linux-kernel - [PATCH V2] iomap: skip unnecessary ifs_block_is

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Message-Id: <20250410054223.3325-1-gouhao@uniontech.com>
Date: Thu, 10 Apr 2025 13:42:23 +0800
From: Gou Hao <gouhao@...ontech.com>
To: gouhao@...ontech.com
Cc: brauner@...nel.org,
	djwong@...nel.org,
	gouhaojake@....com,
	linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-xfs@...r.kernel.org,
	wangyuli@...ontech.com
Subject: [PATCH V2] iomap: skip unnecessary ifs_block_is_uptodate check

prior to the loop, $i is either the first !uptodate block, or
it's past $last.  Assuming there's no overflow (there's no combination
of huge folios and tiny blksize) then yeah, there's no point in
retesting that the same block $i is uptodate since we hold the folio
lock so nobody else could have set uptodate.

Signed-off-by: Gou Hao <gouhao@...ontech.com>
Reviewed-by: "Darrick J. Wong" <djwong@...nel.org>
---
 fs/iomap/buffered-io.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 31553372b33a..2f52e8e61240 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -259,7 +259,7 @@ static void iomap_adjust_read_range(struct inode *inode, struct folio *folio,
 		}
 
 		/* truncate len if we find any trailing uptodate block(s) */
-		for ( ; i <= last; i++) {
+		for (i++; i <= last; i++) {
 			if (ifs_block_is_uptodate(ifs, i)) {
 				plen -= (last - i + 1) * block_size;
 				last = i - 1;
-- 
2.20.1