linux-ext4 - [PATCH 05/10] ext4: Use pagevec_lookup_range() in ext4_find_unwritten

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Date:   Wed, 26 Jul 2017 13:46:59 +0200
From:   Jan Kara <jack@...e.cz>
To:     <linux-mm@...ck.org>
Cc:     Andrew Morton <akpm@...ux-foundation.org>, Jan Kara <jack@...e.cz>,
        linux-ext4@...r.kernel.org, "Theodore Ts'o" <tytso@....edu>
Subject: [PATCH 05/10] ext4: Use pagevec_lookup_range() in ext4_find_unwritten_pgoff()

Use pagevec_lookup_range() in ext4_find_unwritten_pgoff() since we are
interested only in pages in the given range. Simplify the logic as a
result of not getting pages out of range and index getting automatically
advanced.

CC: linux-ext4@...r.kernel.org
CC: "Theodore Ts'o" <tytso@....edu>
Signed-off-by: Jan Kara <jack@...e.cz>
---
 fs/ext4/file.c | 14 ++++----------
 1 file changed, 4 insertions(+), 10 deletions(-)

diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index ab09cb6fcce3..ac39a6a1ea5d 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -494,12 +494,11 @@ static int ext4_find_unwritten_pgoff(struct inode *inode,
 
 	pagevec_init(&pvec, 0);
 	do {
-		int i, num;
+		int i;
 		unsigned long nr_pages;
 
-		num = min_t(pgoff_t, end - index, PAGEVEC_SIZE - 1) + 1;
-		nr_pages = pagevec_lookup(&pvec, inode->i_mapping, &index,
-					  (pgoff_t)num);
+		nr_pages = pagevec_lookup_range(&pvec, inode->i_mapping,
+					&index, end, PAGEVEC_SIZE);
 		if (nr_pages == 0)
 			break;
 
@@ -518,9 +517,6 @@ static int ext4_find_unwritten_pgoff(struct inode *inode,
 				goto out;
 			}
 
-			if (page->index > end)
-				goto out;
-
 			lock_page(page);
 
 			if (unlikely(page->mapping != inode->i_mapping)) {
@@ -560,12 +556,10 @@ static int ext4_find_unwritten_pgoff(struct inode *inode,
 			unlock_page(page);
 		}
 
-		/* The no. of pages is less than our desired, we are done. */
-		if (nr_pages < num)
-			break;
 		pagevec_release(&pvec);
 	} while (index <= end);
 
+	/* There are no pages upto endoff - that would be a hole in there. */
 	if (whence == SEEK_HOLE && lastoff < endoff) {
 		found = 1;
 		*offset = lastoff;
-- 
2.12.3