From: Hisashi Hifumi Subject: Re: [PATCH] jbd jbd2: fix diowritereturningEIOwhentry_to_release_page fails Date: Tue, 19 Aug 2008 16:03:45 +0900 Message-ID: <6.0.0.20.2.20080819113242.03f9e8c8@172.19.0.2> References: <1217971027.7516.20.camel@mingming-laptop> <1218029114.15342.58.camel@think.oraclecorp.com> <20080806135337.GA3615@duck.suse.cz> <1218063477.6383.41.camel@mingming-laptop> <6.0.0.20.2.20080807115853.03f95b78@172.19.0.2> <1218104494.15342.171.camel@think.oraclecorp.com> <6.0.0.20.2.20080808113605.04141328@172.19.0.2> <1218200055.15342.230.camel@think.oraclecorp.com> <6.0.0.20.2.20080811123405.03ec03d0@172.19.0.2> <1218547706.15342.305.camel@think.oraclecorp.com> <20080813101650.GA14392@duck.suse.cz> <1218632396.15342.340.camel@think.oraclecorp.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: Mingming Cao , linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, Zach Brown To: Andrew Morton , Chris Mason , Jan Kara Return-path: In-Reply-To: <1218632396.15342.340.camel@think.oraclecorp.com> References: <1217971027.7516.20.camel@mingming-laptop> <1218029114.15342.58.camel@think.oraclecorp.com> <20080806135337.GA3615@duck.suse.cz> <1218063477.6383.41.camel@mingming-laptop> <6.0.0.20.2.20080807115853.03f95b78@172.19.0.2> <1218104494.15342.171.camel@think.oraclecorp.com> <6.0.0.20.2.20080808113605.04141328@172.19.0.2> <1218200055.15342.230.camel@think.oraclecorp.com> <6.0.0.20.2.20080811123405.03ec03d0@172.19.0.2> <1218547706.15342.305.camel@think.oraclecorp.com> <20080813101650.GA14392@duck.suse.cz> <1218632396.15342.340.camel@think.oraclecorp.com> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org At 21:59 08/08/13, Chris Mason wrote: >On Wed, 2008-08-13 at 12:16 +0200, Jan Kara wrote: > >> > With that said, I don't have strong feelings against falling back to >> > buffered IO when the invalidate fails. Maybe Zach remembers something I >> > don't? >> I don't have a strong opinion either. Falling back to buffered writes is >> simpler at least for ext3/ext4 because properly synchronizing against >> writepage() call does not seem to have a nice solution either in >> do_launder_page() or in releasepage(). OTOH is hides the fact the invalidate >> is failing and so if we screw up something in future and it fails often, it >> might be hard to notice / track down the performance penalty. > >In general, these races don't happen often, and when they do it is >because someone is mixing page cache and O_DIRECT io to the same file. >That is explicitly outside the main use case of O_DIRECT. > >So, I'd rather see us slow down O_DIRECT in the mixed use case than have >big impacts in complexity or speed to other parts of the kernel. If >falling back avoids problems in some filesystems or avoids clearing the >uptodate bit unexpectedly, I'd much rather take the fallback patch. > >-chris Hi Andrew. I think we don't have strong feelings against falling back to buffered writes to fix the direct-io -EIO problem. Please review my patch. Signed-off-by: Hisashi Hifumi diff -Nrup linux-2.6.27-rc3.org/mm/filemap.c linux-2.6.27-rc3/mm/filemap.c --- linux-2.6.27-rc3.org/mm/filemap.c 2008-08-13 13:48:47.000000000 +0900 +++ linux-2.6.27-rc3/mm/filemap.c 2008-08-19 15:45:31.000000000 +0900 @@ -2129,13 +2129,20 @@ generic_file_direct_write(struct kiocb * * After a write we want buffered reads to be sure to go to disk to get * the new data. We invalidate clean cached page from the region we're * about to write. We do this *before* the write so that we can return - * -EIO without clobbering -EIOCBQUEUED from ->direct_IO(). + * without clobbering -EIOCBQUEUED from ->direct_IO(). */ if (mapping->nrpages) { written = invalidate_inode_pages2_range(mapping, pos >> PAGE_CACHE_SHIFT, end); - if (written) + /* + * If a page can not be invalidated, return 0 to fall back + * to buffered write. + */ + if (written) { + if (written == -EBUSY) + return 0; goto out; + } } written = mapping->a_ops->direct_IO(WRITE, iocb, iov, pos, *nr_segs); diff -Nrup linux-2.6.27-rc3.org/mm/truncate.c linux-2.6.27-rc3/mm/truncate.c --- linux-2.6.27-rc3.org/mm/truncate.c 2008-08-13 13:48:48.000000000 +0900 +++ linux-2.6.27-rc3/mm/truncate.c 2008-08-19 12:10:46.000000000 +0900 @@ -380,7 +380,7 @@ static int do_launder_page(struct addres * Any pages which are found to be mapped into pagetables are unmapped prior to * invalidation. * - * Returns -EIO if any pages could not be invalidated. + * Returns -EBUSY if any pages could not be invalidated. */ int invalidate_inode_pages2_range(struct address_space *mapping, pgoff_t start, pgoff_t end) @@ -440,7 +440,7 @@ int invalidate_inode_pages2_range(struct ret2 = do_launder_page(mapping, page); if (ret2 == 0) { if (!invalidate_complete_page2(mapping, page)) - ret2 = -EIO; + ret2 = -EBUSY; } if (ret2 < 0) ret = ret2;