From mboxrd@z Thu Jan 1 00:00:00 1970 From: Theodore Tso Subject: Re: [URGENT PATCH] ext4: fix potential deadlock in ext4_evict_inode() Date: Fri, 26 Aug 2011 07:35:24 -0400 Message-ID: <22BEE903-4141-4D2A-932B-259DF50F14E1@mit.edu> References: <20110826073507.GZ3162@dastard> <20110826084403.GA3162@dastard> <20110826085057.GA13311@infradead.org> <4E57630B.7000202@tao.ma> <20110826091718.GA3179@infradead.org> Mime-Version: 1.0 (Apple Message framework v1244.3) Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Tao Ma , Dave Chinner , Jiaying Zhang , linux-ext4@vger.kernel.org To: Christoph Hellwig Return-path: Received: from DMZ-MAILSEC-SCANNER-7.MIT.EDU ([18.7.68.36]:62509 "EHLO dmz-mailsec-scanner-7.mit.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750897Ab1HZLfa convert rfc822-to-8bit (ORCPT ); Fri, 26 Aug 2011 07:35:30 -0400 In-Reply-To: <20110826091718.GA3179@infradead.org> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Aug 26, 2011, at 5:17 AM, Christoph Hellwig wrote: > The thing I have queued up for 3.2 makes it very simple: we do not > track I/O ends any more at all, outside of the workqueue. >=20 > For buffered I/O we only mark the page uptodate when all unwritten > extent conversion and size updates have finished. All data integrity > callers and inode eviction wait for the pages to be update so we are > covered. >=20 > For direct I/O we only call inode_dio_done and aio_complete once all > unwritten extent size updates are done. Inodes can't be evicted unti= l > we drop a reference to the inode, which can't happen until the > sync or async dio is done and we drop the inode reference the VFS > holds for it. Sync and fsync are only guaranteed to pick up I/O > that has returned to userspace, so we are covered for that as well. Long term, I definitely want to make ext4 do something similar.=20 What we have now is just way too fragile=85 -- Ted -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html