RAMFS

RAMFS

[Alan Cox]

Random quick poking

Does this fix the ramfs problem in -ac ?


--- fs/ramfs/inode.c~	Wed Jan 31 22:02:16 2001
+++ fs/ramfs/inode.c	Fri Feb  2 14:51:47 2001
@@ -174,7 +174,6 @@
 		inode->i_blocks += IBLOCKS_PER_PAGE;
 		rsb->free_pages--;
 		SetPageDirty(page);
-		UnlockPage(page);
 	} else {
 		ClearPageUptodate(page);
 		ret = 0;
@@ -264,6 +263,7 @@
 
 	if (! ramfs_alloc_page(inode, page))
 		return -ENOSPC;
+	UnlockPage(page);
 	return 0;
 }
 
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Re: RAMFS

[Ingo Oeser]

On Fri, Feb 02, 2001 at 03:51:53PM +0000, Alan Cox wrote:
> Does this fix the ramfs problem in -ac ?
> 
> --- fs/ramfs/inode.c~	Wed Jan 31 22:02:16 2001
> +++ fs/ramfs/inode.c	Fri Feb  2 14:51:47 2001
> @@ -174,7 +174,6 @@
>  		inode->i_blocks += IBLOCKS_PER_PAGE;
>  		rsb->free_pages--;
>  		SetPageDirty(page);
> -		UnlockPage(page);
>  	} else {
>  		ClearPageUptodate(page);
>  		ret = 0;
> @@ -264,6 +263,7 @@
>  
>  	if (! ramfs_alloc_page(inode, page))
>  		return -ENOSPC;
> +	UnlockPage(page);
>  	return 0;
>  }

No, so have to unlock it also, if you return -ENOSPC.

So the correct fix seems to be:

--- linux/fs/ramfs/inode.c~	Wed Jan 31 22:02:16 2001
+++ linux/fs/ramfs/inode.c	Fri Feb  2 14:51:47 2001
@@ -174,7 +174,6 @@
 		inode->i_blocks += IBLOCKS_PER_PAGE;
 		rsb->free_pages--;
 		SetPageDirty(page);
-		UnlockPage(page);
 	} else {
 		ClearPageUptodate(page);
 		ret = 0;
@@ -264,6 +263,9 @@
 
- 	if (! ramfs_alloc_page(inode, page))
+ 	if (! ramfs_alloc_page(inode, page)) {
+		UnlockPage(page);
 		return -ENOSPC;
+	}
+	UnlockPage(page);
 	return 0;
 }

This currently works for me (but using 2.4.0 + dwg-ramfs.patch + this patch)

Regards

Ingo Oeser
-- 
10.+11.03.2001 - 3. Chemnitzer LinuxTag <http://www.tu-chemnitz.de/linux/tag>
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Re: RAMFS

[Mike Galbraith]

On Fri, 2 Feb 2001, Ingo Oeser wrote:

> No, so have to unlock it also, if you return -ENOSPC.
> 
> So the correct fix seems to be:
> 
> --- linux/fs/ramfs/inode.c~	Wed Jan 31 22:02:16 2001
> +++ linux/fs/ramfs/inode.c	Fri Feb  2 14:51:47 2001
> @@ -174,7 +174,6 @@
>  		inode->i_blocks += IBLOCKS_PER_PAGE;
>  		rsb->free_pages--;
>  		SetPageDirty(page);
> -		UnlockPage(page);
>  	} else {
>  		ClearPageUptodate(page);
>  		ret = 0;
> @@ -264,6 +263,9 @@
>  
> - 	if (! ramfs_alloc_page(inode, page))
> + 	if (! ramfs_alloc_page(inode, page)) {
> +		UnlockPage(page);
>  		return -ENOSPC;
> +	}
> +	UnlockPage(page);
>  	return 0;
>  }
> 
> This currently works for me (but using 2.4.0 + dwg-ramfs.patch + this patch)

Have you stressed it?  (I see leakiness)

	-Mike

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Re: RAMFS

[Ingo Oeser]

On Fri, Feb 02, 2001 at 08:24:19PM +0100, Mike Galbraith wrote:
> On Fri, 2 Feb 2001, Ingo Oeser wrote:
> > No, so have to unlock it also, if you return -ENOSPC.
> > 
> > So the correct fix seems to be:
[...]
> > This currently works for me (but using 2.4.0 + dwg-ramfs.patch + this patch)
>
> Have you stressed it?  (I see leakiness)

I do reads and writes to it every 5 seconds and sometimes more (
mounted on /tmp, /var/run and the like ) and had an uptime of
about a week (I use it in an embedded-like system and we
sometimes change the system image).

There might be a dentry or inode leak, but that doesn't bite me,
because I only create the files I need once and extend or shrink
them.

But I couldn't stress it too much.

Where exactly do you see the leaks?

PS: For reference, I put the diff to 2.4.0 that I use to
   http://www.tu-chemnitz.de/~ioe/dwg-ramfs.patch

   The original patch has _not_ been done by me, but by
   David Gibson, Linuxcare Australia.

PPS: It would be surprising anyway, if I used the right patch all
   the time, while the wrong one was in acX. That's why I didn't
   submit anything ;-)

Regards

Ingo Oeser
-- 
10.+11.03.2001 - 3. Chemnitzer LinuxTag <http://www.tu-chemnitz.de/linux/tag>
         <<<<<<<<<<<<       come and join the fun       >>>>>>>>>>>>
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Re: RAMFS

[Mike Galbraith]

On Fri, 2 Feb 2001, Ingo Oeser wrote:

> On Fri, Feb 02, 2001 at 08:24:19PM +0100, Mike Galbraith wrote:
> > On Fri, 2 Feb 2001, Ingo Oeser wrote:
> > > No, so have to unlock it also, if you return -ENOSPC.
> > > 
> > > So the correct fix seems to be:
> [...]
> > > This currently works for me (but using 2.4.0 + dwg-ramfs.patch + this patch)
> >
> > Have you stressed it?  (I see leakiness)
> 
> I do reads and writes to it every 5 seconds and sometimes more (
> mounted on /tmp, /var/run and the like ) and had an uptime of
> about a week (I use it in an embedded-like system and we
> sometimes change the system image).
> 
> There might be a dentry or inode leak, but that doesn't bite me,
> because I only create the files I need once and extend or shrink
> them.

That won't show it. I can do that kind of stuff all day long, no
problem whatsoever.

> But I couldn't stress it too much.
> 
> Where exactly do you see the leaks?

(I don't have a solid grip yet.. just starting to seek)

> PS: For reference, I put the diff to 2.4.0 that I use to
>    http://www.tu-chemnitz.de/~ioe/dwg-ramfs.patch
> 
>    The original patch has _not_ been done by me, but by
>    David Gibson, Linuxcare Australia.

I'll take a look at this.. thanks.

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Re: RAMFS

[Mike Galbraith]

On Fri, 2 Feb 2001, Mike Galbraith wrote:

> > Where exactly do you see the leaks?
> 
> (I don't have a solid grip yet.. just starting to seek)

Heh.  I figured this must be a nice defenseless little buglet
I could pick on (ramfs is pretty darn simple).  Critter might
not be quite as defenseless as I presumed ;-)

Using ramfs under vm pressure breaks (hmm.. spinlock) instantly
on my UP box.

	-Mike

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