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51490c89f9
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>
68 lines
2.2 KiB
C
68 lines
2.2 KiB
C
/*
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* sr.h by David Giller
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* CD-ROM disk driver header file
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*
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* adapted from:
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* sd.h Copyright (C) 1992 Drew Eckhardt
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* SCSI disk driver header file by
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* Drew Eckhardt
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*
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* <drew@colorado.edu>
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*
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* Modified by Eric Youngdale eric@andante.org to
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* add scatter-gather, multiple outstanding request, and other
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* enhancements.
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*/
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#ifndef _SR_H
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#define _SR_H
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#include <linux/genhd.h>
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#include <linux/kref.h>
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struct scsi_device;
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/* The CDROM is fairly slow, so we need a little extra time */
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/* In fact, it is very slow if it has to spin up first */
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#define IOCTL_TIMEOUT 30*HZ
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typedef struct scsi_cd {
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struct scsi_driver *driver;
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unsigned capacity; /* size in blocks */
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struct scsi_device *device;
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unsigned int vendor; /* vendor code, see sr_vendor.c */
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unsigned long ms_offset; /* for reading multisession-CD's */
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unsigned use:1; /* is this device still supportable */
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unsigned xa_flag:1; /* CD has XA sectors ? */
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unsigned readcd_known:1; /* drive supports READ_CD (0xbe) */
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unsigned readcd_cdda:1; /* reading audio data using READ_CD */
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struct cdrom_device_info cdi;
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/* We hold gendisk and scsi_device references on probe and use
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* the refs on this kref to decide when to release them */
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struct kref kref;
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struct gendisk *disk;
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} Scsi_CD;
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int sr_do_ioctl(Scsi_CD *, struct packet_command *);
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int sr_lock_door(struct cdrom_device_info *, int);
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int sr_tray_move(struct cdrom_device_info *, int);
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int sr_drive_status(struct cdrom_device_info *, int);
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int sr_disk_status(struct cdrom_device_info *);
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int sr_get_last_session(struct cdrom_device_info *, struct cdrom_multisession *);
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int sr_get_mcn(struct cdrom_device_info *, struct cdrom_mcn *);
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int sr_reset(struct cdrom_device_info *);
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int sr_select_speed(struct cdrom_device_info *cdi, int speed);
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int sr_audio_ioctl(struct cdrom_device_info *, unsigned int, void *);
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int sr_dev_ioctl(struct cdrom_device_info *, unsigned int, unsigned long);
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int sr_is_xa(Scsi_CD *);
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/* sr_vendor.c */
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void sr_vendor_init(Scsi_CD *);
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int sr_cd_check(struct cdrom_device_info *);
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int sr_set_blocklength(Scsi_CD *, int blocklength);
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#endif
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