convert ill defined log2() to ilog2()

It's *wrong* to have
			#define log2(n) ffz(~(n))
It should be *reversed*:
			#define log2(n) flz(~(n))
or
			#define log2(n) fls(n)
or just use
			ilog2(n) defined in linux/log2.h.

This patch follows the last solution, recommended by Andrew Morton.

Cc: <linux-ext4@vger.kernel.org>
Cc: Mingming Cao <cmm@us.ibm.com>
Cc: Bjorn Helgaas <bjorn.helgaas@hp.com>
Cc: Chris Ahna <christopher.j.ahna@intel.com>
Cc: David Mosberger-Tang <davidm@hpl.hp.com>
Cc: Kyle McMartin <kyle@parisc-linux.org>
Cc: Dave Airlie <airlied@linux.ie>
Cc: Dave Jones <davej@codemonkey.org.uk>
Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 4 deletions

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 22158ebfae2a..fc3eb79faa49 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1415,8 +1415,6 @@ static void ext4_orphan_cleanup (struct super_block * sb,
         sb->s_flags = s_flags; /* Restore MS_RDONLY status */
 }
 
-#define log2(n) ffz(~(n))
-
 /*
  * Maximal file size.  There is a direct, and {,double-,triple-}indirect
  * block limit, and also a limit of (2^32 - 1) 512-byte sectors in i_blocks.
@@ -1689,8 +1687,8 @@ static int ext4_fill_super (struct super_block *sb, void *data, int silent)
         sbi->s_desc_per_block = blocksize / EXT4_DESC_SIZE(sb);
         sbi->s_sbh = bh;
         sbi->s_mount_state = le16_to_cpu(es->s_state);
-        sbi->s_addr_per_block_bits = log2(EXT4_ADDR_PER_BLOCK(sb));
-        sbi->s_desc_per_block_bits = log2(EXT4_DESC_PER_BLOCK(sb));
+        sbi->s_addr_per_block_bits = ilog2(EXT4_ADDR_PER_BLOCK(sb));
+        sbi->s_desc_per_block_bits = ilog2(EXT4_DESC_PER_BLOCK(sb));
         for (i=0; i < 4; i++)
                 sbi->s_hash_seed[i] = le32_to_cpu(es->s_hash_seed[i]);
         sbi->s_def_hash_version = es->s_def_hash_version;