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>

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 9aa458c01101cfb8f78010fb112c3da28c7ea80f..d9a063d8a63de0655b2ee34f2ca2d1078bc5735e 100644 (file)
--- 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;
 }
 

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index d37883ce900211d04be347f12286875d7f20257d..a2e520a13630500f096d7e923131790b21fe1cb0 100644 (file)
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -718,7 +718,6 @@ struct f2fs_inode_info {
        struct list_head inmem_pages;   /* inmemory pages managed by f2fs */
        struct task_struct *inmem_task; /* store inmemory task */
        struct mutex inmem_lock;        /* lock for inmemory pages */
-       pgoff_t ra_offset;              /* ongoing readahead offset */
        struct extent_tree *extent_tree;        /* cached extent_tree entry */
 
        /* avoid racing between foreground op and gc */

diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 9749c9ad374f19f8f05507e135abe948d6093370..6a30876ff3744b9aa531f7f2345bffa2d5e503bf 100644 (file)
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -1174,8 +1174,6 @@ static struct inode *f2fs_alloc_inode(struct super_block *sb)
        /* Will be used by directory only */
        fi->i_dir_level = F2FS_SB(sb)->dir_level;
 
-       fi->ra_offset = -1;
-
        return &fi->vfs_inode;
 }