VFS: increase pseudo-filesystem block size to PAGE_SIZE

This commit:

    commit ba52de12
    Author: Theodore Ts'o <tytso@mit.edu>
    Date:   Wed Sep 27 01:50:49 2006 -0700

        [PATCH] inode-diet: Eliminate i_blksize from the inode structure

caused the block size used by pseudo-filesystems to decrease from
PAGE_SIZE to 1024 leading to a doubling of the number of context switches
during a kernbench run.
Signed-off-by: NAlex Nixon <Alex.Nixon@citrix.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Ian Campbell <Ian.Campbell@eu.citrix.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: <stable@kernel.org>		[2.6.25.x, 2.6.26.x]
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

fs/libfs.c

@@ -216,8 +216,8 @@ int get_sb_pseudo(struct file_system_type *fs_type, char *name,
 
 	s->s_flags = MS_NOUSER;
 	s->s_maxbytes = ~0ULL;
-	s->s_blocksize = 1024;
-	s->s_blocksize_bits = 10;
+	s->s_blocksize = PAGE_SIZE;
+	s->s_blocksize_bits = PAGE_SHIFT;
 	s->s_magic = magic;
 	s->s_op = ops ? ops : &simple_super_operations;
 	s->s_time_gran = 1;