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From: Christoph Hellwig <hch@lst.de>
To: Goldwyn Rodrigues <rgoldwyn@suse.com>,
	linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: [PATCH 06/19] iomap: use write_begin to read pages to unshare
Date: Mon,  9 Sep 2019 20:27:09 +0200
Message-ID: <20190909182722.16783-7-hch@lst.de> (raw)
In-Reply-To: <20190909182722.16783-1-hch@lst.de>

Use the existing iomap write_begin code to read the pages unshared
by iomap_file_unshare.  That avoids the extra ->readpage call and
extent tree lookup currently done by read_mapping_page.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/iomap/buffered-io.c | 49 ++++++++++++++----------------------------
 1 file changed, 16 insertions(+), 33 deletions(-)

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index fe099faf540f..a421977a9496 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -533,6 +533,10 @@ iomap_migrate_page(struct address_space *mapping, struct page *newpage,
 EXPORT_SYMBOL_GPL(iomap_migrate_page);
 #endif /* CONFIG_MIGRATION */
 
+enum {
+	IOMAP_WRITE_F_UNSHARE		= (1 << 0),
+};
+
 static void
 iomap_write_failed(struct inode *inode, loff_t pos, unsigned len)
 {
@@ -562,7 +566,7 @@ iomap_read_page_sync(loff_t block_start, struct page *page, unsigned poff,
 }
 
 static int
-__iomap_write_begin(struct inode *inode, loff_t pos, unsigned len,
+__iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, int flags,
 		struct page *page, struct iomap *iomap)
 {
 	struct iomap_page *iop = iomap_page_create(inode, page);
@@ -581,11 +585,14 @@ __iomap_write_begin(struct inode *inode, loff_t pos, unsigned len,
 		if (plen == 0)
 			break;
 
-		if ((from <= poff || from >= poff + plen) &&
+		if (!(flags & IOMAP_WRITE_F_UNSHARE) &&
+		    (from <= poff || from >= poff + plen) &&
 		    (to <= poff || to >= poff + plen))
 			continue;
 
 		if (iomap_block_needs_zeroing(inode, iomap, block_start)) {
+			if (WARN_ON_ONCE(flags & IOMAP_WRITE_F_UNSHARE))
+				return -EIO;
 			zero_user_segments(page, poff, from, to, poff + plen);
 			iomap_set_range_uptodate(page, poff, plen);
 			continue;
@@ -631,7 +638,8 @@ iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, unsigned flags,
 	else if (iomap->flags & IOMAP_F_BUFFER_HEAD)
 		status = __block_write_begin_int(page, pos, len, NULL, iomap);
 	else
-		status = __iomap_write_begin(inode, pos, len, page, iomap);
+		status = __iomap_write_begin(inode, pos, len, flags, page,
+				iomap);
 
 	if (unlikely(status))
 		goto out_unlock;
@@ -854,22 +862,6 @@ iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *iter,
 }
 EXPORT_SYMBOL_GPL(iomap_file_buffered_write);
 
-static struct page *
-__iomap_read_page(struct inode *inode, loff_t offset)
-{
-	struct address_space *mapping = inode->i_mapping;
-	struct page *page;
-
-	page = read_mapping_page(mapping, offset >> PAGE_SHIFT, NULL);
-	if (IS_ERR(page))
-		return page;
-	if (!PageUptodate(page)) {
-		put_page(page);
-		return ERR_PTR(-EIO);
-	}
-	return page;
-}
-
 static loff_t
 iomap_unshare_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
 		struct iomap *iomap)
@@ -885,24 +877,15 @@ iomap_unshare_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
 		return length;
 
 	do {
-		struct page *page, *rpage;
-		unsigned long offset;	/* Offset into pagecache page */
-		unsigned long bytes;	/* Bytes to write to page */
-
-		offset = offset_in_page(pos);
-		bytes = min_t(loff_t, PAGE_SIZE - offset, length);
-
-		rpage = __iomap_read_page(inode, pos);
-		if (IS_ERR(rpage))
-			return PTR_ERR(rpage);
+		unsigned long offset = offset_in_page(pos);
+		unsigned long bytes = min_t(loff_t, PAGE_SIZE - offset, length);
+		struct page *page;
 
-		status = iomap_write_begin(inode, pos, bytes, 0, &page, iomap);
-		put_page(rpage);
+		status = iomap_write_begin(inode, pos, bytes,
+				IOMAP_WRITE_F_UNSHARE, &page, iomap);
 		if (unlikely(status))
 			return status;
 
