +816,11 @@ struct btrfs_ioctl_get_subvol_rootref_args {
__u8 align[7];
};
+struct btrfs_ioctl_subvol_undelete_args {
+ __u64 subvol_id;
+ char name[BTRFS_PATH_NAME_MAX + 1];
+};
+
/* Error codes as returned by the kernel */
enum btrfs_err_code {
BTRFS_ERROR_DEV_RAID1_MIN_NOT_MET = 1,
@@ -940,5 +945,7 @@ enum btrfs_err_code {
struct btrfs_ioctl_get_subvol_rootref_args)
#define BTRFS_IOC_INO_LOOKUP_USER _IOWR(BTRFS_IOCTL_MAGIC, 62, \
struct btrfs_ioctl_ino_lookup_user_args)
+#define BTRFS_IOC_SUBVOL_UNDELETE _IOWR(BTRFS_IOCTL_MAGIC, 63, \
+ struct btrfs_ioctl_subvol_undelete_args)
#endif /* _UAPI_LINUX_BTRFS_H */
--
2.18.0
