From 51490c89f95b8581782e9baa855da166441852be Mon Sep 17 00:00:00 2001 From: Pete Zaitcev Date: Tue, 5 Jul 2005 18:18:08 -0700 Subject: [SCSI] sr.c: Fix getting wrong size Here's the problem. Try to do this on 2.6.12: - Kill udev and HAL - Insert a CD-ROM into a SCSI or USB CD-ROM drive - Run dd if=/dev/scd0 - cat /sys/block/sr0/size - Eject the CD, insert a different one - Run dd if=/dev/scd0 This is likely to do "access beyond the end of device", if you let it - cat /sys/block/sr0/size This shows the size of a previous CD, even though dd was supposed to revalidate the device. - Run dd if=/dev/scd0 The second run of dd works correctly! The bug was introduced in 2.5.31, when Al fixes the recursive opens in partitioning. Before, the code worked like this: - Block layer called cdrom_open directly - cdrom_open called sr_open - sr_open called check_disk_change - check_disk_change called sr_media_change - sr_media_change did cd->needs_disk_change=1 - before returning sr_open tested cd->needs_disk_change and called get_sector_size. In 2.6.12, the check_disk_change is called from cdrom_open only. Thus: - Block layer calls sr_bd_open - sr_bd_open calls cdrom_open - cdrom_open calls sr_open - sr_open tests cd->needs_disk_change, which wasn't set yet; returns - cdrom_open calls check_disk_change - check_disk_change calls sr_media_change - sr_media_change does cd->needs_disk_change=1, but nobody cares Acked by: Alexander Viro Signed-off-by: James Bottomley --- drivers/scsi/sr.c | 24 ++---------------------- 1 file changed, 2 insertions(+), 22 deletions(-) (limited to 'drivers/scsi/sr.c') diff --git a/drivers/scsi/sr.c b/drivers/scsi/sr.c index 2f259f24952..f63d8c6c2a3 100644 --- a/drivers/scsi/sr.c +++ b/drivers/scsi/sr.c @@ -199,15 +199,7 @@ int sr_media_change(struct cdrom_device_info *cdi, int slot) /* check multisession offset etc */ sr_cd_check(cdi); - /* - * If the disk changed, the capacity will now be different, - * so we force a re-read of this information - * Force 2048 for the sector size so that filesystems won't - * be trying to use something that is too small if the disc - * has changed. - */ - cd->needs_sector_size = 1; - cd->device->sector_size = 2048; + get_sectorsize(cd); } return retval; } @@ -538,13 +530,6 @@ static int sr_open(struct cdrom_device_info *cdi, int purpose) if (!scsi_block_when_processing_errors(sdev)) goto error_out; - /* - * If this device did not have media in the drive at boot time, then - * we would have been unable to get the sector size. Check to see if - * this is the case, and try again. - */ - if (cd->needs_sector_size) - get_sectorsize(cd); return 0; error_out: @@ -604,7 +589,6 @@ static int sr_probe(struct device *dev) cd->driver = &sr_template; cd->disk = disk; cd->capacity = 0x1fffff; - cd->needs_sector_size = 1; cd->device->changed = 1; /* force recheck CD type */ cd->use = 1; cd->readcd_known = 0; @@ -694,7 +678,6 @@ static void get_sectorsize(struct scsi_cd *cd) if (the_result) { cd->capacity = 0x1fffff; sector_size = 2048; /* A guess, just in case */ - cd->needs_sector_size = 1; } else { #if 0 if (cdrom_get_last_written(&cd->cdi, @@ -727,7 +710,6 @@ static void get_sectorsize(struct scsi_cd *cd) printk("%s: unsupported sector size %d.\n", cd->cdi.name, sector_size); cd->capacity = 0; - cd->needs_sector_size = 1; } cd->device->sector_size = sector_size; @@ -736,7 +718,6 @@ static void get_sectorsize(struct scsi_cd *cd) * Add this so that we have the ability to correctly gauge * what the device is capable of. */ - cd->needs_sector_size = 0; set_capacity(cd->disk, cd->capacity); } @@ -748,8 +729,7 @@ out: Enomem: cd->capacity = 0x1fffff; - sector_size = 2048; /* A guess, just in case */ - cd->needs_sector_size = 1; + cd->device->sector_size = 2048; /* A guess, just in case */ if (SRpnt) scsi_release_request(SRpnt); goto out; -- cgit v1.2.3