From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752122AbdK1INL (ORCPT ); Tue, 28 Nov 2017 03:13:11 -0500 Received: from szxga04-in.huawei.com ([45.249.212.190]:11444 "EHLO szxga04-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751932AbdK1INI (ORCPT ); Tue, 28 Nov 2017 03:13:08 -0500 Message-ID: <5A1D1A4A.8040506@huawei.com> Date: Tue, 28 Nov 2017 16:11:54 +0800 From: alex chen User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:17.0) Gecko/20130509 Thunderbird/17.0.6 MIME-Version: 1.0 To: Gang He CC: , , , "Goldwyn Rodrigues" , , 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> <5A1CC7BC.3060309@huawei.com> <5A1D65C4020000F90009ACE1@prv-mh.provo.novell.com> <5A1D0003.6060605@huawei.com> <5A1D830E020000F90009ADA7@prv-mh.provo.novell.com> In-Reply-To: <5A1D830E020000F90009ADA7@prv-mh.provo.novell.com> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.177.26.59] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A090201.5A1D1A4D.0071,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0, ip=0.0.0.0, so=2014-11-16 11:51:01, dmn=2013-03-21 17:37:32 X-Mirapoint-Loop-Id: 0edc9bd226a4a7759c27e4d5a76fd146 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Gang, On 2017/11/28 15:38, Gang He wrote: > Hi Alex, > > >>>> >> Hi Gang, >> >> On 2017/11/28 13:33, Gang He wrote: >>> Hello Alex, >>> >>> >>>>>> >>>> Hi Gang, >>>> >>>> On 2017/11/27 17:46, 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. >>>>> >>>>> 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; >>>> I think here the blocks is not overwrite, because the hold is found and the >>>> blocks >>>> should be allocated. >>> If the rec.e_blkno == NULL, this means there is a hole. >>> The file hole means that these blocks are not allocated, it does not like >> unwritten block. >>> The unwritten blocks means that these blocks are allocated, but still have >> not been unwritten. >>> >> If we break the loop when we find the hold, out of this function we will >> allocate the blocks in >> ocfs2_file_write_iter()->..->ocfs2_direct_IO->__blockdev_direct_IO->..->ocfs2_dio_wr_g >> et_block() >> ->ocfs2_write_begin_nolock. Does this violate the semantics of 'IOCB_NOWAIT'; > Yes, then we need to check if this is a overwrite before doing direct-io. > I mean here we should return 0 instead of break and we should immediately return -EAGAIN to upper apps, otherwise, some block allocation will be happen, which violates the semantics of 'IOCB_NOWAIT'. Thanks, Alex >> >> BTW, should we consider the down_write() and ocfs2_inode_lock() in >> ocfs2_dio_wr_get_block() when >> the flag 'IOCB_NOWAIT' is set; > I think that we should not consider that layer lock, otherwise, the code change will become more and more complex and big. > I also refer to ext4 file system code change for this feature(728fbc0e10b7f3ce2ee043b32e3453fd5201c055), they did not do any change in that layer. > OK. > Thanks > Gang > >> >>>>> + >>>>> + 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: >>>> >>>> I think the 'out_up_read' is more readable than the 'out_unlock2' . >>> Ok, I will use more readable tag here. >>>> >>>>> + brelse(di_bh); >>>>> + >>>>> + up_read(&OCFS2_I(inode)->ip_alloc_sem); >>>>> + >>>>> +out_unlock1: >>>> >>>> We should release buffer head here. >>>> >>>>> + 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 mboxrd@z Thu Jan 1 00:00:00 1970 From: alex chen Date: Tue, 28 Nov 2017 16:11:54 +0800 Subject: [Ocfs2-devel] [PATCH 2/3] ocfs2: add ocfs2_overwrite_io function In-Reply-To: <5A1D830E020000F90009ADA7@prv-mh.provo.novell.com> References: <1511775987-841-1-git-send-email-ghe@suse.com> <1511775987-841-3-git-send-email-ghe@suse.com> <5A1CC7BC.3060309@huawei.com> <5A1D65C4020000F90009ACE1@prv-mh.provo.novell.com> <5A1D0003.6060605@huawei.com> <5A1D830E020000F90009ADA7@prv-mh.provo.novell.com> Message-ID: <5A1D1A4A.8040506@huawei.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Gang He Cc: jlbec@evilplan.org, hch@lst.de, ocfs2-devel@oss.oracle.com, Goldwyn Rodrigues , mfasheh@versity.com, linux-kernel@vger.kernel.org Hi Gang, On 2017/11/28 15:38, Gang He wrote: > Hi Alex, > > >>>> >> Hi Gang, >> >> On 2017/11/28 13:33, Gang He wrote: >>> Hello Alex, >>> >>> >>>>>> >>>> Hi Gang, >>>> >>>> On 2017/11/27 17:46, 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. >>>>> >>>>> 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; >>>> I think here the blocks is not overwrite, because the hold is found and the >>>> blocks >>>> should be allocated. >>> If the rec.e_blkno == NULL, this means there is a hole. >>> The file hole means that these blocks are not allocated, it does not like >> unwritten block. >>> The unwritten blocks means that these blocks are allocated, but still have >> not been unwritten. >>> >> If we break the loop when we find the hold, out of this function we will >> allocate the blocks in >> ocfs2_file_write_iter()->..->ocfs2_direct_IO->__blockdev_direct_IO->..->ocfs2_dio_wr_g >> et_block() >> ->ocfs2_write_begin_nolock. Does this violate the semantics of 'IOCB_NOWAIT'; > Yes, then we need to check if this is a overwrite before doing direct-io. > I mean here we should return 0 instead of break and we should immediately return -EAGAIN to upper apps, otherwise, some block allocation will be happen, which violates the semantics of 'IOCB_NOWAIT'. Thanks, Alex >> >> BTW, should we consider the down_write() and ocfs2_inode_lock() in >> ocfs2_dio_wr_get_block() when >> the flag 'IOCB_NOWAIT' is set; > I think that we should not consider that layer lock, otherwise, the code change will become more and more complex and big. > I also refer to ext4 file system code change for this feature(728fbc0e10b7f3ce2ee043b32e3453fd5201c055), they did not do any change in that layer. > OK. > Thanks > Gang > >> >>>>> + >>>>> + 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: >>>> >>>> I think the 'out_up_read' is more readable than the 'out_unlock2' . >>> Ok, I will use more readable tag here. >>>> >>>>> + brelse(di_bh); >>>>> + >>>>> + up_read(&OCFS2_I(inode)->ip_alloc_sem); >>>>> + >>>>> +out_unlock1: >>>> >>>> We should release buffer head here. >>>> >>>>> + 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, >>>>> >>> >>> >>> . >>> > > . >