On 18.11.2017 15:50, Anand Jain wrote:
>
>
> On 11/16/2017 10:11 PM, Nikolay Borisov wrote:
>>
>>
>> On 13.11.2017 07:44, Anand Jain wrote:
>>> Support for a new command is being added here:
>>> btrfs dev ignore <dev>
>>> Which shall undo the effects of the command
>>> btrfs dev scan <dev>
>>>
>>> This cli/ioctl is needed as there is no way to continue to mount in
>>> degraded mode if the device is already scanned, which is required to
>>> recover from the split brain raid conditions.
>>>
>>> This patch proposes to use ioctl #5 as it was empty.
>>> IOW(BTRFS_IOCTL_MAGIC, 5, ..)
>>> If #5 is reserved for some other purpose, I think I should change this.
>>>
>>> Signed-off-by: Anand Jain <anand.j...@oracle.com>
>>> ---
>>> fs/btrfs/super.c | 4 +++
>>> fs/btrfs/volumes.c | 70
>>> ++++++++++++++++++++++++++++++++++++++++++++++
>>> fs/btrfs/volumes.h | 2 ++
>>> include/uapi/linux/btrfs.h | 2 ++
>>> 4 files changed, 78 insertions(+)
>>>
>>> diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
>>> index fa7bad8b22da..64f4beb1526d 100644
>>> --- a/fs/btrfs/super.c
>>> +++ b/fs/btrfs/super.c
>>> @@ -2183,6 +2183,10 @@ static long btrfs_control_ioctl(struct file
>>> *file, unsigned int cmd,
>>> ret = btrfs_scan_one_device(vol->name, FMODE_READ,
>>> &btrfs_fs_type, &fs_devices);
>>> break;
>>> + case BTRFS_IOC_IGNORE_DEV:
>>> + ret = btrfs_ignore_one_device(vol->name, FMODE_READ,
>>> + &btrfs_fs_type, &fs_devices);
>>> + break;
>>> case BTRFS_IOC_DEVICES_READY:
>>> ret = btrfs_scan_one_device(vol->name, FMODE_READ,
>>> &btrfs_fs_type, &fs_devices);
>>> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
>>> index 8ead85dba6f5..1a06a17e111e 100644
>>> --- a/fs/btrfs/volumes.c
>>> +++ b/fs/btrfs/volumes.c
>>> @@ -1181,6 +1181,76 @@ int btrfs_read_disk_super(struct block_device
>>> *bdev, u64 bytenr,
>>> return 0;
>>> }
>>> +static int device_list_remove(struct btrfs_super_block
>>> *disk_super, u64 devid)
>>> +{
>>> + int ret = 0;
>>> + struct btrfs_fs_devices *fs_devices;
>>> + struct btrfs_device *device;
>>> +
>>> + fs_devices = find_fsid(disk_super->fsid);
>>> + if (!fs_devices)
>>> + return -ENOENT;
>>> +
>>> + if (fs_devices->opened)
>>> + return -EPERM;
>>> +
>>> + mutex_lock(&uuid_mutex);
>>> + mutex_lock(&fs_devices->device_list_mutex);
>>> + device = find_device(fs_devices, devid, disk_super->dev_item.uuid);
>>> + if (!device) {
>>> + ret = -ENOENT;
>>> + goto error;
>>> + }
>>> +
>>> + delete_device_from_list(device);
>>> +
>>> +error:
>>> + mutex_unlock(&fs_devices->device_list_mutex);
>>> + mutex_unlock(&uuid_mutex);
>>> +
>>> + return ret;
>>> +}
>>> +
>>> +int btrfs_ignore_one_device(const char *path, fmode_t flags, void
>>> *holder,
>>> + struct btrfs_fs_devices **fs_devices_ret)
>>> +{
>>> + struct btrfs_super_block *disk_super;
>>> + struct block_device *bdev;
>>> + struct page *page;
>>> + int ret = -EINVAL;
>>> + u64 devid;
>>> + u64 bytenr;
>>> +
>>> + bytenr = btrfs_sb_offset(0);
>>> + flags |= FMODE_EXCL;
>>> +
>>> + bdev = blkdev_get_by_path(path, flags, holder);
>>> + if (IS_ERR(bdev)) {
>>> + ret = PTR_ERR(bdev);
>>> + goto error;
>>> + }
>>> +
>>> + if (btrfs_read_disk_super(bdev, bytenr, &page, &disk_super))
>>> + goto error_bdev_put;
>>> +
>>> + devid = btrfs_stack_device_id(&disk_super->dev_item);
>>> +
>>> + ret = device_list_remove(disk_super, devid);
>>> + if (ret)
>>> + pr_err("BTRFS: %pU: device %s uuid %pU devid %llu failed to
>>> unscan: %d",
>>> + disk_super->fsid, path, disk_super->dev_item.uuid, devid, ret);
>>> + else
>>> + pr_info("BTRFS: %pU: device %s uuid %pU devid %llu ran undo scan",
>>> + disk_super->fsid, path, disk_super->dev_item.uuid, devid);
>>
>> There is already btrfs_err and btrfs_info, use those. This will allow to
>> uniquely identify the failing btrfs file system
>
> We don't have fs_info in this context, btrfs_err/info can't be used.
Yes, but we have struct file in btrfs_control_ioctl then can't we do :
struct btrfs_fs_info = btrfs_sb(file_inode(file)->i_sb)
>
>> also the pr_* statements
>> need to be indented after the if/else.
>
> Will do.
>
> Thanks, Anand
>
>>> +
>>> + btrfs_release_disk_super(page);
>>> +
>>> +error_bdev_put:
>>> + blkdev_put(bdev, flags);
>>> +error:
>>> + return ret;
>>> +}
>>> +
>>> /*
>>> * 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 6108fdfec67f..340e40acdab5 100644
>>> --- a/fs/btrfs/volumes.h
>>> +++ b/fs/btrfs/volumes.h
>>> @@ -421,6 +421,8 @@ int btrfs_open_devices(struct btrfs_fs_devices
>>> *fs_devices,
>>> fmode_t flags, void *holder);
>>> int btrfs_scan_one_device(const char *path, fmode_t flags, void
>>> *holder,
>>> struct btrfs_fs_devices **fs_devices_ret);
>>> +int btrfs_ignore_one_device(const char *path, fmode_t flags, void
>>> *holder,
>>> + struct btrfs_fs_devices **fs_devices_ret);
>>> int btrfs_close_devices(struct btrfs_fs_devices *fs_devices);
>>> void btrfs_close_extra_devices(struct btrfs_fs_devices *fs_devices,
>>> int step);
>>> void btrfs_assign_next_active_device(struct btrfs_fs_info *fs_info,
>>> diff --git a/include/uapi/linux/btrfs.h b/include/uapi/linux/btrfs.h
>>> index 378230c163d5..928485c31aa4 100644
>>> --- a/include/uapi/linux/btrfs.h
>>> +++ b/include/uapi/linux/btrfs.h
>>> @@ -739,6 +739,8 @@ 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_IGNORE_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
>>>
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