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Date: Tue, 16 Feb 2021 18:48:24 -0800
From: ira.weiny@...el.com
To: David Sterba <dsterba@...e.cz>
Cc: Ira Weiny <ira.weiny@...el.com>, Chris Mason <clm@...com>,
Josef Bacik <josef@...icpanda.com>,
linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: [PATCH 2/4] fs/btrfs: Convert raid5/6 kmaps to kmap_local_page()
From: Ira Weiny <ira.weiny@...el.com>
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@...el.com>
---
This patch depends on the fix to raid5/6 kmapping sent previously
https://lore.kernel.org/lkml/20210205163943.GD5033@iweiny-DESK2.sc.intel.com/#t
---
fs/btrfs/raid56.c | 57 +++++++++++++++++++++++------------------------
1 file changed, 28 insertions(+), 29 deletions(-)
diff --git a/fs/btrfs/raid56.c b/fs/btrfs/raid56.c
index 9759fb31b73e..04abae305582 100644
--- a/fs/btrfs/raid56.c
+++ b/fs/btrfs/raid56.c
@@ -1233,13 +1233,13 @@ 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) {
@@ -1249,7 +1249,7 @@ 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);
@@ -1258,10 +1258,8 @@ 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]);
}
/*
@@ -1780,6 +1778,7 @@ 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;
@@ -1791,6 +1790,12 @@ static void __raid_recover_end_io(struct btrfs_raid_bio *rbio)
goto cleanup_io;
}
+ 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;
@@ -1814,6 +1819,9 @@ static void __raid_recover_end_io(struct btrfs_raid_bio *rbio)
/* 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++) {
/*
@@ -1827,7 +1835,8 @@ 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 */
@@ -1920,24 +1929,14 @@ 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:
@@ -2362,13 +2361,13 @@ 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;
@@ -2376,7 +2375,7 @@ 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) {
@@ -2399,14 +2398,14 @@ 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);
}
--
2.28.0.rc0.12.gb6a658bd00c9
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