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From: Dan Williams <dan.j.williams@intel.com>
To: Christoph Hellwig <hch@lst.de>
Cc: "Darrick J. Wong" <djwong@kernel.org>,
	Matthew Wilcox <willy@infradead.org>,
	 Andreas Gruenbacher <agruenba@redhat.com>,
	Shiyang Ruan <ruansy.fnst@fujitsu.com>,
	 linux-xfs <linux-xfs@vger.kernel.org>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	 linux-btrfs <linux-btrfs@vger.kernel.org>,
	Linux NVDIMM <nvdimm@lists.linux.dev>,
	 cluster-devel@redhat.com
Subject: Re: [PATCH 11/30] iomap: add the new iomap_iter model
Date: Thu, 19 Aug 2021 14:25:52 -0700	[thread overview]
Message-ID: <CAPcyv4hbSYnOC6Pdi1QShRxGjBAteig7nN1h-5cEvsFDX9SuAQ@mail.gmail.com> (raw)
In-Reply-To: <20210809061244.1196573-12-hch@lst.de>

On Sun, Aug 8, 2021 at 11:23 PM Christoph Hellwig <hch@lst.de> wrote:
>
> The iomap_iter struct provides a convenient way to package up and
> maintain all the arguments to the various mapping and operation
> functions.  It is operated on using the iomap_iter() function that
> is called in loop until the whole range has been processed.  Compared
> to the existing iomap_apply() function this avoid an indirect call
> for each iteration.
>
> For now iomap_iter() calls back into the existing ->iomap_begin and
> ->iomap_end methods, but in the future this could be further optimized
> to avoid indirect calls entirely.
>
> Based on an earlier patch from Matthew Wilcox <willy@infradead.org>.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  fs/iomap/Makefile     |  1 +
>  fs/iomap/core.c       | 79 +++++++++++++++++++++++++++++++++++++++++++
>  fs/iomap/trace.h      | 37 +++++++++++++++++++-
>  include/linux/iomap.h | 56 ++++++++++++++++++++++++++++++
>  4 files changed, 172 insertions(+), 1 deletion(-)
>  create mode 100644 fs/iomap/core.c
>
> diff --git a/fs/iomap/Makefile b/fs/iomap/Makefile
> index eef2722d93a183..6b56b10ded347a 100644
> --- a/fs/iomap/Makefile
> +++ b/fs/iomap/Makefile
> @@ -10,6 +10,7 @@ obj-$(CONFIG_FS_IOMAP)                += iomap.o
>
>  iomap-y                                += trace.o \
>                                    apply.o \
> +                                  core.o \
>                                    buffered-io.o \
>                                    direct-io.o \
>                                    fiemap.o \
> diff --git a/fs/iomap/core.c b/fs/iomap/core.c
> new file mode 100644
> index 00000000000000..89a87a1654e8e6
> --- /dev/null
> +++ b/fs/iomap/core.c
> @@ -0,0 +1,79 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2021 Christoph Hellwig.
> + */
> +#include <linux/fs.h>
> +#include <linux/iomap.h>
> +#include "trace.h"
> +
> +static inline int iomap_iter_advance(struct iomap_iter *iter)
> +{
> +       /* handle the previous iteration (if any) */
> +       if (iter->iomap.length) {
> +               if (iter->processed <= 0)
> +                       return iter->processed;
> +               if (WARN_ON_ONCE(iter->processed > iomap_length(iter)))
> +                       return -EIO;
> +               iter->pos += iter->processed;
> +               iter->len -= iter->processed;
> +               if (!iter->len)
> +                       return 0;
> +       }
> +
> +       /* clear the state for the next iteration */
> +       iter->processed = 0;
> +       memset(&iter->iomap, 0, sizeof(iter->iomap));
> +       memset(&iter->srcmap, 0, sizeof(iter->srcmap));
> +       return 1;
> +}
> +
> +static inline void iomap_iter_done(struct iomap_iter *iter)
> +{
> +       WARN_ON_ONCE(iter->iomap.offset > iter->pos);
> +       WARN_ON_ONCE(iter->iomap.length == 0);
> +       WARN_ON_ONCE(iter->iomap.offset + iter->iomap.length <= iter->pos);
> +
> +       trace_iomap_iter_dstmap(iter->inode, &iter->iomap);
> +       if (iter->srcmap.type != IOMAP_HOLE)
> +               trace_iomap_iter_srcmap(iter->inode, &iter->srcmap);

