On Thu, Jan 03, 2019 at 04:01:37PM +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.jain@xxxxxxxxxx>
> Reviewed-by: Nikolay Borisov <nborisov@xxxxxxxx>
> ---
> v12->v13:
> btrfs.ko returns error on failing to find the given device.
> For no argument (btrfs device scan --forget) if there is
> no device to forget then it shall just return success.
> 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 | 55 +++++++++++++++++++++++++++++++++++-----------
> fs/btrfs/volumes.h | 1 +
> include/uapi/linux/btrfs.h | 2 ++
> 4 files changed, 48 insertions(+), 13 deletions(-)
>
> diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
> index 33cc9aba9c94..a4e8beec0fc5 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 2576b1a379c9..2ab42bfe5d3c 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -734,6 +734,19 @@ static void pending_bios_fn(struct btrfs_work *work)
> run_scheduled_bios(device);
> }
>
> +static bool device_path_matched(const char *path, struct btrfs_device *device)
> +{
> + int found;
> +
> + rcu_read_lock();
> + found = strcmp(rcu_str_deref(device->name), path);
> + rcu_read_unlock();
> +
> + if (!found)
> + return true;
> + return false;
> +}
> +
> /*
> * Search and remove all stale (devices which are not mounted) devices.
> * When both inputs are NULL, it will search and release all stale devices.
> @@ -742,44 +755,47 @@ static void pending_bios_fn(struct btrfs_work *work)
> * skip_dev: Optional. Will skip this device when searching for the stale
> * devices.
> */
> -static void btrfs_free_stale_devices(const char *path,
> +static int btrfs_free_stale_devices(const char *path,
> struct btrfs_device *skip_device)
> {
> struct btrfs_fs_devices *fs_devices, *tmp_fs_devices;
> struct btrfs_device *device, *tmp_device;
> + int ret;
> +
> + if (path)
> + ret = -ENXIO;
> + else
> + ret = 0;
Can you please split this change to another patch? It's a preparatory
work for the new ioctl. The return value meaning should be also
documented in the function comment.
