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From: Dave Chinner <david@fromorbit.com>
To: linux-xfs@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org
Subject: [PATCH 12/16] iomap: zero-around in iomap_page_mkwrite
Date: Wed,  7 Nov 2018 17:31:23 +1100	[thread overview]
Message-ID: <20181107063127.3902-13-david@fromorbit.com> (raw)
In-Reply-To: <20181107063127.3902-1-david@fromorbit.com>

From: Dave Chinner <dchinner@redhat.com>

When we take a write fault over a page in a block size > page size
filesystem, we may have to issue zero-around to initialise all the
pages in the block that mmap is writing to. This is essentially the
same as the zero-around in the buffered write path, with the added
complexity that we have to drop the page lock on the page that
was passed to iomap_page_mkwrite_actor().

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
 fs/iomap.c | 41 ++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 40 insertions(+), 1 deletion(-)

diff --git a/fs/iomap.c b/fs/iomap.c
index 41922fc775c4..7aacd48c593e 100644
--- a/fs/iomap.c
+++ b/fs/iomap.c
@@ -1183,7 +1183,46 @@ iomap_page_mkwrite_actor(struct inode *inode, loff_t pos, loff_t length,
 		void *data, struct iomap *iomap)
 {
 	struct page *page = data;
-	int ret;
+	loff_t ret;
+
+	/*
+	 * if we need to zero-around, we have to unlock the page we were given.
+	 * No big deal, we just have to repeat the "is this page ours" checks
+	 * after relocking it
+	 */
+	if (iomap_need_zero_around(iomap)) {
+		loff_t size;
+
+		/*
+		 * This only happens for block size > page size, so the file
+		 * offset of a page fault should always be page aligned.
+		 */
+		WARN_ON(offset_in_page(pos));
+
+		unlock_page(page);
+		ret = iomap_zero_around(inode, pos, length, iomap);
+		lock_page(page);
+		size = i_size_read(inode);
+		if ((page->mapping != inode->i_mapping) ||
+		    (page_offset(page) > size)) {
+			/* We overload EFAULT to mean page got truncated */
+			return -EFAULT;
+		}
+
+		if (page_offset(page) != pos) {
+			/* it moved in the file! */
+			return -EFAULT;
+		}
+
+		/* return failure now if zeroing had an error */
+		if (ret)
+			return ret;
+
+		/* trim down the length is we straddle EOF. */
+		if (((page->index + 1) << PAGE_SHIFT) > size)
+			length = offset_in_page(size);
+
+	}
 
 	if (iomap->flags & IOMAP_F_BUFFER_HEAD) {
 		ret = __block_write_begin_int(page, pos, length, NULL, iomap);
-- 
2.19.1

  parent reply	other threads:[~2018-11-07 16:01 UTC|newest]

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-07  6:31 [RFC PATCH 00/16] xfs: Block size > PAGE_SIZE support Dave Chinner
2018-11-07  6:31 ` [PATCH 01/16] xfs: drop ->writepage completely Dave Chinner
2018-11-09 15:12   ` Christoph Hellwig
2018-11-12 21:08     ` Dave Chinner
2021-02-02 20:51       ` Darrick J. Wong
2018-11-07  6:31 ` [PATCH 02/16] xfs: move writepage context warnings to writepages Dave Chinner
2018-11-07  6:31 ` [PATCH 03/16] xfs: finobt AG reserves don't consider last AG can be a runt Dave Chinner
2018-11-07 16:55   ` Darrick J. Wong
2018-11-09  0:21     ` Dave Chinner
2018-11-07  6:31 ` [PATCH 04/16] xfs: extent shifting doesn't fully invalidate page cache Dave Chinner
2018-11-07  6:31 ` [PATCH 05/16] iomap: sub-block dio needs to zeroout beyond EOF Dave Chinner
2018-11-09 15:15   ` Christoph Hellwig
2018-11-07  6:31 ` [PATCH 06/16] iomap: support block size > page size for direct IO Dave Chinner
2018-11-08 11:28   ` Nikolay Borisov
2018-11-09 15:18   ` Christoph Hellwig
2018-11-11  1:12     ` Dave Chinner
2018-11-07  6:31 ` [PATCH 07/16] iomap: prepare buffered IO paths for block size > page size Dave Chinner
2018-11-09 15:19   ` Christoph Hellwig
2018-11-11  1:15     ` Dave Chinner
2018-11-07  6:31 ` [PATCH 08/16] iomap: mode iomap_zero_range and friends Dave Chinner
2018-11-09 15:19   ` Christoph Hellwig
2018-11-07  6:31 ` [PATCH 09/16] iomap: introduce zero-around functionality Dave Chinner
2018-11-07  6:31 ` [PATCH 10/16] iomap: enable zero-around for iomap_zero_range() Dave Chinner
2018-11-07  6:31 ` [PATCH 11/16] iomap: Don't mark partial pages zeroing uptodate for zero-around Dave Chinner
2018-11-07  6:31 ` Dave Chinner [this message]
2018-11-07  6:31 ` [PATCH 13/16] xfs: add zero-around controls to iomap Dave Chinner
2018-11-07  6:31 ` [PATCH 14/16] xfs: align writepages to large block sizes Dave Chinner
2018-11-09 15:22   ` Christoph Hellwig
2018-11-11  1:20     ` Dave Chinner
2018-11-11 16:32       ` Christoph Hellwig
2018-11-14 14:19   ` Brian Foster
2018-11-14 21:18     ` Dave Chinner
2018-11-15 12:55       ` Brian Foster
2018-11-16  6:19         ` Dave Chinner
2018-11-16 13:29           ` Brian Foster
2018-11-19  1:14             ` Dave Chinner
2018-11-07  6:31 ` [PATCH 15/16] xfs: expose block size in stat Dave Chinner
2018-11-07  6:31 ` [PATCH 16/16] xfs: enable block size larger than page size support Dave Chinner
2018-11-07 17:14 ` [RFC PATCH 00/16] xfs: Block size > PAGE_SIZE support Darrick J. Wong
2018-11-07 22:04   ` Dave Chinner
2018-11-08  1:38     ` Darrick J. Wong
2018-11-08  9:04       ` Dave Chinner
2018-11-08 22:17         ` Darrick J. Wong
2018-11-08 22:22           ` Dave Chinner

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