Given most of the iomap_iter users don't care about srcmap, i.e. are
not COW cases, they are leaving srcmap zero initialized. Should the
IOMAP types be incremented by one so that there is no IOMAP_HOLE
confusion? In other words, fold something like this?

diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index 479c1da3e221..b9c62d0909b0 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -21,14 +21,23 @@ struct page;
 struct vm_area_struct;
 struct vm_fault;

-/*
- * Types of block ranges for iomap mappings:
+/**
+ * enum iomap_type - Types of block ranges for iomap mappings
+ * @IOMAP_NONE: invalid iomap
+ * @IOMAP_HOLE: no blocks allocated, need allocation
+ * @IOMAP_DELALLOC: delayed allocation blocks
+ * @IOMAP_MAPPED: blocks allocated at @addr
+ * @IOMAP_UNWRITTEN: blocks allocated at @addr in unwritten state
+ * @IOMAP_INLINE: data inline in the inode
  */
-#define IOMAP_HOLE     0       /* no blocks allocated, need allocation */
-#define IOMAP_DELALLOC 1       /* delayed allocation blocks */
-#define IOMAP_MAPPED   2       /* blocks allocated at @addr */
-#define IOMAP_UNWRITTEN        3       /* blocks allocated at @addr
in unwritten state */
-#define IOMAP_INLINE   4       /* data inline in the inode */
+enum iomap_type {
+       IOMAP_NONE = 0,
+       IOMAP_HOLE,
+       IOMAP_DELALLOC
+       IOMAP_MAPPED,
+       IOMAP_UNWRITTEN,
+       IOMAP_INLINE,
+};

 /*
  * Flags reported by the file system from iomap_begin:


> +}
> +
> +/**
> + * iomap_iter - iterate over a ranges in a file
> + * @iter: iteration structue

s/structue/structure/

Other than the minor stuff above, looks good to me:

Reviewed-by: Dan Williams <dan.j.williams@intel.com>

  parent reply	other threads:[~2021-08-19 21:26 UTC|newest]

