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authorDmitry Torokhov <dmitry.torokhov@gmail.com>2007-10-12 21:27:47 -0400
committerDmitry Torokhov <dmitry.torokhov@gmail.com>2007-10-12 21:27:47 -0400
commitb981d8b3f5e008ff10d993be633ad00564fc22cd (patch)
treee292dc07b22308912cf6a58354a608b9e5e8e1fd /Documentation/block/biodoc.txt
parentb11d2127c4893a7315d1e16273bc8560049fa3ca (diff)
parent2b9e0aae1d50e880c58d46788e5e3ebd89d75d62 (diff)
Merge master.kernel.org:/pub/scm/linux/kernel/git/torvalds/linux-2.6
Conflicts: drivers/macintosh/adbhid.c
Diffstat (limited to 'Documentation/block/biodoc.txt')
-rw-r--r--Documentation/block/biodoc.txt30
1 files changed, 15 insertions, 15 deletions
diff --git a/Documentation/block/biodoc.txt b/Documentation/block/biodoc.txt
index 3adaace328a..dc3f49e3e53 100644
--- a/Documentation/block/biodoc.txt
+++ b/Documentation/block/biodoc.txt
@@ -477,9 +477,9 @@ With this multipage bio design:
the same bi_io_vec array, but with the index and size accordingly modified)
- A linked list of bios is used as before for unrelated merges (*) - this
avoids reallocs and makes independent completions easier to handle.
-- Code that traverses the req list needs to make a distinction between
- segments of a request (bio_for_each_segment) and the distinct completion
- units/bios (rq_for_each_bio).
+- 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
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)
@@ -664,14 +664,14 @@ in lvm or md.
3.2.1 Traversing segments and completion units in a request
-The macros bio_for_each_segment() and rq_for_each_bio() should be used for
-traversing the bios in the request list (drivers should avoid directly
-trying to do it themselves). Using these helpers should also make it easier
-to cope with block changes in the future.
+The macro rq_for_each_segment() should be used for traversing the bios
+in the request list (drivers should avoid directly trying to do it
+themselves). Using these helpers should also make it easier to cope
+with block changes in the future.
- rq_for_each_bio(bio, rq)
- bio_for_each_segment(bio_vec, bio, i)
- /* bio_vec is now current segment */
+ struct req_iterator iter;
+ rq_for_each_segment(bio_vec, rq, iter)
+ /* bio_vec is now current segment */
I/O completion callbacks are per-bio rather than per-segment, so drivers
that traverse bio chains on completion need to keep that in mind. Drivers
@@ -740,12 +740,12 @@ Block now offers some simple generic functionality to help support command
queueing (typically known as tagged command queueing), ie manage more than
one outstanding command on a queue at any given time.
- blk_queue_init_tags(request_queue_t *q, int depth)
+ blk_queue_init_tags(struct request_queue *q, int depth)
Initialize internal command tagging structures for a maximum
depth of 'depth'.
- blk_queue_free_tags((request_queue_t *q)
+ blk_queue_free_tags((struct request_queue *q)
Teardown tag info associated with the queue. This will be done
automatically by block if blk_queue_cleanup() is called on a queue
@@ -754,7 +754,7 @@ one outstanding command on a queue at any given time.
The above are initialization and exit management, the main helpers during
normal operations are:
- blk_queue_start_tag(request_queue_t *q, struct request *rq)
+ blk_queue_start_tag(struct request_queue *q, struct request *rq)
Start tagged operation for this request. A free tag number between
0 and 'depth' is assigned to the request (rq->tag holds this number),
@@ -762,7 +762,7 @@ normal operations are:
for this queue is already achieved (or if the tag wasn't started for
some other reason), 1 is returned. Otherwise 0 is returned.
- blk_queue_end_tag(request_queue_t *q, struct request *rq)
+ blk_queue_end_tag(struct request_queue *q, struct request *rq)
End tagged operation on this request. 'rq' is removed from the internal
book keeping structures.
@@ -781,7 +781,7 @@ queue. For instance, on IDE any tagged request error needs to clear both
the hardware and software block queue and enable the driver to sanely restart
all the outstanding requests. There's a third helper to do that:
- blk_queue_invalidate_tags(request_queue_t *q)
+ blk_queue_invalidate_tags(struct request_queue *q)
Clear the internal block tag queue and re-add all the pending requests
to the request queue. The driver will receive them again on the