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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-26 19:00:25 +00:00
![Konstantin Khlebnikov](/assets/img/avatar_default.png)
Requests that triggers flushing volatile writeback cache to disk (barriers) have significant effect to overall performance. Block layer has sophisticated engine for combining several flush requests into one. But there is no statistics for actual flushes executed by disk. Requests which trigger flushes usually are barriers - zero-size writes. This patch adds two iostat counters into /sys/class/block/$dev/stat and /proc/diskstats - count of completed flush requests and their total time. Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Signed-off-by: Jens Axboe <axboe@kernel.dk>
487 lines
14 KiB
C
487 lines
14 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Block data types and constants. Directly include this file only to
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* break include dependency loop.
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*/
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#ifndef __LINUX_BLK_TYPES_H
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#define __LINUX_BLK_TYPES_H
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#include <linux/types.h>
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#include <linux/bvec.h>
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#include <linux/ktime.h>
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struct bio_set;
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struct bio;
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struct bio_integrity_payload;
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struct page;
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struct block_device;
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struct io_context;
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struct cgroup_subsys_state;
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typedef void (bio_end_io_t) (struct bio *);
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/*
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* Block error status values. See block/blk-core:blk_errors for the details.
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* Alpha cannot write a byte atomically, so we need to use 32-bit value.
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*/
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#if defined(CONFIG_ALPHA) && !defined(__alpha_bwx__)
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typedef u32 __bitwise blk_status_t;
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#else
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typedef u8 __bitwise blk_status_t;
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#endif
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#define BLK_STS_OK 0
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#define BLK_STS_NOTSUPP ((__force blk_status_t)1)
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#define BLK_STS_TIMEOUT ((__force blk_status_t)2)
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#define BLK_STS_NOSPC ((__force blk_status_t)3)
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#define BLK_STS_TRANSPORT ((__force blk_status_t)4)
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#define BLK_STS_TARGET ((__force blk_status_t)5)
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#define BLK_STS_NEXUS ((__force blk_status_t)6)
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#define BLK_STS_MEDIUM ((__force blk_status_t)7)
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#define BLK_STS_PROTECTION ((__force blk_status_t)8)
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#define BLK_STS_RESOURCE ((__force blk_status_t)9)
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#define BLK_STS_IOERR ((__force blk_status_t)10)
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/* hack for device mapper, don't use elsewhere: */
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#define BLK_STS_DM_REQUEUE ((__force blk_status_t)11)
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#define BLK_STS_AGAIN ((__force blk_status_t)12)
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/*
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* BLK_STS_DEV_RESOURCE is returned from the driver to the block layer if
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* device related resources are unavailable, but the driver can guarantee
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* that the queue will be rerun in the future once resources become
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* available again. This is typically the case for device specific
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* resources that are consumed for IO. If the driver fails allocating these
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* resources, we know that inflight (or pending) IO will free these
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* resource upon completion.
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*
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* This is different from BLK_STS_RESOURCE in that it explicitly references
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* a device specific resource. For resources of wider scope, allocation
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* failure can happen without having pending IO. This means that we can't
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* rely on request completions freeing these resources, as IO may not be in
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* flight. Examples of that are kernel memory allocations, DMA mappings, or
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* any other system wide resources.
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*/
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#define BLK_STS_DEV_RESOURCE ((__force blk_status_t)13)
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/**
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* blk_path_error - returns true if error may be path related
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* @error: status the request was completed with
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*
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* Description:
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* This classifies block error status into non-retryable errors and ones
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* that may be successful if retried on a failover path.
