| Message ID | 20180726113225.1745-2-anand.jain@oracle.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | btrfs: introduce feature to forget a btrfs device | expand |
On Thu, Jul 26, 2018 at 12:32 PM, Anand Jain <anand.jain@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. And why is the feature needed? What problems does it solve? That is missing from the changelog, no matter how obvious it is to you (or anyone else), it should be mentioned in the changelog. Thanks. > > Signed-off-by: Anand Jain <anand.jain@oracle.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 67de3c0fc85b..470a32af474e 100644 > --- a/fs/btrfs/super.c > +++ b/fs/btrfs/super.c > @@ -2244,6 +2244,9 @@ 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 8844904f9009..cd54a926141a 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); > + 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 049619176831..1602b5faa7e7 100644 > --- a/fs/btrfs/volumes.h > +++ b/fs/btrfs/volumes.h > @@ -405,6 +405,7 @@ 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 > -- > 2.7.0 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html
On 07/26/2018 11:25 PM, Filipe Manana wrote: > On Thu, Jul 26, 2018 at 12:32 PM, Anand Jain <anand.jain@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. > > And why is the feature needed? What problems does it solve? > That is missing from the changelog, no matter how obvious it is to you > (or anyone else), it should be mentioned in the changelog. There are few reasons.. . 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 (patch [1] in the ML explained this). [1] btrfs: handle volume split brain scenario . Running test cases which requires btrfs.ko-reload if the rootfs is btrfs. Thanks, Anand > Thanks. > >> >> Signed-off-by: Anand Jain <anand.jain@oracle.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 67de3c0fc85b..470a32af474e 100644 >> --- a/fs/btrfs/super.c >> +++ b/fs/btrfs/super.c >> @@ -2244,6 +2244,9 @@ 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 8844904f9009..cd54a926141a 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); >> + 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 049619176831..1602b5faa7e7 100644 >> --- a/fs/btrfs/volumes.h >> +++ b/fs/btrfs/volumes.h >> @@ -405,6 +405,7 @@ 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 >> -- >> 2.7.0 >> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html > > > -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index 67de3c0fc85b..470a32af474e 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -2244,6 +2244,9 @@ 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 8844904f9009..cd54a926141a 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); + 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 049619176831..1602b5faa7e7 100644 --- a/fs/btrfs/volumes.h +++ b/fs/btrfs/volumes.h @@ -405,6 +405,7 @@ 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
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. Signed-off-by: Anand Jain <anand.jain@oracle.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(+)