From 650495dedc34daf8590c708a5b48f82ed2787b75 Mon Sep 17 00:00:00 2001 From: Jaegeuk Kim Date: Mon, 13 May 2013 08:38:35 +0900 Subject: [PATCH] f2fs: fix the inconsistent state of data pages In get_lock_data_page, if there is a data race between get_dnode_of_data for node and grab_cache_page for data, f2fs is able to face with the following BUG_ON(dn.data_blkaddr == NEW_ADDR). kernel BUG at /home/zeus/f2fs_test/src/fs/f2fs/data.c:251! [] get_lock_data_page+0x1ec/0x210 [f2fs] Call Trace: [] f2fs_readdir+0x89/0x210 [f2fs] [] ? fillonedir+0x100/0x100 [] ? fillonedir+0x100/0x100 [] vfs_readdir+0xb8/0xe0 [] sys_getdents+0x8f/0x110 [] system_call_fastpath+0x16/0x1b This bug is able to be occurred when the block address of the data block is changed after f2fs_put_dnode(). In order to avoid that, this patch fixes the lock order of node and data blocks in which the node block lock is covered by the data block lock. Signed-off-by: Jaegeuk Kim --- fs/f2fs/data.c | 21 +++++++++++++-------- 1 file changed, 13 insertions(+), 8 deletions(-) diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c index 91ff93b0b0f4..05fb5c6077b8 100644 --- a/fs/f2fs/data.c +++ b/fs/f2fs/data.c @@ -233,19 +233,24 @@ struct page *get_lock_data_page(struct inode *inode, pgoff_t index) struct page *page; int err; - set_new_dnode(&dn, inode, NULL, NULL, 0); - err = get_dnode_of_data(&dn, index, LOOKUP_NODE); - if (err) - return ERR_PTR(err); - f2fs_put_dnode(&dn); - - if (dn.data_blkaddr == NULL_ADDR) - return ERR_PTR(-ENOENT); repeat: page = grab_cache_page(mapping, index); if (!page) return ERR_PTR(-ENOMEM); + set_new_dnode(&dn, inode, NULL, NULL, 0); + err = get_dnode_of_data(&dn, index, LOOKUP_NODE); + if (err) { + f2fs_put_page(page, 1); + return ERR_PTR(err); + } + f2fs_put_dnode(&dn); + + if (dn.data_blkaddr == NULL_ADDR) { + f2fs_put_page(page, 1); + return ERR_PTR(-ENOENT); + } + if (PageUptodate(page)) return page;