Commit 01f28610 authored by Jaegeuk Kim's avatar Jaegeuk Kim
Browse files

f2fs: fix race on allocating and deallocating a dentry block 



There are two threads:
 f2fs_delete_entry()              get_new_data_page()
                                  f2fs_reserve_block()
				  dn.blkaddr = XXX
 lock_page(dentry_block)
 truncate_hole()
 dn.blkaddr = NULL
 unlock_page(dentry_block)
                                  lock_page(dentry_block)
                                  fill the block from XXX address
                                  add new dentries
                                  unlock_page(dentry_block)

Later, f2fs_write_data_page() will truncate the dentry_block, since
its block address is NULL.

The reason for this was due to the wrong lock order.
In this case, we should do f2fs_reserve_block() after locking its dentry block.

Signed-off-by: default avatarJaegeuk Kim <jaegeuk@kernel.org>
parent eaa693f4

fs/f2fs/data.c

+12 −15
Original line number Diff line number Diff line
@@ -1076,20 +1076,22 @@ struct page *get_new_data_page(struct inode *inode, 
	struct page *page;

	struct dnode_of_data dn;

	int err;

repeat:

	page = grab_cache_page(mapping, index);

	if (!page)

		return ERR_PTR(-ENOMEM);



	set_new_dnode(&dn, inode, ipage, NULL, 0);

	err = f2fs_reserve_block(&dn, index);

	if (err)

	if (err) {

		f2fs_put_page(page, 1);

		return ERR_PTR(err);

repeat:

	page = grab_cache_page(mapping, index);

	if (!page) {

		err = -ENOMEM;

		goto put_err;

	}

	if (!ipage)

		f2fs_put_dnode(&dn);



	if (PageUptodate(page))

		return page;

		goto got_it;



	if (dn.data_blkaddr == NEW_ADDR) {

		zero_user_segment(page, 0, PAGE_CACHE_SIZE);
@@ -1104,20 +1106,19 @@ repeat: 
		};

		err = f2fs_submit_page_bio(&fio);

		if (err)

			goto put_err;

			return ERR_PTR(err);



		lock_page(page);

		if (unlikely(!PageUptodate(page))) {

			f2fs_put_page(page, 1);

			err = -EIO;

			goto put_err;

			return ERR_PTR(-EIO);

		}

		if (unlikely(page->mapping != mapping)) {

			f2fs_put_page(page, 1);

			goto repeat;

		}

	}



got_it:

	if (new_i_size &&

		i_size_read(inode) < ((index + 1) << PAGE_CACHE_SHIFT)) {

		i_size_write(inode, ((index + 1) << PAGE_CACHE_SHIFT));
@@ -1125,10 +1126,6 @@ repeat: 
		set_inode_flag(F2FS_I(inode), FI_UPDATE_DIR);

	}

	return page;



put_err:

	f2fs_put_dnode(&dn);

	return ERR_PTR(err);

}



static int __allocate_data_block(struct dnode_of_data *dn)

CRA Git | Maintained and supported by SUSTech CRA and CCSE