Commit fa04a40b authored by David Howells's avatar David Howells
Browse files

afs: Fix to take ref on page when PG_private is set 



Fix afs to take a ref on a page when it sets PG_private on it and to drop
the ref when removing the flag.

Note that in afs_write_begin(), a lot of the time, PG_private is already
set on a page to which we're going to add some data.  In such a case, we
leave the bit set and mustn't increment the page count.

As suggested by Matthew Wilcox, use attach/detach_page_private() where
possible.

Fixes: 31143d5d ("AFS: implement basic file write support")
Reported-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Reviewed-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
parent d383e346

fs/afs/dir.c

+4 −8
Original line number Diff line number Diff line
@@ -281,8 +281,7 @@ static struct afs_read *afs_read_dir(struct afs_vnode *dvnode, struct key *key) 
			if (ret < 0)

				goto error;



			set_page_private(req->pages[i], 1);

			SetPagePrivate(req->pages[i]);

			attach_page_private(req->pages[i], (void *)1);

			unlock_page(req->pages[i]);

			i++;

		} else {
@@ -1975,8 +1974,7 @@ static int afs_dir_releasepage(struct page *page, gfp_t gfp_flags) 


	_enter("{{%llx:%llu}[%lu]}", dvnode->fid.vid, dvnode->fid.vnode, page->index);



	set_page_private(page, 0);

	ClearPagePrivate(page);

	detach_page_private(page);



	/* The directory will need reloading. */

	if (test_and_clear_bit(AFS_VNODE_DIR_VALID, &dvnode->flags))
@@ -2003,8 +2001,6 @@ static void afs_dir_invalidatepage(struct page *page, unsigned int offset, 
		afs_stat_v(dvnode, n_inval);



	/* we clean up only if the entire page is being invalidated */

	if (offset == 0 && length == PAGE_SIZE) {

		set_page_private(page, 0);

		ClearPagePrivate(page);

	}

	if (offset == 0 && length == PAGE_SIZE)

		detach_page_private(page);

}

fs/afs/dir_edit.c

+2 −4
Original line number Diff line number Diff line
@@ -243,10 +243,8 @@ void afs_edit_dir_add(struct afs_vnode *vnode, 
						   index, gfp);

			if (!page)

				goto error;

			if (!PagePrivate(page)) {

				set_page_private(page, 1);

				SetPagePrivate(page);

			}

			if (!PagePrivate(page))

				attach_page_private(page, (void *)1);

			dir_page = kmap(page);

		}

fs/afs/file.c

+2 −6
Original line number Diff line number Diff line
@@ -627,11 +627,9 @@ static void afs_invalidatepage(struct page *page, unsigned int offset, 
#endif



		if (PagePrivate(page)) {

			priv = page_private(page);

			priv = (unsigned long)detach_page_private(page);

			trace_afs_page_dirty(vnode, tracepoint_string("inval"),

					     page->index, priv);

			set_page_private(page, 0);

			ClearPagePrivate(page);

		}

	}
@@ -661,11 +659,9 @@ static int afs_releasepage(struct page *page, gfp_t gfp_flags) 
#endif



	if (PagePrivate(page)) {

		priv = page_private(page);

		priv = (unsigned long)detach_page_private(page);

		trace_afs_page_dirty(vnode, tracepoint_string("rel"),

				     page->index, priv);

		set_page_private(page, 0);

		ClearPagePrivate(page);

	}



	/* indicate that the page can be released */

fs/afs/write.c

+10 −8
Original line number Diff line number Diff line
@@ -151,8 +151,10 @@ int afs_write_begin(struct file *file, struct address_space *mapping, 
	priv |= f;

	trace_afs_page_dirty(vnode, tracepoint_string("begin"),

			     page->index, priv);

	SetPagePrivate(page);

	if (PagePrivate(page))

		set_page_private(page, priv);

	else

		attach_page_private(page, (void *)priv);

	_leave(" = 0");

	return 0;
@@ -334,10 +336,9 @@ static void afs_pages_written_back(struct afs_vnode *vnode, 
		ASSERTCMP(pv.nr, ==, count);



		for (loop = 0; loop < count; loop++) {

			priv = page_private(pv.pages[loop]);

			priv = (unsigned long)detach_page_private(pv.pages[loop]);

			trace_afs_page_dirty(vnode, tracepoint_string("clear"),

					     pv.pages[loop]->index, priv);

			set_page_private(pv.pages[loop], 0);

			end_page_writeback(pv.pages[loop]);

		}

		first += count;
@@ -863,8 +864,10 @@ vm_fault_t afs_page_mkwrite(struct vm_fault *vmf) 
	priv |= 0; /* From */

	trace_afs_page_dirty(vnode, tracepoint_string("mkwrite"),

			     vmf->page->index, priv);

	SetPagePrivate(vmf->page);

	if (PagePrivate(vmf->page))

		set_page_private(vmf->page, priv);

	else

		attach_page_private(vmf->page, (void *)priv);

	file_update_time(file);



	sb_end_pagefault(inode->i_sb);
@@ -926,10 +929,9 @@ int afs_launder_page(struct page *page) 
		ret = afs_store_data(mapping, page->index, page->index, t, f, true);

	}



	priv = (unsigned long)detach_page_private(page);

	trace_afs_page_dirty(vnode, tracepoint_string("laundered"),

			     page->index, priv);

	set_page_private(page, 0);

	ClearPagePrivate(page);



#ifdef CONFIG_AFS_FSCACHE

	if (PageFsCache(page)) {