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md/r5cache: read data into orig_page for prexor of cached data

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With write back cache, we use orig_page to do prexor. This patch
makes sure we read data into orig_page for it.

Flag R5_OrigPageUPTDODATE is added to show whether orig_page
has the latest data from raid disk.

We introduce a helper function uptodate_for_rmw() to simplify
the a couple conditions in handle_stripe_dirtying().

Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Shaohua Li <shli@fb.com>
This commit is contained in:
Song Liu 2017-01-12 17:22:41 -08:00 committed by Shaohua Li
parent d46d29f072
commit 86aa1397dd
3 changed files with 42 additions and 9 deletions
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2
drivers/md/raid5-cache.c
View File

@ -2349,6 +2349,8 @@ void r5c_release_extra_page(struct stripe_head *sh)
struct page *p = sh->dev[i].orig_page;
sh->dev[i].orig_page = sh->dev[i].page;
clear_bit(R5_OrigPageUPTDODATE, &sh->dev[i].flags);
if (!using_disk_info_extra_page)
put_page(p);
}

44
drivers/md/raid5.c
View File

@ -1015,7 +1015,17 @@ again:
if (test_bit(R5_SkipCopy, &sh->dev[i].flags))
WARN_ON(test_bit(R5_UPTODATE, &sh->dev[i].flags));
sh->dev[i].vec.bv_page = sh->dev[i].page;
if (!op_is_write(op) &&
test_bit(R5_InJournal, &sh->dev[i].flags))
/*
* issuing read for a page in journal, this
* must be preparing for prexor in rmw; read
* the data into orig_page
*/
sh->dev[i].vec.bv_page = sh->dev[i].orig_page;
else
sh->dev[i].vec.bv_page = sh->dev[i].page;
bi->bi_vcnt = 1;
bi->bi_io_vec[0].bv_len = STRIPE_SIZE;
bi->bi_io_vec[0].bv_offset = 0;
@ -2380,6 +2390,13 @@ static void raid5_end_read_request(struct bio * bi)
} else if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags))
clear_bit(R5_ReadNoMerge, &sh->dev[i].flags);
if (test_bit(R5_InJournal, &sh->dev[i].flags))
/*
* end read for a page in journal, this
* must be preparing for prexor in rmw
*/
set_bit(R5_OrigPageUPTDODATE, &sh->dev[i].flags);
if (atomic_read(&rdev->read_errors))
atomic_set(&rdev->read_errors, 0);
} else {
@ -3594,6 +3611,21 @@ unhash:
break_stripe_batch_list(head_sh, STRIPE_EXPAND_SYNC_FLAGS);
}
/*
* For RMW in write back cache, we need extra page in prexor to store the
* old data. This page is stored in dev->orig_page.
*
* This function checks whether we have data for prexor. The exact logic
* is:
* R5_UPTODATE && (!R5_InJournal || R5_OrigPageUPTDODATE)
*/
static inline bool uptodate_for_rmw(struct r5dev *dev)
{
return (test_bit(R5_UPTODATE, &dev->flags)) &&
(!test_bit(R5_InJournal, &dev->flags) ||
test_bit(R5_OrigPageUPTDODATE, &dev->flags));
}
static int handle_stripe_dirtying(struct r5conf *conf,
struct stripe_head *sh,
struct stripe_head_state *s,
@ -3625,9 +3657,7 @@ static int handle_stripe_dirtying(struct r5conf *conf,
if ((dev->towrite || i == sh->pd_idx || i == sh->qd_idx ||
test_bit(R5_InJournal, &dev->flags)) &&
!test_bit(R5_LOCKED, &dev->flags) &&
!((test_bit(R5_UPTODATE, &dev->flags) &&
(!test_bit(R5_InJournal, &dev->flags) ||
dev->page != dev->orig_page)) ||
!(uptodate_for_rmw(dev) ||
test_bit(R5_Wantcompute, &dev->flags))) {
if (test_bit(R5_Insync, &dev->flags))
rmw++;
@ -3639,7 +3669,6 @@ static int handle_stripe_dirtying(struct r5conf *conf,
i != sh->pd_idx && i != sh->qd_idx &&
!test_bit(R5_LOCKED, &dev->flags) &&
!(test_bit(R5_UPTODATE, &dev->flags) ||
test_bit(R5_InJournal, &dev->flags) ||
test_bit(R5_Wantcompute, &dev->flags))) {
if (test_bit(R5_Insync, &dev->flags))
rcw++;
@ -3693,9 +3722,7 @@ static int handle_stripe_dirtying(struct r5conf *conf,
i == sh->pd_idx || i == sh->qd_idx ||
test_bit(R5_InJournal, &dev->flags)) &&
!test_bit(R5_LOCKED, &dev->flags) &&
!((test_bit(R5_UPTODATE, &dev->flags) &&
(!test_bit(R5_InJournal, &dev->flags) ||
dev->page != dev->orig_page)) ||
!(uptodate_for_rmw(dev) ||
test_bit(R5_Wantcompute, &dev->flags)) &&
test_bit(R5_Insync, &dev->flags)) {
if (test_bit(STRIPE_PREREAD_ACTIVE,
@ -3722,7 +3749,6 @@ static int handle_stripe_dirtying(struct r5conf *conf,
i != sh->pd_idx && i != sh->qd_idx &&
!test_bit(R5_LOCKED, &dev->flags) &&
!(test_bit(R5_UPTODATE, &dev->flags) ||
test_bit(R5_InJournal, &dev->flags) ||
test_bit(R5_Wantcompute, &dev->flags))) {
rcw++;
if (test_bit(R5_Insync, &dev->flags) &&

5
drivers/md/raid5.h
View File

@ -322,6 +322,11 @@ enum r5dev_flags {
* data and parity being written are in the journal
* device
*/
R5_OrigPageUPTDODATE, /* with write back cache, we read old data into
* dev->orig_page for prexor. When this flag is
* set, orig_page contains latest data in the
* raid disk.
*/
};
/*