On Wed, Jan 02, 2019 at 01:49:31PM +0800, Anand Jain wrote: > Support for a new command 'btrfs dev forget [dev]' is proposed here > to undo the effects of 'btrfs dev scan [dev]'. For this purpose > this patch proposes to use ioctl #5 as it was empty. > IOW(BTRFS_IOCTL_MAGIC, 5, ..) > This patch adds new ioctl BTRFS_IOC_FORGET_DEV which can be sent from > the /dev/btrfs-control to forget one or all devices, (devices which are > not mounted) from the btrfs kernel. > > The argument it takes is struct btrfs_ioctl_vol_args, and ::name can be > set to specify the device path. And all unmounted devices can be removed > from the kernel if no device path is provided. > > Again, the devices are removed only if the relevant fsid aren't mounted. > > This new cli can provide.. > . Release of unwanted btrfs_fs_devices and btrfs_devices memory if the > device is not going to be mounted. > . Ability to mount the device in degraded mode when one of the other > device is corrupted like in split brain raid1. > . Running test cases which requires btrfs.ko-reload if the rootfs > is btrfs. > > Signed-off-by: Anand Jain <anand.j...@oracle.com> > Reviewed-by: Nikolay Borisov <nbori...@suse.com> > --- > v11->v12: fix coding style add spacing before after ":". > v1->v11: Pls ref to the cover-letter. (sorry about that). > > fs/btrfs/super.c | 3 +++ > fs/btrfs/volumes.c | 9 +++++++++ > fs/btrfs/volumes.h | 1 + > include/uapi/linux/btrfs.h | 2 ++ > 4 files changed, 15 insertions(+) > > diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c > index d3c6bbc0aa3a..eba2966913ae 100644 > --- a/fs/btrfs/super.c > +++ b/fs/btrfs/super.c > @@ -2247,6 +2247,9 @@ static long btrfs_control_ioctl(struct file *file, > unsigned int cmd, > ret = PTR_ERR_OR_ZERO(device); > mutex_unlock(&uuid_mutex); > break; > + case BTRFS_IOC_FORGET_DEV: > + ret = btrfs_forget_devices(vol->name); > + break; > case BTRFS_IOC_DEVICES_READY: > mutex_lock(&uuid_mutex); > device = btrfs_scan_one_device(vol->name, FMODE_READ, > diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c > index 8e36cbb355df..48415a9edd46 100644 > --- a/fs/btrfs/volumes.c > +++ b/fs/btrfs/volumes.c > @@ -1397,6 +1397,15 @@ static int btrfs_read_disk_super(struct block_device > *bdev, u64 bytenr, > return 0; > } > > +int btrfs_forget_devices(const char *path) > +{ > + mutex_lock(&uuid_mutex); > + btrfs_free_stale_devices(strlen(path) ? path : NULL, NULL); > + mutex_unlock(&uuid_mutex); > + > + return 0;
I think this should reflect the status of the operation. The ioctl caller has no information about success/error. Eg. an invalid device path passed could return -ENOENT, 0 if it was released and 1 if not. In case of all devices, it's probably ok to return 0.