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authorLinus Torvalds <torvalds@linux-foundation.org>2014-01-30 11:19:05 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2014-01-30 11:19:05 -0800
commitf568849edac8611d603e00bd6cbbcfea09395ae6 (patch)
treeb9472d640fe5d87426d38c9d81d946cf197ad3fb /Documentation/block/biodoc.txt
parentd9894c228b11273e720bb63ba120d1d326fe9d94 (diff)
parent675675ada486dde5bf9aa51665e90706bff11a35 (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.txt7
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