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md/raid1: improve handling of pages allocated for write-behind.

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The current handling and freeing of these pages is a bit fragile.
We only keep the list of allocated pages in each bio, so we need to
still have a valid bio when freeing the pages, which is a bit clumsy.

So simply store the allocated page list in the r1_bio so it can easily
be found and freed when we are finished with the r1_bio.

Signed-off-by: NeilBrown <neilb@suse.de>
This commit is contained in:
NeilBrown 2011-05-11 14:51:19 +10:00
parent 7ca78d57d1
commit af6d7b760c
2 changed files with 29 additions and 30 deletions
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55
drivers/md/raid1.c
View File

@ -297,23 +297,24 @@ static void raid1_end_read_request(struct bio *bio, int error)
rdev_dec_pending(conf->mirrors[mirror].rdev, conf->mddev);
}
static void r1_bio_write_done(r1bio_t *r1_bio, int vcnt, struct bio_vec *bv,
int behind)
static void r1_bio_write_done(r1bio_t *r1_bio)
{
if (atomic_dec_and_test(&r1_bio->remaining))
{
/* it really is the end of this request */
if (test_bit(R1BIO_BehindIO, &r1_bio->state)) {
/* free extra copy of the data pages */
int i = vcnt;
int i = r1_bio->behind_page_count;
while (i--)
safe_put_page(bv[i].bv_page);
safe_put_page(r1_bio->behind_pages[i]);
kfree(r1_bio->behind_pages);
r1_bio->behind_pages = NULL;
}
/* clear the bitmap if all writes complete successfully */
bitmap_endwrite(r1_bio->mddev->bitmap, r1_bio->sector,
r1_bio->sectors,
!test_bit(R1BIO_Degraded, &r1_bio->state),
behind);
test_bit(R1BIO_BehindIO, &r1_bio->state));
md_write_end(r1_bio->mddev);
raid_end_bio_io(r1_bio);
}
@ -386,7 +387,7 @@ static void raid1_end_write_request(struct bio *bio, int error)
* Let's see if all mirrored write operations have finished
* already.
*/
r1_bio_write_done(r1_bio, bio->bi_vcnt, bio->bi_io_vec, behind);
r1_bio_write_done(r1_bio);
if (to_put)
bio_put(to_put);
@ -660,37 +661,36 @@ static void unfreeze_array(conf_t *conf)
/* duplicate the data pages for behind I/O
* We return a list of bio_vec rather than just page pointers
* as it makes freeing easier
*/
static struct bio_vec *alloc_behind_pages(struct bio *bio)
static void alloc_behind_pages(struct bio *bio, r1bio_t *r1_bio)
{
int i;
struct bio_vec *bvec;
struct bio_vec *pages = kzalloc(bio->bi_vcnt * sizeof(struct bio_vec),
struct page **pages = kzalloc(bio->bi_vcnt * sizeof(struct page*),
GFP_NOIO);
if (unlikely(!pages))
goto do_sync_io;
return;
bio_for_each_segment(bvec, bio, i) {
pages[i].bv_page = alloc_page(GFP_NOIO);
if (unlikely(!pages[i].bv_page))
pages[i] = alloc_page(GFP_NOIO);
if (unlikely(!pages[i]))
goto do_sync_io;
memcpy(kmap(pages[i].bv_page) + bvec->bv_offset,
memcpy(kmap(pages[i]) + bvec->bv_offset,
kmap(bvec->bv_page) + bvec->bv_offset, bvec->bv_len);
kunmap(pages[i].bv_page);
kunmap(pages[i]);
kunmap(bvec->bv_page);
}
return pages;
r1_bio->behind_pages = pages;
r1_bio->behind_page_count = bio->bi_vcnt;
set_bit(R1BIO_BehindIO, &r1_bio->state);
return;
do_sync_io:
if (pages)
for (i = 0; i < bio->bi_vcnt && pages[i].bv_page; i++)
put_page(pages[i].bv_page);
for (i = 0; i < bio->bi_vcnt; i++)
if (pages[i])
put_page(pages[i]);
kfree(pages);
PRINTK("%dB behind alloc failed, doing sync I/O\n", bio->bi_size);
return NULL;
}
static int make_request(mddev_t *mddev, struct bio * bio)
@ -702,7 +702,6 @@ static int make_request(mddev_t *mddev, struct bio * bio)
int i, targets = 0, disks;
struct bitmap *bitmap;
unsigned long flags;
struct bio_vec *behind_pages = NULL;
const int rw = bio_data_dir(bio);
const unsigned long do_sync = (bio->bi_rw & REQ_SYNC);
const unsigned long do_flush_fua = (bio->bi_rw & (REQ_FLUSH | REQ_FUA));
@ -855,9 +854,8 @@ static int make_request(mddev_t *mddev, struct bio * bio)
if (bitmap &&
(atomic_read(&bitmap->behind_writes)
< mddev->bitmap_info.max_write_behind) &&
!waitqueue_active(&bitmap->behind_wait) &&
(behind_pages = alloc_behind_pages(bio)) != NULL)
set_bit(R1BIO_BehindIO, &r1_bio->state);
!waitqueue_active(&bitmap->behind_wait))
alloc_behind_pages(bio, r1_bio);
atomic_set(&r1_bio->remaining, 1);
atomic_set(&r1_bio->behind_remaining, 0);
@ -878,7 +876,7 @@ static int make_request(mddev_t *mddev, struct bio * bio)
mbio->bi_rw = WRITE | do_flush_fua | do_sync;
mbio->bi_private = r1_bio;
if (behind_pages) {
if (r1_bio->behind_pages) {
struct bio_vec *bvec;
int j;
@ -890,7 +888,7 @@ static int make_request(mddev_t *mddev, struct bio * bio)
* them all
*/
__bio_for_each_segment(bvec, mbio, j, 0)
bvec->bv_page = behind_pages[j].bv_page;
bvec->bv_page = r1_bio->behind_pages[j];
if (test_bit(WriteMostly, &conf->mirrors[i].rdev->flags))
atomic_inc(&r1_bio->behind_remaining);
}
@ -900,8 +898,7 @@ static int make_request(mddev_t *mddev, struct bio * bio)
bio_list_add(&conf->pending_bio_list, mbio);
spin_unlock_irqrestore(&conf->device_lock, flags);
}
r1_bio_write_done(r1_bio, bio->bi_vcnt, behind_pages, behind_pages != NULL);
kfree(behind_pages); /* the behind pages are attached to the bios now */
r1_bio_write_done(r1_bio);
/* In case raid1d snuck in to freeze_array */
wake_up(&conf->wait_barrier);

4
drivers/md/raid1.h
View File

@ -94,7 +94,9 @@ struct r1bio_s {
int read_disk;
struct list_head retry_list;
struct bitmap_update *bitmap_update;
/* Next two are only valid when R1BIO_BehindIO is set */
struct page **behind_pages;
int behind_page_count;
/*
* if the IO is in WRITE direction, then multiple bios are used.
* We choose the number when they are allocated.