From: Zheng Liu Subject: Re: [PATCH 1/3] ext4: Retry allocation when inline->extent conversion failed Date: Thu, 12 Dec 2013 18:30:20 +0800 Message-ID: <20131212103020.GA3239@gmail.com> References: <1386670440-3158-1-git-send-email-jack@suse.cz> <1386670440-3158-2-git-send-email-jack@suse.cz> <20131212064422.GA16199@gmail.com> <20131212093936.GA1886@quack.suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Ted Tso , Akira Fujita , linux-ext4@vger.kernel.org To: Jan Kara Return-path: Received: from mail-pd0-f180.google.com ([209.85.192.180]:45752 "EHLO mail-pd0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751406Ab3LLK1Q (ORCPT ); Thu, 12 Dec 2013 05:27:16 -0500 Received: by mail-pd0-f180.google.com with SMTP id q10so271462pdj.39 for ; Thu, 12 Dec 2013 02:27:16 -0800 (PST) Content-Disposition: inline In-Reply-To: <20131212093936.GA1886@quack.suse.cz> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Thu, Dec 12, 2013 at 10:39:36AM +0100, Jan Kara wrote: > On Thu 12-12-13 14:44:22, Zheng Liu wrote: > > Hi Jan, > > > > On Tue, Dec 10, 2013 at 11:13:58AM +0100, Jan Kara wrote: > > > Similarly as other ->write_begin functions in ext4, also > > > ext4_da_write_inline_data_begin() should retry allocation if the > > > conversion failed because of ENOSPC. This avoids returning ENOSPC > > > prematurely because of uncommitted block deletions. > > > > I don't see why we need to try again here. If there is no enough space > > in inline data, ext4_da_convert_inline_data_to_extent() just read the > > inline data into a page and clear EXT4_STATE_MAY_INLINE_DATA flag. If > > we try again, we will encounter an ENOSPC error again. So why do we > > need to retry allocation? > Umm, I don't think so. ext4_da_convert_inline_data_to_extent() calls > ext4_da_get_block_prep() and that can falsely fail with ENOSPC if there are > blocks freed in currently running transaction. So we call > ext4_should_retry_alloc() which forces commit of the current transaction > and then we retry the allocation. Ah, I see. Thanks for your explanation. - Zheng > > Honza > > > > > > > Signed-off-by: Jan Kara > > > --- > > > fs/ext4/inline.c | 7 +++++++ > > > 1 file changed, 7 insertions(+) > > > > > > diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c > > > index bae987549dc3..ed6e71fe5e9d 100644 > > > --- a/fs/ext4/inline.c > > > +++ b/fs/ext4/inline.c > > > @@ -849,11 +849,13 @@ int ext4_da_write_inline_data_begin(struct address_space *mapping, > > > handle_t *handle; > > > struct page *page; > > > struct ext4_iloc iloc; > > > + int retries; > > > > > > ret = ext4_get_inode_loc(inode, &iloc); > > > if (ret) > > > return ret; > > > > > > +retry_journal: > > > handle = ext4_journal_start(inode, EXT4_HT_INODE, 1); > > > if (IS_ERR(handle)) { > > > ret = PTR_ERR(handle); > > > @@ -875,6 +877,11 @@ int ext4_da_write_inline_data_begin(struct address_space *mapping, > > > inode, > > > flags, > > > fsdata); > > > + ext4_journal_stop(handle); > > > + handle = NULL; > > > + if (ret == -ENOSPC && > > > + ext4_should_retry_alloc(inode->i_sb, &retries)) > > > + goto retry_journal; > > > goto out; > > > } > > > > > > -- > > > 1.8.1.4 > > > > > > -- > > > 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 > -- > Jan Kara > SUSE Labs, CR