[PATCH] xfs: writepage always has buffers

[PATCH] xfs: writepage always has buffers

[Christoph Hellwig]

These days we always have buffers thanks to ->page_mkwrite.  And we already
have an assert a few lines above tripping in case that was not true due to
a bug.

Signed-off-by: Christoph Hellwig <hch@lst.de>

Index: xfs-dev/fs/xfs/linux-2.6/xfs_aops.c
===================================================================
--- xfs-dev.orig/fs/xfs/linux-2.6/xfs_aops.c	2010-06-28 11:59:29.590253914 +0200
+++ xfs-dev/fs/xfs/linux-2.6/xfs_aops.c	2010-06-28 11:59:48.341006462 +0200
@@ -1072,13 +1072,6 @@ xfs_vm_writepage(
 	if ((current->flags & PF_FSTRANS) && (delalloc || unwritten))
 		goto out_fail;
 
-	/*
-	 * Delay hooking up buffer heads until we have
-	 * made our go/no-go decision.
-	 */
-	if (!page_has_buffers(page))
-		create_empty_buffers(page, 1 << inode->i_blkbits, 0);
-
 	/* Is this page beyond the end of the file? */
 	offset = i_size_read(inode);
 	end_index = offset >> PAGE_CACHE_SHIFT;

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Re: [PATCH] xfs: writepage always has buffers

[Christoph Hellwig]

ping?

On Mon, Jun 28, 2010 at 10:34:57AM -0400, Christoph Hellwig wrote:
> These days we always have buffers thanks to ->page_mkwrite.  And we already
> have an assert a few lines above tripping in case that was not true due to
> a bug.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> 
> Index: xfs-dev/fs/xfs/linux-2.6/xfs_aops.c
> ===================================================================
> --- xfs-dev.orig/fs/xfs/linux-2.6/xfs_aops.c	2010-06-28 11:59:29.590253914 +0200
> +++ xfs-dev/fs/xfs/linux-2.6/xfs_aops.c	2010-06-28 11:59:48.341006462 +0200
> @@ -1072,13 +1072,6 @@ xfs_vm_writepage(
>  	if ((current->flags & PF_FSTRANS) && (delalloc || unwritten))
>  		goto out_fail;
>  
> -	/*
> -	 * Delay hooking up buffer heads until we have
> -	 * made our go/no-go decision.
> -	 */
> -	if (!page_has_buffers(page))
> -		create_empty_buffers(page, 1 << inode->i_blkbits, 0);
> -
>  	/* Is this page beyond the end of the file? */
>  	offset = i_size_read(inode);
>  	end_index = offset >> PAGE_CACHE_SHIFT;
> 
> _______________________________________________
> xfs mailing list
> xfs@oss.sgi.com
> http://oss.sgi.com/mailman/listinfo/xfs
---end quoted text---

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Re: [PATCH] xfs: writepage always has buffers

[Alex Elder]

On Mon, 2010-06-28 at 10:34 -0400, Christoph Hellwig wrote:
> These days we always have buffers thanks to ->page_mkwrite.  And we already
> have an assert a few lines above tripping in case that was not true due to
> a bug.

Should the ASSERT() be made stronger (i.e., BUG_ON())?
Looks to me like we'll crash if it ever happens in a
non-debug kernel, and a BUG() call would more directly
tell us what the problem was...

In an case, this looks OK to me.

> Signed-off-by: Christoph Hellwig <hch@lst.de>

Reviewed-by: Alex Elder <aelder@sgi.com>

> Index: xfs-dev/fs/xfs/linux-2.6/xfs_aops.c
> ===================================================================
> --- xfs-dev.orig/fs/xfs/linux-2.6/xfs_aops.c	2010-06-28 11:59:29.590253914 +0200
> +++ xfs-dev/fs/xfs/linux-2.6/xfs_aops.c	2010-06-28 11:59:48.341006462 +0200
> @@ -1072,13 +1072,6 @@ xfs_vm_writepage(
>  	if ((current->flags & PF_FSTRANS) && (delalloc || unwritten))
>  		goto out_fail;
>  
> -	/*
> -	 * Delay hooking up buffer heads until we have
> -	 * made our go/no-go decision.
> -	 */
> -	if (!page_has_buffers(page))
> -		create_empty_buffers(page, 1 << inode->i_blkbits, 0);
> -
>  	/* Is this page beyond the end of the file? */
>  	offset = i_size_read(inode);
>  	end_index = offset >> PAGE_CACHE_SHIFT;
> 
> _______________________________________________
> xfs mailing list
> xfs@oss.sgi.com
> http://oss.sgi.com/mailman/listinfo/xfs



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Re: [PATCH] xfs: writepage always has buffers

[Christoph Hellwig]

On Sun, Jul 11, 2010 at 10:43:09PM -0500, Alex Elder wrote:
> On Mon, 2010-06-28 at 10:34 -0400, Christoph Hellwig wrote:
> > These days we always have buffers thanks to ->page_mkwrite.  And we already
> > have an assert a few lines above tripping in case that was not true due to
> > a bug.
> 
> Should the ASSERT() be made stronger (i.e., BUG_ON())?
> Looks to me like we'll crash if it ever happens in a
> non-debug kernel, and a BUG() call would more directly
> tell us what the problem was...

The crash tells it quite directly as well, the ASSERT is there more as
a documentation of what we require.

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