[PATCH] ceph: add get_name() NFS export callback

[PATCH] ceph: add get_name() NFS export callback

[Yan, Zheng]

Set WANT_DENTRY flag for the LOOKUPINO MDS request. The flag makes
MDS reply contain dentry trace.

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
---
 fs/ceph/export.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
 fs/ceph/inode.c  | 51 ++++++++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 95 insertions(+), 1 deletion(-)

diff --git a/fs/ceph/export.c b/fs/ceph/export.c
index 4ec1fd5..3c84b49 100644
--- a/fs/ceph/export.c
+++ b/fs/ceph/export.c
@@ -183,9 +183,54 @@ static struct dentry *ceph_get_parent(struct dentry *child)
 	return dentry;
 }
 
+static int ceph_get_name(struct dentry *parent, char *name,
+			 struct dentry *child)
+{
+	struct ceph_mds_client *mdsc;
+	struct ceph_mds_request *req;
+	int err;
+
+	mdsc = ceph_inode_to_client(child->d_inode)->mdsc;
+	req = ceph_mdsc_create_request(mdsc, CEPH_MDS_OP_LOOKUPINO,
+				       USE_ANY_MDS);
+	if (IS_ERR(req))
+		return PTR_ERR(req);
+
+	mutex_lock(&parent->d_inode->i_mutex);
+
+	req->r_inode = child->d_inode;
+	ihold(child->d_inode);
+	req->r_ino2 = ceph_vino(parent->d_inode);
+	req->r_locked_dir = parent->d_inode;
+	req->r_num_caps = 1;
+	err = ceph_mdsc_do_request(mdsc, NULL, req);
+
+	mutex_unlock(&parent->d_inode->i_mutex);
+
+	if (!err) {
+		struct ceph_mds_reply_info_parsed *rinfo = &req->r_reply_info;
+		if (rinfo->head->is_dentry) {
+			memcpy(name, rinfo->dname, rinfo->dname_len);
+			name[rinfo->dname_len] = 0;
+		} else {
+			err = -EOPNOTSUPP;
+		}
+	}
+	ceph_mdsc_put_request(req);
+
+	if (!err)
+		dout("get_name child %p ino %llx.%llx name %s\n",
+		     child, ceph_vinop(child->d_inode), name);
+	else
+		dout("get_name child %p ino %llx.%llx err %d\n",
+		     child, ceph_vinop(child->d_inode), err);
+	return err;
+}
+
 const struct export_operations ceph_export_ops = {
 	.encode_fh = ceph_encode_fh,
 	.fh_to_dentry = ceph_fh_to_dentry,
 	.fh_to_parent = ceph_fh_to_parent,
 	.get_parent = ceph_get_parent,
+	.get_name = ceph_get_name,
 };
diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
index 8bf2384..ff3ee3e 100644
--- a/fs/ceph/inode.c
+++ b/fs/ceph/inode.c
@@ -1044,10 +1044,59 @@ int ceph_fill_trace(struct super_block *sb, struct ceph_mds_request *req,
 					 session, req->r_request_started, -1,
 					 &req->r_caps_reservation);
 			if (err < 0)
-				return err;
+				goto done;
 		} else {
 			WARN_ON_ONCE(1);
 		}
+
+		if (dir && req->r_op == CEPH_MDS_OP_LOOKUPINO) {
+			struct qstr dname;
+			struct dentry *dn, *parent;
+
+			BUG_ON(!rinfo->head->is_target);
+			BUG_ON(req->r_dentry);
+
+			parent = d_find_any_alias(dir);
+			BUG_ON(!parent);
+
+			dname.name = rinfo->dname;
+			dname.len = rinfo->dname_len;
+			dname.hash = full_name_hash(dname.name, dname.len);
+			vino.ino = le64_to_cpu(rinfo->targeti.in->ino);
+			vino.snap = le64_to_cpu(rinfo->targeti.in->snapid);
+retry_lookup:
+			dn = d_lookup(parent, &dname);
+			dout("d_lookup on parent=%p name=%.*s got %p\n",
+			     parent, dname.len, dname.name, dn);
+
+			if (!dn) {
+				dn = d_alloc(parent, &dname);
+				dout("d_alloc %p '%.*s' = %p\n", parent,
+				     dname.len, dname.name, dn);
+				if (dn == NULL) {
+					dput(parent);
+					err = -ENOMEM;
+					goto done;
+				}
+				err = ceph_init_dentry(dn);
+				if (err < 0) {
+					dput(dn);
+					dput(parent);
+					goto done;
+				}
+			} else if (dn->d_inode &&
+				   (ceph_ino(dn->d_inode) != vino.ino ||
+				    ceph_snap(dn->d_inode) != vino.snap)) {
+				dout(" dn %p points to wrong inode %p\n",
+				     dn, dn->d_inode);
+				d_delete(dn);
+				dput(dn);
+				goto retry_lookup;
+			}
+
+			req->r_dentry = dn;
+			dput(parent);
+		}
 	}
 
