|From:||Peter Osterlund <petero2-AT-telia.com>|
|To:||Linus Torvalds <torvalds-AT-linux-foundation.org>|
|Subject:||Re: [patch] scsi: revert "[SCSI] Get rid of scsi_cmnd->done"|
|Date:||06 Jan 2008 03:55:16 +0100|
|Cc:||James Bottomley <James.Bottomley-AT-HansenPartnership.com>, Matthew Wilcox <matthew-AT-wil.cx>, Ingo Molnar <mingo-AT-elte.hu>, linux-kernel-AT-vger.kernel.org, Andrew Morton <akpm-AT-linux-foundation.org>|
Linus Torvalds <email@example.com> writes: > On Wed, 2 Jan 2008, James Bottomley wrote: > > > Look at the taxonomy of the bug. This is the form of the error: > > > > buffer I/O error on device sr0, logical block 20304 > > attempt to access beyond end of device > > sr0: rw=0, want=81224, limit=40944 > > > > The last limit is the most suggestive, that comes straight from > > bdev->bd_inode->i_size>>9 and is supposed to be the size of the block > > device in 512 byte blocks. For a 4.7GB DVD, it's a little small. > > Nothing in the sr code sets this directly (although it does come from > > get_blkdev() for the first opener). pktcdvd does set it, though ... and > > probably wrongly if the drive in question isn't UDF formatted. pktcdvd sets it when opening the /dev/pktcdvd device, but when the drive is later opened as /dev/scd0, there is nothing that sets it back. (Btw, 40944 is possible if the disk is a CDRW that was formatted with "cdrwtool -m 10236".) The problem is that pktcdvd opens the cd device in non-blocking mode when pktsetup is run, and doesn't close it again until pktsetup -d is run. The effect is that if you meanwhile open the cd device, blkdev.c:do_open() doesn't call bd_set_size() because bdev->bd_openers is non-zero. I don't know the correct way to fix this. Maybe adding bd_set_size() to sr.c:get_sectorsize() which already does set_capacity() would work. > .. but you're ignoring the fact that if pktcdvd sets it wrong, then it > should be visible with the pre-commit kernel *also*. I can repeat this bug, both with and without the scsi patch that is claimed to make a difference, both with an external USB drive and an internal IDE drive. To repeat: 1. Start with an empty drive. 2. pktsetup 0 /dev/scd0 3. Insert a CD containing an isofs filesystem. 4. mount /dev/pktcdvd/0 /mnt/tmp 5. umount /mnt/tmp 6. Press the eject button. 7. Insert a DVD containing a non-writable filesystem. 8. mount /dev/scd0 /mnt/tmp 9. find /mnt/tmp -type f -print0 | xargs -0 sha1sum >/dev/null 10. If the DVD contains data beyond the physical size of a CD, you get I/O errors in the terminal, and dmesg reports lots of "attempt to access beyond end of device" errors. -- Peter Osterlund - firstname.lastname@example.org http://web.telia.com/~u89404340 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to email@example.com More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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