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From: Christoph Hellwig <hch@lst.de>
To: linux-xfs@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org, avi@scylladb.com,
	Dave Chinner <dchinner@redhat.com>,
	Brian Foster <bfoster@redhat.com>,
	"Darrick J . Wong" <djwong@kernel.org>
Subject: [PATCH 10/11] iomap: add a IOMAP_DIO_OVERWRITE_ONLY flag
Date: Fri, 22 Jan 2021 17:20:42 +0100	[thread overview]
Message-ID: <20210122162043.616755-11-hch@lst.de> (raw)
In-Reply-To: <20210122162043.616755-1-hch@lst.de>

Add a flag to signal that only pure overwrites are allowed.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
---
 fs/iomap/direct-io.c  | 7 +++++++
 include/linux/iomap.h | 8 ++++++++
 2 files changed, 15 insertions(+)

diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
index 947343730e2c93..65d32364345d22 100644
--- a/fs/iomap/direct-io.c
+++ b/fs/iomap/direct-io.c
@@ -485,6 +485,13 @@ __iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
 		iomap_flags |= IOMAP_NOWAIT;
 	}
 
+	if (dio_flags & IOMAP_DIO_OVERWRITE_ONLY) {
+		ret = -EAGAIN;
+		if (pos >= dio->i_size || pos + count > dio->i_size)
+			goto out_free_dio;
+		iomap_flags |= IOMAP_OVERWRITE_ONLY;
+	}
+
 	ret = filemap_write_and_wait_range(mapping, pos, end);
 	if (ret)
 		goto out_free_dio;
diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index be4e1e1e01e801..1a86f520de560a 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -122,6 +122,7 @@ struct iomap_page_ops {
 #define IOMAP_FAULT		(1 << 3) /* mapping for page fault */
 #define IOMAP_DIRECT		(1 << 4) /* direct I/O */
 #define IOMAP_NOWAIT		(1 << 5) /* do not block */
+#define IOMAP_OVERWRITE_ONLY	(1 << 6) /* only pure overwrites allowed */
 
 struct iomap_ops {
 	/*
@@ -262,6 +263,13 @@ struct iomap_dio_ops {
  */
 #define IOMAP_DIO_FORCE_WAIT	(1 << 0)
 
+/*
+ * Do not allocate blocks or zero partial blocks, but instead fall back to
+ * the caller by returning -EAGAIN.  Used to optimize direct I/O writes that
+ * are not aligned to the file system block size.
+  */
+#define IOMAP_DIO_OVERWRITE_ONLY	(1 << 1)
+
 ssize_t iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
 		const struct iomap_ops *ops, const struct iomap_dio_ops *dops,
 		unsigned int dio_flags);
-- 
2.29.2


  parent reply	other threads:[~2021-01-22 16:46 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-22 16:20 reduce sub-block DIO serialisation v4 Christoph Hellwig
2021-01-22 16:20 ` [PATCH 01/11] xfs: factor out a xfs_ilock_iocb helper Christoph Hellwig
2021-01-22 16:20 ` [PATCH 02/11] xfs: make xfs_file_aio_write_checks IOCB_NOWAIT-aware Christoph Hellwig
2021-01-22 16:20 ` [PATCH 03/11] xfs: cleanup the read/write helper naming Christoph Hellwig
2021-01-22 16:20 ` [PATCH 04/11] xfs: remove the buffered I/O fallback assert Christoph Hellwig
2021-01-22 16:20 ` [PATCH 05/11] xfs: simplify the read/write tracepoints Christoph Hellwig
2021-01-22 16:20 ` [PATCH 06/11] xfs: improve the reflink_bounce_dio_write tracepoint Christoph Hellwig
2021-01-22 16:20 ` [PATCH 07/11] xfs: split the unaligned DIO write code out Christoph Hellwig
2021-01-22 16:20 ` [PATCH 08/11] iomap: rename the flags variable in __iomap_dio_rw Christoph Hellwig
2021-01-22 16:20 ` [PATCH 09/11] iomap: pass a flags argument to iomap_dio_rw Christoph Hellwig
2021-01-22 16:20 ` Christoph Hellwig [this message]
2021-01-22 16:20 ` [PATCH 11/11] xfs: reduce exclusive locking on unaligned dio Christoph Hellwig
2021-01-22 17:24   ` Darrick J. Wong
2021-01-23 18:57 ` reduce sub-block DIO serialisation v4 Darrick J. Wong
2021-02-01 16:58   ` Christoph Hellwig
2021-02-01 17:51     ` Darrick J. Wong
  -- strict thread matches above, loose matches on Subject: below --
2021-01-21  8:58 reduce sub-block DIO serialisation v3 Christoph Hellwig
2021-01-21  8:59 ` [PATCH 10/11] iomap: add a IOMAP_DIO_OVERWRITE_ONLY flag Christoph Hellwig
2021-01-21  9:32   ` Dave Chinner
2021-01-21 13:32   ` Brian Foster
2021-01-21 18:55   ` Darrick J. Wong

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