>
> Steps to reproduce:
> # mkfs.btrfs -f /dev/sdb
> # mount -t btrfs /dev/sdb /mnt
> # btrfs sub create /mnt/dir
> # mount -t btrfs /dev/sdb /mnt -o subvol=dir,subvol=dir
>
> It fails with:
> mount: mount(2) failed: No such file or directory
>
> Btrfs deal with subvolume mounting in a recursive way,
> to avoid looping, it will stripe out 'subvol=xxxx' string,
> then next loop will stop.Problem here is it only deal one
> string once, if users specify mount option multiple times.
> It will loop several times which is not good, and above
> reproducing steps will also return confusing results.
>
> Fix this problem by striping out all 'subvol=xxx' options,
> only last is valid.
>
> Signed-off-by: Wang Shilong <wangshilong1991@xxxxxxxxx>
> ---
> fs/btrfs/super.c | 20 +++++++++++++++++++-
> 1 file changed, 19 insertions(+), 1 deletion(-)
>
> diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
> index 54bd91e..2b2fa4b 100644
> --- a/fs/btrfs/super.c
> +++ b/fs/btrfs/super.c
> @@ -1115,7 +1115,7 @@ static inline int is_subvolume_inode(struct inode *inode)
> * subvolid=0 to make sure we get the actual tree root for path walking to the
> * subvol we want.
> */
> -static char *setup_root_args(char *args)
> +static char *__setup_root_args(char *args)
> {
> unsigned len = strlen(args) + 2 + 1;
> char *src, *dst, *buf;
> @@ -1161,6 +1161,24 @@ static char *setup_root_args(char *args)
> return buf;
> }
>
> +static char *setup_root_args(char *args)
> +{
> + char *p, *new_args;
> +
> + p = new_args = __setup_root_args(args);
> + /* in case users specify subvol=xxx option multiple times */
> + while (p) {
> + p = __setup_root_args(new_args);
Oh, i missed error handling here, will update it..
> + if (p) {
> + kfree(new_args);
> + new_args = p;
> + } else {
> + break;
> + }
> + }
> + return new_args;
> +}
> +
> static struct dentry *mount_subvol(const char *subvol_name, int flags,
> const char *device_name, char *data)
> {
> --
> 1.7.12.4
>
Best Regards,
Wang Shilong
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