Bug 915844

Description of problem:

The man page for mount incorrectly describes the mount option relatime;

       relatime
              Update inode access times relative to modify or change time.  Access time is only updated if the previous access time was  ear-
              lier  than  the  current  modify or change time. (Similar to noatime, but doesn’t break mutt or other applications that need to
              know if a file has been read since the last time it was modified.)

However, this is incorrect. The code in the kernel will update the atime if it is more than 24 hours later than mtime;

/*
 * With relative atime, only update atime if the previous atime is
 * earlier than either the ctime or mtime or if at least a day has
 * passed since the last atime update.
 */
static int relatime_need_update(struct vfsmount *mnt, struct inode *inode,
                             struct timespec now)
{

        if (!(mnt->mnt_flags & MNT_RELATIME))
                return 1;
        /*
         * Is mtime younger than atime? If yes, update atime:
         */
        if (timespec_compare(&inode->i_mtime, &inode->i_atime) >= 0)
                return 1;
        /*
         * Is ctime younger than atime? If yes, update atime:
         */
        if (timespec_compare(&inode->i_ctime, &inode->i_atime) >= 0)
                return 1;

        /*
         * Is the previous atime value older than a day? If yes,
         * update atime:
         */
        if ((long)(now.tv_sec - inode->i_atime.tv_sec) >= 24*60*60)
                return 1;
        /*
         * Good, we can skip the atime update:
         */
        return 0;
}

It is worth mentioning that more recent versions of the man mount page state the correct behaviour.

       relatime
              Update inode access times relative to modify or change time.  Access time is only updated if the previous access time was earlier than  the
              current  modify or change time. (Similar to noatime, but doesn't break mutt or other applications that need to know if a file has been read
              since the last time it was modified.)

              Since Linux 2.6.30, the kernel defaults to the behavior provided by this option (unless noatime was  specified), and the strictatime option
              is  required  to  obtain traditional semantics. In addition, since Linux 2.6.30, the file's last access time is always  updated  if  it  is
              more than 1 day old.

(taken from util-linux 2.20.1)

Version-Release number of selected component (if applicable):

util-linux-ng-2.17.2-12.9.el6.x86_64

How reproducible:

Very :) 

Steps to Reproduce:
1. man mount
2. read entry for "relatime"
  
Actual results:

Incorrectly describes relatime option

Expected results:

Should correctly describe relatime option
Additional info: