f2fs: support lower priority asynchronous readahead in ra_meta_pages
Now, we use ra_meta_pages to reads continuous physical blocks as much as
possible to improve performance of following reads. However, ra_meta_pages
uses a synchronous readahead approach by submitting bio with READ, as READ
is with high priority, it can not be used in the case of preloading blocks,
and it's not sure when these RAed pages will be used.
This patch supports asynchronous readahead in ra_meta_pages by tagging bio
with READA flag in order to allow preloading.
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
index 60a9599..f661d80 100644
--- a/fs/f2fs/checkpoint.c
+++ b/fs/f2fs/checkpoint.c
@@ -140,7 +140,8 @@
/*
* Readahead CP/NAT/SIT/SSA pages
*/
-int ra_meta_pages(struct f2fs_sb_info *sbi, block_t start, int nrpages, int type)
+int ra_meta_pages(struct f2fs_sb_info *sbi, block_t start, int nrpages,
+ int type, bool sync)
{
block_t prev_blk_addr = 0;
struct page *page;
@@ -148,7 +149,7 @@
struct f2fs_io_info fio = {
.sbi = sbi,
.type = META,
- .rw = READ_SYNC | REQ_META | REQ_PRIO,
+ .rw = sync ? (READ_SYNC | REQ_META | REQ_PRIO) : READA,
.encrypted_page = NULL,
};
@@ -214,7 +215,7 @@
f2fs_put_page(page, 0);
if (readahead)
- ra_meta_pages(sbi, index, MAX_BIO_BLOCKS(sbi), META_POR);
+ ra_meta_pages(sbi, index, MAX_BIO_BLOCKS(sbi), META_POR, true);
}
static int f2fs_write_meta_page(struct page *page,
@@ -521,7 +522,7 @@
start_blk = __start_cp_addr(sbi) + 1 + __cp_payload(sbi);
orphan_blocks = __start_sum_addr(sbi) - 1 - __cp_payload(sbi);
- ra_meta_pages(sbi, start_blk, orphan_blocks, META_CP);
+ ra_meta_pages(sbi, start_blk, orphan_blocks, META_CP, true);
for (i = 0; i < orphan_blocks; i++) {
struct page *page = get_meta_page(sbi, start_blk + i);