f2fs: simplify page iteration loops

In several places we want to iterate over all tagged pages in a mapping.
However the code was apparently copied from places that iterate only
over a limited range and thus it checks for index <= end, optimizes the
case where we are coming close to range end which is all pointless when
end == ULONG_MAX.  So just remove this dead code.

[akpm@linux-foundation.org: fix warnings]
Link: http://lkml.kernel.org/r/20171009151359.31984-7-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
index 04fe1df..fb74ec4 100644
--- a/fs/f2fs/checkpoint.c
+++ b/fs/f2fs/checkpoint.c
@@ -305,9 +305,10 @@
 				long nr_to_write, enum iostat_type io_type)
 {
 	struct address_space *mapping = META_MAPPING(sbi);
-	pgoff_t index = 0, end = ULONG_MAX, prev = ULONG_MAX;
+	pgoff_t index = 0, prev = ULONG_MAX;
 	struct pagevec pvec;
 	long nwritten = 0;
+	int nr_pages;
 	struct writeback_control wbc = {
 		.for_reclaim = 0,
 	};
@@ -317,13 +318,9 @@
 
 	blk_start_plug(&plug);
 
-	while (index <= end) {
-		int i, nr_pages;
-		nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
-				PAGECACHE_TAG_DIRTY,
-				min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1);
-		if (unlikely(nr_pages == 0))
-			break;
+	while ((nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
+				PAGECACHE_TAG_DIRTY, PAGEVEC_SIZE))) {
+		int i;
 
 		for (i = 0; i < nr_pages; i++) {
 			struct page *page = pvec.pages[i];