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dm: put all polled dm_io instances into a single list

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Now that bio_split() isn't used by DM's bio splitting, it is a bit
overkill to link dm_io into an hlist given there is only single dm_io
in the list.

Convert to using a single list for holding all dm_io instances
associated with this bio.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
This commit is contained in:
Ming Lei 2022-04-12 16:56:16 +08:00 committed by Mike Snitzer
parent 0f14d60a02
commit ec211631ae
2 changed files with 28 additions and 26 deletions
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2
drivers/md/dm-core.h
View file

@ -259,7 +259,7 @@ struct dm_io {
spinlock_t lock;
unsigned long start_time;
void *data;
struct hlist_node node;
struct dm_io *next;
struct task_struct *map_task;
struct dm_stats_aux stats_aux;

52
drivers/md/dm.c
View file

@ -1559,7 +1559,7 @@ static bool __process_abnormal_io(struct clone_info *ci, struct dm_target *ti,
}
/*
* Reuse ->bi_private as hlist head for storing all dm_io instances
* Reuse ->bi_private as dm_io list head for storing all dm_io instances
* associated with this bio, and this bio's bi_private needs to be
* stored in dm_io->data before the reuse.
*
@ -1567,36 +1567,37 @@ static bool __process_abnormal_io(struct clone_info *ci, struct dm_target *ti,
* touch it after splitting. Meantime it won't be changed by anyone after
* bio is submitted. So this reuse is safe.
*/
static inline struct hlist_head *dm_get_bio_hlist_head(struct bio *bio)
static inline struct dm_io **dm_poll_list_head(struct bio *bio)
{
return (struct hlist_head *)&bio->bi_private;
return (struct dm_io **)&bio->bi_private;
}
static void dm_queue_poll_io(struct bio *bio, struct dm_io *io)
{
struct hlist_head *head = dm_get_bio_hlist_head(bio);
struct dm_io **head = dm_poll_list_head(bio);
if (!(bio->bi_opf & REQ_DM_POLL_LIST)) {
bio->bi_opf |= REQ_DM_POLL_LIST;
/*
* Save .bi_private into dm_io, so that we can reuse
* .bi_private as hlist head for storing dm_io list
* .bi_private as dm_io list head for storing dm_io list
*/
io->data = bio->bi_private;
INIT_HLIST_HEAD(head);
/* tell block layer to poll for completion */
bio->bi_cookie = ~BLK_QC_T_NONE;
io->next = NULL;
} else {
/*
* bio recursed due to split, reuse original poll list,
* and save bio->bi_private too.
*/
io->data = hlist_entry(head->first, struct dm_io, node)->data;
io->data = (*head)->data;
io->next = *head;
}
hlist_add_head(&io->node, head);
*head = io;
}
/*
@ -1685,8 +1686,8 @@ static void dm_split_and_process_bio(struct mapped_device *md,
* Drop the extra reference count for non-POLLED bio, and hold one
* reference for POLLED bio, which will be released in dm_poll_bio
*
* Add every dm_io instance into the hlist_head which is stored in
* bio->bi_private, so that dm_poll_bio can poll them all.
* Add every dm_io instance into the dm_io list head which is stored
* in bio->bi_private, so that dm_poll_bio can poll them all.
*/
if (error || !ci.submit_as_polled) {
/*
@ -1748,18 +1749,16 @@ static bool dm_poll_dm_io(struct dm_io *io, struct io_comp_batch *iob,
static int dm_poll_bio(struct bio *bio, struct io_comp_batch *iob,
unsigned int flags)
{
struct hlist_head *head = dm_get_bio_hlist_head(bio);
struct hlist_head tmp = HLIST_HEAD_INIT;
struct hlist_node *next;
struct dm_io *io;
struct dm_io **head = dm_poll_list_head(bio);
struct dm_io *list = *head;
struct dm_io *tmp = NULL;
struct dm_io *curr, *next;
/* Only poll normal bio which was marked as REQ_DM_POLL_LIST */
if (!(bio->bi_opf & REQ_DM_POLL_LIST))
return 0;
WARN_ON_ONCE(hlist_empty(head));
hlist_move_list(head, &tmp);
WARN_ON_ONCE(!list);
/*
* Restore .bi_private before possibly completing dm_io.
@ -1770,24 +1769,27 @@ static int dm_poll_bio(struct bio *bio, struct io_comp_batch *iob,
* clearing REQ_DM_POLL_LIST here.
*/
bio->bi_opf &= ~REQ_DM_POLL_LIST;
bio->bi_private = hlist_entry(tmp.first, struct dm_io, node)->data;
bio->bi_private = list->data;
hlist_for_each_entry_safe(io, next, &tmp, node) {
if (dm_poll_dm_io(io, iob, flags)) {
hlist_del_init(&io->node);
for (curr = list, next = curr->next; curr; curr = next, next =
curr ? curr->next : NULL) {
if (dm_poll_dm_io(curr, iob, flags)) {
/*
* clone_endio() has already occurred, so no
* error handling is needed here.
*/
__dm_io_dec_pending(io);
__dm_io_dec_pending(curr);
} else {
curr->next = tmp;
tmp = curr;
}
}
/* Not done? */
if (!hlist_empty(&tmp)) {
if (tmp) {
bio->bi_opf |= REQ_DM_POLL_LIST;
/* Reset bio->bi_private to dm_io list head */
hlist_move_list(&tmp, head);
*head = tmp;
return 0;
}
return 1;