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[PATCH] splice: cleanup __generic_file_splice_read() 

The whole shadow/pages logic got overly complex, and this simpler
approach is actually faster in testing.

Signed-off-by: Jens Axboe <axboe@suse.de>
This commit is contained in:
Jens Axboe 2006-04-10 09:03:58 +02:00
parent c0bd1f650b
commit 16c523ddab
1 changed files with 10 additions and 49 deletions
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59
fs/splice.c
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@ -220,10 +220,10 @@ static int __generic_file_splice_read(struct file *in, struct inode *pipe,
{
struct address_space *mapping = in->f_mapping;
unsigned int offset, nr_pages;
struct page *pages[PIPE_BUFFERS], *shadow[PIPE_BUFFERS];
struct page *pages[PIPE_BUFFERS];
struct page *page;
pgoff_t index, pidx;
int i, j;
pgoff_t index;
int i;
index = in->f_pos >> PAGE_CACHE_SHIFT;
offset = in->f_pos & ~PAGE_CACHE_MASK;
@ -237,42 +237,14 @@ static int __generic_file_splice_read(struct file *in, struct inode *pipe,
*/
do_page_cache_readahead(mapping, in, index, nr_pages);
/*
* Get as many pages from the page cache as possible..
* Start IO on the page cache entries we create (we
* can assume that any pre-existing ones we find have
* already had IO started on them).
*/
i = find_get_pages(mapping, index, nr_pages, pages);
/*
* common case - we found all pages and they are contiguous,
* kick them off
*/
if (i && (pages[i - 1]->index == index + i - 1))
goto splice_them;
/*
* fill shadow[] with pages at the right locations, so we only
* have to fill holes
*/
memset(shadow, 0, nr_pages * sizeof(struct page *));
for (j = 0; j < i; j++)
shadow[pages[j]->index - index] = pages[j];
/*
* now fill in the holes
*/
for (i = 0, pidx = index; i < nr_pages; pidx++, i++) {
int error;
if (shadow[i])
continue;
for (i = 0; i < nr_pages; i++, index++) {
/*
* no page there, look one up / create it
*/
page = find_or_create_page(mapping, pidx,
page = find_or_create_page(mapping, index,
mapping_gfp_mask(mapping));
if (!page)
break;
@ -280,31 +252,20 @@ static int __generic_file_splice_read(struct file *in, struct inode *pipe,
if (PageUptodate(page))
unlock_page(page);
else {
error = mapping->a_ops->readpage(in, page);
int error = mapping->a_ops->readpage(in, page);
if (unlikely(error)) {
page_cache_release(page);
break;
}
}
shadow[i] = page;
pages[i] = page;
}
if (!i) {
for (i = 0; i < nr_pages; i++) {
if (shadow[i])
page_cache_release(shadow[i]);
}
return 0;
}
if (i)
return move_to_pipe(pipe, pages, i, offset, len, flags);
memcpy(pages, shadow, i * sizeof(struct page *));
/*
* Now we splice them into the pipe..
*/
splice_them:
return move_to_pipe(pipe, pages, i, offset, len, flags);
return 0;
}
/**