Thread overview: 70+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-09  6:12 switch iomap to an iterator model v2 Christoph Hellwig
2021-08-09  6:12 ` [PATCH 01/30] iomap: fix a trivial comment typo in trace.h Christoph Hellwig
2021-08-09  6:12 ` [PATCH 02/30] iomap: remove the iomap arguments to ->page_{prepare,done} Christoph Hellwig
2021-08-09  6:12 ` [PATCH 03/30] iomap: mark the iomap argument to iomap_sector const Christoph Hellwig
2021-08-09  6:12 ` [PATCH 04/30] iomap: mark the iomap argument to iomap_inline_data const Christoph Hellwig
2021-08-09 16:17   ` Darrick J. Wong
2021-08-09  6:12 ` [PATCH 05/30] iomap: mark the iomap argument to iomap_inline_data_valid const Christoph Hellwig
2021-08-09 16:17   ` Darrick J. Wong
2021-08-09  6:12 ` [PATCH 06/30] fs: mark the iomap argument to __block_write_begin_int const Christoph Hellwig
2021-08-09  6:12 ` [PATCH 07/30] fsdax: mark the iomap argument to dax_iomap_sector as const Christoph Hellwig
2021-08-19 20:35   ` Dan Williams
2021-08-09  6:12 ` [PATCH 08/30] iomap: mark the iomap argument to iomap_read_inline_data const Christoph Hellwig
2021-08-09  6:12 ` [PATCH 09/30] iomap: mark the iomap argument to iomap_read_page_sync const Christoph Hellwig
2021-08-09  6:12 ` [PATCH 10/30] iomap: fix the iomap_readpage_actor return value for inline data Christoph Hellwig
2021-08-10 23:31   ` Darrick J. Wong
2021-08-09  6:12 ` [PATCH 11/30] iomap: add the new iomap_iter model Christoph Hellwig
2021-08-09 22:10   ` Dave Chinner
2021-08-10  6:45     ` Darrick J. Wong
2021-08-10  7:13       ` Christoph Hellwig
2021-08-11  0:31   ` Darrick J. Wong
2021-08-11  5:38     ` Christoph Hellwig
2021-08-11 19:17       ` Darrick J. Wong
2021-08-12  6:49         ` Christoph Hellwig
2021-08-12 18:20           ` Darrick J. Wong
2021-08-13  7:29             ` Christoph Hellwig
2021-08-11 19:17   ` [PATCH v2.1 " Darrick J. Wong
2021-08-17  2:34     ` Dave Chinner
2021-08-19 21:25   ` Dan Williams [this message]
2021-08-20  4:11     ` [PATCH " Christoph Hellwig
2021-08-20 15:27       ` Dan Williams
2021-08-09  6:12 ` [PATCH 12/30] iomap: switch readahead and readpage to use iomap_iter Christoph Hellwig
2021-08-10 23:46   ` Darrick J. Wong
2021-08-09  6:12 ` [PATCH 13/30] iomap: switch iomap_file_buffered_write " Christoph Hellwig
2021-08-10 23:53   ` Darrick J. Wong
2021-08-09  6:12 ` [PATCH 14/30] iomap: switch iomap_file_unshare " Christoph Hellwig
2021-08-10 23:54   ` Darrick J. Wong
2021-08-09  6:12 ` [PATCH 15/30] iomap: switch iomap_zero_range " Christoph Hellwig
2021-08-10 23:54   ` Darrick J. Wong
2021-08-09  6:12 ` [PATCH 16/30] iomap: switch iomap_page_mkwrite " Christoph Hellwig
2021-08-10 23:58   ` Darrick J. Wong
2021-08-09  6:12 ` [PATCH 17/30] iomap: switch __iomap_dio_rw " Christoph Hellwig
2021-08-11  0:17   ` Darrick J. Wong
2021-08-09  6:12 ` [PATCH 18/30] iomap: switch iomap_fiemap " Christoph Hellwig
2021-08-11  0:05   ` Darrick J. Wong
2021-08-09  6:12 ` [PATCH 19/30] iomap: switch iomap_bmap " Christoph Hellwig
2021-08-10  6:39   ` Darrick J. Wong
2021-08-10  7:13     ` Christoph Hellwig
2021-08-11 19:18   ` [PATCH v2.1 " Darrick J. Wong
2021-08-12  6:50     ` Christoph Hellwig
2021-08-17  2:35     ` Dave Chinner
2021-08-09  6:12 ` [PATCH 20/30] iomap: switch iomap_seek_hole " Christoph Hellwig
2021-08-11  0:13   ` Darrick J. Wong
2021-08-09  6:12 ` [PATCH 21/30] iomap: switch iomap_seek_data " Christoph Hellwig
2021-08-11  0:12   ` Darrick J. Wong
2021-08-09  6:12 ` [PATCH 22/30] iomap: switch iomap_swapfile_activate " Christoph Hellwig
2021-08-11  0:08   ` Darrick J. Wong
2021-08-09  6:12 ` [PATCH 23/30] fsdax: switch dax_iomap_rw " Christoph Hellwig
2021-08-11  0:07   ` Darrick J. Wong
2021-08-19 21:55   ` Dan Williams
2021-08-09  6:12 ` [PATCH 24/30] iomap: remove iomap_apply Christoph Hellwig
2021-08-11 19:18   ` [PATCH v2.1 " Darrick J. Wong
2021-08-17  2:36     ` Dave Chinner
2021-08-09  6:12 ` [PATCH 25/30] iomap: pass an iomap_iter to various buffered I/O helpers Christoph Hellwig
2021-08-09  6:12 ` [PATCH 26/30] iomap: rework unshare flag Christoph Hellwig
2021-08-09  6:12 ` [PATCH 27/30] fsdax: factor out helpers to simplify the dax fault code Christoph Hellwig
2021-08-09  6:12 ` [PATCH 28/30] fsdax: factor out a dax_fault_actor() helper Christoph Hellwig
2021-08-09  6:12 ` [PATCH 29/30] fsdax: switch the fault handlers to use iomap_iter Christoph Hellwig
2021-08-09  6:12 ` [PATCH 30/30] iomap: constify iomap_iter_srcmap Christoph Hellwig
2021-08-11 19:19 ` [PATCH 31/30] iomap: move iomap iteration code to iter.c Darrick J. Wong
2021-08-17  2:37   ` Dave Chinner

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