From: Miklos Szeredi <[email protected]>
If a page was invalidated during splicing from file to a pipe, then
generic_file_splice_read() could return a short or zero count.
This manifested itself in rare I/O errors seen on nfs exported fuse
filesystems. This is because nfsd uses splice_direct_to_actor() to
read files, and fuse uses invalidate_inode_pages2() to invalidate
stale data on open.
Fix by redoing the page find/create if it was found to be truncated
(invalidated).
Signed-off-by: Miklos Szeredi <[email protected]>
---
fs/splice.c | 17 +++++++++++++----
1 file changed, 13 insertions(+), 4 deletions(-)
Index: linux-2.6/fs/splice.c
===================================================================
--- linux-2.6.orig/fs/splice.c 2008-06-25 08:18:51.000000000 +0200
+++ linux-2.6/fs/splice.c 2008-06-25 11:57:33.000000000 +0200
@@ -379,13 +379,22 @@ __generic_file_splice_read(struct file *
lock_page(page);
/*
- * page was truncated, stop here. if this isn't the
- * first page, we'll just complete what we already
- * added
+ * Page was truncated, or invalidated by the
+ * filesystem. Redo the find/create, but this time the
+ * page is kept locked, so there's no chance of another
+ * race with truncate/invalidate.
*/
if (!page->mapping) {
unlock_page(page);
- break;
+ page = find_or_create_page(mapping, index,
+ mapping_gfp_mask(mapping));
+
+ if (!page) {
+ error = -ENOMEM;
+ break;
+ }
+ page_cache_release(pages[page_nr]);
+ pages[page_nr] = page;
}
/*
* page was already under io and is now done, great
--
On Wed, Jun 25 2008, Miklos Szeredi wrote:
> From: Miklos Szeredi <[email protected]>
>
> If a page was invalidated during splicing from file to a pipe, then
> generic_file_splice_read() could return a short or zero count.
>
> This manifested itself in rare I/O errors seen on nfs exported fuse
> filesystems. This is because nfsd uses splice_direct_to_actor() to
> read files, and fuse uses invalidate_inode_pages2() to invalidate
> stale data on open.
>
> Fix by redoing the page find/create if it was found to be truncated
> (invalidated).
>
> Signed-off-by: Miklos Szeredi <[email protected]>
> ---
> fs/splice.c | 17 +++++++++++++----
> 1 file changed, 13 insertions(+), 4 deletions(-)
>
> Index: linux-2.6/fs/splice.c
> ===================================================================
> --- linux-2.6.orig/fs/splice.c 2008-06-25 08:18:51.000000000 +0200
> +++ linux-2.6/fs/splice.c 2008-06-25 11:57:33.000000000 +0200
> @@ -379,13 +379,22 @@ __generic_file_splice_read(struct file *
> lock_page(page);
>
> /*
> - * page was truncated, stop here. if this isn't the
> - * first page, we'll just complete what we already
> - * added
> + * Page was truncated, or invalidated by the
> + * filesystem. Redo the find/create, but this time the
> + * page is kept locked, so there's no chance of another
> + * race with truncate/invalidate.
> */
> if (!page->mapping) {
> unlock_page(page);
> - break;
> + page = find_or_create_page(mapping, index,
> + mapping_gfp_mask(mapping));
> +
> + if (!page) {
> + error = -ENOMEM;
> + break;
> + }
> + page_cache_release(pages[page_nr]);
> + pages[page_nr] = page;
> }
> /*
> * page was already under io and is now done, great
This looks good to me, page locking is also consistent. You can add my
acked-by, I'm assuming Linus will just take it directly for 2.6.26.
--
Jens Axboe