diff options
Diffstat (limited to 'block/blk-core.c')
| -rw-r--r-- | block/blk-core.c | 95 |
1 files changed, 49 insertions, 46 deletions
diff --git a/block/blk-core.c b/block/blk-core.c index f58e019..684d7eb 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -1412,31 +1412,8 @@ static inline int bio_check_eod(struct bio *bio, unsigned int nr_sectors) return 0; } -/** - * generic_make_request - hand a buffer to its device driver for I/O - * @bio: The bio describing the location in memory and on the device. - * - * generic_make_request() is used to make I/O requests of block - * devices. It is passed a &struct bio, which describes the I/O that needs - * to be done. - * - * generic_make_request() does not return any status. The - * success/failure status of the request, along with notification of - * completion, is delivered asynchronously through the bio->bi_end_io - * function described (one day) else where. - * - * The caller of generic_make_request must make sure that bi_io_vec - * are set to describe the memory buffer, and that bi_dev and bi_sector are - * set to describe the device address, and the - * bi_end_io and optionally bi_private are set to describe how - * completion notification should be signaled. - * - * generic_make_request and the drivers it calls may use bi_next if this - * bio happens to be merged with someone else, and may change bi_dev and - * bi_sector for remaps as it sees fit. So the values of these fields - * should NOT be depended on after the call to generic_make_request. - */ -static inline void __generic_make_request(struct bio *bio) +static noinline_for_stack bool +generic_make_request_checks(struct bio *bio) { struct request_queue *q; int nr_sectors = bio_sectors(bio); @@ -1515,35 +1492,62 @@ static inline void __generic_make_request(struct bio *bio) /* if bio = NULL, bio has been throttled and will be submitted later. */ if (!bio) - return; + return false; + trace_block_bio_queue(q, bio); - q->make_request_fn(q, bio); - return; + return true; end_io: bio_endio(bio, err); + return false; } -/* - * 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 to keep a list of requests - * submited by a make_request_fn function. - * 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 - * at the tail +/** + * generic_make_request - hand a buffer to its device driver for I/O + * @bio: The bio describing the location in memory and on the device. + * + * generic_make_request() is used to make I/O requests of block + * devices. It is passed a &struct bio, which describes the I/O that needs + * to be done. + * + * generic_make_request() does not return any status. The + * success/failure status of the request, along with notification of + * completion, is delivered asynchronously through the bio->bi_end_io + * function described (one day) else where. + * + * The caller of generic_make_request must make sure that bi_io_vec + * are set to describe the memory buffer, and that bi_dev and bi_sector are + * set to describe the device address, and the + * bi_end_io and optionally bi_private are set to describe how + * completion notification should be signaled. + * + * generic_make_request and the drivers it calls may use bi_next if this + * bio happens to be merged with someone else, and may resubmit the bio to + * a lower device by calling into generic_make_request recursively, which + * means the bio should NOT be touched after the call to ->make_request_fn. */ void generic_make_request(struct bio *bio) { struct bio_list bio_list_on_stack; + if (!generic_make_request_checks(bio)) + return; + + /* + * 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 to keep a list of requests submited by a + * make_request_fn function. 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 at the tail + */ if (current->bio_list) { - /* make_request is active */ bio_list_add(current->bio_list, bio); return; } + /* following loop may be a bit non-obvious, and so deserves some * explanation. * Before entering the loop, bio->bi_next is NULL (as all callers @@ -1551,22 +1555,21 @@ void generic_make_request(struct bio *bio) * We pretend that we have just taken it off a longer list, so * 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 + * added. ->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 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. + * bio_list, and call into ->make_request() again. */ BUG_ON(bio->bi_next); bio_list_init(&bio_list_on_stack); current->bio_list = &bio_list_on_stack; do { - __generic_make_request(bio); + struct request_queue *q = bdev_get_queue(bio->bi_bdev); + + q->make_request_fn(q, bio); + bio = bio_list_pop(current->bio_list); } while (bio); current->bio_list = NULL; /* deactivate */ |
