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Commit b7178a5f authored by Zhao Lei's avatar Zhao Lei Committed by Chris Mason
Browse files

btrfs: Use unified stripe_page's index calculation 



We are using different index calculation method for stripe_page in
current code:
1: (rbio->stripe_len / PAGE_CACHE_SIZE) * stripe_index + page_index
2: DIV_ROUND_UP(rbio->stripe_len, PAGE_CACHE_SIZE) * stripe_index + page_index
3: DIV_ROUND_UP(rbio->stripe_len * stripe_index, PAGE_CACHE_SIZE) + page_index
...

They can get same result when stripe_len align to PAGE_CACHE_SIZE,
this is why current code can work, intruduce and use a common function
for calculation is a better choose.

Signed-off-by: default avatarZhao Lei <zhaolei@cn.fujitsu.com>
Signed-off-by: default avatarChris Mason <clm@fb.com>
parent bfca9a6d

fs/btrfs/raid56.c

+21 −22
Original line number Diff line number Diff line
@@ -609,13 +609,28 @@ static int rbio_can_merge(struct btrfs_raid_bio *last, 
	return 1;

}



static int rbio_stripe_page_index(struct btrfs_raid_bio *rbio, int stripe,

				  int index)

{

	return stripe * rbio->stripe_npages + index;

}



/*

 * these are just the pages from the rbio array, not from anything

 * the FS sent down to us

 */

static struct page *rbio_stripe_page(struct btrfs_raid_bio *rbio, int stripe,

				     int index)

{

	return rbio->stripe_pages[rbio_stripe_page_index(rbio, stripe, index)];

}



/*

 * helper to index into the pstripe

 */

static struct page *rbio_pstripe_page(struct btrfs_raid_bio *rbio, int index)

{

	index += (rbio->nr_data * rbio->stripe_len) >> PAGE_CACHE_SHIFT;

	return rbio->stripe_pages[index];

	return rbio_stripe_page(rbio, rbio->nr_data, index);

}



/*
@@ -626,10 +641,7 @@ static struct page *rbio_qstripe_page(struct btrfs_raid_bio *rbio, int index) 
{

	if (rbio->nr_data + 1 == rbio->real_stripes)

		return NULL;



	index += ((rbio->nr_data + 1) * rbio->stripe_len) >>

		PAGE_CACHE_SHIFT;

	return rbio->stripe_pages[index];

	return rbio_stripe_page(rbio, rbio->nr_data + 1, index);

}



/*
@@ -947,8 +959,7 @@ static struct page *page_in_rbio(struct btrfs_raid_bio *rbio, 
 */

static unsigned long rbio_nr_pages(unsigned long stripe_len, int nr_stripes)

{

	unsigned long nr = stripe_len * nr_stripes;

	return DIV_ROUND_UP(nr, PAGE_CACHE_SIZE);

	return DIV_ROUND_UP(stripe_len, PAGE_CACHE_SIZE) * nr_stripes;

}



/*
@@ -1026,13 +1037,13 @@ static int alloc_rbio_pages(struct btrfs_raid_bio *rbio) 
	return 0;

}



/* allocate pages for just the p/q stripes */

/* only allocate pages for p/q stripes */

static int alloc_rbio_parity_pages(struct btrfs_raid_bio *rbio)

{

	int i;

	struct page *page;



	i = (rbio->nr_data * rbio->stripe_len) >> PAGE_CACHE_SHIFT;

	i = rbio_stripe_page_index(rbio, rbio->nr_data, 0);



	for (; i < rbio->nr_pages; i++) {

		if (rbio->stripe_pages[i])
@@ -1120,18 +1131,6 @@ static void validate_rbio_for_rmw(struct btrfs_raid_bio *rbio) 
	}

}



/*

 * these are just the pages from the rbio array, not from anything

 * the FS sent down to us

 */

static struct page *rbio_stripe_page(struct btrfs_raid_bio *rbio, int stripe, int page)

{

	int index;

	index = stripe * (rbio->stripe_len >> PAGE_CACHE_SHIFT);

	index += page;

	return rbio->stripe_pages[index];

}



/*

 * helper function to walk our bio list and populate the bio_pages array with

 * the result.  This seems expensive, but it is faster than constantly