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Sat, 12 Sep 2020 04:04:44 +0000 (UTC) Received: from [10.72.12.33] (ovpn-12-33.pek2.redhat.com [10.72.12.33]) by smtp.corp.redhat.com (Postfix) with ESMTPS id B479F7B7A0; Sat, 12 Sep 2020 04:04:42 +0000 (UTC) Subject: Re: [PATCH v5 0/2] ceph: metrics for opened files, pinned caps and opened inodes To: Jeff Layton , Ilya Dryomov Cc: "Yan, Zheng" , Patrick Donnelly , Ceph Development References: <20200903130140.799392-1-xiubli@redhat.com> <449a56624f3dd4e2a4a4cf95cd24d69c53700b6d.camel@kernel.org> <9a5c5d2f-d105-21c4-327e-5ad18bf49518@redhat.com> From: Xiubo Li Message-ID: Date: Sat, 12 Sep 2020 12:04:39 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Sender: ceph-devel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: ceph-devel@vger.kernel.org On 2020/9/12 3:46, Jeff Layton wrote: > On Fri, 2020-09-11 at 07:49 -0400, Jeff Layton wrote: >> On Fri, 2020-09-11 at 11:43 +0800, Xiubo Li wrote: >>> On 2020/9/10 20:13, Jeff Layton wrote: >>>> On Thu, 2020-09-10 at 08:00 +0200, Ilya Dryomov wrote: >>>>> On Thu, Sep 10, 2020 at 2:59 AM Xiubo Li wrote: >>>>>> On 2020/9/10 4:34, Ilya Dryomov wrote: >>>>>>> On Thu, Sep 3, 2020 at 4:22 PM Xiubo Li wrote: >>>>>>>> On 2020/9/3 22:18, Jeff Layton wrote: >>>>>>>>> On Thu, 2020-09-03 at 09:01 -0400, xiubli@redhat.com wrote: >>>>>>>>>> From: Xiubo Li >>>>>>>>>> >>>>>>>>>> Changed in V5: >>>>>>>>>> - Remove mdsc parsing helpers except the ceph_sb_to_mdsc() >>>>>>>>>> - Remove the is_opened member. >>>>>>>>>> >>>>>>>>>> Changed in V4: >>>>>>>>>> - A small fix about the total_inodes. >>>>>>>>>> >>>>>>>>>> Changed in V3: >>>>>>>>>> - Resend for V2 just forgot one patch, which is adding some helpers >>>>>>>>>> support to simplify the code. >>>>>>>>>> >>>>>>>>>> Changed in V2: >>>>>>>>>> - Add number of inodes that have opened files. >>>>>>>>>> - Remove the dir metrics and fold into files. >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> Xiubo Li (2): >>>>>>>>>> ceph: add ceph_sb_to_mdsc helper support to parse the mdsc >>>>>>>>>> ceph: metrics for opened files, pinned caps and opened inodes >>>>>>>>>> >>>>>>>>>> fs/ceph/caps.c | 41 +++++++++++++++++++++++++++++++++++++---- >>>>>>>>>> fs/ceph/debugfs.c | 11 +++++++++++ >>>>>>>>>> fs/ceph/dir.c | 20 +++++++------------- >>>>>>>>>> fs/ceph/file.c | 13 ++++++------- >>>>>>>>>> fs/ceph/inode.c | 11 ++++++++--- >>>>>>>>>> fs/ceph/locks.c | 2 +- >>>>>>>>>> fs/ceph/metric.c | 14 ++++++++++++++ >>>>>>>>>> fs/ceph/metric.h | 7 +++++++ >>>>>>>>>> fs/ceph/quota.c | 10 +++++----- >>>>>>>>>> fs/ceph/snap.c | 2 +- >>>>>>>>>> fs/ceph/super.h | 6 ++++++ >>>>>>>>>> 11 files changed, 103 insertions(+), 34 deletions(-) >>>>>>>>>> >>>>>>>>> Looks good. I went ahead and merge this into testing. >>>>>>>>> >>>>>>>>> Small merge conflict in quota.c, which I guess is probably due to not >>>>>>>>> basing this on testing branch. I also dropped what looks like an >>>>>>>>> unrelated hunk in the second patch. >>>>>>>>> >>>>>>>>> In the future, if you can be sure that patches you post apply cleanly to >>>>>>>>> testing branch then that would make things easier. >>>>>>>> Okay, will do it. >>>>>>> Hi Xiubo, >>>>>>> >>>>>>> There is a problem with lifetimes here. mdsc isn't guaranteed to exist >>>>>>> when ->free_inode() is called. This can lead to crashes on a NULL mdsc >>>>>>> in ceph_free_inode() in case of e.g. "umount -f". I know it was Jeff's >>>>>>> suggestion to move the decrement of total_inodes into ceph_free_inode(), >>>>>>> but it doesn't look like it can be easily deferred past ->evict_inode(). >>>>>> Okay, I will take a look. >>>>> Given that it's just a counter which we don't care about if the >>>>> mount is going away, some form of "if (mdsc)" check might do, but >>>>> need to make sure