From 7e75bf3ff3a716d7b21d8fb43bf823115801c1e9 Mon Sep 17 00:00:00 2001 From: David Sterba Date: Fri, 18 Mar 2011 22:56:43 +0000 Subject: [PATCH] btrfs: properly access unaligned checksum buffer On Fri, Mar 18, 2011 at 11:56:53AM -0400, Chris Mason wrote: > Thanks for fielding this one. Does put_unaligned_le32 optimize away on > platforms with efficient access? It would be great if we didn't need > the #ifdef. (quicktest: assembly output is same for put_unaligned_le32 and direct assignment on my x86_64) I was originally following examples in Documentation/unaligned-memory-access.txt. From other code it seems to me that the define CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS is intended for larger portions of code. Macros/wrappers for {put,get}_unaligned* are chosen via arch//include/asm/unaligned.h accordingly, therefore it's safe to use put_unaligned_le32 without the ifdef. dave Signed-off-by: Chris Mason --- fs/btrfs/disk-io.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 00cbb41af660..2bdb124333ab 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -29,6 +29,7 @@ #include #include #include +#include #include "compat.h" #include "ctree.h" #include "disk-io.h" @@ -198,7 +199,7 @@ u32 btrfs_csum_data(struct btrfs_root *root, char *data, u32 seed, size_t len) void btrfs_csum_final(u32 crc, char *result) { - *(__le32 *)result = ~cpu_to_le32(crc); + put_unaligned_le32(~crc, result); } /* -- GitLab