Re: [PATCH v3 4/8] ceph: add a new flag to indicate whether parent is locked

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On Sat, 2017-02-04 at 11:16 +0800, Yan, Zheng wrote:
> > On 4 Feb 2017, at 02:04, Jeff Layton <jlayton@xxxxxxxxxx> wrote:
> > 
> > struct ceph_mds_request has an r_locked_dir pointer, which is set to
> > indicate the parent inode and that its i_rwsem is locked.  In some
> > critical places, we need to be able to indicate the parent inode to the
> > request handling code, even when its i_rwsem may not be locked.
> > 
> > Most of the code that operates on r_locked_dir doesn't require that the
> > i_rwsem be locked. We only really need it to handle manipulation of the
> > dcache. The rest (filling of the inode, updating dentry leases, etc.)
> > already has its own locking.
> > 
> > Add a new r_req_flags bit that indicates whether the parent is locked
> > when doing the request, and rename the pointer to "r_parent". For now,
> > all the places that set r_parent also set this flag, but that will
> > change in a later patch.
> > 
> > Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
> > ---
> > fs/ceph/dir.c        | 21 ++++++++++++++-------
> > fs/ceph/export.c     |  3 ++-
> > fs/ceph/file.c       |  3 ++-
> > fs/ceph/inode.c      | 17 ++++++++++-------
> > fs/ceph/mds_client.c | 24 ++++++++++++------------
> > fs/ceph/mds_client.h |  3 ++-
> > 6 files changed, 42 insertions(+), 29 deletions(-)
> > 
> > diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
> > index 5fb86d71220e..c8562b8a8c7e 100644
> > --- a/fs/ceph/dir.c
> > +++ b/fs/ceph/dir.c
> > @@ -752,7 +752,8 @@ static struct dentry *ceph_lookup(struct inode *dir, struct dentry *dentry,
> > 		mask |= CEPH_CAP_XATTR_SHARED;
> > 	req->r_args.getattr.mask = cpu_to_le32(mask);
> > 
> > -	req->r_locked_dir = dir;
> > +	req->r_parent = dir;
> > +	set_bit(CEPH_MDS_R_PARENT_LOCKED, &req->r_req_flags);
> > 	err = ceph_mdsc_do_request(mdsc, NULL, req);
> > 	err = ceph_handle_snapdir(req, dentry, err);
> > 	dentry = ceph_finish_lookup(req, dentry, err);
> > @@ -813,7 +814,8 @@ static int ceph_mknod(struct inode *dir, struct dentry *dentry,
> > 	}
> > 	req->r_dentry = dget(dentry);
> > 	req->r_num_caps = 2;
> > -	req->r_locked_dir = dir;
> > +	req->r_parent = dir;
> > +	set_bit(CEPH_MDS_R_PARENT_LOCKED, &req->r_req_flags);
> > 	req->r_args.mknod.mode = cpu_to_le32(mode);
> > 	req->r_args.mknod.rdev = cpu_to_le32(rdev);
> > 	req->r_dentry_drop = CEPH_CAP_FILE_SHARED;
> > @@ -864,7 +866,8 @@ static int ceph_symlink(struct inode *dir, struct dentry *dentry,
> > 		ceph_mdsc_put_request(req);
> > 		goto out;
> > 	}
> > -	req->r_locked_dir = dir;
> > +	req->r_parent = dir;
> > +	set_bit(CEPH_MDS_R_PARENT_LOCKED, &req->r_req_flags);
> > 	req->r_dentry = dget(dentry);
> > 	req->r_num_caps = 2;
> > 	req->r_dentry_drop = CEPH_CAP_FILE_SHARED;
> > @@ -913,7 +916,8 @@ static int ceph_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
> > 
> > 	req->r_dentry = dget(dentry);
> > 	req->r_num_caps = 2;
> > -	req->r_locked_dir = dir;
> > +	req->r_parent = dir;
> > +	set_bit(CEPH_MDS_R_PARENT_LOCKED, &req->r_req_flags);
> > 	req->r_args.mkdir.mode = cpu_to_le32(mode);
> > 	req->r_dentry_drop = CEPH_CAP_FILE_SHARED;
> > 	req->r_dentry_unless = CEPH_CAP_FILE_EXCL;
> > @@ -957,7 +961,8 @@ static int ceph_link(struct dentry *old_dentry, struct inode *dir,
> > 	req->r_dentry = dget(dentry);
> > 	req->r_num_caps = 2;
> > 	req->r_old_dentry = dget(old_dentry);
> > -	req->r_locked_dir = dir;
> > +	req->r_parent = dir;
> > +	set_bit(CEPH_MDS_R_PARENT_LOCKED, &req->r_req_flags);