that it covers possible races, if any. >>>>> >>>> Good catch, Ilya. >>>> >>>> What may be best is to move the increment out of ceph_alloc_inode and >>>> instead put it in ceph_set_ino_cb. Then the decrement can go back into >>>> ceph_evict_inode. >>> Hi Jeff, Ilya >>> >>> Checked the code, it seems in the ceph_evict_inode() we will also hit >>> the same issue . >>> >>> With the '-f' options when umounting, it will skip the inodes whose >>> i_count ref > 0. And then free the fsc/mdsc in ceph. And later the >>> iput_final() will call the ceph_evict_inode() and then ceph_free_inode(). >>> >>> Could we just check if !!(sb->s_flags & SB_ACTIVE) is false will we skip >>> the counting ? >>> >> Note that umount -f (MNT_FORCE) just means that ceph_umount_begin is >> called before unmounting. >> >> If what you're saying it true, then we have bigger problems. >> ceph_evict_inode does this today when ci->i_snap_realm is set: >> >> struct ceph_mds_client *mdsc = ceph_inode_to_client(inode)->mdsc; >> >> ...and then goes on to use that mdsc pointer. >> > Now that I look, I don't think that this is a problem. ceph_kill_sb > calls generic_shutdown_super, which calls evict_inodes before the client > is torn down. That should ensure that the mdsc is still good when evict > is called. > > We will need to move the increment into the iget5_locked "set" function. > Maybe we can squash the patch below into yours? Yeah, the following patch looks good. Thanks. > > ----------------------8<--------------------------- > > ceph: use total_inodes to count hashed inodes instead of allocated ones > > We can't guarantee that the mdsc will still be around when free_inode is > called, so move this into evict_inode instead. The increment then will > need to be moved when the thing is hashed, so move that into the set > callback. > > Reported-by: Ilya Dryomov > Signed-off-by: Jeff Layton > --- > fs/ceph/inode.c | 12 ++++++------ > 1 file changed, 6 insertions(+), 6 deletions(-) > > diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c > index 5b9d2ff8af34..39c13fefba8a 100644 > --- a/fs/ceph/inode.c > +++ b/fs/ceph/inode.c > @@ -42,10 +42,13 @@ static void ceph_inode_work(struct work_struct *work); > static int ceph_set_ino_cb(struct inode *inode, void *data) > { > struct ceph_inode_info *ci = ceph_inode(inode); > + struct ceph_mds_client *mdsc = ceph_sb_to_mdsc(inode->i_sb); > > ci->i_vino = *(struct ceph_vino *)data; > inode->i_ino = ceph_vino_to_ino_t(ci->i_vino); > inode_set_iversion_raw(inode, 0); > + percpu_counter_inc(&mdsc->metric.total_inodes); > + > return 0; > } > > @@ -425,7 +428,6 @@ static int ceph_fill_fragtree(struct inode *inode, > */ > struct inode *ceph_alloc_inode(struct super_block *sb) > { > - struct ceph_mds_client *mdsc = ceph_sb_to_mdsc(sb); > struct ceph_inode_info *ci; > int i; > > @@ -525,17 +527,12 @@ struct inode *ceph_alloc_inode(struct super_block *sb) > > ci->i_meta_err = 0; > > - percpu_counter_inc(&mdsc->metric.total_inodes); > - > return &ci->vfs_inode; > } > > void ceph_free_inode(struct inode *inode) > { > struct ceph_inode_info *ci = ceph_inode(inode); > - struct ceph_mds_client *mdsc = ceph_sb_to_mdsc(inode->i_sb); > - > - percpu_counter_dec(&mdsc->metric.total_inodes); > > kfree(ci->i_symlink); > kmem_cache_free(ceph_inode_cachep, ci); > @@ -544,11 +541,14 @@ void ceph_free_inode(struct inode *inode) > void ceph_evict_inode(struct inode *inode) > { > struct ceph_inode_info *ci = ceph_inode(inode); > + struct ceph_mds_client *mdsc = ceph_sb_to_mdsc(inode->i_sb); > struct ceph_inode_frag *frag; > struct rb_node *n; > > dout("evict_inode %p ino %llx.%llx\n", inode, ceph_vinop(inode)); > > + percpu_counter_dec(&mdsc->metric.total_inodes); > + > truncate_inode_pages_final(&inode->i_data); > clear_inode(inode); >