linux/include/scsi/scsi_driver.h
Linus Torvalds 7b3d9545f9 Revert "scsi: revert "[SCSI] Get rid of scsi_cmnd->done""
This reverts commit ac40532ef0, which gets
us back the original cleanup of 6f5391c283.

It turns out that the bug that was triggered by that commit was
apparently not actually triggered by that commit at all, and just the
testing conditions had changed enough to make it appear to be due to it.

The real problem seems to have been found by Peter Osterlund:

  "pktcdvd sets it [block device size] 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."

In particular, to repeat the bug (regardless of whether commit
6f5391c283 is applied or not):

  " 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."

which in turn is because the nested open after the media change won't
cause the size to be set properly (because the original open still holds
the block device, and we only do the bd_set_size() when we don't have
other people holding the device open).

The proper fix for that is probably to just do something like

	bdev->bd_inode->i_size = (loff_t)get_capacity(disk)<<9;

in fs/block_dev.c:do_open() even for the cases where we're not the
original opener (but *not* call bd_set_size(), since that will also
change the block size of the device).

Cc: Peter Osterlund <petero2@telia.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Matthew Wilcox <matthew@wil.cx>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-01-06 10:17:12 -08:00

37 lines
995 B
C

#ifndef _SCSI_SCSI_DRIVER_H
#define _SCSI_SCSI_DRIVER_H
#include <linux/device.h>
struct module;
struct scsi_cmnd;
struct scsi_device;
struct request;
struct request_queue;
struct scsi_driver {
struct module *owner;
struct device_driver gendrv;
void (*rescan)(struct device *);
int (*done)(struct scsi_cmnd *);
};
#define to_scsi_driver(drv) \
container_of((drv), struct scsi_driver, gendrv)
extern int scsi_register_driver(struct device_driver *);
#define scsi_unregister_driver(drv) \
driver_unregister(drv);
extern int scsi_register_interface(struct class_interface *);
#define scsi_unregister_interface(intf) \
class_interface_unregister(intf)
int scsi_setup_blk_pc_cmnd(struct scsi_device *sdev, struct request *req);
int scsi_setup_fs_cmnd(struct scsi_device *sdev, struct request *req);
int scsi_prep_state_check(struct scsi_device *sdev, struct request *req);
int scsi_prep_return(struct request_queue *q, struct request *req, int ret);
#endif /* _SCSI_SCSI_DRIVER_H */