f2fs: Remove readahead collision detection

With the new ->readahead operation, locked pages are added to the page
cache, preventing two threads from racing with each other to read the
same chunk of file, so this is dead code.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

1 files changed, 0 insertions, 25 deletions

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 9aa458c01101..d9a063d8a63d 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -2265,11 +2265,6 @@ out:
 /*
  * This function was originally taken from fs/mpage.c, and customized for f2fs.
  * Major change was from block_size == page_size in f2fs by default.
- *
- * Note that the aops->readpages() function is ONLY used for read-ahead. If
- * this function ever deviates from doing just read-ahead, it should either
- * use ->readpage() or do the necessary surgery to decouple ->readpages()
- * from read-ahead.
  */
 static int f2fs_mpage_readpages(struct inode *inode,
 		struct readahead_control *rac, struct page *page)
@@ -2292,7 +2287,6 @@ static int f2fs_mpage_readpages(struct inode *inode,
 	unsigned nr_pages = rac ? readahead_count(rac) : 1;
 	unsigned max_nr_pages = nr_pages;
 	int ret = 0;
-	bool drop_ra = false;
 
 	map.m_pblk = 0;
 	map.m_lblk = 0;
@@ -2303,26 +2297,10 @@ static int f2fs_mpage_readpages(struct inode *inode,
 	map.m_seg_type = NO_CHECK_TYPE;
 	map.m_may_create = false;
 
-	/*
-	 * Two readahead threads for same address range can cause race condition
-	 * which fragments sequential read IOs. So let's avoid each other.
-	 */
-	if (rac && readahead_count(rac)) {
-		if (READ_ONCE(F2FS_I(inode)->ra_offset) == readahead_index(rac))
-			drop_ra = true;
-		else
-			WRITE_ONCE(F2FS_I(inode)->ra_offset,
-						readahead_index(rac));
-	}
-
 	for (; nr_pages; nr_pages--) {
 		if (rac) {
 			page = readahead_page(rac);
 			prefetchw(&page->flags);
-			if (drop_ra) {
-				f2fs_put_page(page, 1);
-				continue;
-			}
 		}
 
 #ifdef CONFIG_F2FS_FS_COMPRESSION
@@ -2385,9 +2363,6 @@ next_page:
 	}
 	if (bio)
 		__submit_bio(F2FS_I_SB(inode), bio, DATA);
-
-	if (rac && readahead_count(rac) && !drop_ra)
-		WRITE_ONCE(F2FS_I(inode)->ra_offset, -1);
 	return ret;
 }