From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965625AbaH1KPO (ORCPT ); Thu, 28 Aug 2014 06:15:14 -0400 Received: from mailout4.samsung.com ([203.254.224.34]:14610 "EHLO mailout4.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934503AbaH1KPL (ORCPT ); Thu, 28 Aug 2014 06:15:11 -0400 X-AuditID: cbfee691-f79546d0000011a1-0c-53ff011cf320 Date: Thu, 28 Aug 2014 19:13:32 +0900 From: Changman Lee To: Chao Yu Cc: "'Jaegeuk Kim'" , linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net Subject: Re: [f2fs-dev] [PATCH] f2fs: reposition unlock_new_inode to prevent accessing invalid inode Message-id: <20140828101332.GB6808@lcm> References: <009101cfc119$8e7a5a00$ab6f0e00$@samsung.com> <20140828014736.GA6808@lcm> <003801cfc29d$a370dad0$ea529070$@samsung.com> MIME-version: 1.0 Content-type: text/plain; charset=us-ascii Content-disposition: inline In-reply-to: <003801cfc29d$a370dad0$ea529070$@samsung.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFuphkeLIzCtJLcpLzFFi42I5/e+Zsa4M4/9gg0dXtCz+N31ks3iyfhaz xaVF7haXd81hc2Dx2LSqk81j94LPTB59W1YxenzeJBfAEsVlk5Kak1mWWqRvl8CVseByO0vB AfWK57/PMzUwnpDtYuTkkBAwkfjV954RwhaTuHBvPVsXIxeHkMAyRonLm1eywBStmHWGFcQW EljEKHGijxOi6CejxOOll9hBEiwCqhIvvh9nA7HZBLQk2k+vBWsWEVCS+DV/EVgzs0CexJcr W4BsDg5hgTSJJXP4QExeAXWJtl1qECNbGSX+flgB1sorICjxY/I9FohWLYn1O48zQdjSEo/+ zgBbyylgJXHhag9YjaiAisSUk9vYIG5exS5xudUH4jQBiW+TD7GA7JIQkJXYdIAZokRS4uCK GywTGMVmIdk2C8m2WUi2LWBkXsUomlqQXFCclF5kqlecmFtcmpeul5yfu4kREkkTdzDeP2B9 iFGAg1GJh3dGwr9gIdbEsuLK3EOMpkBXTGSWEk3OB8ZrXkm8obGZkYWpiamxkbmlmZI4r470 z2AhgfTEktTs1NSC1KL4otKc1OJDjEwcnFINjJuMJebsPx1/pdxrySTusnf1H/J0Dqh5Bd/m Y0qd4BHC/H7m+eCpZjyPKvcu8zNaHLVo+ommtP9vOu96X38UtNevc5Nz1OoF6x6I/DuZolBZ t34j//pPM9oWChWGOMVXNdy96hgiKOSidt3Pib0kS9rEu9Dg9Yf5f8Od7CZbPuTZ3cyccJHX QomlOCPRUIu5qDgRAM8fRR+fAgAA X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFrrOIsWRmVeSWpSXmKPExsVy+t9jAV0Zxv/BBrduqFn8b/rIZvFk/Sxm i0uL3C0u75rD5sDisWlVJ5vH7gWfmTz6tqxi9Pi8SS6AJaqB0SYjNTEltUghNS85PyUzL91W yTs43jne1MzAUNfQ0sJcSSEvMTfVVsnFJ0DXLTMHaKWSQlliTilQKCCxuFhJ3w7ThNAQN10L mMYIXd+QILgeIwM0kLCOMWPB5XaWggPqFc9/n2dqYDwh28XIySEhYCKxYtYZVghbTOLCvfVs ILaQwCJGiRN9nF2MXED2T0aJx0svsYMkWARUJV58Pw5WxCagJdF+ei0LiC0ioCTxa/4isEHM AnkSX65sAbI5OIQF0iSWzOEDMXkF1CXadqlBjGxllPj7YQVYK6+AoMSPyfdYIFq1JNbvPM4E YUtLPPo7A2wtp4CVxIWrPWA1ogIqElNObmObwCgwC0n7LCTts5C0L2BkXsUomlqQXFCclJ5r pFecmFtcmpeul5yfu4kRHKnPpHcwrmqwOMQowMGoxMPrEPcvWIg1say4MvcQowQHs5II77Q/ QCHelMTKqtSi/Pii0pzU4kOMpsDAmMgsJZqcD0wieSXxhsYmZkaWRmYWRibm5krivAdbrQOF BNITS1KzU1MLUotg+pg4OKUaGGPiLuRYNqswH7mWsCL6YtPyFwVpvKkTs2zs5qj1VOeuZmyP VmYyeMxQY3rrf+qnlZ9CkuveO0ht0/njue/YK+OHoZOULm49eir4ccj3jJkl6hM1pjzuf9n2 XeazzJlLIReE9ztP2CYsbNK+9d6NmYV/E0VV/Vj9Z6g5TQm8cSnr4XGDvKK/cUosxRmJhlrM RcWJADLfYQrqAgAA DLP-Filter: Pass X-MTR: 20000000000000000@CPGS X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On Thu, Aug 28, 2014 at 04:53:01PM +0800, Chao Yu wrote: > Hi Changman, > > > -----Original Message----- > > From: Changman Lee [mailto:cm224.lee@samsung.com] > > Sent: Thursday, August 28, 2014 9:48 AM > > To: Chao Yu > > Cc: Jaegeuk Kim; linux-kernel@vger.kernel.org; linux-f2fs-devel@lists.sourceforge.net > > Subject: Re: [f2fs-dev] [PATCH] f2fs: reposition unlock_new_inode to prevent accessing invalid > > inode > > > > Hi Chao, > > > > I agree it's correct unlock_new_inode should be located after make_bad_inode. > > > > About this scenario, > > I think we should check some condition if this could be occured; > > I think this condition is the almost impossible but which can happen theoretically. > > > A inode allocated newly could be victim by gc thread. > > Then, f2fs_iget called by Thread A have to fail because we handled it as > > bad_inode in Thread