Commit 7b61cf54 authored by Tao Ma's avatar Tao Ma
Browse files

ocfs2: Add readahead support for CoW. 



Add a new function ocfs2_readahead_for_cow so that
we start readahead before we start our CoW.

Signed-off-by: default avatarTao Ma <tao.ma@oracle.com>
parent 15502712

fs/ocfs2/refcounttree.c

+24 −0
Original line number Diff line number Diff line
@@ -3398,6 +3398,28 @@ static int ocfs2_replace_cow(struct ocfs2_cow_context *context) 
	return ret;

}



static void ocfs2_readahead_for_cow(struct inode *inode,

				    struct file *file,

				    u32 start, u32 len)

{

	struct address_space *mapping;

	pgoff_t index;

	unsigned long num_pages;

	int cs_bits = OCFS2_SB(inode->i_sb)->s_clustersize_bits;



	if (!file)

		return;



	mapping = file->f_mapping;

	num_pages = (len << cs_bits) >> PAGE_CACHE_SHIFT;

	if (!num_pages)

		num_pages = 1;



	index = ((loff_t)start << cs_bits) >> PAGE_CACHE_SHIFT;

	page_cache_sync_readahead(mapping, &file->f_ra, file,

				  index, num_pages);

}



/*

 * Starting at cpos, try to CoW write_len clusters.  Don't CoW

 * past max_cpos.  This will stop when it runs into a hole or an
@@ -3433,6 +3455,8 @@ static int ocfs2_refcount_cow_hunk(struct inode *inode, 


	BUG_ON(cow_len == 0);



	ocfs2_readahead_for_cow(inode, file, cow_start, cow_len);



	context = kzalloc(sizeof(struct ocfs2_cow_context), GFP_NOFS);

	if (!context) {

		ret = -ENOMEM;