On Tue, Oct 17, 2023 at 05:30:44PM -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@xxxxxxxxxx>
> ---
> fs/nfs/client.c | 2 +
> fs/nfs/nfs4client.c | 4 ++
> fs/nfs/nfs4proc.c | 1 +
> fs/nfs/nfs4xdr.c | 7 ++--
> fs/nfs/sysfs.c | 81 +++++++++++++++++++++++++++++++++++++++
> include/linux/nfs_fs_sb.h | 1 +
> include/linux/nfs_xdr.h | 1 +
> 7 files changed, 93 insertions(+), 4 deletions(-)
Admittedly, it would be much easier for humans to use if the API was
based on the symbolic names of the bits rather than a triplet of raw
hexadecimal values.
> diff --git a/fs/nfs/client.c b/fs/nfs/client.c
> index 44eca51b2808..e9aa1fd4335f 100644
> --- a/fs/nfs/client.c
> +++ b/fs/nfs/client.c
> @@ -922,6 +922,8 @@ 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;
> + memcpy(target->readdir_attrs, source->readdir_attrs,
> + sizeof(target->readdir_attrs));
> }
> 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..6d4f52bf47b3 100644
> --- a/fs/nfs/sysfs.c
> +++ b/fs/nfs/sysfs.c
> @@ -270,7 +270,82 @@ shutdown_store(struct kobject *kobj, struct kobj_attribute *attr,
> return count;
> }
>
> +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_shutdown = __ATTR_RW(shutdown);
> +static struct kobj_attribute nfs_sysfs_attr_v4_readdir_attrs = __ATTR_RW(v4_readdir_attrs);
>
> #define RPC_CLIENT_NAME_SIZE 64
>
> @@ -325,6 +400,12 @@ 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);
> +
> + 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);
> }
> 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
>
--
Chuck Lever
