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author | Zhao Lei <zhaolei@cn.fujitsu.com> | 2015-03-03 20:38:46 +0800 |
---|---|---|
committer | Chris Mason <clm@fb.com> | 2016-01-20 07:22:16 -0800 |
commit | b7178a5f0372a51260cf6e74d828e315e43dfc86 (patch) | |
tree | 2791d81ab923fd046de7b8f944714b7079c72d97 /fs/btrfs | |
parent | bfca9a6d4b1322ba36235e8a652f05a9668ef59b (diff) | |
download | linux-b7178a5f0372a51260cf6e74d828e315e43dfc86.tar.gz linux-b7178a5f0372a51260cf6e74d828e315e43dfc86.tar.bz2 linux-b7178a5f0372a51260cf6e74d828e315e43dfc86.zip |
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 <zhaolei@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>
Diffstat (limited to 'fs/btrfs')
-rw-r--r-- | fs/btrfs/raid56.c | 43 |
1 files 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]) @@ -1121,18 +1132,6 @@ 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 * searching through the bio list as we setup the IO in finish_rmw or stripe |