Relative atime (was Re: What's in ocfs2.git)

Relative atime (was Re: What's in ocfs2.git)

[Valerie Henson]

On Mon, Dec 04, 2006 at 04:10:07PM -0800, Mark Fasheh wrote:
> Hi Steve,
> 
> On Mon, Dec 04, 2006 at 10:54:53AM +0000, Steven Whitehouse wrote:
> > > In the future, I'd like to see a "relative atime" mode, which functions
> > > in the manner described by Valerie Henson at:
> > > 
> > > http://lkml.org/lkml/2006/8/25/380
> > > 
> > I'd like to second that. [adding Val Henson to the "to"] What (if
> > anything) remains to be done before the relative atime patch is ready to
> > go upstream? I'm happy to help out here if required,
> Last time I looked at them, things seemed to be in pretty good shape - it
> wasn't a very large patch series.

Yep, the relative atime patch is tiny and pretty much done - just
needs some soak time in -mm and a little more review (cc'd Viro and
fsdevel).  Kernel patch against 2.6.18-rc4 appended, patch to mount
following. (Note that my web server suffered a RAID failure and my
patches page is unavailable till the restore finishes.)

-VAL

Add "relatime" (relative atime) support.  Relative atime only updates
the atime if the previous atime is older than the mtime or ctime.
Like noatime, but useful for applications like mutt that need to know
when a file has been read since it was last modified.

Signed-off-by: Valerie Henson <val_henson@linux.intel.com>

---
 fs/inode.c            |   11 ++++++++++-
 fs/namespace.c        |    5 ++++-
 include/linux/fs.h    |    1 +
 include/linux/mount.h |    1 +
 4 files changed, 16 insertions(+), 2 deletions(-)

--- linux-2.6.18-rc4-relatime.orig/fs/inode.c
+++ linux-2.6.18-rc4-relatime/fs/inode.c
@@ -1200,7 +1200,16 @@ void touch_atime(struct vfsmount *mnt, s
 		return;

 	now = current_fs_time(inode->i_sb);
-	if (!timespec_equal(&inode->i_atime, &now)) {
+	if (timespec_equal(&inode->i_atime, &now))
+		return;
+	/*
+	 * With relative atime, only update atime if the previous
+	 * atime is earlier than either the ctime or mtime.
+	 */
+	if (!mnt ||
+	    !(mnt->mnt_flags & MNT_RELATIME) ||
+	    (timespec_compare(&inode->i_atime, &inode->i_mtime) < 0) ||
+	    (timespec_compare(&inode->i_atime, &inode->i_ctime) < 0)) {
 		inode->i_atime = now;
 		mark_inode_dirty_sync(inode);
 	}
--- linux-2.6.18-rc4-relatime.orig/fs/namespace.c
+++ linux-2.6.18-rc4-relatime/fs/namespace.c
@@ -376,6 +376,7 @@ static int show_vfsmnt(struct seq_file *
 		{ MNT_NOEXEC, ",noexec" },
 		{ MNT_NOATIME, ",noatime" },
 		{ MNT_NODIRATIME, ",nodiratime" },
+		{ MNT_RELATIME, ",relatime" },
 		{ 0, NULL }
 	};
 	struct proc_fs_info *fs_infop;
@@ -1413,9 +1414,11 @@ long do_mount(char *dev_name, char *dir_
 		mnt_flags |= MNT_NOATIME;
 	if (flags & MS_NODIRATIME)
 		mnt_flags |= MNT_NODIRATIME;
+	if (flags & MS_RELATIME)
+		mnt_flags |= MNT_RELATIME;

 	flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE |
-		   MS_NOATIME | MS_NODIRATIME);
+		   MS_NOATIME | MS_NODIRATIME | MS_RELATIME);

 	/* ... and get the mountpoint */
 	retval = path_lookup(dir_name, LOOKUP_FOLLOW, &nd);
--- linux-2.6.18-rc4-relatime.orig/include/linux/fs.h
+++ linux-2.6.18-rc4-relatime/include/linux/fs.h
@@ -119,6 +119,7 @@ extern int dir_notify_enable;
 #define MS_PRIVATE	(1<<18)	/* change to private */
 #define MS_SLAVE	(1<<19)	/* change to slave */
 #define MS_SHARED	(1<<20)	/* change to shared */
+#define MS_RELATIME	(1<<21)	/* Update atime relative to mtime/ctime. */
 #define MS_ACTIVE	(1<<30)
 #define MS_NOUSER	(1<<31)

