Commit 1b3b4a1a authored by Trond Myklebust's avatar Trond Myklebust
Browse files

NFS: Fix a write request leak in nfs_invalidate_page() 



Ryusuke Konishi says:

The recent truncate_complete_page() clears the dirty flag from a page
before calling a_ops->invalidatepage(),
^^^^^^
static void
truncate_complete_page(struct address_space *mapping, struct page *page)
{
        ...
        cancel_dirty_page(page, PAGE_CACHE_SIZE);  <--- Inserted here at
kernel 2.6.20

        if (PagePrivate(page))
                do_invalidatepage(page, 0);   ---> will call
a_ops->invalidatepage()
        ...
}

and this is disturbing nfs_wb_page_priority() from calling 
nfs_writepage_locked() that is expected to handle the pending
request (=nfs_page) associated with the page.

int nfs_wb_page_priority(struct inode *inode, struct page *page, int how)
{
        ...
        if (clear_page_dirty_for_io(page)) {
                ret = nfs_writepage_locked(page, &wbc);
                if (ret < 0)
                        goto out;
        }
        ...
}

Since truncate_complete_page() will get rid of the page after
a_ops->invalidatepage() returns, the request (=nfs_page) associated
with the page becomes a garbage in nfs_inode->nfs_page_tree.
------------------------

Fix this by ensuring that nfs_wb_page_priority() recognises that it may
also need to clear out non-dirty pages that have an nfs_page associated
with them.

Signed-off-by: default avatarTrond Myklebust <Trond.Myklebust@netapp.com>
parent 7d1cca72

fs/nfs/file.c

+1 −1
Original line number Diff line number Diff line
@@ -316,7 +316,7 @@ static void nfs_invalidate_page(struct page *page, unsigned long offset) 
	if (offset != 0)

		return;

	/* Cancel any unstarted writes on this page */

	nfs_wb_page_priority(page->mapping->host, page, FLUSH_INVALIDATE);

	nfs_wb_page_cancel(page->mapping->host, page);

}



static int nfs_release_page(struct page *page, gfp_t gfp)

fs/nfs/write.c

+44 −0
Original line number Diff line number Diff line
@@ -1396,6 +1396,50 @@ out: 
	return ret;

}



int nfs_wb_page_cancel(struct inode *inode, struct page *page)

{

	struct nfs_page *req;

	loff_t range_start = page_offset(page);

	loff_t range_end = range_start + (loff_t)(PAGE_CACHE_SIZE - 1);

	struct writeback_control wbc = {

		.bdi = page->mapping->backing_dev_info,

		.sync_mode = WB_SYNC_ALL,

		.nr_to_write = LONG_MAX,

		.range_start = range_start,

		.range_end = range_end,

	};

	int ret = 0;



	BUG_ON(!PageLocked(page));

	for (;;) {

		req = nfs_page_find_request(page);

		if (req == NULL)

			goto out;

		if (test_bit(PG_NEED_COMMIT, &req->wb_flags)) {

			nfs_release_request(req);

			break;

		}

		if (nfs_lock_request_dontget(req)) {

			nfs_inode_remove_request(req);

			/*

			 * In case nfs_inode_remove_request has marked the

			 * page as being dirty

			 */

			cancel_dirty_page(page, PAGE_CACHE_SIZE);

			nfs_unlock_request(req);

			break;

		}

		ret = nfs_wait_on_request(req);

		if (ret < 0)

			goto out;

	}

	if (!PagePrivate(page))

		return 0;

	ret = nfs_sync_mapping_wait(page->mapping, &wbc, FLUSH_INVALIDATE);

out:

	return ret;

}



int nfs_wb_page_priority(struct inode *inode, struct page *page, int how)

{

	loff_t range_start = page_offset(page);

include/linux/nfs_fs.h

+1 −0
Original line number Diff line number Diff line
@@ -431,6 +431,7 @@ extern int nfs_sync_mapping_range(struct address_space *, loff_t, loff_t, int); 
extern int nfs_wb_all(struct inode *inode);

extern int nfs_wb_page(struct inode *inode, struct page* page);

extern int nfs_wb_page_priority(struct inode *inode, struct page* page, int how);

extern int nfs_wb_page_cancel(struct inode *inode, struct page* page);

#if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)

extern int  nfs_commit_inode(struct inode *, int);

extern struct nfs_write_data *nfs_commit_alloc(void);

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