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authorZhao Lei <zhaolei@cn.fujitsu.com>2015-03-03 20:38:46 +0800
committerChris Mason <clm@fb.com>2016-01-20 07:22:16 -0800
commitb7178a5f0372a51260cf6e74d828e315e43dfc86 (patch)
tree2791d81ab923fd046de7b8f944714b7079c72d97 /fs/btrfs
parentbfca9a6d4b1322ba36235e8a652f05a9668ef59b (diff)
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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.c43
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