[PATCH] avoid one conditional branch in touch_atime()

I added IS_NOATIME(inode) macro definition in include/linux/fs.h, true if
the inode superblock is marked readonly or noatime.

This new macro is then used in touch_atime() instead of separatly testing
MS_RDONLY and MS_NOATIME

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/inode.c

@@ -1160,11 +1160,9 @@ void touch_atime(struct vfsmount *mnt, struct dentry *dentry)
 	struct inode *inode = dentry->d_inode;
 	struct timespec now;
 
-	if (IS_RDONLY(inode))
-		return;
 	if (inode->i_flags & S_NOATIME)
 		return;
-	if (inode->i_sb->s_flags & MS_NOATIME)
+	if (IS_NOATIME(inode))
 		return;
 	if ((inode->i_sb->s_flags & MS_NODIRATIME) && S_ISDIR(inode->i_mode))
 		return;

include/linux/fs.h

@@ -169,6 +169,7 @@ extern int dir_notify_enable;
 #define IS_DIRSYNC(inode)	(__IS_FLG(inode, MS_SYNCHRONOUS|MS_DIRSYNC) || \
 					((inode)->i_flags & (S_SYNC|S_DIRSYNC)))
 #define IS_MANDLOCK(inode)	__IS_FLG(inode, MS_MANDLOCK)
+#define IS_NOATIME(inode)   __IS_FLG(inode, MS_RDONLY|MS_NOATIME)
 
 #define IS_NOQUOTA(inode)	((inode)->i_flags & S_NOQUOTA)
 #define IS_APPEND(inode)	((inode)->i_flags & S_APPEND)