forked from Minki/linux
7b3d9545f9
This reverts commitac40532ef0, which gets us back the original cleanup of6f5391c283. 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 commit6f5391c283is 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>
57 lines
1.5 KiB
C
57 lines
1.5 KiB
C
#ifndef _SCSI_DISK_H
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#define _SCSI_DISK_H
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/*
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* More than enough for everybody ;) The huge number of majors
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* is a leftover from 16bit dev_t days, we don't really need that
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* much numberspace.
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*/
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#define SD_MAJORS 16
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/*
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* This is limited by the naming scheme enforced in sd_probe,
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* add another character to it if you really need more disks.
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*/
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#define SD_MAX_DISKS (((26 * 26) + 26 + 1) * 26)
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/*
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* Time out in seconds for disks and Magneto-opticals (which are slower).
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*/
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#define SD_TIMEOUT (30 * HZ)
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#define SD_MOD_TIMEOUT (75 * HZ)
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/*
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* Number of allowed retries
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*/
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#define SD_MAX_RETRIES 5
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#define SD_PASSTHROUGH_RETRIES 1
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/*
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* Size of the initial data buffer for mode and read capacity data
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*/
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#define SD_BUF_SIZE 512
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struct scsi_disk {
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struct scsi_driver *driver; /* always &sd_template */
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struct scsi_device *device;
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struct class_device cdev;
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struct gendisk *disk;
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unsigned int openers; /* protected by BKL for now, yuck */
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sector_t capacity; /* size in 512-byte sectors */
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u32 index;
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u8 media_present;
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u8 write_prot;
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unsigned WCE : 1; /* state of disk WCE bit */
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unsigned RCD : 1; /* state of disk RCD bit, unused */
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unsigned DPOFUA : 1; /* state of disk DPOFUA bit */
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};
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#define to_scsi_disk(obj) container_of(obj,struct scsi_disk,cdev)
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#define sd_printk(prefix, sdsk, fmt, a...) \
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(sdsk)->disk ? \
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sdev_printk(prefix, (sdsk)->device, "[%s] " fmt, \
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(sdsk)->disk->disk_name, ##a) : \
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sdev_printk(prefix, (sdsk)->device, fmt, ##a)
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#endif /* _SCSI_DISK_H */
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