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*
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* Return:
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* %false - retrying failover path will not help
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* %true - may succeed if retried
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*/
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static inline bool blk_path_error(blk_status_t error)
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{
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switch (error) {
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case BLK_STS_NOTSUPP:
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case BLK_STS_NOSPC:
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case BLK_STS_TARGET:
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case BLK_STS_NEXUS:
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case BLK_STS_MEDIUM:
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case BLK_STS_PROTECTION:
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return false;
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}
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/* Anything else could be a path failure, so should be retried */
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return true;
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}
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/*
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* From most significant bit:
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* 1 bit: reserved for other usage, see below
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* 12 bits: original size of bio
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* 51 bits: issue time of bio
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*/
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#define BIO_ISSUE_RES_BITS 1
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#define BIO_ISSUE_SIZE_BITS 12
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#define BIO_ISSUE_RES_SHIFT (64 - BIO_ISSUE_RES_BITS)
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#define BIO_ISSUE_SIZE_SHIFT (BIO_ISSUE_RES_SHIFT - BIO_ISSUE_SIZE_BITS)
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#define BIO_ISSUE_TIME_MASK ((1ULL << BIO_ISSUE_SIZE_SHIFT) - 1)
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#define BIO_ISSUE_SIZE_MASK \
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(((1ULL << BIO_ISSUE_SIZE_BITS) - 1) << BIO_ISSUE_SIZE_SHIFT)
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#define BIO_ISSUE_RES_MASK (~((1ULL << BIO_ISSUE_RES_SHIFT) - 1))
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/* Reserved bit for blk-throtl */
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#define BIO_ISSUE_THROTL_SKIP_LATENCY (1ULL << 63)
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struct bio_issue {
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u64 value;
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};
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static inline u64 __bio_issue_time(u64 time)
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{
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return time & BIO_ISSUE_TIME_MASK;
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}
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static inline u64 bio_issue_time(struct bio_issue *issue)
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{
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return __bio_issue_time(issue->value);
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}
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static inline sector_t bio_issue_size(struct bio_issue *issue)
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{
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return ((issue->value & BIO_ISSUE_SIZE_MASK) >> BIO_ISSUE_SIZE_SHIFT);
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}
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static inline void bio_issue_init(struct bio_issue *issue,
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sector_t size)
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{
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size &= (1ULL << BIO_ISSUE_SIZE_BITS) - 1;
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issue->value = ((issue->value & BIO_ISSUE_RES_MASK) |
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(ktime_get_ns() & BIO_ISSUE_TIME_MASK) |
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((u64)size << BIO_ISSUE_SIZE_SHIFT));
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}
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/*
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* main unit of I/O for the block layer and lower layers (ie drivers and
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* stacking drivers)
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*/
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struct bio {
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struct bio *bi_next; /* request queue link */
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struct gendisk *bi_disk;
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unsigned int bi_opf; /* bottom bits req flags,
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* top bits REQ_OP. Use
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* accessors.
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*/
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unsigned short bi_flags; /* status, etc and bvec pool number */
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unsigned short bi_ioprio;
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unsigned short bi_write_hint;
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blk_status_t bi_status;
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u8 bi_partno;
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atomic_t __bi_remaining;
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struct bvec_iter bi_iter;
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bio_end_io_t *bi_end_io;
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void *bi_private;
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#ifdef CONFIG_BLK_CGROUP
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/*
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* Represents the association of the css and request_queue for the bio.
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* If a bio goes direct to device, it will not have a blkg as it will
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* not have a request_queue associated with it. The reference is put
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* on release of the bio.
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*/
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struct blkcg_gq *bi_blkg;
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struct bio_issue bi_issue;
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#ifdef CONFIG_BLK_CGROUP_IOCOST
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u64 bi_iocost_cost;
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#endif
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#endif
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union {
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#if defined(CONFIG_BLK_DEV_INTEGRITY)
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struct bio_integrity_payload *bi_integrity; /* data integrity */
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#endif
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};
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unsigned short bi_vcnt; /* how many bio_vec's */
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/*
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* Everything starting with bi_max_vecs will be preserved by bio_reset()
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*/
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unsigned short bi_max_vecs; /* max bvl_vecs we can hold */
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atomic_t __bi_cnt; /* pin count */
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struct bio_vec *bi_io_vec; /* the actual vec list */
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struct bio_set *bi_pool;
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/*
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* We can inline a number of vecs at the end of the bio, to avoid
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* double allocations for a small number of bio_vecs. This member
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* MUST obviously be kept at the very end of the bio.
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*/
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struct bio_vec bi_inline_vecs[0];
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};
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#define BIO_RESET_BYTES offsetof(struct bio, bi_max_vecs)
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/*
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* bio flags
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*/
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enum {
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BIO_NO_PAGE_REF, /* don't put release vec pages */
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BIO_CLONED, /* doesn't own data */
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BIO_BOUNCED, /* bio is a bounce bio */
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BIO_USER_MAPPED, /* contains user pages */
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BIO_NULL_MAPPED, /* contains invalid user pages */
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BIO_WORKINGSET, /* contains userspace workingset pages */
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BIO_QUIET, /* Make BIO Quiet */
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BIO_CHAIN, /* chained bio, ->bi_remaining in effect */
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BIO_REFFED, /* bio has elevated ->bi_cnt */
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BIO_THROTTLED, /* This bio has already been subjected to
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* throttling rules. Don't do it again. */
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BIO_TRACE_COMPLETION, /* bio_endio() should trace the final completion
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* of this bio. */
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BIO_QUEUE_ENTERED, /* can use blk_queue_enter_live() */
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BIO_TRACKED, /* set if bio goes through the rq_qos path */
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BIO_FLAG_LAST
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};
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/* See BVEC_POOL_OFFSET below before adding new flags */
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/*
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* We support 6 different bvec pools, the last one is magic in that it
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* is backed by a mempool.
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*/
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#define BVEC_POOL_NR 6
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#define BVEC_POOL_MAX (BVEC_POOL_NR - 1)
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/*
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* Top 3 bits of bio flags indicate the pool the bvecs came from. We add
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* 1 to the actual index so that 0 indicates that there are no bvecs to be
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* freed.
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*/
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#define BVEC_POOL_BITS (3)
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#define BVEC_POOL_OFFSET (16 - BVEC_POOL_BITS)
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#define BVEC_POOL_IDX(bio) ((bio)->bi_flags >> BVEC_POOL_OFFSET)
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#if (1<< BVEC_POOL_BITS) < (BVEC_POOL_NR+1)
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# error "BVEC_POOL_BITS is too small"
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#endif
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/*
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* Flags starting here get preserved by bio_reset() - this includes
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* only BVEC_POOL_IDX()
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*/
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#define BIO_RESET_BITS BVEC_POOL_OFFSET
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typedef __u32 __bitwise blk_mq_req_flags_t;
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/*
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* Operations and flags common to the bio and request structures.
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* We use 8 bits for encoding the operation, and the remaining 24 for flags.
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*
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* The least significant bit of the operation number indicates the data
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* transfer direction:
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*
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* - if the least significant bit is set transfers are TO the device
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* - if the least significant bit is not set transfers are FROM the device
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*
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* If a operation does not transfer data the least significant bit has no
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* meaning.
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*/
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#define REQ_OP_BITS 8
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#define REQ_OP_MASK ((1 << REQ_OP_BITS) - 1)
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#define REQ_FLAG_BITS 24
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enum req_opf {
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/* read sectors from the device */
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REQ_OP_READ = 0,
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/* write sectors to the device */
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REQ_OP_WRITE = 1,
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/* flush the volatile write cache */
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REQ_OP_FLUSH = 2,
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/* discard sectors */
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REQ_OP_DISCARD = 3,
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/* securely erase sectors */
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REQ_OP_SECURE_ERASE = 5,
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/* reset a zone write pointer */
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REQ_OP_ZONE_RESET = 6,
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/* write the same sector many times */
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REQ_OP_WRITE_SAME = 7,
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/* reset all the zone present on the device */
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REQ_OP_ZONE_RESET_ALL = 8,
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/* write the zero filled sector many times */
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REQ_OP_WRITE_ZEROES = 9,
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/* Open a zone */
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REQ_OP_ZONE_OPEN = 10,
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/* Close a zone */
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REQ_OP_ZONE_CLOSE = 11,
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/* Transition a zone to full */
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REQ_OP_ZONE_FINISH = 12,
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/* SCSI passthrough using struct scsi_request */
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REQ_OP_SCSI_IN = 32,
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REQ_OP_SCSI_OUT = 33,
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/* Driver private requests */
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REQ_OP_DRV_IN = 34,
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REQ_OP_DRV_OUT = 35,
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REQ_OP_LAST,
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};
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enum req_flag_bits {
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__REQ_FAILFAST_DEV = /* no driver retries of device errors */
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REQ_OP_BITS,
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__REQ_FAILFAST_TRANSPORT, /* no driver retries of transport errors */
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__REQ_FAILFAST_DRIVER, /* no driver retries of driver errors */
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__REQ_SYNC, /* request is sync (sync write or read) */
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__REQ_META, /* metadata io request */
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__REQ_PRIO, /* boost priority in cfq */
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__REQ_NOMERGE, /* don't touch this for merging */
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__REQ_IDLE, /* anticipate more IO after this one */
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__REQ_INTEGRITY, /* I/O includes block integrity payload */
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__REQ_FUA, /* forced unit access */
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__REQ_PREFLUSH, /* request for cache flush */
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__REQ_RAHEAD, /* read ahead, can fail anytime */
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__REQ_BACKGROUND, /* background IO */
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__REQ_NOWAIT, /* Don't wait if request will block */
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__REQ_NOWAIT_INLINE, /* Return would-block error inline */
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/*
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* When a shared kthread needs to issue a bio for a cgroup, doing
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* so synchronously can lead to priority inversions as the kthread
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* can be trapped waiting for that cgroup. CGROUP_PUNT flag makes
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* submit_bio() punt the actual issuing to a dedicated per-blkcg
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* work item to avoid such priority inversions.
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*/
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__REQ_CGROUP_PUNT,
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/* command specific flags for REQ_OP_WRITE_ZEROES: */
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__REQ_NOUNMAP, /* do not free blocks when zeroing */
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__REQ_HIPRI,
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/* for driver use */
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__REQ_DRV,
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__REQ_SWAP, /* swapping request. */
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__REQ_NR_BITS, /* stops here */
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};
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#define REQ_FAILFAST_DEV (1ULL << __REQ_FAILFAST_DEV)
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#define REQ_FAILFAST_TRANSPORT (1ULL << __REQ_FAILFAST_TRANSPORT)
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#define REQ_FAILFAST_DRIVER (1ULL << __REQ_FAILFAST_DRIVER)
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#define REQ_SYNC (1ULL << __REQ_SYNC)
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#define REQ_META (1ULL << __REQ_META)
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#define REQ_PRIO (1ULL << __REQ_PRIO)
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#define REQ_NOMERGE (1ULL << __REQ_NOMERGE)
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#define REQ_IDLE (1ULL << __REQ_IDLE)
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#define REQ_INTEGRITY (1ULL << __REQ_INTEGRITY)
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#define REQ_FUA (1ULL << __REQ_FUA)
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#define REQ_PREFLUSH (1ULL << __REQ_PREFLUSH)
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#define REQ_RAHEAD (1ULL << __REQ_RAHEAD)
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#define REQ_BACKGROUND (1ULL << __REQ_BACKGROUND)
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#define REQ_NOWAIT (1ULL << __REQ_NOWAIT)
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#define REQ_NOWAIT_INLINE (1ULL << __REQ_NOWAIT_INLINE)
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#define REQ_CGROUP_PUNT (1ULL << __REQ_CGROUP_PUNT)
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#define REQ_NOUNMAP (1ULL << __REQ_NOUNMAP)
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#define REQ_HIPRI (1ULL << __REQ_HIPRI)
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#define REQ_DRV (1ULL << __REQ_DRV)
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#define REQ_SWAP (1ULL << __REQ_SWAP)
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#define REQ_FAILFAST_MASK \
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(REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT | REQ_FAILFAST_DRIVER)
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#define REQ_NOMERGE_FLAGS \
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(REQ_NOMERGE | REQ_PREFLUSH | REQ_FUA)
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enum stat_group {
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STAT_READ,
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STAT_WRITE,
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STAT_DISCARD,
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STAT_FLUSH,
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NR_STAT_GROUPS
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};
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#define bio_op(bio) \
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((bio)->bi_opf & REQ_OP_MASK)
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#define req_op(req) \
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((req)->cmd_flags & REQ_OP_MASK)
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/* obsolete, don't use in new code */
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static inline void bio_set_op_attrs(struct bio *bio, unsigned op,
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unsigned op_flags)
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{
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bio->bi_opf = op | op_flags;
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}
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static inline bool op_is_write(unsigned int op)
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{
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return (op & 1);
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}
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/*
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* Check if the bio or request is one that needs special treatment in the
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* flush state machine.