> > 	req->r_dentry_drop = CEPH_CAP_FILE_SHARED;
> > 	req->r_dentry_unless = CEPH_CAP_FILE_EXCL;
> > 	/* release LINK_SHARED on source inode (mds will lock it) */
> > @@ -1023,7 +1028,8 @@ static int ceph_unlink(struct inode *dir, struct dentry *dentry)
> > 	}
> > 	req->r_dentry = dget(dentry);
> > 	req->r_num_caps = 2;
> > -	req->r_locked_dir = dir;
> > +	req->r_parent = dir;
> > +	set_bit(CEPH_MDS_R_PARENT_LOCKED, &req->r_req_flags);
> > 	req->r_dentry_drop = CEPH_CAP_FILE_SHARED;
> > 	req->r_dentry_unless = CEPH_CAP_FILE_EXCL;
> > 	req->r_inode_drop = drop_caps_for_unlink(inode);
> > @@ -1066,7 +1072,8 @@ static int ceph_rename(struct inode *old_dir, struct dentry *old_dentry,
> > 	req->r_num_caps = 2;
> > 	req->r_old_dentry = dget(old_dentry);
> > 	req->r_old_dentry_dir = old_dir;
> > -	req->r_locked_dir = new_dir;
> > +	req->r_parent = new_dir;
> > +	set_bit(CEPH_MDS_R_PARENT_LOCKED, &req->r_req_flags);
> > 	req->r_old_dentry_drop = CEPH_CAP_FILE_SHARED;
> > 	req->r_old_dentry_unless = CEPH_CAP_FILE_EXCL;
> > 	req->r_dentry_drop = CEPH_CAP_FILE_SHARED;
> > diff --git a/fs/ceph/export.c b/fs/ceph/export.c
> > index 180bbef760f2..e8f11fa565c5 100644
> > --- a/fs/ceph/export.c
> > +++ b/fs/ceph/export.c
> > @@ -207,7 +207,8 @@ static int ceph_get_name(struct dentry *parent, char *name,
> > 	req->r_inode = d_inode(child);
> > 	ihold(d_inode(child));
> > 	req->r_ino2 = ceph_vino(d_inode(parent));
> > -	req->r_locked_dir = d_inode(parent);
> > +	req->r_parent = d_inode(parent);
> > +	set_bit(CEPH_MDS_R_PARENT_LOCKED, &req->r_req_flags);
> > 	req->r_num_caps = 2;
> > 	err = ceph_mdsc_do_request(mdsc, NULL, req);
> > 
> > diff --git a/fs/ceph/file.c b/fs/ceph/file.c
> > index 19419eb87f38..a91239c4b31c 100644
> > --- a/fs/ceph/file.c
> > +++ b/fs/ceph/file.c
> > @@ -310,7 +310,8 @@ int ceph_atomic_open(struct inode *dir, struct dentry *dentry,
> >                mask |= CEPH_CAP_XATTR_SHARED;
> >        req->r_args.open.mask = cpu_to_le32(mask);
> > 
> > -	req->r_locked_dir = dir;           /* caller holds dir->i_mutex */
> > +	req->r_parent = dir;
> > +	set_bit(CEPH_MDS_R_PARENT_LOCKED, &req->r_req_flags);
> > 	err = ceph_mdsc_do_request(mdsc,
> > 				   (flags & (O_CREAT|O_TRUNC)) ? dir : NULL,
> > 				   req);
> > diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
> > index e54ba03d3df7..b4b61da03dbf 100644
> > --- a/fs/ceph/inode.c
> > +++ b/fs/ceph/inode.c
> > @@ -1122,13 +1122,13 @@ int ceph_fill_trace(struct super_block *sb, struct ceph_mds_request *req)
> > 
> > 	if (!rinfo->head->is_target && !rinfo->head->is_dentry) {
> > 		dout("fill_trace reply is empty!\n");
> > -		if (rinfo->head->result == 0 && req->r_locked_dir)
> > +		if (rinfo->head->result == 0 && req->r_parent)
> > 			ceph_invalidate_dir_request(req);
> > 		return 0;
> > 	}
> > 
> > 	if (rinfo->head->is_dentry) {
> > -		struct inode *dir = req->r_locked_dir;
> > +		struct inode *dir = req->r_parent;
> > 
> > 		if (dir) {
> > 			err = fill_inode(dir, NULL,
> > @@ -1216,7 +1216,9 @@ int ceph_fill_trace(struct super_block *sb, struct ceph_mds_request *req)
> > 	 * ignore null lease/binding on snapdir ENOENT, or else we
> > 	 * will have trouble splicing in the virtual snapdir later
> > 	 */
> > -	if (rinfo->head->is_dentry && req->r_locked_dir &&
> > +	if (rinfo->head->is_dentry &&
> > +            !test_bit(CEPH_MDS_R_ABORTED, &req->r_req_flags) &&
> 
> why adding the !ABORTED check back. I think previous patch add:
> 
> if (test_bit(CEPH_MDS_R_ABORTED, &req->r_req_flags))
>   goto done;
> 

Oof, good catch -- I screwed that up.