--- linux-2.6.18-rc4-relatime.orig/include/linux/mount.h
+++ linux-2.6.18-rc4-relatime/include/linux/mount.h
@@ -27,6 +27,7 @@ struct namespace;
 #define MNT_NOEXEC	0x04
 #define MNT_NOATIME	0x08
 #define MNT_NODIRATIME	0x10
+#define MNT_RELATIME	0x20

 #define MNT_SHRINKABLE	0x100

Re: Relative atime (was Re: What's in ocfs2.git)

[Valerie Henson]

On Mon, Dec 04, 2006 at 04:36:20PM -0800, Valerie Henson wrote:
> On Mon, Dec 04, 2006 at 04:10:07PM -0800, Mark Fasheh wrote:
> > Hi Steve,
> > 
> > On Mon, Dec 04, 2006 at 10:54:53AM +0000, Steven Whitehouse wrote:
> > > > In the future, I'd like to see a "relative atime" mode, which functions
> > > > in the manner described by Valerie Henson at:
> > > > 
> > > > http://lkml.org/lkml/2006/8/25/380
> > > > 
> > > I'd like to second that. [adding Val Henson to the "to"] What (if
> > > anything) remains to be done before the relative atime patch is ready to
> > > go upstream? I'm happy to help out here if required,
> > Last time I looked at them, things seemed to be in pretty good shape - it
> > wasn't a very large patch series.

And the userland part.

-VAL

Add the "relatime" (relative atime) option support to mount.  Relative
atime only updates the atime if the previous atime is older than the
mtime or ctime.  Like noatime, but useful for applications like mutt
that need to know when a file has been read since it was last
modified.

Signed-off-by: Valerie Henson <val_henson@linux.intel.com>

---
 mount/mount.8           |    7 +++++++
 mount/mount.c           |    6 ++++++
 mount/mount_constants.h |    4 ++++
 3 files changed, 17 insertions(+)
--- util-linux-2.13-pre7.orig/mount/mount.8
+++ util-linux-2.13-pre7/mount/mount.8
@@ -586,6 +586,13 @@ access on the news spool to speed up new
 .B nodiratime
 Do not update directory inode access times on this filesystem.
 .TP
+.B 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.)
+.TP
 .B noauto
 Can only be mounted explicitly (i.e., the
 .B \-a
--- util-linux-2.13-pre7.orig/mount/mount.c
+++ util-linux-2.13-pre7/mount/mount.c
@@ -164,6 +164,12 @@ static const struct opt_map opt_map[] =
   { "diratime",	0, 1, MS_NODIRATIME },	/* Update dir access times */
   { "nodiratime", 0, 0, MS_NODIRATIME },/* Do not update dir access times */
 #endif
+#ifdef MS_RELATIME
+  { "relatime", 0, 0, MS_RELATIME },	/* Update access times relative to
+					   mtime/ctime */
+  { "norelatime", 0, 1, MS_RELATIME },	/* Update access time without regard
+					   to mtime/ctime */
+#endif
   { NULL,	0, 0, 0		}
 };

--- util-linux-2.13-pre7.orig/mount/mount_constants.h
+++ util-linux-2.13-pre7/mount/mount_constants.h
@@ -57,6 +57,10 @@ if we have a stack or plain mount - moun
 #ifndef MS_VERBOSE
 #define MS_VERBOSE	0x8000	/* 32768 */
 #endif
+#ifndef MS_RELATIME
+#define MS_RELATIME   0x200000	/* 200000: Update access times relative
+				   to mtime/ctime */
+#endif
 /*
  * Magic mount flag number. Had to be or-ed to the flag values.
  */

Re: Relative atime (was Re: What's in ocfs2.git)

[Mark Fasheh]

On Mon, Dec 04, 2006 at 04:36:20PM -0800, Valerie Henson wrote:
> > Last time I looked at them, things seemed to be in pretty good shape - it
> > wasn't a very large patch series.
> 
> Yep, the relative atime patch is tiny and pretty much done - just
> needs some soak time in -mm and a little more review (cc'd Viro and
> fsdevel).  Kernel patch against 2.6.18-rc4 appended, patch to mount
> following. (Note that my web server suffered a RAID failure and my
> patches page is unavailable till the restore finishes.)

