f2fs: check truncation of mapping after lock_page

We call lock_page when we need to update a page after readpage.
Between grab and lock page, the page can be truncated by other thread.
So, we should check the page after lock_page whether it was truncated or not.

Signed-off-by: Jaegeuk Kim <[e-mail]>

fs/f2fs/checkpoint.c

···
 		goto repeat;
 
 	lock_page(page);
+	if (page->mapping != mapping) {
+		f2fs_put_page(page, 1);
+		goto repeat;
+	}
 out:
 	mark_page_accessed(page);
 	return page;

fs/f2fs/data.c

···
 
 	if (dn.data_blkaddr == NULL_ADDR)
 		return ERR_PTR(-ENOENT);
-
+repeat:
 	page = grab_cache_page(mapping, index);
 	if (!page)
 		return ERR_PTR(-ENOMEM);
···
 	if (!PageUptodate(page)) {
 		f2fs_put_page(page, 1);
 		return ERR_PTR(-EIO);
+	}
+	if (page->mapping != mapping) {
+		f2fs_put_page(page, 1);
+		goto repeat;
 	}
 	return page;
 }
···
 		}
 	}
 	f2fs_put_dnode(&dn);
-
+repeat:
 	page = grab_cache_page(mapping, index);
 	if (!page)
 		return ERR_PTR(-ENOMEM);
···
 		if (!PageUptodate(page)) {
 			f2fs_put_page(page, 1);
 			return ERR_PTR(-EIO);
+		}
+		if (page->mapping != mapping) {
+			f2fs_put_page(page, 1);
+			goto repeat;
 		}
 	}
 
···
 	*fsdata = NULL;
 
 	f2fs_balance_fs(sbi);
-
+repeat:
 	page = grab_cache_page_write_begin(mapping, index, flags);
 	if (!page)
 		return -ENOMEM;
···
 		if (!PageUptodate(page)) {
 			f2fs_put_page(page, 1);
 			return -EIO;
+		}
+		if (page->mapping != mapping) {
+			f2fs_put_page(page, 1);
+			goto repeat;
 		}
 	}
 out:

fs/f2fs/file.c

···
 		return;
 
 	lock_page(page);
+	if (page->mapping != inode->i_mapping) {
+		f2fs_put_page(page, 1);
+		return;
+	}
 	wait_on_page_writeback(page);
 	zero_user(page, offset, PAGE_CACHE_SIZE - offset);
 	set_page_dirty(page);

fs/f2fs/node.c

···
 int truncate_inode_blocks(struct inode *inode, pgoff_t from)
 {
 	struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
+	struct address_space *node_mapping = sbi->node_inode->i_mapping;
 	int err = 0, cont = 1;
 	int level, offset[4], noffset[4];
 	unsigned int nofs = 0;
···
 	trace_f2fs_truncate_inode_blocks_enter(inode, from);
 
 	level = get_node_path(from, offset, noffset);
-
+restart:
 	page = get_node_page(sbi, inode->i_ino);
 	if (IS_ERR(page)) {
 		trace_f2fs_truncate_inode_blocks_exit(inode, PTR_ERR(page));
···
 		if (offset[1] == 0 &&
 				rn->i.i_nid[offset[0] - NODE_DIR1_BLOCK]) {
 			lock_page(page);
+			if (page->mapping != node_mapping) {
+				f2fs_put_page(page, 1);
+				goto restart;
+			}
 			wait_on_page_writeback(page);
 			rn->i.i_nid[offset[0] - NODE_DIR1_BLOCK] = 0;
 			set_page_dirty(page);
···
 	struct address_space *mapping = sbi->node_inode->i_mapping;
 	struct page *page;
 	int err;
-
+repeat:
 	page = grab_cache_page(mapping, nid);
 	if (!page)
 		return ERR_PTR(-ENOMEM);
···
 	if (!PageUptodate(page)) {
 		f2fs_put_page(page, 1);
 		return ERR_PTR(-EIO);
+	}
+	if (page->mapping != mapping) {
+		f2fs_put_page(page, 1);
+		goto repeat;
 	}
 got_it:
 	BUG_ON(nid != nid_of_node(page));
···
 	nid = get_nid(parent, start, false);
 	if (!nid)
 		return ERR_PTR(-ENOENT);
-
+repeat:
 	page = grab_cache_page(mapping, nid);
 	if (!page)
 		return ERR_PTR(-ENOMEM);
···
 	blk_finish_plug(&plug);
 
 	lock_page(page);
-
+	if (page->mapping != mapping) {
+		f2fs_put_page(page, 1);
+		goto repeat;
+	}
 page_hit:
 	if (!PageUptodate(page)) {
 		f2fs_put_page(page, 1);