On 11/14/2018 07:15 PM, Filipe Manana wrote:
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.
will fix.
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.
Makes sense. Will fix.
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.
Sure. Thanks for the feedback. -Anand
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
