lkml.org 
[lkml]   [2008]   [Jun]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: generic_file_splice_read() issues
On Wed, Jun 25 2008, Miklos Szeredi wrote:
> | error = 0;
> | while (spd.nr_pages < nr_pages) {
> | /*
> | * Page could be there, find_get_pages_contig() breaks on
> | * the first hole.
> | */
> | page = find_get_page(mapping, index);
> | if (!page) {
> | /*
> | * page didn't exist, allocate one.
> | */
> | page = page_cache_alloc_cold(mapping);
> | if (!page)
>
> error = -ENOMEM?

Looks like it, indeed.

> | break;
> |
> | error = add_to_page_cache_lru(page, mapping, index,
> | mapping_gfp_mask(mapping));
> | if (unlikely(error)) {
> | page_cache_release(page);
> | if (error == -EEXIST)
>
> error = 0? It may not matter, but leaving error as EEXIST is
> confusing at best (and coupled with the above missing ENOMEM could
> result in really weird errors for splice() ;).

Lets move the error assignment inside that loop, ala

- error = 0;
while (spd.nr_pages < nr_pages) {
+ error = 0;

But yes, that also looks like a bug. Good spotting!

> |
> | /*
> | * need to read in the page
> | */
> | error = mapping->a_ops->readpage(in, page);
> | if (unlikely(error)) {
> | /*
> | * We really should re-lookup the page here,
> | * but it complicates things a lot. Instead
> | * lets just do what we already stored, and
> | * we'll get it the next time we are called.
> | */
> | if (error == AOP_TRUNCATED_PAGE)
> | error = 0;
>
> This may also cause similar issues as the invalidatation race. I'd
> think it would be better not to be sloppy here.

Perhaps we can abstract that bit out into a small helper function, tied
in with your previous patch.

--
Jens Axboe



\
 
 \ /
  Last update: 2008-06-25 16:13    [W:0.048 / U:0.632 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site