From b7178a5f0372a51260cf6e74d828e315e43dfc86 Mon Sep 17 00:00:00 2001 From: Zhao Lei Date: Tue, 3 Mar 2015 20:38:46 +0800 Subject: [PATCH] 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: Zhao Lei Signed-off-by: Chris Mason --- fs/btrfs/raid56.c | 43 +++++++++++++++++++++---------------------- 1 file changed, 21 insertions(+), 22 deletions(-) diff --git a/fs/btrfs/raid56.c b/fs/btrfs/raid56.c index 9ee11b41ba5d..c435fe0f86e4 100644 --- a/fs/btrfs/raid56.c +++ b/fs/btrfs/raid56.c @@ -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 -- 2.20.1