btrfs: raid56: convert kmaps to kmap_local_page
These kmaps are thread local and don't need to be atomic. So they can use
the more efficient kmap_local_page(). However, the mapping of pages in
the stripes and the additional parity and qstripe pages are a bit
trickier because the unmapping must occur in the opposite order from the
mapping. Furthermore, the pointer array in __raid_recover_end_io() may
get reordered.
Convert these calls to kmap_local_page() taking care to reverse the
unmappings of any page arrays as well as being careful with the mappings
of any special pages such as the parity and qstripe pages.
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/raid56.c b/fs/btrfs/raid56.c
index 633b4b1..bb768c3 100644
--- a/fs/btrfs/raid56.c
+++ b/fs/btrfs/raid56.c
@@ -1232,13 +1232,13 @@ static noinline void finish_rmw(struct btrfs_raid_bio *rbio)
/* first collect one page from each data stripe */
for (stripe = 0; stripe < nr_data; stripe++) {
p = page_in_rbio(rbio, stripe, pagenr, 0);
- pointers[stripe] = kmap(p);
+ pointers[stripe] = kmap_local_page(p);
}
/* then add the parity stripe */
p = rbio_pstripe_page(rbio, pagenr);
SetPageUptodate(p);
- pointers[stripe++] = kmap(p);
+ pointers[stripe++] = kmap_local_page(p);
if (has_qstripe) {
@@ -1248,7 +1248,7 @@ static noinline void finish_rmw(struct btrfs_raid_bio *rbio)
*/
p = rbio_qstripe_page(rbio, pagenr);
SetPageUptodate(p);
- pointers[stripe++] = kmap(p);
+ pointers[stripe++] = kmap_local_page(p);
raid6_call.gen_syndrome(rbio->real_stripes, PAGE_SIZE,
pointers);
@@ -1257,10 +1257,8 @@ static noinline void finish_rmw(struct btrfs_raid_bio *rbio)
copy_page(pointers[nr_data], pointers[0]);
run_xor(pointers + 1, nr_data - 1, PAGE_SIZE);
}
-
-
- for (stripe = 0; stripe < rbio->real_stripes; stripe++)
- kunmap(page_in_rbio(rbio, stripe, pagenr, 0));
+ for (stripe = stripe - 1; stripe >= 0; stripe--)
+ kunmap_local(pointers[stripe]);
}
/*
@@ -1777,6 +1775,7 @@ static void __raid_recover_end_io(struct btrfs_raid_bio *rbio)
{
int pagenr, stripe;
void **pointers;
+ void **unmap_array;
int faila = -1, failb = -1;
struct page *page;
blk_status_t err;
@@ -1788,6 +1787,16 @@ static void __raid_recover_end_io(struct btrfs_raid_bio *rbio)
goto cleanup_io;
}
+ /*
+ * Store copy of pointers that does not get reordered during
+ * reconstruction so that kunmap_local works.
+ */
+ unmap_array = kcalloc(rbio->real_stripes, sizeof(void *), GFP_NOFS);
+ if (!unmap_array) {
+ err = BLK_STS_RESOURCE;
+ goto cleanup_pointers;
+ }
+
faila = rbio->faila;
failb = rbio->failb;
@@ -1809,8 +1818,11 @@ static void __raid_recover_end_io(struct btrfs_raid_bio *rbio)
!test_bit(pagenr, rbio->dbitmap))
continue;
- /* setup our array of pointers with pages
- * from each stripe
+ /*
+ * Setup our array of pointers with pages from each stripe
+ *
+ * NOTE: store a duplicate array of pointers to preserve the
+ * pointer order
*/
for (stripe = 0; stripe < rbio->real_stripes; stripe++) {
/*
@@ -1824,7 +1836,8 @@ static void __raid_recover_end_io(struct btrfs_raid_bio *rbio)
} else {
page = rbio_stripe_page(rbio, stripe, pagenr);
}
- pointers[stripe] = kmap(page);
+ pointers[stripe] = kmap_local_page(page);
+ unmap_array[stripe] = pointers[stripe];
}
/* all raid6 handling here */
@@ -1917,24 +1930,14 @@ static void __raid_recover_end_io(struct btrfs_raid_bio *rbio)
}
}
}
- for (stripe = 0; stripe < rbio->real_stripes; stripe++) {
- /*
- * if we're rebuilding a read, we have to use
- * pages from the bio list
- */
- if ((rbio->operation == BTRFS_RBIO_READ_REBUILD ||
- rbio->operation == BTRFS_RBIO_REBUILD_MISSING) &&
- (stripe == faila || stripe == failb)) {
- page = page_in_rbio(rbio, stripe, pagenr, 0);
- } else {
- page = rbio_stripe_page(rbio, stripe, pagenr);
- }
- kunmap(page);
- }
+ for (stripe = rbio->real_stripes - 1; stripe >= 0; stripe--)
+ kunmap_local(unmap_array[stripe]);
}
err = BLK_STS_OK;
cleanup:
+ kfree(unmap_array);
+cleanup_pointers:
kfree(pointers);
cleanup_io:
@@ -2359,13 +2362,13 @@ static noinline void finish_parity_scrub(struct btrfs_raid_bio *rbio,
goto cleanup;
}
SetPageUptodate(q_page);
- pointers[rbio->real_stripes - 1] = kmap(q_page);
+ pointers[rbio->real_stripes - 1] = kmap_local_page(q_page);
}
atomic_set(&rbio->error, 0);
/* Map the parity stripe just once */
- pointers[nr_data] = kmap(p_page);
+ pointers[nr_data] = kmap_local_page(p_page);
for_each_set_bit(pagenr, rbio->dbitmap, rbio->stripe_npages) {
struct page *p;
@@ -2373,7 +2376,7 @@ static noinline void finish_parity_scrub(struct btrfs_raid_bio *rbio,
/* first collect one page from each data stripe */
for (stripe = 0; stripe < nr_data; stripe++) {
p = page_in_rbio(rbio, stripe, pagenr, 0);
- pointers[stripe] = kmap(p);
+ pointers[stripe] = kmap_local_page(p);
}
if (has_qstripe) {
@@ -2396,14 +2399,14 @@ static noinline void finish_parity_scrub(struct btrfs_raid_bio *rbio,
bitmap_clear(rbio->dbitmap, pagenr, 1);
kunmap_local(parity);
- for (stripe = 0; stripe < nr_data; stripe++)
- kunmap(page_in_rbio(rbio, stripe, pagenr, 0));
+ for (stripe = nr_data - 1; stripe >= 0; stripe--)
+ kunmap_local(pointers[stripe]);
}
- kunmap(p_page);
+ kunmap_local(pointers[nr_data]);
__free_page(p_page);
if (q_page) {
- kunmap(q_page);
+ kunmap_local(pointers[rbio->real_stripes - 1]);
__free_page(q_page);
}