On Wed, Nov 14, 2018 at 9:14 AM Anand Jain <anand.j...@oracle.com> 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>
> ---
> 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 345c64d810d4..f99db6899004 100644
> --- a/fs/btrfs/super.c
> +++ b/fs/btrfs/super.c
> @@ -2246,6 +2246,9 @@ 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 f435d397019e..e1365a122657 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -1208,6 +1208,15 @@ 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);
One space before : and another one after it please.
Now the more important: don't use strlen, use strnlen. Some malicious
or sloppy user might have passed a non-null terminated string, you
don't want strlen to go past the limits of btrfs_ioctl_vol_args for
obvious reasons.
Also, please, not just to make a maintainer's life easier, but current
and future reviewers, add the patch version to each patch's subject
and not just the cover letter. Also list (after ---) what changes
between each patch version in the patch itself and not the cover
letter.
V12, here we go.
> + mutex_unlock(&uuid_mutex);
> +
> + return 0;
> +}
> +
> /*
> * Look for a btrfs signature on a device. This may be called out of the
> mount path
> * and we are not allowed to call set_blocksize during the scan. The
> superblock
> diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
> index aefce895e994..180297d04938 100644
> --- a/fs/btrfs/volumes.h
> +++ b/fs/btrfs/volumes.h
> @@ -406,6 +406,7 @@ int btrfs_open_devices(struct btrfs_fs_devices
> *fs_devices,
> fmode_t flags, void *holder);
> struct btrfs_device *btrfs_scan_one_device(const char *path,
> fmode_t flags, void *holder);
> +int btrfs_forget_devices(const char *path);
> int btrfs_close_devices(struct btrfs_fs_devices *fs_devices);
> void btrfs_free_extra_devids(struct btrfs_fs_devices *fs_devices, int step);
> void btrfs_assign_next_active_device(struct btrfs_device *device,
> diff --git a/include/uapi/linux/btrfs.h b/include/uapi/linux/btrfs.h
> index 5ca1d21fc4a7..b1be7f828cb4 100644
> --- a/include/uapi/linux/btrfs.h
> +++ b/include/uapi/linux/btrfs.h
> @@ -836,6 +836,8 @@ enum btrfs_err_code {
> struct btrfs_ioctl_vol_args)
> #define BTRFS_IOC_SCAN_DEV _IOW(BTRFS_IOCTL_MAGIC, 4, \
> struct btrfs_ioctl_vol_args)
> +#define BTRFS_IOC_FORGET_DEV _IOW(BTRFS_IOCTL_MAGIC, 5, \
> + struct btrfs_ioctl_vol_args)
> /* trans start and trans end are dangerous, and only for
> * use by applications that know how to avoid the
> * resulting deadlocks
> --
> 1.8.3.1
>
--
Filipe David Manana,
“Whether you think you can, or you think you can't — you're right.”
