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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: Tao Ma <tao.ma@oracle.com>
This commit is contained in:
Tao Ma 2010-06-17 14:14:36 +08:00
parent 155027121f
commit 7b61cf54a2
1 changed files with 24 additions and 0 deletions
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24
fs/ocfs2/refcounttree.c
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@ -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;