diff options
author | Linus Torvalds <torvalds@linux-foundation.org> | 2014-01-30 11:19:05 -0800 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-01-30 11:19:05 -0800 |
commit | f568849edac8611d603e00bd6cbbcfea09395ae6 (patch) | |
tree | b9472d640fe5d87426d38c9d81d946cf197ad3fb /Documentation/block/biodoc.txt | |
parent | d9894c228b11273e720bb63ba120d1d326fe9d94 (diff) | |
parent | 675675ada486dde5bf9aa51665e90706bff11a35 (diff) |
Merge branch 'for-3.14/core' of git://git.kernel.dk/linux-block
Pull core block IO changes from Jens Axboe:
"The major piece in here is the immutable bio_ve series from Kent, the
rest is fairly minor. It was supposed to go in last round, but
various issues pushed it to this release instead. The pull request
contains:
- Various smaller blk-mq fixes from different folks. Nothing major
here, just minor fixes and cleanups.
- Fix for a memory leak in the error path in the block ioctl code
from Christian Engelmayer.
- Header export fix from CaiZhiyong.
- Finally the immutable biovec changes from Kent Overstreet. This
enables some nice future work on making arbitrarily sized bios
possible, and splitting more efficient. Related fixes to immutable
bio_vecs:
- dm-cache immutable fixup from Mike Snitzer.
- btrfs immutable fixup from Muthu Kumar.
- bio-integrity fix from Nic Bellinger, which is also going to stable"
* 'for-3.14/core' of git://git.kernel.dk/linux-block: (44 commits)
xtensa: fixup simdisk driver to work with immutable bio_vecs
block/blk-mq-cpu.c: use hotcpu_notifier()
blk-mq: for_each_* macro correctness
block: Fix memory leak in rw_copy_check_uvector() handling
bio-integrity: Fix bio_integrity_verify segment start bug
block: remove unrelated header files and export symbol
blk-mq: uses page->list incorrectly
blk-mq: use __smp_call_function_single directly
btrfs: fix missing increment of bi_remaining
Revert "block: Warn and free bio if bi_end_io is not set"
block: Warn and free bio if bi_end_io is not set
blk-mq: fix initializing request's start time
block: blk-mq: don't export blk_mq_free_queue()
block: blk-mq: make blk_sync_queue support mq
block: blk-mq: support draining mq queue
dm cache: increment bi_remaining when bi_end_io is restored
block: fixup for generic bio chaining
block: Really silence spurious compiler warnings
block: Silence spurious compiler warnings
block: Kill bio_pair_split()
...
Diffstat (limited to 'Documentation/block/biodoc.txt')
-rw-r--r-- | Documentation/block/biodoc.txt | 7 |
1 files changed, 3 insertions, 4 deletions
diff --git a/Documentation/block/biodoc.txt b/Documentation/block/biodoc.txt index 8df5e8e6dceb..2101e718670d 100644 --- a/Documentation/block/biodoc.txt +++ b/Documentation/block/biodoc.txt @@ -447,14 +447,13 @@ struct bio_vec { * main unit of I/O for the block layer and lower layers (ie drivers) */ struct bio { - sector_t bi_sector; struct bio *bi_next; /* request queue link */ struct block_device *bi_bdev; /* target device */ unsigned long bi_flags; /* status, command, etc */ unsigned long bi_rw; /* low bits: r/w, high: priority */ unsigned int bi_vcnt; /* how may bio_vec's */ - unsigned int bi_idx; /* current index into bio_vec array */ + struct bvec_iter bi_iter; /* current index into bio_vec array */ unsigned int bi_size; /* total size in bytes */ unsigned short bi_phys_segments; /* segments after physaddr coalesce*/ @@ -480,7 +479,7 @@ With this multipage bio design: - Code that traverses the req list can find all the segments of a bio by using rq_for_each_segment. This handles the fact that a request has multiple bios, each of which can have multiple segments. -- Drivers which can't process a large bio in one shot can use the bi_idx +- Drivers which can't process a large bio in one shot can use the bi_iter field to keep track of the next bio_vec entry to process. (e.g a 1MB bio_vec needs to be handled in max 128kB chunks for IDE) [TBD: Should preferably also have a bi_voffset and bi_vlen to avoid modifying @@ -589,7 +588,7 @@ driver should not modify these values. The block layer sets up the nr_sectors and current_nr_sectors fields (based on the corresponding hard_xxx values and the number of bytes transferred) and updates it on every transfer that invokes end_that_request_first. It does the same for the -buffer, bio, bio->bi_idx fields too. +buffer, bio, bio->bi_iter fields too. The buffer field is just a virtual address mapping of the current segment of the i/o buffer in cases where the buffer resides in low-memory. For high |