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blk: introduce REQ_SWAP

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Just like REQ_META, it's important to know the IO coming down is swap
in order to guard against potential IO priority inversion issues with
cgroups.  Add REQ_SWAP and use it for all swap IO, and add it to our
bio_issue_as_root_blkg helper.

Signed-off-by: Josef Bacik <jbacik@fb.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Josef Bacik 2018-07-03 11:14:53 -04:00 committed by Jens Axboe
parent 903d23f0a3
commit 0d1e0c7cd5
3 changed files with 4 additions and 3 deletions
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2
include/linux/blk-cgroup.h
View File

@ -254,7 +254,7 @@ static inline struct blkcg *bio_blkcg(struct bio *bio)
*/
static inline bool bio_issue_as_root_blkg(struct bio *bio)
{
return (bio->bi_opf & REQ_META);
return (bio->bi_opf & (REQ_META | REQ_SWAP)) != 0;
}
/**

3
include/linux/blk_types.h
View File

@ -329,7 +329,7 @@ enum req_flag_bits {
/* for driver use */
__REQ_DRV,
__REQ_SWAP, /* swapping request. */
__REQ_NR_BITS, /* stops here */
};
@ -351,6 +351,7 @@ enum req_flag_bits {
#define REQ_NOUNMAP (1ULL << __REQ_NOUNMAP)
#define REQ_DRV (1ULL << __REQ_DRV)
#define REQ_SWAP (1ULL << __REQ_SWAP)
#define REQ_FAILFAST_MASK \
(REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT | REQ_FAILFAST_DRIVER)

2
mm/page_io.c
View File

@ -338,7 +338,7 @@ int __swap_writepage(struct page *page, struct writeback_control *wbc,
ret = -ENOMEM;
goto out;
}
bio->bi_opf = REQ_OP_WRITE | wbc_to_write_flags(wbc);
bio->bi_opf = REQ_OP_WRITE | REQ_SWAP | wbc_to_write_flags(wbc);
count_swpout_vm_event(page);
set_page_writeback(page);
unlock_page(page);