B. However, f2fs_iget could still get inode. > > How about check it using is_bad_inode() in f2fs_iget. > > Yes, agreed. How about return -EIO when this inode we iget_locked is bad? Hmm.. It might be better to check return value of f2fs_iget like other f/s. - a/fs/f2fs/gc.c +++ b/fs/f2fs/gc.c @@ -595,6 +595,8 @@ next_step: inode = f2fs_iget(sb, dni.ino); if (IS_ERR(inode)) continue; + else if (is_bad_inode(inode)) + continue; Thanks, Changman > > Thanks, > Yu > > > > > Thanks, > > > > On Tue, Aug 26, 2014 at 06:35:29PM +0800, Chao Yu wrote: > > > As the race condition on the inode cache, following scenario can appear: > > > [Thread a] [Thread b] > > > ->f2fs_mkdir > > > ->f2fs_add_link > > > ->__f2fs_add_link > > > ->init_inode_metadata failed here > > > ->gc_thread_func > > > ->f2fs_gc > > > ->do_garbage_collect > > > ->gc_data_segment > > > ->f2fs_iget > > > ->iget_locked > > > ->wait_on_inode > > > ->unlock_new_inode > > > ->move_data_page > > > ->make_bad_inode > > > ->iput > > > > > > When we fail in create/symlink/mkdir/mknod/tmpfile, the new allocated inode > > > should be set as bad to avoid being accessed by other thread. But in above > > > scenario, it allows f2fs to access the invalid inode before this inode was set > > > as bad. > > > This patch fix the potential problem, and this issue was found by code review. > > > > > > Signed-off-by: Chao Yu > > > --- > > > fs/f2fs/namei.c | 10 +++++----- > > > 1 file changed, 5 insertions(+), 5 deletions(-) > > > > > > diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c > > > index 6b53ce9..845f1be 100644 > > > --- a/fs/f2fs/namei.c > > > +++ b/fs/f2fs/namei.c > > > @@ -134,8 +134,8 @@ static int f2fs_create(struct inode *dir, struct dentry *dentry, umode_t > > mode, > > > return 0; > > > out: > > > clear_nlink(inode); > > > - unlock_new_inode(inode); > > > make_bad_inode(inode); > > > + unlock_new_inode(inode); > > > iput(inode); > > > alloc_nid_failed(sbi, ino); > > > return err; > > > @@ -267,8 +267,8 @@ static int f2fs_symlink(struct inode *dir, struct dentry *dentry, > > > return err; > > > out: > > > clear_nlink(inode); > > > - unlock_new_inode(inode); > > > make_bad_inode(inode); > > > + unlock_new_inode(inode); > > > iput(inode); > > > alloc_nid_failed(sbi, inode->i_ino); > > > return err; > > > @@ -308,8 +308,8 @@ static int f2fs_mkdir(struct inode *dir, struct dentry *dentry, umode_t > > mode) > > > out_fail: > > > clear_inode_flag(F2FS_I(inode), FI_INC_LINK); > > > clear_nlink(inode); > > > - unlock_new_inode(inode); > > > make_bad_inode(inode); > > > + unlock_new_inode(inode); > > > iput(inode); > > > alloc_nid_failed(sbi, inode->i_ino); > > > return err; > > > @@ -354,8 +354,8 @@ static int f2fs_mknod(struct inode *dir, struct dentry *dentry, > > > return 0; > > > out: > > > clear_nlink(inode); > > > - unlock_new_inode(inode); > > > make_bad_inode(inode); > > > + unlock_new_inode(inode); > > > iput(inode); > > > alloc_nid_failed(sbi, inode->i_ino); > > > return err; > > > @@ -688,8 +688,8 @@ release_out: > > > out: > > > f2fs_unlock_op(sbi); > > > clear_nlink(inode); > > > - unlock_new_inode(inode); > > > make_bad_inode(inode); > > > + unlock_new_inode(inode); > > > iput(inode); > > > alloc_nid_failed(sbi, inode->i_ino); > > > return err; > > > -- > > > 2.0.0.421.g786a89d > > > > > > > > > > > > ------------------------------------------------------------------------------ > > > Slashdot TV. > > > Video for Nerds. Stuff that matters. > > > http://tv.slashdot.org/ > > > _______________________________________________ > > > Linux-f2fs-devel mailing list > > > Linux-f2fs-devel@lists.sourceforge.net > > > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel