From 83b7b44e1c1e9e493ccd4146558481ab5af0116a Mon Sep 17 00:00:00 2001
From: Eric Dumazet <dada1@cosmosbay.com>
Date: Wed, 6 Dec 2006 20:38:53 -0800
Subject: [PATCH] [PATCH] fs: reorder some 'struct inode' fields to speedup
i_size manipulations
On 32bits SMP platforms, 64bits i_size is protected by a seqcount
(i_size_seqcount).
When i_size is read or written, i_size_seqcount is read/written as well, so
it make sense to group these two fields together in the same cache line.
This patch moves i_size_seqcount next to i_size, and also moves i_version
to let offsetof(struct inode, i_size) being 0x40 instead of 0x3c (for
32bits platforms).
For 64 bits platforms, i_size_seqcount doesnt exist, and the move of a
'long i_version' should not introduce a new hole because of padding.
Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---
include/linux/fs.h | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index d791bae9de9c8..3a1927e516d04 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -548,12 +548,15 @@ struct inode {
uid_t i_uid;
gid_t i_gid;
dev_t i_rdev;
+ unsigned long i_version;
loff_t i_size;
+#ifdef __NEED_I_SIZE_ORDERED
+ seqcount_t i_size_seqcount;
+#endif
struct timespec i_atime;
struct timespec i_mtime;
struct timespec i_ctime;
unsigned int i_blkbits;
- unsigned long i_version;
blkcnt_t i_blocks;
unsigned short i_bytes;
spinlock_t i_lock; /* i_blocks, i_bytes, maybe i_size */
@@ -598,9 +601,6 @@ struct inode {
void *i_security;
#endif
void *i_private; /* fs or device private pointer */
-#ifdef __NEED_I_SIZE_ORDERED
- seqcount_t i_size_seqcount;
-#endif
};
/*
--
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