Helo Anand,
>
>
> Following this patch the idea is to use lblkid to scan
> for the btrfs disks by default which means we don't
> use BTRFS_SCAN_PROC any more.
Firstly, i would like to know if we will get any different results between scanning
/proc/partions and using lbkid.
If not, why we can use liblkid totally,since this is more simple.
Thanks,
Wang
> which implies commands btrfs filesystem show and btrfs device scan will
> use lblkid to scan disks instead of current /proc/partitions
> by default.
>
> So now the question is, if there is any need to have option to scan
> using /proc/partitions ? and instead of removing it completely
> would we need it under a new option '-p' (in filesystem show and
> device scan) so that user can use /proc/partitions when needed,
> I really don't know what would be that circumstance though,
>
> Any thoughts?
>
> Thanks Anand
>
>
>
> On 09/27/2013 11:45 PM, Anand Jain wrote:
>> Signed-off-by: Anand Jain <anand.jain@xxxxxxxxxx>
>> ---
>> utils.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
>> utils.h | 2 ++
>> 2 files changed, 56 insertions(+)
>>
>> diff --git a/utils.c b/utils.c
>> index c6022fc..ccb5199 100644
>> --- a/utils.c
>> +++ b/utils.c
>> @@ -1914,6 +1914,57 @@ int test_dev_for_mkfs(char *file, int force_overwrite, char *estr)
>> return 0;
>> }
>>
>> +int test_skip_this_disk(char *path)
>> +{
>> + int fd;
>> + /* this will eliminate disks which are mounted (btrfs)
>> + * and non-dm disk path when dm is enabled
>> + */
>> + fd = open(path, O_RDWR|O_EXCL);
>> + if (fd < 0)
>> + return 1;
>> + close(fd);
>> + return 0;
>> +}
>> +
>> +int btrfs_scan_lblkid(int update_kernel)
>> +{
>> + int fd = -1;
>> + u64 num_devices;
>> + struct btrfs_fs_devices *tmp_devices;
>> + blkid_dev_iterate iter = NULL;
>> + blkid_dev dev = NULL;
>> + blkid_cache cache = NULL;
>> + char path[PATH_MAX];
>> +
>> + if (blkid_get_cache(&cache, 0) < 0) {
>> + printf("ERROR: lblkid cache get failed\n");
>> + return 1;
>> + }
>> + blkid_probe_all(cache);
>> + iter = blkid_dev_iterate_begin(cache);
>> + blkid_dev_set_search(iter, "TYPE", "btrfs");
>> + while (blkid_dev_next(iter, &dev) == 0) {
>> + dev = blkid_verify(cache, dev);
>> + if (!dev)
>> + continue;
>> + /* if we are here its definitly a btrfs disk*/
>> + strcpy(path, blkid_dev_devname(dev));
>> + if (test_skip_this_disk(path))
>> + continue;
>> +
>> + fd = open(path, O_RDONLY);
>> + btrfs_scan_one_device(fd, path, &tmp_devices,
>> + &num_devices, BTRFS_SUPER_INFO_OFFSET);
>> + close(fd);
>> + fd = -1;
>> + if (update_kernel)
>> + btrfs_register_one_device(path);
>> + }
>> + blkid_dev_iterate_end(iter);
>> + return 0;
>> +}
>> +
>> /*
>> * scans devs for the btrfs
>> */
>> @@ -1928,6 +1979,9 @@ int scan_for_btrfs(int where, int update_kernel)
>> case BTRFS_SCAN_DEV:
>> ret = btrfs_scan_one_dir("/dev", update_kernel);
>> break;
>> + case BTRFS_SCAN_LBLKID:
>> + ret = btrfs_scan_lblkid(update_kernel);
>> + break;
>> }
>> return ret;
>> }
>> diff --git a/utils.h b/utils.h
>> index e944685..0f31db7 100644
>> --- a/utils.h
>> +++ b/utils.h
>> @@ -28,6 +28,7 @@
>> #define BTRFS_SCAN_PROC (1ULL << 0)
>> #define BTRFS_SCAN_DEV (1ULL << 1)
>> #define BTRFS_SCAN_MOUNTED (1ULL << 2)
>> +#define BTRFS_SCAN_LBLKID (1ULL << 3)
>>
>> #define BTRFS_UPDATE_KERNEL 1
>>
>> @@ -89,5 +90,6 @@ int csum_tree_block(struct btrfs_root *root, struct extent_buffer *buf,
>> int verify);
>> int ask_user(char *question);
>> int lookup_ino_rootid(int fd, u64 *rootid);
>> +int btrfs_scan_lblkid(int update_kernel);
>>
>> #endif
>>
>
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