2b14290078
The last_sector_bug flag was added to work around a bug in certain usb cardreaders, where they would crash if a multiple sector read included the last sector. The original implementation avoids this by e.g. splitting an 8 sector read which includes the last sector into a 7 sector read, and a single sector read for the last sector. The flag is enabled for all USB devices. This revealed a second bug in other usb cardreaders, which crash when they get a multiple sector read which stops 1 sector short of the last sector. Affected hardware includes the Kingston "MobileLite" external USB cardreader and the internal USB cardreader on the Asus EeePC. Extend the last_sector_bug workaround to ensure that any access which touches the last 8 hardware sectors of the device is a single sector long. Requests are shrunk as necessary to meet this constraint. This gives us a safety margin against potential unknown or future bugs affecting multi-sector access to the end of the device. The two known bugs only affect the last 2 sectors. However, they suggest that these devices are prone to fencepost errors and that multi-sector access to the end of the device is not well tested. Popular OS's use multi-sector accesses, but they rarely read the last few sectors. Linux (with udev & vol_id) automatically reads sectors from the end of the device on insertion. It is assumed that single sector accesses are more thoroughly tested during development. Signed-off-by: Alan Jenkins <alan-jenkins@tuffmail.co.uk> Tested-by: Alan Jenkins <alan-jenkins@tuffmail.co.uk> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
116 lines
3.2 KiB
C
116 lines
3.2 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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/*
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* Number of sectors at the end of the device to avoid multi-sector
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* accesses to in the case of last_sector_bug
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*/
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#define SD_LAST_BUGGY_SECTORS 8
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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 device dev;
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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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u8 protection_type;/* Data Integrity Field */
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unsigned previous_state : 1;
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unsigned ATO : 1; /* state of disk ATO bit */
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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,dev)
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static inline struct scsi_disk *scsi_disk(struct gendisk *disk)
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{
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return container_of(disk->private_data, struct scsi_disk, driver);
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}
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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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/*
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* A DIF-capable target device can be formatted with different
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* protection schemes. Currently 0 through 3 are defined:
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*
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* Type 0 is regular (unprotected) I/O
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*
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* Type 1 defines the contents of the guard and reference tags
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*
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* Type 2 defines the contents of the guard and reference tags and
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* uses 32-byte commands to seed the latter
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*
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* Type 3 defines the contents of the guard tag only
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*/
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enum sd_dif_target_protection_types {
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SD_DIF_TYPE0_PROTECTION = 0x0,
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SD_DIF_TYPE1_PROTECTION = 0x1,
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SD_DIF_TYPE2_PROTECTION = 0x2,
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SD_DIF_TYPE3_PROTECTION = 0x3,
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};
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/*
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* Data Integrity Field tuple.
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*/
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struct sd_dif_tuple {
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__be16 guard_tag; /* Checksum */
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__be16 app_tag; /* Opaque storage */
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__be32 ref_tag; /* Target LBA or indirect LBA */
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};
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#if defined(CONFIG_BLK_DEV_INTEGRITY)
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extern void sd_dif_op(struct scsi_cmnd *, unsigned int, unsigned int);
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extern void sd_dif_config_host(struct scsi_disk *);
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extern int sd_dif_prepare(struct request *rq, sector_t, unsigned int);
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extern void sd_dif_complete(struct scsi_cmnd *, unsigned int);
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#else /* CONFIG_BLK_DEV_INTEGRITY */
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#define sd_dif_op(a, b, c) do { } while (0)
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#define sd_dif_config_host(a) do { } while (0)
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#define sd_dif_prepare(a, b, c) (0)
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#define sd_dif_complete(a, b) (0)
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#endif /* CONFIG_BLK_DEV_INTEGRITY */
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#endif /* _SCSI_DISK_H */
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