Commit 94a0b58d authored by Ira Weiny's avatar Ira Weiny Committed by David Sterba
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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: default avatarIra Weiny <ira.weiny@intel.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 58c1a35c

fs/btrfs/raid56.c

+34 −31
Original line number Diff line number Diff line
@@ -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);

	}