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NFS: Avoid races between writebacks and truncation 

Currently, there is no serialisation between NFS asynchronous writebacks
and truncation at the page level due to the fact that nfs_sync_inode()
cannot lock the pages that it is about to write out.

This means that it is possible to be flushing out data (and calling something
like set_page_writeback()) while the page cache is busy evicting the page.
Oops...

Use the hooks provided in try_to_release_page() to ensure that dirty pages
are always written back to storage before we evict them.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
This commit is contained in:
Trond Myklebust 2006-03-20 13:44:04 -05:00
parent b92dccf65b
commit cd52ed3553
2 changed files with 21 additions and 2 deletions
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13
fs/nfs/file.c
View File

@ -316,6 +316,17 @@ static int nfs_commit_write(struct file *file, struct page *page, unsigned offse
return status;
}
static int nfs_invalidate_page(struct page *page, unsigned long offset)
{
/* FIXME: we really should cancel any unstarted writes on this page */
return 1;
}
static int nfs_release_page(struct page *page, gfp_t gfp)
{
return !nfs_wb_page(page->mapping->host, page);
}
struct address_space_operations nfs_file_aops = {
.readpage = nfs_readpage,
.readpages = nfs_readpages,
@ -324,6 +335,8 @@ struct address_space_operations nfs_file_aops = {
.writepages = nfs_writepages,
.prepare_write = nfs_prepare_write,
.commit_write = nfs_commit_write,
.invalidatepage = nfs_invalidate_page,
.releasepage = nfs_release_page,
#ifdef CONFIG_NFS_DIRECTIO
.direct_IO = nfs_direct_IO,
#endif

10
fs/nfs/pagelist.c
View File

@ -85,6 +85,10 @@ nfs_create_request(struct nfs_open_context *ctx, struct inode *inode,
atomic_set(&req->wb_complete, 0);
req->wb_index = page->index;
page_cache_get(page);
BUG_ON(PagePrivate(page));
BUG_ON(!PageLocked(page));
BUG_ON(page->mapping->host != inode);
SetPagePrivate(page);
req->wb_offset = offset;
req->wb_pgbase = offset;
req->wb_bytes = count;
@ -147,8 +151,10 @@ void nfs_clear_page_writeback(struct nfs_page *req)
*/
void nfs_clear_request(struct nfs_page *req)
{
if (req->wb_page) {
page_cache_release(req->wb_page);
struct page *page = req->wb_page;
if (page != NULL) {
ClearPagePrivate(page);
page_cache_release(page);
req->wb_page = NULL;
}
}