[PATCH] fs: reorder some 'struct inode' fields to speedup i_size manipulations

[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>