ocfs2: Add readhead during CoW.

In CoW, when we meet with a readahead page, we know
it is time to move the readahead window. So carry
out a new readahead.

Signed-off-by: Tao Ma <tao.ma@oracle.com>

diff --git a/fs/ocfs2/refcounttree.c b/fs/ocfs2/refcounttree.c
index ad08c11..47549f6 100644 (file)
--- a/fs/ocfs2/refcounttree.c
+++ b/fs/ocfs2/refcounttree.c
@@ -49,6 +49,7 @@
 
 struct ocfs2_cow_context {
        struct inode *inode;
+       struct file *file;
        u32 cow_start;
        u32 cow_len;
        struct ocfs2_extent_tree data_et;
@@ -2922,13 +2923,16 @@ static int ocfs2_duplicate_clusters_by_page(handle_t *handle,
        u64 new_block = ocfs2_clusters_to_blocks(sb, new_cluster);
        struct page *page;
        pgoff_t page_index;
-       unsigned int from, to;
+       unsigned int from, to, readahead_pages;
        loff_t offset, end, map_end;
        struct address_space *mapping = context->inode->i_mapping;
 
        mlog(0, "old_cluster %u, new %u, len %u at offset %u\n", old_cluster,
             new_cluster, new_len, cpos);
 
+       readahead_pages =
+               (ocfs2_cow_contig_clusters(sb) <<
+                OCFS2_SB(sb)->s_clustersize_bits) >> PAGE_CACHE_SHIFT;
        offset = ((loff_t)cpos) << OCFS2_SB(sb)->s_clustersize_bits;
        end = offset + (new_len << OCFS2_SB(sb)->s_clustersize_bits);
        /*
@@ -2959,6 +2963,14 @@ static int ocfs2_duplicate_clusters_by_page(handle_t *handle,
                if (PAGE_CACHE_SIZE <= OCFS2_SB(sb)->s_clustersize)
                        BUG_ON(PageDirty(page));
 
+               if (PageReadahead(page) && context->file) {
+                       page_cache_async_readahead(mapping,
+                                                  &context->file->f_ra,
+                                                  context->file,
+                                                  page, page_index,
+                                                  readahead_pages);
+               }
+
                if (!PageUptodate(page)) {
                        ret = block_read_full_page(page, ocfs2_get_block);
                        if (ret) {
@@ -3478,6 +3490,7 @@ static int ocfs2_refcount_cow_hunk(struct inode *inode,
        context->ref_root_bh = ref_root_bh;
        context->cow_duplicate_clusters = ocfs2_duplicate_clusters_by_page;
        context->get_clusters = ocfs2_di_get_clusters;
+       context->file = file;
 
        ocfs2_init_dinode_extent_tree(&context->data_et,
                                      INODE_CACHE(inode), di_bh);