Well, here's what the ocfs2 patch would look like. If we care to push this
forward, some time in -mm would be nice...
	--Mark

From: Mark Fasheh <mark.fasheh@oracle.com>
Date: Tue, 5 Dec 2006 14:13:41 -0800
Subject: [PATCH] ocfs2: relative atime support

Update ocfs2_should_update_atime() to understand the MNT_RELATIME flag and
to test against mtime / ctime accordingly.

Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
---
 fs/ocfs2/file.c |    9 +++++++++
 1 files changed, 9 insertions(+), 0 deletions(-)

diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index 8786b3c..16a9b5e 100644
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -154,6 +154,15 @@ int ocfs2_should_update_atime(struct ino
 		return 0;
 
 	now = CURRENT_TIME;
+
+	if (vfsmnt->mnt_flags & MNT_RELATIME) {
+		if ((timespec_compare(&inode->i_atime, &inode->i_mtime) < 0) ||
+		    (timespec_compare(&inode->i_atime, &inode->i_ctime) < 0))
+			return 1;
+
+		return 0;
+	}
+
 	if ((now.tv_sec - inode->i_atime.tv_sec <= osb->s_atime_quantum))
 		return 0;
 	else
-- 
1.4.2.4

Re: Relative atime (was Re: What's in ocfs2.git)

[Andrew Morton]

On Tue, 5 Dec 2006 14:20:27 -0800
Mark Fasheh <mark.fasheh@oracle.com> wrote:

> Update ocfs2_should_update_atime() to understand the MNT_RELATIME flag and
> to test against mtime / ctime accordingly.
> 
> ...
>
> --- a/fs/ocfs2/file.c
> +++ b/fs/ocfs2/file.c
> @@ -154,6 +154,15 @@ int ocfs2_should_update_atime(struct ino
>  		return 0;
>  
>  	now = CURRENT_TIME;
> +
> +	if (vfsmnt->mnt_flags & MNT_RELATIME) {
> +		if ((timespec_compare(&inode->i_atime, &inode->i_mtime) < 0) ||
> +		    (timespec_compare(&inode->i_atime, &inode->i_ctime) < 0))
> +			return 1;
> +
> +		return 0;

So if atime == mtime == ctime, we don't update the atime.

I think we should.  It seems risky to leave them all equal.

Re: Relative atime (was Re: What's in ocfs2.git)

[Andrew Morton]

> On Mon, 4 Dec 2006 16:36:20 -0800 Valerie Henson <val_henson@linux.intel.com> wrote:
> Add "relatime" (relative atime) support.  Relative atime only updates
> the atime if the previous atime is older than the mtime or ctime.
> Like noatime, but useful for applications like mutt that need to know
> when a file has been read since it was last modified.

That seems like a good idea.

I found touch_atime() to be rather putrid, so I hacked it around a bit.  The
end result:

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)
		return;
	if ((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) {
		if (mnt->mnt_flags & MNT_NOATIME)
			return;
		if ((mnt->mnt_flags & MNT_NODIRATIME) && S_ISDIR(inode->i_mode))
			return;

		if (mnt->mnt_flags & MNT_RELATIME) {
			/*
			 * With relative atime, only update atime if the
			 * previous atime is earlier than either the ctime or
			 * mtime.
			 */
			if (timespec_compare(&inode->i_mtime,
						&inode->i_atime) < 0 &&
			    timespec_compare(&inode->i_ctime,
						&inode->i_atime) < 0)
				return;
		}
	}

	now = current_fs_time(inode->i_sb);
	if (timespec_equal(&inode->i_atime, &now))
		return;

	inode->i_atime = now;
	mark_inode_dirty_sync(inode);
}

Does it still look right?

Note the reordering to avoid the current_fs_time() call if poss.


That's the easy part.   How are we going to get mount(8) patched?

