f2fs: compress: fix overwrite may reduce compress ratio unproperly

when overwrite only first block of cluster, since cluster is not full, it
will call f2fs_write_raw_pages when f2fs_write_multi_pages, and cause the
whole cluster become uncompressed eventhough data can be compressed.
this may will make random write bench score reduce a lot.

root# dd if=/dev/zero of=./fio-test bs=1M count=1

root# sync

root# echo 3 > /proc/sys/vm/drop_caches

root# f2fs_io get_cblocks ./fio-test

root# dd if=/dev/zero of=./fio-test bs=4K count=1 oflag=direct conv=notrunc

w/o patch:
root# f2fs_io get_cblocks ./fio-test
189

w/ patch:
root# f2fs_io get_cblocks ./fio-test
192

Signed-off-by: Fengnan Chang <changfengnan@vivo.com>
Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

1 files changed, 19 insertions, 0 deletions

diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c
index 9b663eaf4805..7588e4e817b8 100644
--- a/fs/f2fs/compress.c
+++ b/fs/f2fs/compress.c
@@ -881,6 +881,25 @@ bool f2fs_cluster_can_merge_page(struct compress_ctx *cc, pgoff_t index)
 	return is_page_in_cluster(cc, index);
 }
 
+bool f2fs_all_cluster_page_loaded(struct compress_ctx *cc, struct pagevec *pvec,
+				int index, int nr_pages)
+{
+	unsigned long pgidx;
+	int i;
+
+	if (nr_pages - index < cc->cluster_size)
+		return false;
+
+	pgidx = pvec->pages[index]->index;
+
+	for (i = 1; i < cc->cluster_size; i++) {
+		if (pvec->pages[index + i]->index != pgidx + i)
+			return false;
+	}
+
+	return true;
+}
+
 static bool cluster_has_invalid_data(struct compress_ctx *cc)
 {
 	loff_t i_size = i_size_read(cc->inode);