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>

fs/f2fs/checkpoint.c

@@ -305,9 +305,10 @@ long sync_meta_pages(struct f2fs_sb_info *sbi, enum page_type type,
 				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 @@ long sync_meta_pages(struct f2fs_sb_info *sbi, enum page_type type,
 
 	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];

fs/f2fs/node.c

@@ -1277,21 +1277,17 @@ release_page:
 
 static struct page *last_fsync_dnode(struct f2fs_sb_info *sbi, nid_t ino)
 {
-	pgoff_t index, end;
+	pgoff_t index;
 	struct pagevec pvec;
 	struct page *last_page = NULL;
+	int nr_pages;
 
 	pagevec_init(&pvec, 0);
 	index = 0;
-	end = ULONG_MAX;
-
-	while (index <= end) {
-		int i, nr_pages;
-		nr_pages = pagevec_lookup_tag(&pvec, NODE_MAPPING(sbi), &index,
-				PAGECACHE_TAG_DIRTY,
-				min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1);
-		if (nr_pages == 0)
-			break;
+
+	while ((nr_pages = pagevec_lookup_tag(&pvec, NODE_MAPPING(sbi), &index,
+				PAGECACHE_TAG_DIRTY, PAGEVEC_SIZE))) {
+		int i;
 
 		for (i = 0; i < nr_pages; i++) {
 			struct page *page = pvec.pages[i];
@@ -1425,13 +1421,14 @@ static int f2fs_write_node_page(struct page *page,
 int fsync_node_pages(struct f2fs_sb_info *sbi, struct inode *inode,
 			struct writeback_control *wbc, bool atomic)
 {
-	pgoff_t index, end;
+	pgoff_t index;
 	pgoff_t last_idx = ULONG_MAX;
 	struct pagevec pvec;
 	int ret = 0;
 	struct page *last_page = NULL;
 	bool marked = false;
 	nid_t ino = inode->i_ino;
+	int nr_pages;
 
 	if (atomic) {
 		last_page = last_fsync_dnode(sbi, ino);
@@ -1441,15 +1438,10 @@ int fsync_node_pages(struct f2fs_sb_info *sbi, struct inode *inode,
 retry:
 	pagevec_init(&pvec, 0);
 	index = 0;
-	end = ULONG_MAX;
-
-	while (index <= end) {
-		int i, nr_pages;
-		nr_pages = pagevec_lookup_tag(&pvec, NODE_MAPPING(sbi), &index,
-				PAGECACHE_TAG_DIRTY,
-				min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1);
-		if (nr_pages == 0)
-			break;
+
+	while ((nr_pages = pagevec_lookup_tag(&pvec, NODE_MAPPING(sbi), &index,
+				PAGECACHE_TAG_DIRTY, PAGEVEC_SIZE))) {
+		int i;
 
 		for (i = 0; i < nr_pages; i++) {
 			struct page *page = pvec.pages[i];
@@ -1548,25 +1540,21 @@ out:
 int sync_node_pages(struct f2fs_sb_info *sbi, struct writeback_control *wbc,
 				bool do_balance, enum iostat_type io_type)
 {
-	pgoff_t index, end;
+	pgoff_t index;
 	struct pagevec pvec;
 	int step = 0;
 	int nwritten = 0;
 	int ret = 0;
+	int nr_pages;
 
 	pagevec_init(&pvec, 0);
 
 next_step:
 	index = 0;
-	end = ULONG_MAX;
-
-	while (index <= end) {
-		int i, nr_pages;
-		nr_pages = pagevec_lookup_tag(&pvec, NODE_MAPPING(sbi), &index,
-				PAGECACHE_TAG_DIRTY,
-				min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1);
-		if (nr_pages == 0)
-			break;
+
+	while ((nr_pages = pagevec_lookup_tag(&pvec, NODE_MAPPING(sbi), &index,
+				PAGECACHE_TAG_DIRTY, PAGEVEC_SIZE))) {
+		int i;
 
 		for (i = 0; i < nr_pages; i++) {
 			struct page *page = pvec.pages[i];
@@ -1655,27 +1643,20 @@ out:
 
 int wait_on_node_pages_writeback(struct f2fs_sb_info *sbi, nid_t ino)
 {
-	pgoff_t index = 0, end = ULONG_MAX;
+	pgoff_t index = 0;
 	struct pagevec pvec;
 	int ret2, ret = 0;
+	int nr_pages;
 
 	pagevec_init(&pvec, 0);
 
-	while (index <= end) {
-		int i, nr_pages;
-		nr_pages = pagevec_lookup_tag(&pvec, NODE_MAPPING(sbi), &index,
-				PAGECACHE_TAG_WRITEBACK,
-				min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1);
-		if (nr_pages == 0)
-			break;
+	while ((nr_pages = pagevec_lookup_tag(&pvec, NODE_MAPPING(sbi), &index,
+				PAGECACHE_TAG_WRITEBACK, PAGEVEC_SIZE))) {
+		int i;
 
 		for (i = 0; i < nr_pages; i++) {
 			struct page *page = pvec.pages[i];
 
-			/* until radix tree lookup accepts end_index */
-			if (unlikely(page->index > end))
-				continue;
-
 			if (ino && ino_of_node(page) == ino) {
 				f2fs_wait_on_page_writeback(page, NODE, true);
 				if (TestClearPageError(page))