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![Tejun Heo](/assets/img/avatar_default.png)
Now that the backend conversion is complete, export sequenced FLUSH/FUA capability through REQ_FLUSH/FUA flags. REQ_FLUSH means the device cache should be flushed before executing the request. REQ_FUA means that the data in the request should be on non-volatile media on completion. Block layer will choose the correct way of implementing the semantics and execute it. The request may be passed to the device directly if the device can handle it; otherwise, it will be sequenced using one or more proxy requests. Devices will never see REQ_FLUSH and/or FUA which it doesn't support. Also, unlike the original REQ_HARDBARRIER, REQ_FLUSH/FUA requests are never failed with -EOPNOTSUPP. If the underlying device doesn't support FLUSH/FUA, the block layer simply make those noop. IOW, it no longer distinguishes between writeback cache which doesn't support cache flush and writethrough/no cache. Devices which have WB cache w/o flush are very difficult to come by these days and there's nothing much we can do anyway, so it doesn't make sense to require everyone to implement -EOPNOTSUPP handling. This will simplify filesystems and block drivers as they can drop -EOPNOTSUPP retry logic for barriers. * QUEUE_ORDERED_* are removed and QUEUE_FSEQ_* are moved into blk-flush.c. * REQ_FLUSH w/o data can also be directly passed to drivers without sequencing but some drivers assume that zero length requests don't have rq->bio which isn't true for these requests requiring the use of proxy requests. * REQ_COMMON_MASK now includes REQ_FLUSH | REQ_FUA so that they are copied from bio to request. * WRITE_BARRIER is marked deprecated and WRITE_FLUSH, WRITE_FUA and WRITE_FLUSH_FUA are added. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Christoph Hellwig <hch@infradead.org> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
194 lines
6.5 KiB
C
194 lines
6.5 KiB
C
/*
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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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#ifdef CONFIG_BLOCK
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#include <linux/types.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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typedef void (bio_end_io_t) (struct bio *, int);
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typedef void (bio_destructor_t) (struct bio *);
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/*
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* was unsigned short, but we might as well be ready for > 64kB I/O pages
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*/
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struct bio_vec {
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struct page *bv_page;
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unsigned int bv_len;
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unsigned int bv_offset;
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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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sector_t bi_sector; /* device address in 512 byte
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sectors */
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struct bio *bi_next; /* request queue link */
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struct block_device *bi_bdev;
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unsigned long bi_flags; /* status, command, etc */
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unsigned long bi_rw; /* bottom bits READ/WRITE,
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* top bits priority
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*/
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unsigned short bi_vcnt; /* how many bio_vec's */
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unsigned short bi_idx; /* current index into bvl_vec */
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/* Number of segments in this BIO after
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* physical address coalescing is performed.
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*/
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unsigned int bi_phys_segments;
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unsigned int bi_size; /* residual I/O count */
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/*
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* To keep track of the max segment size, we account for the
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* sizes of the first and last mergeable segments in this bio.
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*/
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unsigned int bi_seg_front_size;
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unsigned int bi_seg_back_size;
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unsigned int bi_max_vecs; /* max bvl_vecs we can hold */
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unsigned int bi_comp_cpu; /* completion CPU */
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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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bio_end_io_t *bi_end_io;
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void *bi_private;
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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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bio_destructor_t *bi_destructor; /* destructor */
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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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/*
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* bio flags
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*/
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#define BIO_UPTODATE 0 /* ok after I/O completion */
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#define BIO_RW_BLOCK 1 /* RW_AHEAD set, and read/write would block */
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#define BIO_EOF 2 /* out-out-bounds error */
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#define BIO_SEG_VALID 3 /* bi_phys_segments valid */
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#define BIO_CLONED 4 /* doesn't own data */
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#define BIO_BOUNCED 5 /* bio is a bounce bio */
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#define BIO_USER_MAPPED 6 /* contains user pages */
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#define BIO_EOPNOTSUPP 7 /* not supported */
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#define BIO_CPU_AFFINE 8 /* complete bio on same CPU as submitted */
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#define BIO_NULL_MAPPED 9 /* contains invalid user pages */
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#define BIO_FS_INTEGRITY 10 /* fs owns integrity data, not block layer */
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#define BIO_QUIET 11 /* Make BIO Quiet */
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#define bio_flagged(bio, flag) ((bio)->bi_flags & (1 << (flag)))
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/*
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* top 4 bits of bio flags indicate the pool this bio came from
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*/
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#define BIO_POOL_BITS (4)
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#define BIO_POOL_NONE ((1UL << BIO_POOL_BITS) - 1)
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#define BIO_POOL_OFFSET (BITS_PER_LONG - BIO_POOL_BITS)
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#define BIO_POOL_MASK (1UL << BIO_POOL_OFFSET)
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#define BIO_POOL_IDX(bio) ((bio)->bi_flags >> BIO_POOL_OFFSET)
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#endif /* CONFIG_BLOCK */
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/*
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* Request flags. For use in the cmd_flags field of struct request, and in
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* bi_rw of struct bio. Note that some flags are only valid in either one.