Re: Relative atime (was Re: What's in ocfs2.git)

[Valerie Henson]

On Tue, Dec 05, 2006 at 08:58:02PM -0800, Andrew Morton wrote:
> > On Mon, 4 Dec 2006 16:36:20 -0800 Valerie Henson <val_henson@linux.intel.com> wrote:
> > Add "relatime" (relative atime) support.  Relative atime only updates
> > the atime if the previous atime is older than the mtime or ctime.
> > Like noatime, but useful for applications like mutt that need to know
> > when a file has been read since it was last modified.
> 
> That seems like a good idea.
> 
> I found touch_atime() to be rather putrid, so I hacked it around a bit.  The
> end result:

I like that rather better - add my:

Signed-off-by: Valerie Henson <val_henson@linux.intel.com>

> That's the easy part.   How are we going to get mount(8) patched?

Well, the nodiratime documentation got in. (I was going to add that as
part of this apatch, but lo and behold.)

-VAL

Re: Relative atime (was Re: What's in ocfs2.git)

[Eric Dumazet]

On Wednesday 06 December 2006 05:58, Andrew Morton wrote:
> > On Mon, 4 Dec 2006 16:36:20 -0800 Valerie Henson
> > <val_henson@linux.intel.com> wrote: Add "relatime" (relative atime)
> > support.  Relative atime only updates the atime if the previous atime is
> > older than the mtime or ctime. Like noatime, but useful for applications
> > like mutt that need to know when a file has been read since it was last
> > modified.
>
> That seems like a good idea.
>
> I found touch_atime() to be rather putrid, so I hacked it around a bit. 

I find this function full of tests...

> The end result:
>
> void touch_atime(struct vfsmount *mnt, struct dentry *dentry)
> {
> 	struct inode *inode = dentry->d_inode;
> 	struct timespec now;
>
> 	if (IS_RDONLY(inode))
> 		return;

While we are adding new tests, we could try to be smart here testing both 
MS_RDONLY and MS_NOATIME.

if (__IS_FLG(inode, MS_RDONLY | MS_NOATIME))
	return;

> 	if (inode->i_flags & S_NOATIME)
> 		return;

> 	if (inode->i_sb->s_flags & MS_NOATIME)
> 		return;
So that that one can be deleted.

>        if ((inode->i_sb->s_flags & MS_NODIRATIME) && S_ISDIR(inode->i_mode))
>                return;

	if (__IS_FLG(inode, MS_NODIRATIME) && S_ISDIR(inode->i_mode))
		return;

Eric
-
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: Relative atime (was Re: What's in ocfs2.git)

[Arjan van de Ven]

> 
> > 	if (inode->i_sb->s_flags & MS_NOATIME)
> > 		return;
> So that that one can be deleted.


Hi,

I would mostly expect the compiler to be relatively smart about this and
group a bunch of these tests together... so I rather see readable code
than optimized code for something the compiler should be doing for us ;)

Greetings,
   Arjan van de Ven

Re: Relative atime (was Re: What's in ocfs2.git)

[Valerie Henson]

On Tue, Dec 05, 2006 at 08:58:02PM -0800, Andrew Morton wrote:
> That's the easy part.   How are we going to get mount(8) patched?

Karel, interested in taking a look at the following patch?  The kernel
bits are in -mm currently.

-VAL

Add the "relatime" (relative atime) option support to mount.  Relative
atime only updates the atime if the previous atime is older than the
mtime or ctime.  Like noatime, but useful for applications like mutt
that need to know when a file has been read since it was last
modified.

Cc: Adrian Bunk <bunk@stusta.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Karel Zak <kzak@redhat.com>

Signed-off-by: Valerie Henson <val_henson@linux.intel.com>

---
 mount/mount.8           |    7 +++++++
 mount/mount.c           |    6 ++++++
 mount/mount_constants.h |    4 ++++
 3 files changed, 17 insertions(+)

--- util-linux-2.13-pre7.orig/mount/mount.8
+++ util-linux-2.13-pre7/mount/mount.8
@@ -586,6 +586,13 @@ access on the news spool to speed up new
 .B nodiratime
 Do not update directory inode access times on this filesystem.
 .TP
+.B 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.)
+.TP
 .B noauto
 Can only be mounted explicitly (i.e., the
 .B \-a
--- util-linux-2.13-pre7.orig/mount/mount.c
+++ util-linux-2.13-pre7/mount/mount.c
@@ -164,6 +164,12 @@ static const struct opt_map opt_map[] = 
   { "diratime",	0, 1, MS_NODIRATIME },	/* Update dir access times */
   { "nodiratime", 0, 0, MS_NODIRATIME },/* Do not update dir access times */
 #endif
+#ifdef MS_RELATIME
+  { "relatime", 0, 0, MS_RELATIME },	/* Update access times relative to
+					   mtime/ctime */
+  { "norelatime", 0, 1, MS_RELATIME },	/* Update access time without regard
+					   to mtime/ctime */
+#endif
   { NULL,	0, 0, 0		}
 };
 
