[PATCH] iomap: wait for batched folios to be stable in __iomap_get_folio

[PATCH] iomap: wait for batched folios to be stable in __iomap_get_folio

[Christoph Hellwig]

__iomap_get_folio needs to wait for writeback to finish if the file
requires folios to be stable for writes.  For the regular path this is
taken care of by __filemap_get_folio, but for the newly added batch
lookup it has to be done manually.

This fixes xfs/131 failures when running on PI-capable hardware.

Fixes: 395ed1ef0012 ("iomap: optional zero range dirty folio processing")
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/iomap/buffered-io.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index fd9a2cf95620..6beb876658c0 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -851,6 +851,7 @@ static struct folio *__iomap_get_folio(struct iomap_iter *iter,
 		}
 
 		folio_get(folio);
+		folio_wait_stable(folio);
 		return folio;
 	}
 
-- 
2.47.3

Re: [PATCH] iomap: wait for batched folios to be stable in __iomap_get_folio

[Darrick J. Wong]

On Tue, Jan 13, 2026 at 04:39:17PM +0100, Christoph Hellwig wrote:
> __iomap_get_folio needs to wait for writeback to finish if the file
> requires folios to be stable for writes.  For the regular path this is
> taken care of by __filemap_get_folio, but for the newly added batch
> lookup it has to be done manually.
> 
> This fixes xfs/131 failures when running on PI-capable hardware.
> 
> Fixes: 395ed1ef0012 ("iomap: optional zero range dirty folio processing")
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  fs/iomap/buffered-io.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
> index fd9a2cf95620..6beb876658c0 100644
> --- a/fs/iomap/buffered-io.c
> +++ b/fs/iomap/buffered-io.c
> @@ -851,6 +851,7 @@ static struct folio *__iomap_get_folio(struct iomap_iter *iter,
>  		}
>  
>  		folio_get(folio);
> +		folio_wait_stable(folio);

Heh, oops.  That's a little too easy to miss. :(

I wonder if we ought to have a filemap_fbatch_next() that would take
care of the relocking, revalidation, and stabilization... but this spot
fix is good as-is.

Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>

--D

>  		return folio;
>  	}
>  
> -- 
> 2.47.3
> 

Re: [PATCH] iomap: wait for batched folios to be stable in __iomap_get_folio

[Brian Foster]

On Tue, Jan 13, 2026 at 04:39:17PM +0100, Christoph Hellwig wrote:
> __iomap_get_folio needs to wait for writeback to finish if the file
> requires folios to be stable for writes.  For the regular path this is
> taken care of by __filemap_get_folio, but for the newly added batch
> lookup it has to be done manually.
> 
> This fixes xfs/131 failures when running on PI-capable hardware.
> 
> Fixes: 395ed1ef0012 ("iomap: optional zero range dirty folio processing")
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---

Reviewed-by: Brian Foster <bfoster@redhat.com>

>  fs/iomap/buffered-io.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
> index fd9a2cf95620..6beb876658c0 100644
> --- a/fs/iomap/buffered-io.c
> +++ b/fs/iomap/buffered-io.c
> @@ -851,6 +851,7 @@ static struct folio *__iomap_get_folio(struct iomap_iter *iter,
>  		}
>  
>  		folio_get(folio);
> +		folio_wait_stable(folio);
>  		return folio;
>  	}
>  
> -- 
> 2.47.3
> 
> 

Re: [PATCH] iomap: wait for batched folios to be stable in __iomap_get_folio

[Christoph Hellwig]

On Tue, Jan 13, 2026 at 07:48:55AM -0800, Darrick J. Wong wrote:
> I wonder if we ought to have a filemap_fbatch_next() that would take
> care of the relocking, revalidation, and stabilization... but this spot
> fix is good as-is.

Let's wait until we have another user or two.  Premature refactoring
tends to backfire.

Re: [PATCH] iomap: wait for batched folios to be stable in __iomap_get_folio

[Brian Foster]

On Tue, Jan 13, 2026 at 04:58:05PM +0100, Christoph Hellwig wrote:
> On Tue, Jan 13, 2026 at 07:48:55AM -0800, Darrick J. Wong wrote:
> > I wonder if we ought to have a filemap_fbatch_next() that would take
> > care of the relocking, revalidation, and stabilization... but this spot
> > fix is good as-is.
> 
> Let's wait until we have another user or two.  Premature refactoring
> tends to backfire.
> 

I agree on not being too aggressive on that... I do like the idea
though, so I'll try to keep it in mind if this happens to expand down
the road. Thanks for the fix.

Brian

Re: [PATCH] iomap: wait for batched folios to be stable in __iomap_get_folio

[Darrick J. Wong]

On Tue, Jan 13, 2026 at 11:12:01AM -0500, Brian Foster wrote:
> On Tue, Jan 13, 2026 at 04:58:05PM +0100, Christoph Hellwig wrote:
> > On Tue, Jan 13, 2026 at 07:48:55AM -0800, Darrick J. Wong wrote:
> > > I wonder if we ought to have a filemap_fbatch_next() that would take
> > > care of the relocking, revalidation, and stabilization... but this spot
> > > fix is good as-is.
> > 
> > Let's wait until we have another user or two.  Premature refactoring
> > tends to backfire.
> > 
> 
> I agree on not being too aggressive on that... I do like the idea
> though, so I'll try to keep it in mind if this happens to expand down
> the road. Thanks for the fix.

<nod> Making the second user do the refactoring is ok with me. :)

--D

> Brian
> 
> 

Re: [PATCH] iomap: wait for batched folios to be stable in __iomap_get_folio

[Christian Brauner]

On Tue, 13 Jan 2026 16:39:17 +0100, Christoph Hellwig wrote:
> __iomap_get_folio needs to wait for writeback to finish if the file
> requires folios to be stable for writes.  For the regular path this is
> taken care of by __filemap_get_folio, but for the newly added batch
> lookup it has to be done manually.
> 
> This fixes xfs/131 failures when running on PI-capable hardware.
> 
> [...]

Applied to the vfs.fixes branch of the vfs/vfs.git tree.
Patches in the vfs.fixes branch should appear in linux-next soon.

Please report any outstanding bugs that were missed during review in a
new review to the original patch series allowing us to drop it.

It's encouraged to provide Acked-bys and Reviewed-bys even though the
patch has now been applied. If possible patch trailers will be updated.

Note that commit hashes shown below are subject to change due to rebase,
trailer updates or similar. If in doubt, please check the listed branch.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git
branch: vfs.fixes

[1/1] iomap: wait for batched folios to be stable in __iomap_get_folio
      https://git.kernel.org/vfs/vfs/c/561940a7ee81