From: Mingming Subject: Re: Performance of ext4 Date: Tue, 24 Jun 2008 10:58:46 -0700 Message-ID: <1214330326.27507.303.camel@BVR-FS.beaverton.ibm.com> References: <20080616181353.GA20686@skywalker> <20080619155645.GA8582@mit.edu> <485A8C2D.1090806@redhat.com> <20080619174211.GB9119@mit.edu> <20080620085922.GH9119@mit.edu> <20080623174508.GA7216@skywalker> <1214267492.27507.285.camel@BVR-FS.beaverton.ibm.com> <20080624030721.GB10469@skywalker> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: Holger Kiehl , Theodore Tso , Eric Sandeen , Jan Kara , Solofo.Ramangalahy@bull.net, Nick Dokos , linux-ext4@vger.kernel.org, linux-kernel To: "Aneesh Kumar K.V" Return-path: Received: from e36.co.us.ibm.com ([32.97.110.154]:38644 "EHLO e36.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751097AbYFXR61 (ORCPT ); Tue, 24 Jun 2008 13:58:27 -0400 In-Reply-To: <20080624030721.GB10469@skywalker> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Tue, 2008-06-24 at 08:37 +0530, Aneesh Kumar K.V wrote: > On Mon, Jun 23, 2008 at 05:31:32PM -0700, Mingming wrote: > > > > On Mon, 2008-06-23 at 23:15 +0530, Aneesh Kumar K.V wrote: > > > > > I found one place where we fail to update i_disksize. Can you try this > > > patch ? > > > > > > diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c > > > index 33f940b..9fa737f 100644 > > > --- a/fs/ext4/inode.c > > > +++ b/fs/ext4/inode.c > > > @@ -1620,7 +1620,10 @@ static int ext4_da_writepage(struct page *page, > > > loff_t size; > > > unsigned long len; > > > handle_t *handle = NULL; > > > + ext4_lblk_t block; > > > + loff_t disksize; > > > struct buffer_head *page_bufs; > > > + struct buffer_head *bh, *head; > > > struct inode *inode = page->mapping->host; > > > > > > handle = ext4_journal_current_handle(); > > > @@ -1662,6 +1665,38 @@ static int ext4_da_writepage(struct page *page, > > > else > > > ret = block_write_full_page(page, ext4_da_get_block_write, wbc); > > > > > > + if (ret) > > > + return ret; > > > + /* > > > + * When called via shrink_page_list and if we don't have any unmapped > > > + * buffer_head we still could have written some new content in an > > > + * already mapped buffer. That means we need to extent i_disksize here > > > + */ > > > > In this case(when extend the file without need block allocation), > > wouldn't make sense to update the i_disksize at write_end() time? So > > that the window of i_size different from i_disksize could be much > > smaller in this case. > > > > > > Something like below? (untested) > > In this case you will have to start a transaction in write_begin . With > the below code transaction is started inside page_lock. Also I don't > think we need needed_blocks credit just 1 should be enough because we > are not doing any block allocation here. We just need to update the > inode block. > > Right! I will update the patch and merge it to the patch queue. Mingming > -aneesh > > > > > Signed-off-by: Mingming Cao > > --- > > fs/ext4/inode.c | 66 ++++++++++++++++++++++++++++++++++++++++++++++++++------ > > 1 file changed, 60 insertions(+), 6 deletions(-) > > > > Index: linux-2.6.26-rc6/fs/ext4/inode.c > > =================================================================== > > --- linux-2.6.26-rc6.orig/fs/ext4/inode.c 2008-06-23 17:28:01.000000000 -0700 > > +++ linux-2.6.26-rc6/fs/ext4/inode.c 2008-06-23 17:28:10.000000000 -0700 > > @@ -1573,6 +1573,65 @@ static int ext4_da_write_begin(struct fi > > return ret; > > } > > > > +static int ext4_bh_unmapped_or_delay(handle_t *handle, struct buffer_head *bh) > > +{ > > + return !buffer_mapped(bh) || buffer_delay(bh); > > +} > > + > > +static int ext4_da_write_end(struct file *file, > > + struct address_space *mapping, > > + loff_t pos, unsigned len, unsigned copied, > > + struct page *page, void *fsdata) > > +{ > > + handle_t *handle = NULL; > > + struct inode *inode = mapping->host; > > + int needed_blocks = ext4_writepage_trans_blocks(inode); > > + unsigned from, to; > > + int ret = 0, ret2; > > + > > + from = pos & (PAGE_CACHE_SIZE - 1); > > + to = from + len; > > + > > + if (ret == 0) { > > + /* > > + * generic_write_end() will run mark_inode_dirty() if i_size > > + * changes. So let's piggyback the i_disksize mark_inode_dirty > > + * into that. > > + */ > > + loff_t new_i_size; > > + > > + new_i_size = pos + copied; > > + if (new_i_size > EXT4_I(inode)->i_disksize) > > + if (!walk_page_buffers(NULL, page_buffers(page), > > + 0, len, NULL, ext4_bh_unmapped_or_delay)){ > > + /* > > + * Updating i_disksize when extending file without > > + * need block allocation > > + */ > > + handle = ext4_journal_start(inode, needed_blocks); > > + if (IS_ERR(handle)) { > > + ret = PTR_ERR(handle); > > + return ret; > > + } > > + if (ext4_should_order_data(inode)) > > + ret = ext4_jbd2_file_inode(handle, inode); > > + > > + EXT4_I(inode)->i_disksize = new_i_size; > > + } > > + ret2 = generic_write_end(file, mapping, pos, len, copied, > > + page, fsdata); > > + copied = ret2; > > + if (ret2 < 0) > > + ret = ret2; > > + } > > + if (handle) > > + ret2 = ext4_journal_stop(handle); > > + if (!ret) > > + ret = ret2; > > + > > + return ret ? ret : copied; > > +} > > + > > static void ext4_da_invalidatepage(struct page *page, unsigned long offset) > > { > > struct buffer_head *head, *bh; > > @@ -1682,11 +1741,6 @@ static int bput_one(handle_t *handle, st > > return 0; > > } > > > > -static int ext4_bh_unmapped_or_delay(handle_t *handle, struct buffer_head *bh) > > -{ > > - return !buffer_mapped(bh) || buffer_delay(bh); > > -} > > - > > /* > > * Note that we don't need to start a transaction unless we're journaling data > > * because we should have holes filled from ext4_page_mkwrite(). We even don't > > @@ -2050,7 +2104,7 @@ static const struct address_space_operat > > .writepages = ext4_da_writepages, > > .sync_page = block_sync_page, > > .write_begin = ext4_da_write_begin, > > - .write_end = generic_write_end, > > + .write_end = ext4_da_write_end, > > .bmap = ext4_bmap, > > .invalidatepage = ext4_da_invalidatepage, > > .releasepage = ext4_releasepage, > > > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-ext4" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html