The function will traverse the root from the fs_info->dead_roots and try
to call btrfs_undelete_subvolume() to recover them.
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 | 83 ++++++++++++++++++++++++++++++++++++++
include/uapi/linux/btrfs.h | 9 +++++
2 files changed, 92 insertions(+)
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 7a11c4f8e450..83b9839799d0 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1980,6 +1980,87 @@ static int btrfs_undelete_subvolume(const struct path
*parent,
return ret;
}
+static int btrfs_ioctl_undelete(struct file *file, void __user *argp)
+{
+ struct btrfs_ioctl_undelete_args __user *uarg;
+ struct btrfs_ioctl_undelete_args *args;
+ struct inode *inode = file_inode(file);
+ struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+ struct btrfs_root *root, *tmp;
+ char *name;
+ u64 count = 0;
+ u64 objectid;
+ int err = 0, ret;
+
+ /* copy search header and buffer size */
+ uarg = (struct btrfs_ioctl_undelete_args __user *)argp;
+ args = memdup_user(uarg, sizeof(*args));
+ if (IS_ERR(args))
+ return PTR_ERR(args);
+ args->name[BTRFS_PATH_NAME_MAX] = '\0';
+
+ name = kzalloc(BTRFS_PATH_NAME_MAX + 1, GFP_KERNEL);
+ if (IS_ERR(name)) {
+ err = PTR_ERR(name);
+ goto free_args;
+ }
+
+ if (!capable(CAP_SYS_ADMIN)) {
+ err = -EPERM;
+ goto free;
+ }
+
+ err = mnt_want_write_file(file);
+ if (err)
+ goto free;
+
+ /* 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);
+
+ list_for_each_entry_safe(root, tmp, &fs_info->dead_roots, root_list) {
+ objectid = root->root_key.objectid;
+ snprintf(name, BTRFS_PATH_NAME_MAX, "%s%llu", args->name,
+ objectid);
+ ret = btrfs_undelete_subvolume(&file->f_path, root, name,
+ strlen(name));
+ if (ret)
+ continue;
+
+ /*
+ * Feel free to remove this root from dead_root list since we
+ * have recover it successfully.
+ */
+ spin_lock(&fs_info->trans_lock);
+ list_del_init(&root->root_list);
+ spin_unlock(&fs_info->trans_lock);
+
+ if ((count + 1) * sizeof(objectid) > args->buf_size)
+ continue;
+
+ /* copy the subvolume id to user space */
+ ret = copy_to_user(&uarg->buf[count], &objectid,
+ sizeof(objectid));
+ if (ret)
+ err = -EFAULT;
+ count++;
+ }
+
+ mutex_unlock(&fs_info->cleaner_mutex);
+ mnt_drop_write_file(file);
+
+ /* copy the count to user space */
+ if (copy_to_user(&uarg->count, &count, sizeof(count)))
+ err = -EFAULT;
+free:
+ kfree(name);
+free_args:
+ kfree(args);
+ return err;
+}
+
static noinline int btrfs_ioctl_subvol_getflags(struct file *file,
void __user *arg)
{
@@ -6089,6 +6170,8 @@ 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..25d030687b27 100644
--- a/include/uapi/linux/btrfs.h
+++ b/include/uapi/linux/btrfs.h
@@ -816,6 +816,13 @@ struct btrfs_ioctl_get_subvol_rootref_args {
__u8 align[7];
};
+struct btrfs_ioctl_undelete_args {
+ char name[BTRFS_PATH_NAME_MAX + 1]; /* in - subvolume name prefix */
+ __u64 buf_size; /* in - size of buffer */
+ __u64 count; /* out - store number of recoverd subvolumes */
+ __u64 buf[0]; /* out - store ids of recoverd subolumes */
+};
+
/* Error codes as returned by the kernel */
enum btrfs_err_code {
BTRFS_ERROR_DEV_RAID1_MIN_NOT_MET = 1,
@@ -940,5 +947,7 @@ 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_undelete_args)
#endif /* _UAPI_LINUX_BTRFS_H */
--
2.18.0
--
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