[PATCH v2 0/2] NFSv4 READDIR d_type fixup

[PATCH v2 0/2] NFSv4 READDIR d_type fixup

[Benjamin Coddington]

This is a combined posting of two previously posted patches.  The first
unconditionally adds the type attribute to the list of requested attributes
for v4 READDIR.  The second patch enables a per-mount modification via sysfs
of any of the attributes the client will currently decode for v4 READDIR.

The first patch solves a real problem but may cause a performance regression
for some servers that require extra processing to return inode information
along with the namespace.  We performed an informal survey of most of the
major NFSv4 server vendors and although we did not learn of any that may be
impacted, the potential remains.

The second patch gives us a way to disable this new READDIR behavior should
we find a serious impact in an existing setup.  I would appreciate serious
consideration of this patch in light of the number of claimed performance
regressions that have been reported almost every time we touch this
sensitive operation on the client.

For example:

echo 0x800 0x800000 0x0 > /sys/fs/nfs/0\:57/v4_readdir_attrs

.. will revert the behavior change from patch 1.

Changes on v2:
	- fix patch 2/2 to compile without CONFIG_NFS_4

Benjamin Coddington (2):
  NFSv4: Always ask for type with READDIR
  NFSv4: Allow per-mount tuning of READDIR attrs

 fs/nfs/client.c           |  4 ++
 fs/nfs/nfs4client.c       |  4 ++
 fs/nfs/nfs4proc.c         |  1 +
 fs/nfs/nfs4xdr.c          |  9 ++--
 fs/nfs/sysfs.c            | 86 +++++++++++++++++++++++++++++++++++++++
 include/linux/nfs_fs_sb.h |  1 +
 include/linux/nfs_xdr.h   |  1 +
 7 files changed, 101 insertions(+), 5 deletions(-)


base-commit: 401644852d0b2a278811de38081be23f74b5bb04
-- 
2.41.0

[PATCH v2 1/2] NFSv4: Always ask for type with READDIR

[Benjamin Coddington]

Again we have claimed regressions for walking a directory tree, this time
with the "find" utility which always tries to optimize away asking for any
attributes until it has a complete list of entries.  This behavior makes
the readdir plus heuristic do the wrong thing, which causes a storm of
GETATTRs to determine each entry's type in order to continue the walk.

For v4 add the type attribute to each READDIR request to include it no
matter the heuristic.  This allows a simple `find` command to proceed
quickly through a directory tree.

Suggested-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
---
 fs/nfs/nfs4xdr.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
index deec76cf5afe..7200d6f7cd7b 100644
--- a/fs/nfs/nfs4xdr.c
+++ b/fs/nfs/nfs4xdr.c
@@ -1602,7 +1602,7 @@ static void encode_read(struct xdr_stream *xdr, const struct nfs_pgio_args *args
 static void encode_readdir(struct xdr_stream *xdr, const struct nfs4_readdir_arg *readdir, struct rpc_rqst *req, struct compound_hdr *hdr)
 {
 	uint32_t attrs[3] = {
-		FATTR4_WORD0_RDATTR_ERROR,
+		FATTR4_WORD0_TYPE|FATTR4_WORD0_RDATTR_ERROR,
 		FATTR4_WORD1_MOUNTED_ON_FILEID,
 	};
 	uint32_t dircount = readdir->count;
@@ -1612,7 +1612,7 @@ static void encode_readdir(struct xdr_stream *xdr, const struct nfs4_readdir_arg
 	unsigned int i;
 
 	if (readdir->plus) {
-		attrs[0] |= FATTR4_WORD0_TYPE|FATTR4_WORD0_CHANGE|FATTR4_WORD0_SIZE|
+		attrs[0] |= FATTR4_WORD0_CHANGE|FATTR4_WORD0_SIZE|
 			FATTR4_WORD0_FSID|FATTR4_WORD0_FILEHANDLE|FATTR4_WORD0_FILEID;
 		attrs[1] |= FATTR4_WORD1_MODE|FATTR4_WORD1_NUMLINKS|FATTR4_WORD1_OWNER|
 			FATTR4_WORD1_OWNER_GROUP|FATTR4_WORD1_RAWDEV|
-- 
2.41.0

[PATCH v2 2/2] NFSv4: Allow per-mount tuning of READDIR attrs

[Benjamin Coddington]

Expose a per-mount knob in sysfs to set the READDIR requested attributes
for a non-plus READDIR request.

