linux-kernel - Re: [PATCH v2 3/8] fsdax: zero the edges if source is HOLE or UNWRITTEN

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Message-Id: <20221201163929.ddd992063d9872ab33459bbf@linux-foundation.org>
Date:   Thu, 1 Dec 2022 16:39:29 -0800
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     "Darrick J. Wong" <djwong@...nel.org>
Cc:     Shiyang Ruan <ruansy.fnst@...itsu.com>,
        linux-kernel@...r.kernel.org, linux-xfs@...r.kernel.org,
        nvdimm@...ts.linux.dev, linux-fsdevel@...r.kernel.org,
        david@...morbit.com, dan.j.williams@...el.com
Subject: Re: [PATCH v2 3/8] fsdax: zero the edges if source is HOLE or
 UNWRITTEN

On Thu, 1 Dec 2022 15:58:11 -0800 "Darrick J. Wong" <djwong@...nel.org> wrote:

> > --- a/fs/dax.c
> > +++ b/fs/dax.c
> > @@ -1092,7 +1092,7 @@ static int dax_iomap_direct_access(const struct iomap *iomap, loff_t pos,
> >  }
> >  
> >  /**
> > - * dax_iomap_cow_copy - Copy the data from source to destination before write
> > + * dax_iomap_copy_around - Copy the data from source to destination before write
> 
>  * dax_iomap_copy_around - Prepare for an unaligned write to a
>  * shared/cow page by copying the data before and after the range to be
>  * written.

Thanks, I added this:

--- a/fs/dax.c~fsdax-zero-the-edges-if-source-is-hole-or-unwritten-fix
+++ a/fs/dax.c
@@ -1092,7 +1092,8 @@ out:
 }
 
 /**
- * dax_iomap_copy_around - Copy the data from source to destination before write
+ * dax_iomap_copy_around - Prepare for an unaligned write to a shared/cow page
+ * by copying the data before and after the range to be written.
  * @pos:	address to do copy from.
  * @length:	size of copy operation.
  * @align_size:	aligned w.r.t align_size (either PMD_SIZE or PAGE_SIZE)
_