linux-ext4 - [PATCH 2/3] fs: remove the buffer_unwritten check in page_seek_hole

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Date:   Thu, 31 May 2018 20:07:23 +0200
From:   Christoph Hellwig <hch@....de>
To:     linux-xfs@...r.kernel.org
Cc:     Andreas Gruenbacher <agruenba@...hat.com>,
        linux-fsdevel@...r.kernel.org, linux-ext4@...r.kernel.org
Subject: [PATCH 2/3] fs: remove the buffer_unwritten check in page_seek_hole_data

We only call into this function through the iomap iterators, so we already
know the buffer is unwritten.  In addition to that we always require the
uptodate flag that is ORed with the result anyway.

Signed-off-by: Christoph Hellwig <hch@....de>
Reviewed-by: Andreas Gruenbacher <agruenba@...hat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@...cle.com>
Reviewed-by: Dave Chinner <dchinner@...hat.com>
---
 fs/iomap.c | 13 ++++---------
 1 file changed, 4 insertions(+), 9 deletions(-)

diff --git a/fs/iomap.c b/fs/iomap.c
index f553a2d8a5fa..e93bd4eb7fa7 100644
--- a/fs/iomap.c
+++ b/fs/iomap.c
@@ -827,14 +827,9 @@ page_seek_hole_data(struct page *page, loff_t lastoff, int whence)
 			continue;
 
 		/*
-		 * Unwritten extents that have data in the page cache covering
-		 * them can be identified by the BH_Unwritten state flag.
-		 * Pages with multiple buffers might have a mix of holes, data
-		 * and unwritten extents - any buffer with valid data in it
-		 * should have BH_Uptodate flag set on it.
+		 * Any buffer with valid data in it should have BH_Uptodate set.
 		 */
-
-		if ((buffer_unwritten(bh) || buffer_uptodate(bh)) == seek_data)
+		if (buffer_uptodate(bh) == seek_data)
 			return lastoff;
 
 		lastoff = offset;
@@ -846,8 +841,8 @@ page_seek_hole_data(struct page *page, loff_t lastoff, int whence)
  * Seek for SEEK_DATA / SEEK_HOLE in the page cache.
  *
  * Within unwritten extents, the page cache determines which parts are holes
- * and which are data: unwritten and uptodate buffer heads count as data;
- * everything else counts as a hole.
+ * and which are data: uptodate buffer heads count as data; everything else
+ * counts as a hole.
  *
  * Returns the resulting offset on successs, and -ENOENT otherwise.
  */
-- 
2.17.0