For example:

  echo 0x800 0x800000 0x0 > /sys/fs/nfs/0\:57/v4_readdir_attrs

.. will revert the client to only request rdattr_error and
mounted_on_fileid for any non "plus" READDIR, as before the patch
preceeding this one in this series.  This provides existing installations
an option to fix a potential performance regression that may occur after
NFS clients update to request additional default READDIR attributes.

Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
---
 fs/nfs/client.c           |  4 ++
 fs/nfs/nfs4client.c       |  4 ++
 fs/nfs/nfs4proc.c         |  1 +
 fs/nfs/nfs4xdr.c          |  7 ++--
 fs/nfs/sysfs.c            | 86 +++++++++++++++++++++++++++++++++++++++
 include/linux/nfs_fs_sb.h |  1 +
 include/linux/nfs_xdr.h   |  1 +
 7 files changed, 100 insertions(+), 4 deletions(-)

diff --git a/fs/nfs/client.c b/fs/nfs/client.c
index 44eca51b2808..981a2437b752 100644
--- a/fs/nfs/client.c
+++ b/fs/nfs/client.c
@@ -922,6 +922,10 @@ void nfs_server_copy_userdata(struct nfs_server *target, struct nfs_server *sour
 	target->options = source->options;
 	target->auth_info = source->auth_info;
 	target->port = source->port;
+#if IS_ENABLED(CONFIG_NFS_V4)
+	memcpy(target->readdir_attrs, source->readdir_attrs,
+			sizeof(target->readdir_attrs));
+#endif
 }
 EXPORT_SYMBOL_GPL(nfs_server_copy_userdata);
 
diff --git a/fs/nfs/nfs4client.c b/fs/nfs/nfs4client.c
index 11e3a285594c..3bbfb4244c14 100644
--- a/fs/nfs/nfs4client.c
+++ b/fs/nfs/nfs4client.c
@@ -1115,6 +1115,10 @@ static int nfs4_server_common_setup(struct nfs_server *server,
 
 	nfs4_server_set_init_caps(server);
 
+	/* Default (non-plus) v4 readdir attributes */
+	server->readdir_attrs[0] = FATTR4_WORD0_TYPE|FATTR4_WORD0_RDATTR_ERROR;
+	server->readdir_attrs[1] = FATTR4_WORD1_MOUNTED_ON_FILEID;
+
 	/* Probe the root fh to retrieve its FSID and filehandle */
 	error = nfs4_get_rootfh(server, mntfh, auth_probe);
 	if (error < 0)
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 7016eaadf555..0f0028de7941 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -5113,6 +5113,7 @@ static int _nfs4_proc_readdir(struct nfs_readdir_arg *nr_arg,
 		.pgbase = 0,
 		.count = nr_arg->page_len,
 		.plus = nr_arg->plus,
+		.server = server,
 	};
 	struct nfs4_readdir_res res;
 	struct rpc_message msg = {
diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
index 7200d6f7cd7b..45a9b40b801e 100644
--- a/fs/nfs/nfs4xdr.c
+++ b/fs/nfs/nfs4xdr.c
@@ -1601,16 +1601,15 @@ static void encode_read(struct xdr_stream *xdr, const struct nfs_pgio_args *args
 
 static void encode_readdir(struct xdr_stream *xdr, const struct nfs4_readdir_arg *readdir, struct rpc_rqst *req, struct compound_hdr *hdr)
 {
-	uint32_t attrs[3] = {
-		FATTR4_WORD0_TYPE|FATTR4_WORD0_RDATTR_ERROR,
-		FATTR4_WORD1_MOUNTED_ON_FILEID,
-	};
+	uint32_t attrs[3];
 	uint32_t dircount = readdir->count;
 	uint32_t maxcount = readdir->count;
 	__be32 *p, verf[2];
 	uint32_t attrlen = 0;
 	unsigned int i;
 
+	memcpy(attrs, readdir->server->readdir_attrs, sizeof(attrs));
+
 	if (readdir->plus) {
 		attrs[0] |= FATTR4_WORD0_CHANGE|FATTR4_WORD0_SIZE|
 			FATTR4_WORD0_FSID|FATTR4_WORD0_FILEHANDLE|FATTR4_WORD0_FILEID;
diff --git a/fs/nfs/sysfs.c b/fs/nfs/sysfs.c
index bf378ecd5d9f..03ada52aaee0 100644
--- a/fs/nfs/sysfs.c
+++ b/fs/nfs/sysfs.c
@@ -272,6 +272,84 @@ shutdown_store(struct kobject *kobj, struct kobj_attribute *attr,
 
 static struct kobj_attribute nfs_sysfs_attr_shutdown = __ATTR_RW(shutdown);
 
+#if IS_ENABLED(CONFIG_NFS_V4)
+static ssize_t
+v4_readdir_attrs_show(struct kobject *kobj, struct kobj_attribute *attr,
+				char *buf)
+{
+	struct nfs_server *server;
+	server = container_of(kobj, struct nfs_server, kobj);
+
+	return sysfs_emit(buf, "0x%x 0x%x 0x%x\n",
+			server->readdir_attrs[0],
+			server->readdir_attrs[1],
+			server->readdir_attrs[2]);
+}
+
+static ssize_t
+v4_readdir_attrs_store(struct kobject *kobj, struct kobj_attribute *attr,
+				const char *buf, size_t count)
+{
+	struct nfs_server *server;
+	u32 attrs[3];
+	char p[36], *v;
+	size_t token = 0;
+	int i;
+
+	if (count > 36)
+		return -EINVAL;
+
+	v = strncpy(p, buf, count);
+
+	for (i = 0; i < 3; i++) {
+		token += strcspn(v, " ") + 1;
+		if (token > 34)
+			return -EINVAL;
+
+		p[token - 1] = '\0';
+		if (kstrtoint(v, 0, &attrs[i]))
+			return -EINVAL;
+		v = &p[token];
+	}
+
+	/* Allow only what we decode - see decode_getfattr_attrs() */
+	if (attrs[0] & ~(FATTR4_WORD0_TYPE |
+			FATTR4_WORD0_CHANGE |
+			FATTR4_WORD0_SIZE |
+			FATTR4_WORD0_FSID |
+			FATTR4_WORD0_RDATTR_ERROR |
+			FATTR4_WORD0_FILEHANDLE |
+			FATTR4_WORD0_FILEID |
+			FATTR4_WORD0_FS_LOCATIONS) ||
+		attrs[1] & ~(FATTR4_WORD1_MODE |
+			FATTR4_WORD1_NUMLINKS |
+			FATTR4_WORD1_OWNER |
+			FATTR4_WORD1_OWNER_GROUP |
+			FATTR4_WORD1_RAWDEV |
+			FATTR4_WORD1_SPACE_USED |
+			FATTR4_WORD1_TIME_ACCESS |
+			FATTR4_WORD1_TIME_METADATA |
+			FATTR4_WORD1_TIME_MODIFY |
+			FATTR4_WORD1_MOUNTED_ON_FILEID) ||
+		attrs[2] & ~(FATTR4_WORD2_MDSTHRESHOLD |
+			FATTR4_WORD2_SECURITY_LABEL))
+		return -EINVAL;
+
+	server = container_of(kobj, struct nfs_server, kobj);
+
+	if (attrs[0])
+		server->readdir_attrs[0] = attrs[0];
+	if (attrs[1])
+		server->readdir_attrs[1] = attrs[1];
+	if (attrs[2])
+		server->readdir_attrs[2] = attrs[2];
+
+	return count;
+}
+
+static struct kobj_attribute nfs_sysfs_attr_v4_readdir_attrs = __ATTR_RW(v4_readdir_attrs);
+#endif /* CONFIG_NFS_V4 */
+
 #define RPC_CLIENT_NAME_SIZE 64
 
 void nfs_sysfs_link_rpc_client(struct nfs_server *server,
@@ -325,6 +403,14 @@ void nfs_sysfs_add_server(struct nfs_server *server)
 	if (ret < 0)
 		pr_warn("NFS: sysfs_create_file_ns for server-%d failed (%d)\n",
 			server->s_sysfs_id, ret);
+
+#if IS_ENABLED(CONFIG_NFS_V4)
+	ret = sysfs_create_file_ns(&server->kobj, &nfs_sysfs_attr_v4_readdir_attrs.attr,
+				nfs_netns_server_namespace(&server->kobj));
+	if (ret < 0)
+		pr_warn("NFS: sysfs_create_file_ns for server-%d failed (%d)\n",
+			server->s_sysfs_id, ret);
+#endif /* IS_ENABLED(CONFIG_NFS_V4) */
 }
 EXPORT_SYMBOL_GPL(nfs_sysfs_add_server);
 
diff --git a/include/linux/nfs_fs_sb.h b/include/linux/nfs_fs_sb.h
index cd628c4b011e..db87261b7cd7 100644
--- a/include/linux/nfs_fs_sb.h
+++ b/include/linux/nfs_fs_sb.h
@@ -219,6 +219,7 @@ struct nfs_server {
 						   of change attribute, size, ctime
 						   and mtime attributes supported by
 						   the server */
+	u32			readdir_attrs[3]; /* V4 tuneable default readdir attrs */
 	u32			acl_bitmask;	/* V4 bitmask representing the ACEs
 						   that are supported on this
 						   filesystem */
diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
index 12bbb5c63664..e05d861b1788 100644
--- a/include/linux/nfs_xdr.h
+++ b/include/linux/nfs_xdr.h
@@ -1142,6 +1142,7 @@ struct nfs4_readdir_arg {
 	struct page **			pages;	/* zero-copy data */
 	unsigned int			pgbase;	/* zero-copy data */
 	const u32 *			bitmask;
+	const struct nfs_server		*server;
 	bool				plus;
 };
 
-- 
2.41.0

Re: [PATCH v2 2/2] NFSv4: Allow per-mount tuning of READDIR attrs

[Jeff Layton]

On Thu, 2023-10-19 at 09:34 -0400, Benjamin Coddington wrote:
> Expose a per-mount knob in sysfs to set the READDIR requested attributes
> for a non-plus READDIR request.
> 
> For example:
> 
>   echo 0x800 0x800000 0x0 > /sys/fs/nfs/0\:57/v4_readdir_attrs
> 
> .. will revert the client to only request rdattr_error and
> mounted_on_fileid for any non "plus" READDIR, as before the patch
> preceeding this one in this series.  This provides existing installations
> an option to fix a potential performance regression that may occur after
> NFS clients update to request additional default READDIR attributes.
> 
> Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
> ---
>  fs/nfs/client.c           |  4 ++
>  fs/nfs/nfs4client.c       |  4 ++
>  fs/nfs/nfs4proc.c         |  1 +
>  fs/nfs/nfs4xdr.c          |  7 ++--
>  fs/nfs/sysfs.c            | 86 +++++++++++++++++++++++++++++++++++++++
>  include/linux/nfs_fs_sb.h |  1 +
>  include/linux/nfs_xdr.h   |  1 +
>  7 files changed, 100 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/nfs/client.c b/fs/nfs/client.c
> index 44eca51b2808..981a2437b752 100644
> --- a/fs/nfs/client.c
> +++ b/fs/nfs/client.c
> @@ -922,6 +922,10 @@ void nfs_server_copy_userdata(struct nfs_server *target, struct nfs_server *sour
>  	target->options = source->options;
>  	target->auth_info = source->auth_info;
>  	target->port = source->port;
> +#if IS_ENABLED(CONFIG_NFS_V4)
> +	memcpy(target->readdir_attrs, source->readdir_attrs,
> +			sizeof(target->readdir_attrs));
> +#endif
>  }
>  EXPORT_SYMBOL_GPL(nfs_server_copy_userdata);
>  
> diff --git a/fs/nfs/nfs4client.c b/fs/nfs/nfs4client.c
> index 11e3a285594c..3bbfb4244c14 100644
> --- a/fs/nfs/nfs4client.c
> +++ b/fs/nfs/nfs4client.c
> @@ -1115,6 +1115,10 @@ static int nfs4_server_common_setup(struct nfs_server *server,
>  
>  	nfs4_server_set_init_caps(server);
>  
> +	/* Default (non-plus) v4 readdir attributes */
> +	server->readdir_attrs[0] = FATTR4_WORD0_TYPE|FATTR4_WORD0_RDATTR_ERROR;
> +	server->readdir_attrs[1] = FATTR4_WORD1_MOUNTED_ON_FILEID;
> +
>  	/* Probe the root fh to retrieve its FSID and filehandle */
>  	error = nfs4_get_rootfh(server, mntfh, auth_probe);
>  	if (error < 0)
> diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
> index 7016eaadf555..0f0028de7941 100644
> --- a/fs/nfs/nfs4proc.c
> +++ b/fs/nfs/nfs4proc.c
> @@ -5113,6 +5113,7 @@ static int _nfs4_proc_readdir(struct nfs_readdir_arg *nr_arg,
>  		.pgbase = 0,
>  		.count = nr_arg->page_len,
>  		.plus = nr_arg->plus,
> +		.server = server,
>  	};
>  	struct nfs4_readdir_res res;
>  	struct rpc_message msg = {
> diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
> index 7200d6f7cd7b..45a9b40b801e 100644
> --- a/fs/nfs/nfs4xdr.c
> +++ b/fs/nfs/nfs4xdr.c
> @@ -1601,16 +1601,15 @@ static void encode_read(struct xdr_stream *xdr, const struct nfs_pgio_args *args
>  
>  static void encode_readdir(struct xdr_stream *xdr, const struct nfs4_readdir_arg *readdir, struct rpc_rqst *req, struct compound_hdr *hdr)
>  {
> -	uint32_t attrs[3] = {
> -		FATTR4_WORD0_TYPE|FATTR4_WORD0_RDATTR_ERROR,
> -		FATTR4_WORD1_MOUNTED_ON_FILEID,
> -	};
> +	uint32_t attrs[3];
>  	uint32_t dircount = readdir->count;
>  	uint32_t maxcount = readdir->count;
>  	__be32 *p, verf[2];
>  	uint32_t attrlen = 0;
>  	unsigned int i;
>  
> +	memcpy(attrs, readdir->server->readdir_attrs, sizeof(attrs));
> +
>  	if (readdir->plus) {
>  		attrs[0] |= FATTR4_WORD0_CHANGE|FATTR4_WORD0_SIZE|
>  			FATTR4_WORD0_FSID|FATTR4_WORD0_FILEHANDLE|FATTR4_WORD0_FILEID;
> diff --git a/fs/nfs/sysfs.c b/fs/nfs/sysfs.c
> index bf378ecd5d9f..03ada52aaee0 100644
> --- a/fs/nfs/sysfs.c
> +++ b/fs/nfs/sysfs.c
> @@ -272,6 +272,84 @@ shutdown_store(struct kobject *kobj, struct kobj_attribute *attr,
>  
>  static struct kobj_attribute nfs_sysfs_attr_shutdown = __ATTR_RW(shutdown);
>  
> +#if IS_ENABLED(CONFIG_NFS_V4)
> +static ssize_t
> +v4_readdir_attrs_show(struct kobject *kobj, struct kobj_attribute *attr,
> +				char *buf)
> +{
> +	struct nfs_server *server;
> +	server = container_of(kobj, struct nfs_server, kobj);
> +
> +	return sysfs_emit(buf, "0x%x 0x%x 0x%x\n",
> +			server->readdir_attrs[0],
> +			server->readdir_attrs[1],
> +			server->readdir_attrs[2]);
> +}
> +
> +static ssize_t
> +v4_readdir_attrs_store(struct kobject *kobj, struct kobj_attribute *attr,
> +				const char *buf, size_t count)
> +{
> +	struct nfs_server *server;
> +	u32 attrs[3];
> +	char p[36], *v;
> +	size_t token = 0;
> +	int i;
> +
> +	if (count > 36)
> +		return -EINVAL;
> +
> +	v = strncpy(p, buf, count);
> +
> +	for (i = 0; i < 3; i++) {
> +		token += strcspn(v, " ") + 1;
> +		if (token > 34)
> +			return -EINVAL;
> +
> +		p[token - 1] = '\0';
> +		if (kstrtoint(v, 0, &attrs[i]))
> +			return -EINVAL;
> +		v = &p[token];
> +	}
> +
> +	/* Allow only what we decode - see decode_getfattr_attrs() */
> +	if (attrs[0] & ~(FATTR4_WORD0_TYPE |
> +			FATTR4_WORD0_CHANGE |
> +			FATTR4_WORD0_SIZE |
> +			FATTR4_WORD0_FSID |
> +			FATTR4_WORD0_RDATTR_ERROR |
> +			FATTR4_WORD0_FILEHANDLE |
> +			FATTR4_WORD0_FILEID |
> +			FATTR4_WORD0_FS_LOCATIONS) ||
> +		attrs[1] & ~(FATTR4_WORD1_MODE |
> +			FATTR4_WORD1_NUMLINKS |
> +			FATTR4_WORD1_OWNER |
> +			FATTR4_WORD1_OWNER_GROUP |
> +			FATTR4_WORD1_RAWDEV |
> +			FATTR4_WORD1_SPACE_USED |
> +			FATTR4_WORD1_TIME_ACCESS |
> +			FATTR4_WORD1_TIME_METADATA |
> +			FATTR4_WORD1_TIME_MODIFY |
> +			FATTR4_WORD1_MOUNTED_ON_FILEID) ||
> +		attrs[2] & ~(FATTR4_WORD2_MDSTHRESHOLD |
> +			FATTR4_WORD2_SECURITY_LABEL))
> +		return -EINVAL;
> +
> +	server = container_of(kobj, struct nfs_server, kobj);
> +
> +	if (attrs[0])
> +		server->readdir_attrs[0] = attrs[0];
> +	if (attrs[1])
> +		server->readdir_attrs[1] = attrs[1];
> +	if (attrs[2])
> +		server->readdir_attrs[2] = attrs[2];
> +
> +	return count;
> +}
> +
> +static struct kobj_attribute nfs_sysfs_attr_v4_readdir_attrs = __ATTR_RW(v4_readdir_attrs);
> +#endif /* CONFIG_NFS_V4 */
> +
>  #define RPC_CLIENT_NAME_SIZE 64
>  
>  void nfs_sysfs_link_rpc_client(struct nfs_server *server,
> @@ -325,6 +403,14 @@ void nfs_sysfs_add_server(struct nfs_server *server)
>  	if (ret < 0)
>  		pr_warn("NFS: sysfs_create_file_ns for server-%d failed (%d)\n",
>  			server->s_sysfs_id, ret);
> +
> +#if IS_ENABLED(CONFIG_NFS_V4)
> +	ret = sysfs_create_file_ns(&server->kobj, &nfs_sysfs_attr_v4_readdir_attrs.attr,
> +				nfs_netns_server_namespace(&server->kobj));
> +	if (ret < 0)
> +		pr_warn("NFS: sysfs_create_file_ns for server-%d failed (%d)\n",
> +			server->s_sysfs_id, ret);
> +#endif /* IS_ENABLED(CONFIG_NFS_V4) */
>  }
>  EXPORT_SYMBOL_GPL(nfs_sysfs_add_server);
>  
> diff --git a/include/linux/nfs_fs_sb.h b/include/linux/nfs_fs_sb.h
> index cd628c4b011e..db87261b7cd7 100644
> --- a/include/linux/nfs_fs_sb.h
> +++ b/include/linux/nfs_fs_sb.h
> @@ -219,6 +219,7 @@ struct nfs_server {
>  						   of change attribute, size, ctime
>  						   and mtime attributes supported by
>  						   the server */
> +	u32			readdir_attrs[3]; /* V4 tuneable default readdir attrs */
>  	u32			acl_bitmask;	/* V4 bitmask representing the ACEs
>  						   that are supported on this
>  						   filesystem */
> diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
> index 12bbb5c63664..e05d861b1788 100644
> --- a/include/linux/nfs_xdr.h
> +++ b/include/linux/nfs_xdr.h
> @@ -1142,6 +1142,7 @@ struct nfs4_readdir_arg {
>  	struct page **			pages;	/* zero-copy data */
>  	unsigned int			pgbase;	/* zero-copy data */
>  	const u32 *			bitmask;
> +	const struct nfs_server		*server;
>  	bool				plus;
>  };
>  

If you are going to add this, then I think the consensus from
yesterday's comments was to put it behind a new Kconfig option. Maybe
there could be a new CONFIG_NFS_TWEAKS or something that exposes this
interface (and other stuff we're not sure about making generally
available).
-- 
Jeff Layton <jlayton@kernel.org>

Re: [PATCH v2 2/2] NFSv4: Allow per-mount tuning of READDIR attrs

[Benjamin Coddington]

On 19 Oct 2023, at 12:55, Jeff Layton wrote:

> If you are going to add this, then I think the consensus from
> yesterday's comments was to put it behind a new Kconfig option. Maybe
> there could be a new CONFIG_NFS_TWEAKS or something that exposes this
> interface (and other stuff we're not sure about making generally
> available).

Right.  I was hoping the discussion would continue, and this version was
just to make the robot happy.  I'll send it again with it config-ed out in a
few days if there's no other discussion.

Ben