From: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>
To: Chris Mason <clm@fb.com>, Josef Bacik <josef@toxicpanda.com>,
David Sterba <dsterba@suse.com>, Nick Terrell <terrelln@fb.com>,
linux-kernel@vger.kernel.org, linux-btrfs@vger.kernel.org,
kernel-team@fb.com
Cc: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>
Subject: [PATCH 2/2] btrfs: Allocate page arrays using bulk page allocator.
Date: Mon, 28 Mar 2022 16:14:29 -0400 [thread overview]
Message-ID: <9cbd861d3b302e19b990848ea747d2ea91d01aed.1648497027.git.sweettea-kernel@dorminy.me> (raw)
Message-ID: <20220328201429.uw1CoeUegRjHFA0xLFVmitPvavJDIvdzfMEVwmWuBX8@z> (raw)
In-Reply-To: <cover.1648497027.git.sweettea-kernel@dorminy.me>
While calling alloc_page() in a loop is an effective way to populate an
array of pages, the kernel provides a method to allocate pages in bulk.
alloc_pages_bulk_array() populates the NULL slots in a page array, trying to
grab more than one page at a time.
Unfortunately, it doesn't guarantee allocating all slots in the array,
but it's easy to call it in a loop and return an error if no progress
occurs. Similar code can be found in xfs/xfs_buf.c:xfs_buf_alloc_pages().
Signed-off-by: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>
---
fs/btrfs/ctree.c | 25 ++++++++++++++++---------
1 file changed, 16 insertions(+), 9 deletions(-)
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 4e81e75c8e7c..37711a66e726 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -102,17 +102,24 @@ void btrfs_free_path(struct btrfs_path *p)
*/
int btrfs_alloc_page_array(unsigned long nr_pages, struct page **page_array)
{
- int i;
- for (i = 0; i < nr_pages; i++) {
- struct page *page;
- if (page_array[i])
+ long allocated = 0;
+ for (;;) {
+ long last = allocated;
+
+ allocated = alloc_pages_bulk_array(GFP_NOFS, nr_pages,
+ page_array);
+ if (allocated == nr_pages)
+ return 0;
+
+ if (allocated != last)
continue;
- page = alloc_page(GFP_NOFS);
- if (!page)
- return -ENOMEM;
- page_array[i] = page;
+ /*
+ * During this iteration, no page could be allocated, even
+ * though alloc_pages_bulk_array() falls back to alloc_page()
+ * if it could not bulk-allocate. So we must be out of memory.
+ */
+ return -ENOMEM;
}
- return 0;
}
/*
--
2.35.1
next prev parent reply other threads:[~2022-03-28 20:14 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <cover.1648497027.git.sweettea-kernel@dorminy.me>
2022-03-28 20:14 ` [PATCH 1/2] btrfs: Factor out allocating an array of pages Sweet Tea Dorminy
2022-03-28 23:09 ` David Sterba
2022-03-30 19:01 ` Sweet Tea Dorminy
2022-03-29 10:04 ` Filipe Manana
2022-03-29 18:30 ` Nikolay Borisov
2022-03-28 20:14 ` Sweet Tea Dorminy [this message]
2022-03-28 20:14 ` [PATCH 2/2] btrfs: Allocate page arrays using bulk page allocator Sweet Tea Dorminy
2022-03-29 18:31 ` Nikolay Borisov
2022-03-28 20:14 [PATCH 0/2] btrfs: Allocate page arrays more efficiently Sweet Tea Dorminy
2022-03-28 21:58 ` David Sterba
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