-		WARN_ON_ONCE(!PageUptodate(page));
-
 		status = iomap_write_end(inode, pos, bytes, bytes, page, iomap);
 		if (unlikely(status <= 0)) {
 			if (WARN_ON_ONCE(status == 0))
-- 
2.20.1


  parent reply index

Thread overview: 54+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-09 18:27 iomap and xfs COW cleanups Christoph Hellwig
2019-09-09 18:27 ` [PATCH 01/19] iomap: better document the IOMAP_F_* flags Christoph Hellwig
2019-09-14  0:42   ` Allison Collins
2019-09-16 18:08   ` Darrick J. Wong
2019-09-09 18:27 ` [PATCH 02/19] iomap: remove the unused iomap argument to __iomap_write_end Christoph Hellwig
2019-09-14  0:42   ` Allison Collins
2019-09-16 18:10   ` Darrick J. Wong
2019-09-09 18:27 ` [PATCH 03/19] iomap: always use AOP_FLAG_NOFS in iomap_write_begin Christoph Hellwig
2019-09-16 18:11   ` Darrick J. Wong
2019-09-09 18:27 ` [PATCH 04/19] iomap: ignore non-shared or non-data blocks in xfs_file_dirty Christoph Hellwig
2019-09-16 18:12   ` Darrick J. Wong
2019-09-09 18:27 ` [PATCH 05/19] iomap: move the zeroing case out of iomap_read_page_sync Christoph Hellwig
2019-09-16 18:17   ` Darrick J. Wong
2019-09-09 18:27 ` Christoph Hellwig [this message]
2019-09-16 18:34   ` [PATCH 06/19] iomap: use write_begin to read pages to unshare Darrick J. Wong
2019-09-30 11:07     ` Christoph Hellwig
2019-10-08 15:12       ` Darrick J. Wong
2019-09-09 18:27 ` [PATCH 07/19] iomap: use a srcmap for a read-modify-write I/O Christoph Hellwig
2019-09-10 12:48   ` Goldwyn Rodrigues
2019-09-10 14:39     ` hch
2019-09-16 17:57       ` Darrick J. Wong
2019-09-16 18:42   ` Darrick J. Wong
2019-09-18 18:15     ` Darrick J. Wong
2019-09-09 18:27 ` [PATCH 08/19] xfs: also call xfs_file_iomap_end_delalloc for zeroing operations Christoph Hellwig
2019-09-18 17:09   ` Darrick J. Wong
2019-09-09 18:27 ` [PATCH 09/19] xfs: remove xfs_reflink_dirty_extents Christoph Hellwig
2019-09-18 17:17   ` Darrick J. Wong
2019-09-18 17:25     ` Christoph Hellwig
2019-09-18 17:31       ` Darrick J. Wong
2019-09-09 18:27 ` [PATCH 10/19] xfs: pass two imaps to xfs_reflink_allocate_cow Christoph Hellwig
2019-09-18 17:26   ` Darrick J. Wong
2019-09-30 11:10     ` Christoph Hellwig
2019-09-09 18:27 ` [PATCH 11/19] xfs: refactor xfs_file_iomap_begin_delay Christoph Hellwig
2019-09-18 17:30   ` Darrick J. Wong
2019-09-09 18:27 ` [PATCH 12/19] xfs: fill out the srcmap in iomap_begin Christoph Hellwig
2019-09-18 17:52   ` Darrick J. Wong
2019-10-01  6:26     ` Christoph Hellwig
2019-09-09 18:27 ` [PATCH 13/19] xfs: factor out a helper to calculate the end_fsb Christoph Hellwig
2019-09-14  0:42   ` Allison Collins
2019-09-18 17:55   ` Darrick J. Wong
2019-09-09 18:27 ` [PATCH 14/19] xfs: split out a new set of read-only iomap ops Christoph Hellwig
2019-09-18 17:56   ` Darrick J. Wong
2019-09-09 18:27 ` [PATCH 15/19] xfs: move xfs_file_iomap_begin_delay around Christoph Hellwig
2019-09-18 17:59   ` Darrick J. Wong
2019-09-30 11:14     ` Christoph Hellwig
2019-09-09 18:27 ` [PATCH 16/19] xfs: split the iomap ops for buffered vs direct writes Christoph Hellwig
2019-09-18 18:00   ` Darrick J. Wong
2019-09-09 18:27 ` [PATCH 17/19] xfs: rename the whichfork variable in xfs_buffered_write_iomap_begin Christoph Hellwig
2019-09-14  0:42   ` Allison Collins
2019-09-18 18:00   ` Darrick J. Wong
2019-09-09 18:27 ` [PATCH 18/19] xfs: cleanup xfs_iomap_write_unwritten Christoph Hellwig
2019-09-18 18:06   ` Darrick J. Wong
2019-09-09 18:27 ` [PATCH 19/19] xfs: improve the IOMAP_NOWAIT check for COW inodes Christoph Hellwig
2019-09-18 18:09   ` Darrick J. Wong

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