 	if (rinfo->head->is_target) {
-- 
1.8.5.3

Re: [PATCH] ceph: add get_name() NFS export callback

[Sage Weil]

On Thu, 6 Mar 2014, Yan, Zheng wrote:
> Set WANT_DENTRY flag for the LOOKUPINO MDS request. The flag makes
> MDS reply contain dentry trace.
> 
> Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
> ---
>  fs/ceph/export.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
>  fs/ceph/inode.c  | 51 ++++++++++++++++++++++++++++++++++++++++++++++++++-
>  2 files changed, 95 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/ceph/export.c b/fs/ceph/export.c
> index 4ec1fd5..3c84b49 100644
> --- a/fs/ceph/export.c
> +++ b/fs/ceph/export.c
> @@ -183,9 +183,54 @@ static struct dentry *ceph_get_parent(struct dentry *child)
>  	return dentry;
>  }
>  
> +static int ceph_get_name(struct dentry *parent, char *name,
> +			 struct dentry *child)
> +{
> +	struct ceph_mds_client *mdsc;
> +	struct ceph_mds_request *req;
> +	int err;
> +
> +	mdsc = ceph_inode_to_client(child->d_inode)->mdsc;
> +	req = ceph_mdsc_create_request(mdsc, CEPH_MDS_OP_LOOKUPINO,
> +				       USE_ANY_MDS);
> +	if (IS_ERR(req))
> +		return PTR_ERR(req);
> +
> +	mutex_lock(&parent->d_inode->i_mutex);
> +
> +	req->r_inode = child->d_inode;
> +	ihold(child->d_inode);
> +	req->r_ino2 = ceph_vino(parent->d_inode);
> +	req->r_locked_dir = parent->d_inode;
> +	req->r_num_caps = 1;
> +	err = ceph_mdsc_do_request(mdsc, NULL, req);

This one also worries me.  If the r_locked_dir isn't the current parent 
anymore, then below in ceph_fill_trace we will be doing a d_alloc etc in 
the wrong directory... at least with the current version of LOOKUPINO.  Is 
there an MDS patch that is verifying ino2 is correct?  Otherwise, we might 
be creating a dentry and setting up a lease etc in a different directory  
than what the MDS has.

Sigh... the nfsd's behavior when trying to reconnect things is clearly 
confusing to me.  Even reading through 
Documentation/filesystems/nfs/Exporting it isn't obvious what nfsd is 
actually doing with these methods, or what happens if the filesystem isn't 
in the state it expects it to be.

Anyway, it sounds like as long as we prevent ceph_fill_inode from putting 
a dentry in the wrong directory then this is good!

sage

> +
> +	mutex_unlock(&parent->d_inode->i_mutex);
> +
> +	if (!err) {
> +		struct ceph_mds_reply_info_parsed *rinfo = &req->r_reply_info;
> +		if (rinfo->head->is_dentry) {
> +			memcpy(name, rinfo->dname, rinfo->dname_len);
> +			name[rinfo->dname_len] = 0;
> +		} else {
> +			err = -EOPNOTSUPP;
> +		}
> +	}
> +	ceph_mdsc_put_request(req);
> +
> +	if (!err)
> +		dout("get_name child %p ino %llx.%llx name %s\n",
> +		     child, ceph_vinop(child->d_inode), name);
> +	else
> +		dout("get_name child %p ino %llx.%llx err %d\n",
> +		     child, ceph_vinop(child->d_inode), err);
> +	return err;
> +}
> +
>  const struct export_operations ceph_export_ops = {
>  	.encode_fh = ceph_encode_fh,
>  	.fh_to_dentry = ceph_fh_to_dentry,
>  	.fh_to_parent = ceph_fh_to_parent,
>  	.get_parent = ceph_get_parent,
> +	.get_name = ceph_get_name,
>  };
> diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
> index 8bf2384..ff3ee3e 100644
> --- a/fs/ceph/inode.c
> +++ b/fs/ceph/inode.c
> @@ -1044,10 +1044,59 @@ int ceph_fill_trace(struct super_block *sb, struct ceph_mds_request *req,
>  					 session, req->r_request_started, -1,
>  					 &req->r_caps_reservation);
>  			if (err < 0)
> -				return err;
> +				goto done;
>  		} else {
>  			WARN_ON_ONCE(1);
>  		}
> +
> +		if (dir && req->r_op == CEPH_MDS_OP_LOOKUPINO) {
> +			struct qstr dname;
> +			struct dentry *dn, *parent;
> +
> +			BUG_ON(!rinfo->head->is_target);
> +			BUG_ON(req->r_dentry);
> +
> +			parent = d_find_any_alias(dir);
> +			BUG_ON(!parent);
> +
> +			dname.name = rinfo->dname;
> +			dname.len = rinfo->dname_len;
> +			dname.hash = full_name_hash(dname.name, dname.len);
> +			vino.ino = le64_to_cpu(rinfo->targeti.in->ino);
> +			vino.snap = le64_to_cpu(rinfo->targeti.in->snapid);
> +retry_lookup:
> +			dn = d_lookup(parent, &dname);
> +			dout("d_lookup on parent=%p name=%.*s got %p\n",
> +			     parent, dname.len, dname.name, dn);
> +
> +			if (!dn) {
> +				dn = d_alloc(parent, &dname);
> +				dout("d_alloc %p '%.*s' = %p\n", parent,
> +				     dname.len, dname.name, dn);
> +				if (dn == NULL) {
> +					dput(parent);
> +					err = -ENOMEM;
> +					goto done;
> +				}
> +				err = ceph_init_dentry(dn);
> +				if (err < 0) {
> +					dput(dn);
> +					dput(parent);
> +					goto done;
> +				}
> +			} else if (dn->d_inode &&
> +				   (ceph_ino(dn->d_inode) != vino.ino ||
> +				    ceph_snap(dn->d_inode) != vino.snap)) {
> +				dout(" dn %p points to wrong inode %p\n",
> +				     dn, dn->d_inode);
> +				d_delete(dn);
> +				dput(dn);
> +				goto retry_lookup;
> +			}
> +
> +			req->r_dentry = dn;
> +			dput(parent);
> +		}
>  	}
>  
>  	if (rinfo->head->is_target) {
> -- 
> 1.8.5.3
> 
> --
> To unsubscribe from this list: send the line "unsubscribe ceph-devel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 
> 

Re: [PATCH] ceph: add get_name() NFS export callback

[Christoph Hellwig]

On Thu, Mar 06, 2014 at 08:45:28AM -0800, Sage Weil wrote:
> This one also worries me.  If the r_locked_dir isn't the current parent 
> anymore, then below in ceph_fill_trace we will be doing a d_alloc etc in 
> the wrong directory... at least with the current version of LOOKUPINO.  Is 
> there an MDS patch that is verifying ino2 is correct?  Otherwise, we might 
> be creating a dentry and setting up a lease etc in a different directory  
> than what the MDS has.
> 
> Sigh... the nfsd's behavior when trying to reconnect things is clearly 
> confusing to me.  Even reading through 
> Documentation/filesystems/nfs/Exporting it isn't obvious what nfsd is 
> actually doing with these methods, or what happens if the filesystem isn't 
> in the state it expects it to be.

After the last round of refactoring by Bruce the code should be fairly
readable now.

Anyway, the basic problem is that a directory dentry must always be
connected up to the filesystem root for proper operation, and for
each level of the diretory hierachy nfsd (or rather exportfs) does the
following:

1) call ->get_parent to get the parent.  fail unless this returns a
   parent dentry.

2) call ->get_name for the parent, dentry pair
   assume already connected by other ways if it returns -ENOENT, fail
   for any other error return

3) call lookup_one_len on parent, name return from ->get_name to
   connect the dentry into parent.  If this returns a different dentry
   assume a rename race which should have connected dentry.  Although
   we ensure it really is connected and return -ESTALE otherwise.

Re: [PATCH] ceph: add get_name() NFS export callback

[Yan, Zheng]

On 03/07/2014 12:45 AM, Sage Weil wrote:
> On Thu, 6 Mar 2014, Yan, Zheng wrote:
>> Set WANT_DENTRY flag for the LOOKUPINO MDS request. The flag makes
>> MDS reply contain dentry trace.
>>
>> Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
>> ---
>>  fs/ceph/export.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
>>  fs/ceph/inode.c  | 51 ++++++++++++++++++++++++++++++++++++++++++++++++++-
>>  2 files changed, 95 insertions(+), 1 deletion(-)
>>
>> diff --git a/fs/ceph/export.c b/fs/ceph/export.c
>> index 4ec1fd5..3c84b49 100644
>> --- a/fs/ceph/export.c
>> +++ b/fs/ceph/export.c
>> @@ -183,9 +183,54 @@ static struct dentry *ceph_get_parent(struct dentry *child)
>>  	return dentry;
>>  }
>>  
>> +static int ceph_get_name(struct dentry *parent, char *name,
>> +			 struct dentry *child)
>> +{
>> +	struct ceph_mds_client *mdsc;
>> +	struct ceph_mds_request *req;
>> +	int err;
>> +
>> +	mdsc = ceph_inode_to_client(child->d_inode)->mdsc;
>> +	req = ceph_mdsc_create_request(mdsc, CEPH_MDS_OP_LOOKUPINO,
>> +				       USE_ANY_MDS);
>> +	if (IS_ERR(req))
>> +		return PTR_ERR(req);
>> +
>> +	mutex_lock(&parent->d_inode->i_mutex);
>> +
>> +	req->r_inode = child->d_inode;
>> +	ihold(child->d_inode);
>> +	req->r_ino2 = ceph_vino(parent->d_inode);
>> +	req->r_locked_dir = parent->d_inode;
>> +	req->r_num_caps = 1;
>> +	err = ceph_mdsc_do_request(mdsc, NULL, req);
> 
> This one also worries me.  If the r_locked_dir isn't the current parent 
> anymore, then below in ceph_fill_trace we will be doing a d_alloc etc in 
> the wrong directory... at least with the current version of LOOKUPINO.  Is 
> there an MDS patch that is verifying ino2 is correct?  Otherwise, we might 
> be creating a dentry and setting up a lease etc in a different directory  
> than what the MDS has.

see https://github.com/ceph/ceph/pull/1385. It checks the inos.

> 
> Sigh... the nfsd's behavior when trying to reconnect things is clearly 
> confusing to me.  Even reading through 
> Documentation/filesystems/nfs/Exporting it isn't obvious what nfsd is 
> actually doing with these methods, or what happens if the filesystem isn't 
> in the state it expects it to be.
> 
> Anyway, it sounds like as long as we prevent ceph_fill_inode from putting 
> a dentry in the wrong directory then this is good!
> 
> sage
> 
>> +
>> +	mutex_unlock(&parent->d_inode->i_mutex);
>> +
>> +	if (!err) {
>> +		struct ceph_mds_reply_info_parsed *rinfo = &req->r_reply_info;
>> +		if (rinfo->head->is_dentry) {
>> +			memcpy(name, rinfo->dname, rinfo->dname_len);
>> +			name[rinfo->dname_len] = 0;
>> +		} else {
>> +			err = -EOPNOTSUPP;
>> +		}
>> +	}
>> +	ceph_mdsc_put_request(req);
>> +
>> +	if (!err)
>> +		dout("get_name child %p ino %llx.%llx name %s\n",
>> +		     child, ceph_vinop(child->d_inode), name);
>> +	else
>> +		dout("get_name child %p ino %llx.%llx err %d\n",
>> +		     child, ceph_vinop(child->d_inode), err);
>> +	return err;
>> +}
>> +
>>  const struct export_operations ceph_export_ops = {
>>  	.encode_fh = ceph_encode_fh,
>>  	.fh_to_dentry = ceph_fh_to_dentry,
>>  	.fh_to_parent = ceph_fh_to_parent,
>>  	.get_parent = ceph_get_parent,
>> +	.get_name = ceph_get_name,
>>  };
>> diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
>> index 8bf2384..ff3ee3e 100644
>> --- a/fs/ceph/inode.c
>> +++ b/fs/ceph/inode.c
>> @@ -1044,10 +1044,59 @@ int ceph_fill_trace(struct super_block *sb, struct ceph_mds_request *req,
>>  					 session, req->r_request_started, -1,
>>  					 &req->r_caps_reservation);
>>  			if (err < 0)
>> -				return err;
>> +				goto done;
>>  		} else {
>>  			WARN_ON_ONCE(1);
>>  		}
>> +
>> +		if (dir && req->r_op == CEPH_MDS_OP_LOOKUPINO) {
>> +			struct qstr dname;
>> +			struct dentry *dn, *parent;
>> +
>> +			BUG_ON(!rinfo->head->is_target);
>> +			BUG_ON(req->r_dentry);
>> +
>> +			parent = d_find_any_alias(dir);
>> +			BUG_ON(!parent);
>> +
>> +			dname.name = rinfo->dname;
>> +			dname.len = rinfo->dname_len;
>> +			dname.hash = full_name_hash(dname.name, dname.len);
>> +			vino.ino = le64_to_cpu(rinfo->targeti.in->ino);
>> +			vino.snap = le64_to_cpu(rinfo->targeti.in->snapid);
>> +retry_lookup:
>> +			dn = d_lookup(parent, &dname);
>> +			dout("d_lookup on parent=%p name=%.*s got %p\n",
>> +			     parent, dname.len, dname.name, dn);
>> +
>> +			if (!dn) {
>> +				dn = d_alloc(parent, &dname);
>> +				dout("d_alloc %p '%.*s' = %p\n", parent,
>> +				     dname.len, dname.name, dn);
>> +				if (dn == NULL) {
>> +					dput(parent);
>> +					err = -ENOMEM;
>> +					goto done;
>> +				}
>> +				err = ceph_init_dentry(dn);
>> +				if (err < 0) {
>> +					dput(dn);
>> +					dput(parent);
>> +					goto done;
>> +				}
>> +			} else if (dn->d_inode &&
>> +				   (ceph_ino(dn->d_inode) != vino.ino ||
>> +				    ceph_snap(dn->d_inode) != vino.snap)) {
>> +				dout(" dn %p points to wrong inode %p\n",
>> +				     dn, dn->d_inode);
>> +				d_delete(dn);
>> +				dput(dn);
>> +				goto retry_lookup;
>> +			}
>> +
>> +			req->r_dentry = dn;
>> +			dput(parent);
>> +		}
>>  	}
>>  
>>  	if (rinfo->head->is_target) {
>> -- 
>> 1.8.5.3
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe ceph-devel" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>
>>