--- util-linux-2.13-pre7.orig/mount/mount_constants.h
+++ util-linux-2.13-pre7/mount/mount_constants.h
@@ -57,6 +57,10 @@ if we have a stack or plain mount - moun
 #ifndef MS_VERBOSE
 #define MS_VERBOSE	0x8000	/* 32768 */
 #endif
+#ifndef MS_RELATIME
+#define MS_RELATIME   0x200000	/* 200000: Update access times relative
+				   to mtime/ctime */
+#endif
 /*
  * Magic mount flag number. Had to be or-ed to the flag values.
  */

Re: Relative atime (was Re: What's in ocfs2.git)

[Karel Zak]

On Fri, Dec 08, 2006 at 07:15:14PM -0800, Valerie Henson wrote:
> On Tue, Dec 05, 2006 at 08:58:02PM -0800, Andrew Morton wrote:
> > That's the easy part.   How are we going to get mount(8) patched?
> 
> Karel, interested in taking a look at the following patch?  The kernel
> bits are in -mm currently.

 The patch looks good. I'll add it to my development util-linux tree.
 Thanks.

    Karel

> Add the "relatime" (relative atime) option support to mount.  Relative
> atime only updates the atime if the previous atime is older than the
> mtime or ctime.  Like noatime, but useful for applications like mutt
> that need to know when a file has been read since it was last
> modified.
> 
> Cc: Adrian Bunk <bunk@stusta.de>
> Cc: Al Viro <viro@zeniv.linux.org.uk>
> Cc: Karel Zak <kzak@redhat.com>
> 
> Signed-off-by: Valerie Henson <val_henson@linux.intel.com>
> 
> ---
>  mount/mount.8           |    7 +++++++
>  mount/mount.c           |    6 ++++++
>  mount/mount_constants.h |    4 ++++
>  3 files changed, 17 insertions(+)
> 
> --- util-linux-2.13-pre7.orig/mount/mount.8
> +++ util-linux-2.13-pre7/mount/mount.8
> @@ -586,6 +586,13 @@ access on the news spool to speed up new
>  .B nodiratime
>  Do not update directory inode access times on this filesystem.
>  .TP
> +.B 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.)
> +.TP
>  .B noauto
>  Can only be mounted explicitly (i.e., the
>  .B \-a
> --- util-linux-2.13-pre7.orig/mount/mount.c
> +++ util-linux-2.13-pre7/mount/mount.c
> @@ -164,6 +164,12 @@ static const struct opt_map opt_map[] = 
>    { "diratime",	0, 1, MS_NODIRATIME },	/* Update dir access times */
>    { "nodiratime", 0, 0, MS_NODIRATIME },/* Do not update dir access times */
>  #endif
> +#ifdef MS_RELATIME
> +  { "relatime", 0, 0, MS_RELATIME },	/* Update access times relative to
> +					   mtime/ctime */
> +  { "norelatime", 0, 1, MS_RELATIME },	/* Update access time without regard
> +					   to mtime/ctime */
> +#endif
>    { NULL,	0, 0, 0		}
>  };
>  
> --- util-linux-2.13-pre7.orig/mount/mount_constants.h
> +++ util-linux-2.13-pre7/mount/mount_constants.h
> @@ -57,6 +57,10 @@ if we have a stack or plain mount - moun
>  #ifndef MS_VERBOSE
>  #define MS_VERBOSE	0x8000	/* 32768 */
>  #endif
> +#ifndef MS_RELATIME
> +#define MS_RELATIME   0x200000	/* 200000: Update access times relative
> +				   to mtime/ctime */
> +#endif
>  /*
>   * Magic mount flag number. Had to be or-ed to the flag values.
>   */
> -
> To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

-- 
 Karel Zak  <kzak@redhat.com>