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authorPete Zaitcev <zaitcev@redhat.com>2005-07-05 18:18:08 -0700
committerJames Bottomley <jejb@titanic.(none)>2005-08-28 11:14:12 -0500
commit51490c89f95b8581782e9baa855da166441852be (patch)
tree3be27d5e30c114d5d69fe21a4a079a64f2016354 /include
parent8224bfa84d510630b40ea460b2bb380c91acb8ae (diff)
[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>
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