linux-kernel - [PATCH 3.16 82/83] btrfs: volumes: Cleanup stripe size calculation

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Message-ID: <lsq.1574264230.176031096@decadent.org.uk>
Date:   Wed, 20 Nov 2019 15:38:32 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "David Sterba" <dsterba@...e.com>, "Qu Wenruo" <wqu@...e.com>,
        "Hans van Kranenburg" <Hans.van.Kranenburg@...dix.com>,
        "Gu Jinxiang" <gujx@...fujitsu.com>,
        "Nikolay Borisov" <nborisov@...e.com>
Subject: [PATCH 3.16 82/83] btrfs: volumes: Cleanup stripe size calculation

3.16.78-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Qu Wenruo <wqu@...e.com>

commit 793ff2c88c6397b3531c08cc4f920619b56a9def upstream.

Cleanup the following things:
1) open coded SZ_16M round up
2) use min() to replace open-coded size comparison
3) code style

Signed-off-by: Qu Wenruo <wqu@...e.com>
Reviewed-by: Nikolay Borisov <nborisov@...e.com>
Reviewed-by: Gu Jinxiang <gujx@...fujitsu.com>
[ reformat comment ]
Signed-off-by: David Sterba <dsterba@...e.com>
[bwh: Backported to 3.16 as dependency of commit baf92114c7
 "btrfs: alloc_chunk: fix more DUP stripe size handling":
 - Add #include <linux/sizes.h> for definition of SZ_16M]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
Cc: Hans van Kranenburg <Hans.van.Kranenburg@...dix.com>
---
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -27,6 +27,7 @@
 #include <linux/kthread.h>
 #include <linux/raid/pq.h>
 #include <linux/semaphore.h>
+#include <linux/sizes.h>
 #include <asm/div64.h>
 #include "ctree.h"
 #include "extent_map.h"
@@ -4273,18 +4274,17 @@ static int __btrfs_alloc_chunk(struct bt
 	 * and compare that answer with the max chunk size
 	 */
 	if (stripe_size * data_stripes > max_chunk_size) {
-		u64 mask = (1ULL << 24) - 1;
-
 		stripe_size = div_u64(max_chunk_size, data_stripes);
 
 		/* bump the answer up to a 16MB boundary */
-		stripe_size = (stripe_size + mask) & ~mask;
+		stripe_size = round_up(stripe_size, SZ_16M);
 
-		/* but don't go higher than the limits we found
-		 * while searching for free extents
+		/*
+		 * But don't go higher than the limits we found while searching
+		 * for free extents
 		 */
-		if (stripe_size > devices_info[ndevs-1].max_avail)
-			stripe_size = devices_info[ndevs-1].max_avail;
+		stripe_size = min(devices_info[ndevs - 1].max_avail,
+				  stripe_size);
 	}
 
 	/* align to BTRFS_STRIPE_LEN */