Re: [RFC][PATCH v2] mount.btrfs helper

[Goffredo Baroncelli <kreijack@inwind.it>]

On 12/04/2014 03:09 AM, Anand Jain wrote:
> 
> 
> On 01/12/2014 01:43, Goffredo Baroncelli wrote:
>> Hi all,
>> 
>> this patch provides a "mount.btrfs" helper for the mount command. A
>> btrfs filesystem could span several disks. This helper scans all
>> the partitions to discover all the disks required to mount a
>> filesystem. So it would not necessary any-more to "scan" the
>> partitions to mount a filesystem.
>> 
>> mount.btrfs passes in the option parameters the devices required to
>> mount a filesystem. Supposing that a filesystem is composed by
>> several disks (/dev/sd[cdef]), when the user runs "mount /dev/sdd
>> /mnt", mount.btrfs is called and it executes the the mount(2)
>> syscall as below:
>> 
>> mount("/dev/sdd", "/mnt", "btrfs", 0, "device=/dev/sdc,device=/dev/sde,device=/de/vsdf").
> 
> 
> in linux its bit messy that there are different name/paths to the
> same device, its the way it is. So btrfs-progs normalizes these paths
> to "a" thing and provide it to the kernel during btrfs dev scan. 
> since device path normalization is done at the user space level not
> in the kernel, the device paths sent using mount option would miss
> this part.

Good point. I have to normalize the path. I put this in my todo list.

What I am not sure is the case when the user passes the devices via 
device=.... options explicitly.
In this case I prefer to leave these as are... The (super user) know what 
he is doing....

> 
> -Anand
> 
> 
[...]


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