btrfs: volumes: Cleanup stripe size calculation

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@suse.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Gu Jinxiang <gujx@cn.fujitsu.com>
[ reformat comment ]
Signed-off-by: David Sterba <dsterba@suse.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@decadent.org.uk>
Cc: Hans van Kranenburg <hans.van.kranenburg@mendix.com>

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index b4b98a75ca8bbaf61176439d0c2d89d6579d0a8a..be403072114ae9e4a3254754179db947b72cdc52 100644 (file)
--- 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 btrfs_trans_handle *trans,
         * 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 */