Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753050AbaBSJgr (ORCPT ); Wed, 19 Feb 2014 04:36:47 -0500 Received: from nbl-ex10-fe01.nebula.fi ([188.117.32.121]:56242 "EHLO ex10.nebula.fi" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751260AbaBSJgp (ORCPT ); Wed, 19 Feb 2014 04:36:45 -0500 Message-ID: <1392802602.32597.2.camel@ultrabook> Subject: Re: [PATCH] hfsplus: fix concurrent acess of alloc_blocks From: Sougata Santra Reply-To: To: Andrew Morton CC: Christoph Hellwig , , , Vyacheslav Dubeyko , "Joe Perches" , Alexey Khoroshilov Date: Wed, 19 Feb 2014 11:36:42 +0200 In-Reply-To: <20140218140642.fdc6a406f22de69bdf73e66e@linux-foundation.org> References: <1392639647.29849.11.camel@ultrabook> <20140218140642.fdc6a406f22de69bdf73e66e@linux-foundation.org> Organization: Tuxera Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.6.4 (3.6.4-3.fc18) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Originating-IP: [194.100.106.164] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2014-02-18 at 14:06 -0800, Andrew Morton wrote: > On Mon, 17 Feb 2014 14:20:47 +0200 Sougata Santra wrote: > > > > > Concurrent access to alloc_blocks in hfsplus_inode_info is > > protected by extents_lock mutex. This patch fixes two > > instances where alloc_blocks modification was not protected > > with this lock. This fixes possible allocation bitmap > > corruption in race conditions while extending and truncating > > files. > > > > ... > > > > --- a/fs/hfsplus/extents.c > > +++ b/fs/hfsplus/extents.c > > @@ -498,11 +498,13 @@ int hfsplus_file_extend(struct inode *inode) > > goto insert_extent; > > } > > out: > > - mutex_unlock(&hip->extents_lock); > > if (!res) { > > hip->alloc_blocks += len; > > + mutex_unlock(&hip->extents_lock); > > hfsplus_mark_inode_dirty(inode, HFSPLUS_I_ALLOC_DIRTY); > > + return 0; > > } > > + mutex_unlock(&hip->extents_lock); > > return res; > > > > This looks OK. > > > @@ -592,9 +594,9 @@ void hfsplus_file_truncate(struct inode *inode) > > hfs_brec_remove(&fd); > > } > > hfs_find_exit(&fd); > > - mutex_unlock(&hip->extents_lock); > > > > hip->alloc_blocks = blk_cnt; > > + mutex_unlock(&hip->extents_lock); > > out: > > hip->phys_size = inode->i_size; > > hip->fs_blocks = (inode->i_size + sb->s_blocksize - 1) >> > > But this does not. To provide locking for > hfsplus_inode_info.alloc_blocks, we must take the lock *before* taking > a local copy of ->alloc_blocks. > > Please review: > > --- a/fs/hfsplus/extents.c~hfsplus-fix-concurrent-acess-of-alloc_blocks-fix > +++ a/fs/hfsplus/extents.c > @@ -556,11 +556,13 @@ void hfsplus_file_truncate(struct inode > > blk_cnt = (inode->i_size + HFSPLUS_SB(sb)->alloc_blksz - 1) >> > HFSPLUS_SB(sb)->alloc_blksz_shift; > + > + mutex_lock(&hip->extents_lock); > + > alloc_cnt = hip->alloc_blocks; > if (blk_cnt == alloc_cnt) > - goto out; > + goto out_unlock; > > - mutex_lock(&hip->extents_lock); > res = hfs_find_init(HFSPLUS_SB(sb)->ext_tree, &fd); > if (res) { > mutex_unlock(&hip->extents_lock); > @@ -594,6 +596,7 @@ void hfsplus_file_truncate(struct inode > hfs_find_exit(&fd); > > hip->alloc_blocks = blk_cnt; > +out_unlock: > mutex_unlock(&hip->extents_lock); > out: > hip->phys_size = inode->i_size; > _ > This is good, Missed it. Thank you. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/