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*/
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static inline bool op_is_flush(unsigned int op)
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{
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return op & (REQ_FUA | REQ_PREFLUSH);
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}
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/*
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* Reads are always treated as synchronous, as are requests with the FUA or
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* PREFLUSH flag. Other operations may be marked as synchronous using the
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* REQ_SYNC flag.
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*/
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static inline bool op_is_sync(unsigned int op)
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{
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return (op & REQ_OP_MASK) == REQ_OP_READ ||
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(op & (REQ_SYNC | REQ_FUA | REQ_PREFLUSH));
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}
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static inline bool op_is_discard(unsigned int op)
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{
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return (op & REQ_OP_MASK) == REQ_OP_DISCARD;
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}
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/*
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* Check if a bio or request operation is a zone management operation, with
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* the exception of REQ_OP_ZONE_RESET_ALL which is treated as a special case
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* due to its different handling in the block layer and device response in
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* case of command failure.
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*/
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static inline bool op_is_zone_mgmt(enum req_opf op)
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{
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switch (op & REQ_OP_MASK) {
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case REQ_OP_ZONE_RESET:
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case REQ_OP_ZONE_OPEN:
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case REQ_OP_ZONE_CLOSE:
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case REQ_OP_ZONE_FINISH:
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return true;
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default:
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return false;
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}
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}
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static inline int op_stat_group(unsigned int op)
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{
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if (op_is_discard(op))
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return STAT_DISCARD;
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return op_is_write(op);
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}
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typedef unsigned int blk_qc_t;
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#define BLK_QC_T_NONE -1U
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#define BLK_QC_T_EAGAIN -2U
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#define BLK_QC_T_SHIFT 16
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#define BLK_QC_T_INTERNAL (1U << 31)
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static inline bool blk_qc_t_valid(blk_qc_t cookie)
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{
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return cookie != BLK_QC_T_NONE && cookie != BLK_QC_T_EAGAIN;
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}
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static inline unsigned int blk_qc_t_to_queue_num(blk_qc_t cookie)
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{
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return (cookie & ~BLK_QC_T_INTERNAL) >> BLK_QC_T_SHIFT;
|
|
}
|
|
|
|
static inline unsigned int blk_qc_t_to_tag(blk_qc_t cookie)
|
|
{
|
|
return cookie & ((1u << BLK_QC_T_SHIFT) - 1);
|
|
}
|
|
|
|
static inline bool blk_qc_t_is_internal(blk_qc_t cookie)
|
|
{
|
|
return (cookie & BLK_QC_T_INTERNAL) != 0;
|
|
}
|
|
|
|
struct blk_rq_stat {
|
|
u64 mean;
|
|
u64 min;
|
|
u64 max;
|
|
u32 nr_samples;
|
|
u64 batch;
|
|
};
|
|
|
|
#endif /* __LINUX_BLK_TYPES_H */
|