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block: kill swap_io_context() 

It blindly copies everything in the io_context, including the lock.
That doesn't work so well for either lock ordering or lockdep.

There seems zero point in swapping io contexts on a request to request
merge, so the best point of action is to just remove it.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This commit is contained in:
Jens Axboe 2008-02-01 11:34:49 +01:00
parent 8bdd3f8a69
commit 3bc217ffe6
3 changed files with 0 additions and 24 deletions
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14
block/as-iosched.c
View File

@ -1268,22 +1268,8 @@ static void as_merged_requests(struct request_queue *q, struct request *req,
*/
if (!list_empty(&req->queuelist) && !list_empty(&next->queuelist)) {
if (time_before(rq_fifo_time(next), rq_fifo_time(req))) {
struct io_context *rioc = RQ_IOC(req);
struct io_context *nioc = RQ_IOC(next);
list_move(&req->queuelist, &next->queuelist);
rq_set_fifo_time(req, rq_fifo_time(next));
/*
* Don't copy here but swap, because when anext is
* removed below, it must contain the unused context
*/
if (rioc != nioc) {
double_spin_lock(&rioc->lock, &nioc->lock,
rioc < nioc);
swap_io_context(&rioc, &nioc);
double_spin_unlock(&rioc->lock, &nioc->lock,
rioc < nioc);
}
}
}

9
block/blk-ioc.c
View File

@ -176,15 +176,6 @@ void copy_io_context(struct io_context **pdst, struct io_context **psrc)
}
EXPORT_SYMBOL(copy_io_context);
void swap_io_context(struct io_context **ioc1, struct io_context **ioc2)
{
struct io_context *temp;
temp = *ioc1;
*ioc1 = *ioc2;
*ioc2 = temp;
}
EXPORT_SYMBOL(swap_io_context);
int __init blk_ioc_init(void)
{
iocontext_cachep = kmem_cache_create("blkdev_ioc",

1
include/linux/blkdev.h
View File

@ -39,7 +39,6 @@ void exit_io_context(void);
struct io_context *get_io_context(gfp_t gfp_flags, int node);
struct io_context *alloc_io_context(gfp_t gfp_flags, int node);
void copy_io_context(struct io_context **pdst, struct io_context **psrc);
void swap_io_context(struct io_context **ioc1, struct io_context **ioc2);
struct request;
typedef void (rq_end_io_fn)(struct request *, int);