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*/
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enum rq_flag_bits {
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/* common flags */
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__REQ_WRITE, /* not set, read. set, write */
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__REQ_FAILFAST_DEV, /* no driver retries of device errors */
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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_HARDBARRIER, /* may not be passed by drive either */
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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_DISCARD, /* request to discard sectors */
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__REQ_NOIDLE, /* don't anticipate more IO after this one */
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/* bio only flags */
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__REQ_UNPLUG, /* unplug the immediately after submission */
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__REQ_RAHEAD, /* read ahead, can fail anytime */
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/* request only flags */
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__REQ_SORTED, /* elevator knows about this request */
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__REQ_SOFTBARRIER, /* may not be passed by ioscheduler */
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__REQ_FUA, /* forced unit access */
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__REQ_NOMERGE, /* don't touch this for merging */
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__REQ_STARTED, /* drive already may have started this one */
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__REQ_DONTPREP, /* don't call prep for this one */
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__REQ_QUEUED, /* uses queueing */
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__REQ_ELVPRIV, /* elevator private data attached */
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__REQ_FAILED, /* set if the request failed */
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__REQ_QUIET, /* don't worry about errors */
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__REQ_PREEMPT, /* set for "ide_preempt" requests */
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__REQ_ALLOCED, /* request came from our alloc pool */
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__REQ_COPY_USER, /* contains copies of user pages */
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__REQ_INTEGRITY, /* integrity metadata has been remapped */
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__REQ_FLUSH, /* request for cache flush */
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__REQ_IO_STAT, /* account I/O stat */
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__REQ_MIXED_MERGE, /* merge of different types, fail separately */
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__REQ_SECURE, /* secure discard (used with __REQ_DISCARD) */
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__REQ_NR_BITS, /* stops here */
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};
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#define REQ_WRITE (1 << __REQ_WRITE)
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#define REQ_FAILFAST_DEV (1 << __REQ_FAILFAST_DEV)
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#define REQ_FAILFAST_TRANSPORT (1 << __REQ_FAILFAST_TRANSPORT)
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#define REQ_FAILFAST_DRIVER (1 << __REQ_FAILFAST_DRIVER)
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#define REQ_HARDBARRIER (1 << __REQ_HARDBARRIER)
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#define REQ_SYNC (1 << __REQ_SYNC)
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#define REQ_META (1 << __REQ_META)
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#define REQ_DISCARD (1 << __REQ_DISCARD)
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#define REQ_NOIDLE (1 << __REQ_NOIDLE)
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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_COMMON_MASK \
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(REQ_WRITE | REQ_FAILFAST_MASK | REQ_HARDBARRIER | REQ_SYNC | \
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REQ_META | REQ_DISCARD | REQ_NOIDLE | REQ_FLUSH | REQ_FUA)
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#define REQ_UNPLUG (1 << __REQ_UNPLUG)
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#define REQ_RAHEAD (1 << __REQ_RAHEAD)
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#define REQ_SORTED (1 << __REQ_SORTED)
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#define REQ_SOFTBARRIER (1 << __REQ_SOFTBARRIER)
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#define REQ_FUA (1 << __REQ_FUA)
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#define REQ_NOMERGE (1 << __REQ_NOMERGE)
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#define REQ_STARTED (1 << __REQ_STARTED)
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#define REQ_DONTPREP (1 << __REQ_DONTPREP)
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#define REQ_QUEUED (1 << __REQ_QUEUED)
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#define REQ_ELVPRIV (1 << __REQ_ELVPRIV)
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#define REQ_FAILED (1 << __REQ_FAILED)
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#define REQ_QUIET (1 << __REQ_QUIET)
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#define REQ_PREEMPT (1 << __REQ_PREEMPT)
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#define REQ_ALLOCED (1 << __REQ_ALLOCED)
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#define REQ_COPY_USER (1 << __REQ_COPY_USER)
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#define REQ_INTEGRITY (1 << __REQ_INTEGRITY)
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#define REQ_FLUSH (1 << __REQ_FLUSH)
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#define REQ_IO_STAT (1 << __REQ_IO_STAT)
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#define REQ_MIXED_MERGE (1 << __REQ_MIXED_MERGE)
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#define REQ_SECURE (1 << __REQ_SECURE)
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#endif /* __LINUX_BLK_TYPES_H */
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