[PATCH] per-mountpoint noatime/nodiratime

Turn noatime and nodiratime into per-mount instead of per-sb flags.

After all the preparations this is a rather trivial patch. The mount code
needs to treat the two options as per-mount instead of per-superblock, and
touch_atime needs to be changed to check the new MNT_ flags in addition to
the MS_ flags that are kept for filesystems that are always
noatime/nodiratime but not user settable anymore. Besides that core code
only nfs needed an update because it's leaving atime updates to the server
and thus sets the S_NOATIME flag on every inode, but needs to know whether
it's a real noatime mount for an getattr optimization.

While we're at it I've killed the IS_NOATIME/IS_NODIRATIME macros that were
only used by touch_atime.

Signed-off-by: Christoph Hellwig <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

fs/inode.c

···
 #include <linux/cdev.h>
 #include <linux/bootmem.h>
 #include <linux/inotify.h>
+#include <linux/mount.h>
 
 /*
  * This is needed for the following functions:
···
 	struct inode *inode = dentry->d_inode;
 	struct timespec now;
 
-	/* per-mountpoint checks will go here */
-	if (IS_NOATIME(inode))
-		return;
-	if (IS_NODIRATIME(inode) && S_ISDIR(inode->i_mode))
-		return;
 	if (IS_RDONLY(inode))
+		return;
+
+	if ((inode->i_flags & S_NOATIME) ||
+	    (inode->i_sb->s_flags & MS_NOATIME) ||
+	    ((inode->i_sb->s_flags & MS_NODIRATIME) && S_ISDIR(inode->i_mode)))
+		return;
+
+	/*
+	 * We may have a NULL vfsmount when coming from NFSD
+	 */
+	if (mnt &&
+	    ((mnt->mnt_flags & MNT_NOATIME) ||
+	     ((mnt->mnt_flags & MNT_NODIRATIME) && S_ISDIR(inode->i_mode))))
 		return;
 
 	now = current_fs_time(inode->i_sb);

fs/namespace.c

···
 		{ MS_SYNCHRONOUS, ",sync" },
 		{ MS_DIRSYNC, ",dirsync" },
 		{ MS_MANDLOCK, ",mand" },
-		{ MS_NOATIME, ",noatime" },
-		{ MS_NODIRATIME, ",nodiratime" },
 		{ 0, NULL }
 	};
 	static struct proc_fs_info mnt_info[] = {
 		{ MNT_NOSUID, ",nosuid" },
 		{ MNT_NODEV, ",nodev" },
 		{ MNT_NOEXEC, ",noexec" },
+		{ MNT_NOATIME, ",noatime" },
+		{ MNT_NODIRATIME, ",nodiratime" },
 		{ 0, NULL }
 	};
 	struct proc_fs_info *fs_infop;
···
 		mnt_flags |= MNT_NODEV;
 	if (flags & MS_NOEXEC)
 		mnt_flags |= MNT_NOEXEC;
-	flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE);
+	if (flags & MS_NOATIME)
+		mnt_flags |= MNT_NOATIME;
+	if (flags & MS_NODIRATIME)
+		mnt_flags |= MNT_NODIRATIME;
+
+	flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE |
+		   MS_NOATIME | MS_NODIRATIME);
 
 	/* ... and get the mountpoint */
 	retval = path_lookup(dir_name, LOOKUP_FOLLOW, &nd);

fs/nfs/inode.c

···
 
 	/* Flush out writes to the server in order to update c/mtime */
 	nfs_sync_inode(inode, 0, 0, FLUSH_WAIT|FLUSH_NOCOMMIT);
-	if (__IS_FLG(inode, MS_NOATIME))
+
+	/*
+	 * We may force a getattr if the user cares about atime.
+	 *
+	 * Note that we only have to check the vfsmount flags here:
+	 *  - NFS always sets S_NOATIME by so checking it would give a
+	 *    bogus result
+	 *  - NFS never sets MS_NOATIME or MS_NODIRATIME so there is
+	 *    no point in checking those.
+	 */
+ 	if ((mnt->mnt_flags & MNT_NOATIME) ||
+ 	    ((mnt->mnt_flags & MNT_NODIRATIME) && S_ISDIR(inode->i_mode)))
 		need_atime = 0;
-	else if (__IS_FLG(inode, MS_NODIRATIME) && S_ISDIR(inode->i_mode))
-		need_atime = 0;
-	/* We may force a getattr if the user cares about atime */
+
 	if (need_atime)
 		err = __nfs_revalidate_inode(NFS_SERVER(inode), inode);
 	else

fs/xfs/linux-2.6/xfs_iops.c

···
 #include <linux/xattr.h>
 #include <linux/namei.h>
 
+#define IS_NOATIME(inode) ((inode->i_sb->s_flags & MS_NOATIME) ||	\
+	(S_ISDIR(inode->i_mode) && inode->i_sb->s_flags & MS_NODIRATIME))
+
 /*
  * Change the requested timestamp in the given inode.
  * We don't lock across timestamp updates, and we don't log them but

include/linux/fs.h

···
 /*
  * Superblock flags that can be altered by MS_REMOUNT
  */
-#define MS_RMT_MASK	(MS_RDONLY|MS_SYNCHRONOUS|MS_MANDLOCK|MS_NOATIME|\
-			 MS_NODIRATIME)
+#define MS_RMT_MASK	(MS_RDONLY|MS_SYNCHRONOUS|MS_MANDLOCK)
 
 /*
  * Old magic mount flag and mask
···
 #define IS_NOQUOTA(inode)	((inode)->i_flags & S_NOQUOTA)
 #define IS_APPEND(inode)	((inode)->i_flags & S_APPEND)
 #define IS_IMMUTABLE(inode)	((inode)->i_flags & S_IMMUTABLE)
-#define IS_NOATIME(inode)	(__IS_FLG(inode, MS_NOATIME) || ((inode)->i_flags & S_NOATIME))
-#define IS_NODIRATIME(inode)	__IS_FLG(inode, MS_NODIRATIME)
 #define IS_POSIXACL(inode)	__IS_FLG(inode, MS_POSIXACL)
 
 #define IS_DEADDIR(inode)	((inode)->i_flags & S_DEAD)

include/linux/mount.h

···
 #define MNT_NOSUID	0x01
 #define MNT_NODEV	0x02
 #define MNT_NOEXEC	0x04
-#define MNT_SHARED	0x10	/* if the vfsmount is a shared mount */
-#define MNT_UNBINDABLE	0x20	/* if the vfsmount is a unbindable mount */
+#define MNT_NOATIME	0x08
+#define MNT_NODIRATIME	0x10
 
-#define MNT_PNODE_MASK	(MNT_SHARED | MNT_UNBINDABLE)
+#define MNT_SHARED	0x1000	/* if the vfsmount is a shared mount */
+#define MNT_UNBINDABLE	0x2000	/* if the vfsmount is a unbindable mount */
+#define MNT_PNODE_MASK	0x3000	/* propogation flag mask */
 
 struct vfsmount {
 	struct list_head mnt_hash;