We want to keep the R_ABORTED checks where r_aborted is checked now, as
that will allow us to update the dentry leases even when the task that
spawned the call was aborted.

I'll fix that in the ceph-client/testing branch, but I'll not bother
reposting unless there are other problems that need fixing in here.

> > +	    test_bit(CEPH_MDS_R_PARENT_LOCKED, &req->r_req_flags) &&
> > 	    (rinfo->head->is_target || strncmp(req->r_dentry->d_name.name,
> > 					       fsc->mount_options->snapdir_name,
> > 					       req->r_dentry->d_name.len))) {
> > @@ -1225,7 +1227,7 @@ int ceph_fill_trace(struct super_block *sb, struct ceph_mds_request *req)
> > 		 * mknod symlink mkdir  : null -> new inode
> > 		 * unlink               : linked -> null
> > 		 */
> > -		struct inode *dir = req->r_locked_dir;
> > +		struct inode *dir = req->r_parent;
> > 		struct dentry *dn = req->r_dentry;
> > 		bool have_dir_cap, have_lease;
> > 
> > @@ -1319,10 +1321,11 @@ int ceph_fill_trace(struct super_block *sb, struct ceph_mds_request *req)
> > 			update_dentry_lease(dn, rinfo->dlease, session,
> > 					    req->r_request_started);
> > 		dout(" final dn %p\n", dn);
> > -	} else if (req->r_op == CEPH_MDS_OP_LOOKUPSNAP ||
> > -		   req->r_op == CEPH_MDS_OP_MKSNAP) {
> > +	} else if ((req->r_op == CEPH_MDS_OP_LOOKUPSNAP ||
> > +		    req->r_op == CEPH_MDS_OP_MKSNAP) &&
> > +		   !test_bit(CEPH_MDS_R_ABORTED, &req->r_req_flags)) {
> 
> same here
> 
> > 		struct dentry *dn = req->r_dentry;
> > -		struct inode *dir = req->r_locked_dir;
> > +		struct inode *dir = req->r_parent;
> > 
> > 		/* fill out a snapdir LOOKUPSNAP dentry */
> > 		BUG_ON(!dn);
> > diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
> > index ccf75a3260e8..52521f339745 100644
> > --- a/fs/ceph/mds_client.c
> > +++ b/fs/ceph/mds_client.c
> > @@ -547,8 +547,8 @@ void ceph_mdsc_release_request(struct kref *kref)
> > 		ceph_put_cap_refs(ceph_inode(req->r_inode), CEPH_CAP_PIN);
> > 		iput(req->r_inode);
> > 	}
> > -	if (req->r_locked_dir)
> > -		ceph_put_cap_refs(ceph_inode(req->r_locked_dir), CEPH_CAP_PIN);
> > +	if (req->r_parent)
> > +		ceph_put_cap_refs(ceph_inode(req->r_parent), CEPH_CAP_PIN);
> > 	iput(req->r_target_inode);
> > 	if (req->r_dentry)
> > 		dput(req->r_dentry);
> > @@ -735,7 +735,7 @@ static int __choose_mds(struct ceph_mds_client *mdsc,
> > 
> > 		rcu_read_lock();
> > 		parent = req->r_dentry->d_parent;
> > -		dir = req->r_locked_dir ? : d_inode_rcu(parent);
> > +		dir = req->r_parent ? : d_inode_rcu(parent);
> > 
> > 		if (!dir || dir->i_sb != mdsc->fsc->sb) {
> > 			/*  not this fs or parent went negative */
> > @@ -1894,7 +1894,7 @@ static struct ceph_msg *create_request_message(struct ceph_mds_client *mdsc,
> > 	int ret;
> > 
> > 	ret = set_request_path_attr(req->r_inode, req->r_dentry,
> > -			      req->r_locked_dir, req->r_path1, req->r_ino1.ino,
> > +			      req->r_parent, req->r_path1, req->r_ino1.ino,
> > 			      &path1, &pathlen1, &ino1, &freepath1);
> > 	if (ret < 0) {
> > 		msg = ERR_PTR(ret);
> > @@ -1956,7 +1956,7 @@ static struct ceph_msg *create_request_message(struct ceph_mds_client *mdsc,
> > 		      mds, req->r_inode_drop, req->r_inode_unless, 0);
> > 	if (req->r_dentry_drop)
> > 		releases += ceph_encode_dentry_release(&p, req->r_dentry,
> > -				req->r_locked_dir, mds, req->r_dentry_drop,
> > +				req->r_parent, mds, req->r_dentry_drop,
> > 				req->r_dentry_unless);
> > 	if (req->r_old_dentry_drop)
> > 		releases += ceph_encode_dentry_release(&p, req->r_old_dentry,
> > @@ -2095,14 +2095,14 @@ static int __prepare_send_request(struct ceph_mds_client *mdsc,
> > 	rhead->oldest_client_tid = cpu_to_le64(__get_oldest_tid(mdsc));
> > 	if (test_bit(CEPH_MDS_R_GOT_UNSAFE, &req->r_req_flags))
> > 		flags |= CEPH_MDS_FLAG_REPLAY;
> > -	if (req->r_locked_dir)
> > +	if (req->r_parent)
> > 		flags |= CEPH_MDS_FLAG_WANT_DENTRY;
> > 	rhead->flags = cpu_to_le32(flags);
> > 	rhead->num_fwd = req->r_num_fwd;
> > 	rhead->num_retry = req->r_attempts - 1;
> > 	rhead->ino = 0;
> > 
> > -	dout(" r_locked_dir = %p\n", req->r_locked_dir);
> > +	dout(" r_parent = %p\n", req->r_parent);
> > 	return 0;
> > }
> > 
> > @@ -2282,11 +2282,11 @@ int ceph_mdsc_do_request(struct ceph_mds_client *mdsc,
> > 
> > 	dout("do_request on %p\n", req);
> > 
> > -	/* take CAP_PIN refs for r_inode, r_locked_dir, r_old_dentry */
> > +	/* take CAP_PIN refs for r_inode, r_parent, r_old_dentry */
> > 	if (req->r_inode)
> > 		ceph_get_cap_refs(ceph_inode(req->r_inode), CEPH_CAP_PIN);
> > -	if (req->r_locked_dir)
> > -		ceph_get_cap_refs(ceph_inode(req->r_locked_dir), CEPH_CAP_PIN);
> > +	if (req->r_parent)
> > +		ceph_get_cap_refs(ceph_inode(req->r_parent), CEPH_CAP_PIN);
> > 	if (req->r_old_dentry_dir)
> > 		ceph_get_cap_refs(ceph_inode(req->r_old_dentry_dir),
> > 				  CEPH_CAP_PIN);
> > @@ -2336,7 +2336,7 @@ int ceph_mdsc_do_request(struct ceph_mds_client *mdsc,
> > 		set_bit(CEPH_MDS_R_ABORTED, &req->r_req_flags);
> > 		mutex_unlock(&req->r_fill_mutex);
> > 
> > -		if (req->r_locked_dir &&
> > +		if (req->r_parent &&
> > 		    (req->r_op & CEPH_MDS_OP_WRITE))
> > 			ceph_invalidate_dir_request(req);
> > 	} else {
> > @@ -2355,7 +2355,7 @@ int ceph_mdsc_do_request(struct ceph_mds_client *mdsc,
> >  */
> > void ceph_invalidate_dir_request(struct ceph_mds_request *req)
> > {
> > -	struct inode *inode = req->r_locked_dir;
> > +	struct inode *inode = req->r_parent;
> > 
> > 	dout("invalidate_dir_request %p (complete, lease(s))\n", inode);
> > 
> > diff --git a/fs/ceph/mds_client.h b/fs/ceph/mds_client.h
> > index 409b0e3c3b7a..ac0475a2daa7 100644
> > --- a/fs/ceph/mds_client.h
> > +++ b/fs/ceph/mds_client.h
> > @@ -202,7 +202,7 @@ struct ceph_mds_request {
> > 	char *r_path1, *r_path2;
> > 	struct ceph_vino r_ino1, r_ino2;
> > 
> > -	struct inode *r_locked_dir; /* dir (if any) i_mutex locked by vfs */
> > +	struct inode *r_parent;		    /* parent dir inode */
> > 	struct inode *r_target_inode;       /* resulting inode */
> > 
> > #define CEPH_MDS_R_DIRECT_IS_HASH	(1) /* r_direct_hash is valid */
> > @@ -211,6 +211,7 @@ struct ceph_mds_request {
> > #define CEPH_MDS_R_GOT_SAFE		(4) /* got a safe reply */
> > #define CEPH_MDS_R_GOT_RESULT		(5) /* got a result */
> > #define CEPH_MDS_R_DID_PREPOPULATE	(6) /* prepopulated readdir */
> > +#define CEPH_MDS_R_PARENT_LOCKED	(7) /* is r_parent->i_rwsem wlocked? */
> > 	unsigned long	r_req_flags;
> > 
> > 	struct mutex r_fill_mutex;
> > -- 
> > 2.9.3
> > 
> 
> 

-- 
Jeff Layton <jlayton@xxxxxxxxxx>
--
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