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Commit bddd87c7 authored by Akinobu Mita's avatar Akinobu Mita Committed by Jens Axboe
Browse files

blk-core: use BIO list management functions 



Now that the bio list management stuff is generic, convert
generic_make_request to use bio lists instead of its own private bio
list implementation.

Signed-off-by: default avatarAkinobu Mita <akinobu.mita@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
parent d02f0cff

block/blk-core.c

+14 −17
Original line number Diff line number Diff line
@@ -1490,9 +1490,9 @@ static inline void __generic_make_request(struct bio *bio) 
/*

 * We only want one ->make_request_fn to be active at a time,

 * else stack usage with stacked devices could be a problem.

 * So use current->bio_{list,tail} to keep a list of requests

 * So use current->bio_list to keep a list of requests

 * submited by a make_request_fn function.

 * current->bio_tail is also used as a flag to say if

 * current->bio_list is also used as a flag to say if

 * generic_make_request is currently active in this task or not.

 * If it is NULL, then no make_request is active.  If it is non-NULL,

 * then a make_request is active, and new requests should be added
@@ -1500,11 +1500,11 @@ static inline void __generic_make_request(struct bio *bio) 
 */

void generic_make_request(struct bio *bio)

{

	if (current->bio_tail) {

	struct bio_list bio_list_on_stack;



	if (current->bio_list) {

		/* make_request is active */

		*(current->bio_tail) = bio;

		bio->bi_next = NULL;

		current->bio_tail = &bio->bi_next;

		bio_list_add(current->bio_list, bio);

		return;

	}

	/* following loop may be a bit non-obvious, and so deserves some
@@ -1512,30 +1512,27 @@ void generic_make_request(struct bio *bio) 
	 * Before entering the loop, bio->bi_next is NULL (as all callers

	 * ensure that) so we have a list with a single bio.

	 * We pretend that we have just taken it off a longer list, so

	 * we assign bio_list to the next (which is NULL) and bio_tail

	 * to &bio_list, thus initialising the bio_list of new bios to be

	 * we assign bio_list to a pointer to the bio_list_on_stack,

	 * thus initialising the bio_list of new bios to be

	 * added.  __generic_make_request may indeed add some more bios

	 * through a recursive call to generic_make_request.  If it

	 * did, we find a non-NULL value in bio_list and re-enter the loop

	 * from the top.  In this case we really did just take the bio

	 * of the top of the list (no pretending) and so fixup bio_list and

	 * bio_tail or bi_next, and call into __generic_make_request again.

	 * of the top of the list (no pretending) and so remove it from

	 * bio_list, and call into __generic_make_request again.

	 *

	 * The loop was structured like this to make only one call to

	 * __generic_make_request (which is important as it is large and

	 * inlined) and to keep the structure simple.

	 */

	BUG_ON(bio->bi_next);

	bio_list_init(&bio_list_on_stack);

	current->bio_list = &bio_list_on_stack;

	do {

		current->bio_list = bio->bi_next;

		if (bio->bi_next == NULL)

			current->bio_tail = &current->bio_list;

		else

			bio->bi_next = NULL;

		__generic_make_request(bio);

		bio = current->bio_list;

		bio = bio_list_pop(current->bio_list);

	} while (bio);

	current->bio_tail = NULL; /* deactivate */

	current->bio_list = NULL; /* deactivate */

}

EXPORT_SYMBOL(generic_make_request);

include/linux/sched.h

+2 −2
Original line number Diff line number Diff line
@@ -97,7 +97,7 @@ struct sched_param { 
struct exec_domain;

struct futex_pi_state;

struct robust_list_head;

struct bio;

struct bio_list;

struct fs_struct;

struct bts_context;

struct perf_event_context;
@@ -1466,7 +1466,7 @@ struct task_struct { 
	void *journal_info;



/* stacked block device info */

	struct bio *bio_list, **bio_tail;

	struct bio_list *bio_list;



/* VM state */

	struct reclaim_state *reclaim_state;