Messages in this thread | | | Date | Fri, 11 Feb 2011 14:04:12 +0100 | From | Felix Blanke <> | Subject | Re: LOOP_GET_STATUS(64) truncates pathnames to 64 chars (was Re: Bug in mkfs.btrfs?!) |
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Hi,
are you sure that patch is in the kernel?
I'm using 2.6.37 and don't have those attribues in my /sys.
Felix
On 10. February 2011 - 13:29, Petr Uzel wrote: > Date: Thu, 10 Feb 2011 13:29:27 +0100 > From: Petr Uzel <petr.uzel@suse.cz> > To: Chris Samuel <chris@csamuel.org> > Cc: Felix Blanke <felixblanke@gmail.com>, kreijack@inwind.it, Hugo Mills > <hugo-lkml@carfax.org.uk>, linux-btrfs@vger.kernel.org, Linux Kernel > <linux-kernel@vger.kernel.org> > Subject: Re: LOOP_GET_STATUS(64) truncates pathnames to 64 chars (was Re: > Bug in mkfs.btrfs?!) > Mail-Followup-To: Chris Samuel <chris@csamuel.org>, Felix Blanke > <felixblanke@gmail.com>, kreijack@inwind.it, Hugo Mills > <hugo-lkml@carfax.org.uk>, linux-btrfs@vger.kernel.org, Linux Kernel > <linux-kernel@vger.kernel.org> > > On Tue, Jan 25, 2011 at 11:15:11AM +1100, Chris Samuel wrote: > > /* > > * CC'd to linux-kernel in case they have any feedback on this. > > * > > * Long thread, trying to work out why mkfs.btrfs failed to > > * make a filesystem on an encrypted loopback mount called > > * /dev/loop2. Cause turned out to be mkfs.btrfs calling > > * LOOP_GET_STATUS to find out if the block device was mounted > > * and getting a truncated device name back and so it later > > * fails when lstat() is called on the truncated device path. > > * > > * The long device name for the encrypted loopback mount was > > * because /dev/disk/by-id/$ID was used when Felix created it > > * to cope with devices moving around. > > */ > > > > On 25/01/11 00:01, Felix Blanke wrote: > > > > > you were talking about the LOOP_GET_STATUS function. I'm not > > > quite sure where does it came from. Is it part of the kernel? > > > Or does it come from the util-linux package? > > > > It's in the kernel, and there is both LOOP_GET_STATUS (old > > implementation) and LOOP_GET_STATUS64 (new implementation). > > > > They return structures called loop_info and loop_info64 > > respectively and both are defined in include/linux/loop.h . > > > > Sadly in both cases the lengths of paths are defined to be > > LO_NAME_SIZE which is currently 64 and hence either > > implementation will cause the problematic: > > > > lstat("/dev/disk/by-id/ata-INTEL_SSDSA2M160G2GC_CVPO939201JX160AGN-par", > > 0x7fffa30b3cf0) = -1 ENOENT (No such file or directory) > > > > I've CC'd this to the LKML in case they have any feedback on > > this apparent problem with the API. > > Since 2.6.37, you can get full path to the backing file from sys: > cat /sys/block/loopX/loop/backing_file > > See > http://linux.derkeiler.com/Mailing-Lists/Kernel/2010-07/msg10996.html > > > HTH, > > Petr > > -- > Petr Uzel > IRC: ptr_uzl @ freenode
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