Can't mount removable device if device name changes.

Can't mount removable device if device name changes.

[cwillu]

I've got a btrfs on an sd card, which I'm using as the root fs on a
beagle.  That's not the problem :)

The machine I generate my images on has an internal sd reader, and I
also have a usb card reader.  After creating the fs on the internal
reader, I ended up plugging it in on the external reader.

internal: sdd
external: sdh

mount /dev/sdh2 /mnt -t btrfs
> mount: /dev/sdh2: can't read superblock
[15035.538462] device fsid 48fadf7ed76537-bb9c7266ecb8b2 devid transid
8986 /dev/sdh2
[15035.538462] open /dev/sdd2 failed

If I plug it back into the internal reader, it mounts fine on /dev/sdd2.

An strace of btrfsctl -a shows it reading /dev/sdh2, and there's no
mention of /dev/sdd:
> open("/dev/sdh2", O_RDONLY)             = 4
> pread(4, "\2067kF\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 2859, 65536) = 2859

The fs mounts fine on the external reader on a different machine.

Re: Can't mount removable device if device name changes.

[TARUISI Hiroaki]

Hi,

 What is your kernel version?
 Btrfs hols device names which construct filesystems and
updating device name(device renaming) is merged just in
last month.

Regards,
taruisi

(2010/04/11 10:49), cwillu wrote:
> I've got a btrfs on an sd card, which I'm using as the root fs on a
> beagle.  That's not the problem :)
> 
> The machine I generate my images on has an internal sd reader, and I
> also have a usb card reader.  After creating the fs on the internal
> reader, I ended up plugging it in on the external reader.
> 
> internal: sdd
> external: sdh
> 
> mount /dev/sdh2 /mnt -t btrfs
>> mount: /dev/sdh2: can't read superblock
> [15035.538462] device fsid 48fadf7ed76537-bb9c7266ecb8b2 devid transid
> 8986 /dev/sdh2
> [15035.538462] open /dev/sdd2 failed
> 
> If I plug it back into the internal reader, it mounts fine on /dev/sdd2.
> 
> An strace of btrfsctl -a shows it reading /dev/sdh2, and there's no
> mention of /dev/sdd:
>> open("/dev/sdh2", O_RDONLY)             = 4
>> pread(4, "\2067kF\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 2859, 65536) = 2859
> 
> The fs mounts fine on the external reader on a different machine.
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-- 
taruisi