diff options
author | Pete Zaitcev <zaitcev@redhat.com> | 2005-07-06 01:18:08 (GMT) |
---|---|---|
committer | James Bottomley <jejb@titanic.(none)> | 2005-08-28 16:14:12 (GMT) |
commit | 51490c89f95b8581782e9baa855da166441852be (patch) | |
tree | 3be27d5e30c114d5d69fe21a4a079a64f2016354 /drivers/scsi/sr.c | |
parent | 8224bfa84d510630b40ea460b2bb380c91acb8ae (diff) | |
download | linux-51490c89f95b8581782e9baa855da166441852be.tar.xz |
[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 <aviro@redhat.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
Diffstat (limited to 'drivers/scsi/sr.c')
-rw-r--r-- | drivers/scsi/sr.c | 24 |
1 files changed, 2 insertions, 22 deletions
diff --git a/drivers/scsi/sr.c b/drivers/scsi/sr.c index 2f259f2..f63d8c6 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; |