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[209.132.180.67]) by mx.google.com with ESMTP id i5si24171906pgt.379.2017.11.27.21.41.10; Mon, 27 Nov 2017 21:41:22 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751381AbdK1Fke convert rfc822-to-8bit (ORCPT + 77 others); Tue, 28 Nov 2017 00:40:34 -0500 Received: from prv-mh.provo.novell.com ([137.65.248.74]:51295 "EHLO prv-mh.provo.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750975AbdK1Fkd (ORCPT ); Tue, 28 Nov 2017 00:40:33 -0500 Received: from INET-PRV-MTA by prv-mh.provo.novell.com with Novell_GroupWise; Mon, 27 Nov 2017 22:40:32 -0700 Message-Id: <5A1D674A020000F90009AD06@prv-mh.provo.novell.com> X-Mailer: Novell GroupWise Internet Agent 14.2.2 Date: Mon, 27 Nov 2017 22:40:26 -0700 From: "Gang He" To: , , , "Goldwyn Rodrigues" , Cc: , Subject: Re: [Ocfs2-devel] [PATCH 2/3] ocfs2: add ocfs2_overwrite_io function References: <1511775987-841-1-git-send-email-ghe@suse.com> <1511775987-841-3-git-send-email-ghe@suse.com> <63ADC13FD55D6546B7DECE290D39E373F1470B4A@H3CMLB12-EX.srv.huawei-3com.com> In-Reply-To: <63ADC13FD55D6546B7DECE290D39E373F1470B4A@H3CMLB12-EX.srv.huawei-3com.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8BIT Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Changwei, >>> > Hi, > Gang > > On 2017/11/27 17:48, Gang He wrote: >> Add ocfs2_overwrite_io function, which is used to judge if >> overwrite allocated blocks, otherwise, the write will bring extra >> block allocation overhead. >> > > Can you elaborate how this overhead is introduced? > Forgive me, I don't figure it. If the blocks have been allocated, we just write these block directly. If these blocks have not been allocated, that means we need to allocate these block firstly before write, this allocation will bring the IO invoking be blocked, if the upper application does not want take this kind of overhead, he can pass a nowait flag to avoid and return immediately with a -EAGAIN error. Thanks Gang > > Thanks, > Changwei > >> Signed-off-by: Gang He >> --- >> fs/ocfs2/extent_map.c | 67 > +++++++++++++++++++++++++++++++++++++++++++++++++++ >> fs/ocfs2/extent_map.h | 3 +++ >> 2 files changed, 70 insertions(+) >> >> diff --git a/fs/ocfs2/extent_map.c b/fs/ocfs2/extent_map.c >> index e4719e0..98bf325 100644 >> --- a/fs/ocfs2/extent_map.c >> +++ b/fs/ocfs2/extent_map.c >> @@ -832,6 +832,73 @@ int ocfs2_fiemap(struct inode *inode, struct > fiemap_extent_info *fieinfo, >> return ret; >> } >> >> +/* Is IO overwriting allocated blocks? */ >> +int ocfs2_overwrite_io(struct inode *inode, u64 map_start, u64 map_len, >> + int wait) >> +{ >> + int ret = 0, is_last; >> + u32 mapping_end, cpos; >> + struct ocfs2_super *osb = OCFS2_SB(inode->i_sb); >> + struct buffer_head *di_bh = NULL; >> + struct ocfs2_extent_rec rec; >> + >> + if (wait) >> + ret = ocfs2_inode_lock(inode, &di_bh, 0); >> + else >> + ret = ocfs2_try_inode_lock(inode, &di_bh, 0); >> + if (ret) >> + goto out; >> + >> + if (wait) >> + down_read(&OCFS2_I(inode)->ip_alloc_sem); >> + else { >> + if (!down_read_trylock(&OCFS2_I(inode)->ip_alloc_sem)) { >> + ret = -EAGAIN; >> + goto out_unlock1; >> + } >> + } >> + >> + if ((OCFS2_I(inode)->ip_dyn_features & OCFS2_INLINE_DATA_FL) && >> + ((map_start + map_len) <= i_size_read(inode))) >> + goto out_unlock2; >> + >> + cpos = map_start >> osb->s_clustersize_bits; >> + mapping_end = ocfs2_clusters_for_bytes(inode->i_sb, >> + map_start + map_len); >> + is_last = 0; >> + while (cpos < mapping_end && !is_last) { >> + ret = ocfs2_get_clusters_nocache(inode, di_bh, cpos, >> + NULL, &rec, &is_last); >> + if (ret) { >> + mlog_errno(ret); >> + goto out_unlock2; >> + } >> + >> + if (rec.e_blkno == 0ULL) >> + break; >> + >> + if (rec.e_flags & OCFS2_EXT_REFCOUNTED) >> + break; >> + >> + cpos = le32_to_cpu(rec.e_cpos) + >> + le16_to_cpu(rec.e_leaf_clusters); >> + } >> + >> + if (cpos < mapping_end) >> + ret = 1; >> + >> +out_unlock2: >> + brelse(di_bh); >> + >> + up_read(&OCFS2_I(inode)->ip_alloc_sem); >> + >> +out_unlock1: >> + ocfs2_inode_unlock(inode, 0); >> + >> +out: >> + return (ret ? 0 : 1); >> +} >> + >> int ocfs2_seek_data_hole_offset(struct file *file, loff_t *offset, int > whence) >> { >> struct inode *inode = file->f_mapping->host; >> diff --git a/fs/ocfs2/extent_map.h b/fs/ocfs2/extent_map.h >> index 67ea57d..fd9e86a 100644 >> --- a/fs/ocfs2/extent_map.h >> +++ b/fs/ocfs2/extent_map.h >> @@ -53,6 +53,9 @@ int ocfs2_extent_map_get_blocks(struct inode *inode, u64 > v_blkno, u64 *p_blkno, >> int ocfs2_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, >> u64 map_start, u64 map_len); >> >> +int ocfs2_overwrite_io(struct inode *inode, u64 map_start, u64 map_len, >> + int wait); >> + >> int ocfs2_seek_data_hole_offset(struct file *file, loff_t *offset, int > origin); >> >> int ocfs2_xattr_get_clusters(struct inode *inode, u32 v_cluster, >> From 1585286857759367358@xxx Tue Nov 28 05:36:00 +0000 2017 X-GM-THRID: 1585212205986077742 X-Gmail-Labels: Inbox,Category Forums,HistoricalUnread