Re: [PATCH 4/6] nfs: Teach NFS about swap cache pages

Trond Myklebust
2006-08-25T20:04:10Z

On Fri, 2006-08-25 at 17:37 +0200, Peter Zijlstra wrote:
> Teach the NFS client how to treat PG_swapcache pages.
>
> Replace all occurences of page->index and page->mapping in the NFS client
> with the new page_file_index() and page_file_mapping() functions.
>
> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
> ---
> fs/nfs/dir.c | 4 ++--
> fs/nfs/file.c | 6 +++---
> fs/nfs/pagelist.c | 8 ++++----
> fs/nfs/read.c | 10 +++++-----
> fs/nfs/write.c | 34 +++++++++++++++++-----------------
> 5 files changed, 31 insertions(+), 31 deletions(-)

<snip>

> @@ -821,7 +821,7 @@ int nfs_updatepage(struct file *file, st
> unsigned int offset, unsigned int count)
> {
> struct nfs_open_context *ctx = (struct nfs_open_context *)file->private_data;
> - struct inode *inode = page->mapping->host;
> + struct inode *inode = page_file_mapping(page)->host;
> struct nfs_page *req;
> int status = 0;
>
> @@ -854,12 +854,12 @@ int nfs_updatepage(struct file *file, st
> offset = 0;
> if (unlikely(end_offs < 0)) {
> /* Do nothing */
> - } else if (page->index == end_index) {
> + } else if (page_file_index(page) == end_index) {

Is this necessary? When will we ever call nfs_updatepage() with a swap
page? AFAICS, the swap stuff always uses page dirtying and (ugh)
writepage().

> unsigned int pglen;
> pglen = (unsigned int)(end_offs & (PAGE_CACHE_SIZE-1)) + 1;
> if (count < pglen)
> count = pglen;
> - } else if (page->index < end_index)
> + } else if (page_file_index(page) < end_index)
> count = PAGE_CACHE_SIZE;
> }
>
> Index: linux-2.6/fs/nfs/dir.c
> ===================================================================
> --- linux-2.6.orig/fs/nfs/dir.c
> +++ linux-2.6/fs/nfs/dir.c
> @@ -177,7 +177,7 @@ int nfs_readdir_filler(nfs_readdir_descr
>
> dfprintk(DIRCACHE, "NFS: %s: reading cookie %Lu into page %lu\n",
> __FUNCTION__, (long long)desc->entry->cookie,
> - page->index);
> + page_file_index(page));
>
> again:
> timestamp = jiffies;
> @@ -201,7 +201,7 @@ int nfs_readdir_filler(nfs_readdir_descr
> * Note: assumes we have exclusive access to this mapping either
> * through inode->i_mutex or some other mechanism.
> */
> - if (page->index == 0)
> + if (page_file_index(page) == 0)
> invalidate_inode_pages2_range(inode->i_mapping, PAGE_CACHE_SIZE, -1);
> unlock_page(page);
> return 0;

Why are we worried about the possibility of NFS readdir pages being swap
pages?

Cheers,
Trond