39c60a0948
Some arrays synchronize their full non volatile cache when the sd driver sends a SYNCHRONIZE CACHE command. Unfortunately, they can have Terrabytes of this and we send a SYNCHRONIZE CACHE for every barrier if an array reports it has a writeback cache. This leads to massive slowdowns on journalled filesystems. The fix is to allow userspace to turn off the writeback cache setting as a temporary measure (i.e. without doing the MODE SELECT to write it back to the device), so even though the device reported it has a writeback cache, the user, knowing that the cache is non volatile and all they care about is filesystem correctness, can turn that bit off in the kernel and avoid the performance ruinous (and safety irrelevant) SYNCHRONIZE CACHE commands. The way you do this is add a 'temporary' prefix when performing the usual cache setting operations, so echo temporary write through > /sys/class/scsi_disk/<disk>/cache_type Reported-by: Ric Wheeler <rwheeler@redhat.com> Cc: <stable@vger.kernel.org> Signed-off-by: James Bottomley <JBottomley@Parallels.com>
186 lines
4.5 KiB
C
186 lines
4.5 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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* 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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#define SD_FLUSH_TIMEOUT (60 * HZ)
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#define SD_WRITE_SAME_TIMEOUT (120 * 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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#define SD_MAX_MEDIUM_TIMEOUTS 2
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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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enum {
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SD_EXT_CDB_SIZE = 32, /* Extended CDB size */
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SD_MEMPOOL_SIZE = 2, /* CDB pool size */
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};
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enum {
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SD_MAX_WS10_BLOCKS = 0xffff,
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SD_MAX_WS16_BLOCKS = 0x7fffff,
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};
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enum {
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SD_LBP_FULL = 0, /* Full logical block provisioning */
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SD_LBP_UNMAP, /* Use UNMAP command */
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SD_LBP_WS16, /* Use WRITE SAME(16) with UNMAP bit */
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SD_LBP_WS10, /* Use WRITE SAME(10) with UNMAP bit */
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SD_LBP_ZERO, /* Use WRITE SAME(10) with zero payload */
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SD_LBP_DISABLE, /* Discard disabled due to failed cmd */
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};
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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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atomic_t openers;
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sector_t capacity; /* size in 512-byte sectors */
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u32 max_ws_blocks;
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u32 max_unmap_blocks;
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u32 unmap_granularity;
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u32 unmap_alignment;
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u32 index;
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unsigned int physical_block_size;
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unsigned int max_medium_access_timeouts;
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unsigned int medium_access_timed_out;
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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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u8 provisioning_mode;
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unsigned ATO : 1; /* state of disk ATO bit */
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unsigned cache_override : 1; /* temp override of WCE,RCD */
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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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unsigned first_scan : 1;
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unsigned lbpme : 1;
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unsigned lbprz : 1;
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unsigned lbpu : 1;
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unsigned lbpws : 1;
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unsigned lbpws10 : 1;
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unsigned lbpvpd : 1;
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unsigned ws16 : 1;
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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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static inline int scsi_medium_access_command(struct scsi_cmnd *scmd)
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{
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switch (scmd->cmnd[0]) {
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case READ_6:
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case READ_10:
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case READ_12:
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case READ_16:
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case SYNCHRONIZE_CACHE:
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case VERIFY:
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case VERIFY_12:
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case VERIFY_16:
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case WRITE_6:
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case WRITE_10:
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case WRITE_12:
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case WRITE_16:
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case WRITE_SAME:
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case WRITE_SAME_16:
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case UNMAP:
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return 1;
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case VARIABLE_LENGTH_CMD:
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switch (scmd->cmnd[9]) {
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case READ_32:
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case VERIFY_32:
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case WRITE_32:
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case WRITE_SAME_32:
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return 1;
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}
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}
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return 0;
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}
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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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#ifdef CONFIG_BLK_DEV_INTEGRITY
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extern void sd_dif_config_host(struct scsi_disk *);
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extern void 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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static inline void sd_dif_config_host(struct scsi_disk *disk)
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{
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}
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static inline int sd_dif_prepare(struct request *rq, sector_t s, unsigned int a)
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{
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return 0;
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}
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static inline void sd_dif_complete(struct scsi_cmnd *cmd, unsigned int a)
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{
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}
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#endif /* CONFIG_BLK_DEV_INTEGRITY */
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#endif /* _SCSI_DISK_H */
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