Hi Neil-
> On Mar 19, 2021, at 6:38 PM, NeilBrown <neilb@xxxxxxx> wrote:
>
>
> mountd can now monitor clients appearing and disappearing in
> /proc/fs/nfsd/clients, and will log these events, in liu of the logging
> of mount/unmount events for NFSv3.
>
> Currently it cannot distinguish between unconfirmed clients (which might
> be transient and totally uninteresting) and confirmed clients.
>
> So add a "status: " line which reports either "confirmed" or
> "unconfirmed", and use fsnotify to report that the info file
> has been modified.
>
> This requires a bit of infrastructure to keep the dentry for the "info"
> file. There is no need to take a counted reference as the dentry must
> remain around until the client is removed.
>
> Signed-off-by: NeilBrown <neilb@xxxxxxx>
> ---
> fs/nfsd/nfs4state.c | 19 +++++++++++++++----
> fs/nfsd/nfsctl.c | 14 ++++++++------
> fs/nfsd/nfsd.h | 4 +++-
> fs/nfsd/state.h | 4 ++++
> 4 files changed, 30 insertions(+), 11 deletions(-)
>
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index 97447a64bad0..ec1b2dd8fd45 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -43,6 +43,7 @@
> #include <linux/sunrpc/addr.h>
> #include <linux/jhash.h>
> #include <linux/string_helpers.h>
> +#include <linux/fsnotify.h>
> #include "xdr4.h"
> #include "xdr4cb.h"
> #include "vfs.h"
> @@ -2352,6 +2353,10 @@ static int client_info_show(struct seq_file *m, void *v)
> memcpy(&clid, &clp->cl_clientid, sizeof(clid));
> seq_printf(m, "clientid: 0x%llx\n", clid);
> seq_printf(m, "address: \"%pISpc\"\n", (struct sockaddr *)&clp->cl_addr);
> + if (test_bit(NFSD4_CLIENT_CONFIRMED, &clp->cl_flags))
> + seq_puts(m, "status: confirmed\n");
> + else
> + seq_puts(m, "status: unconfirmed\n");
> seq_printf(m, "name: ");
> seq_quote_mem(m, clp->cl_name.data, clp->cl_name.len);
> seq_printf(m, "\nminor version: %d\n", clp->cl_minorversion);
> @@ -2702,6 +2707,7 @@ static struct nfs4_client *create_client(struct xdr_netobj name,
> int ret;
> struct net *net = SVC_NET(rqstp);
> struct nfsd_net *nn = net_generic(net, nfsd_net_id);
> + struct dentry *dentries[ARRAY_SIZE(client_files)];
>
> clp = alloc_client(name);
> if (clp == NULL)
> @@ -2721,9 +2727,11 @@ static struct nfs4_client *create_client(struct xdr_netobj name,
> memcpy(&clp->cl_addr, sa, sizeof(struct sockaddr_storage));
> clp->cl_cb_session = NULL;
> clp->net = net;
> - clp->cl_nfsd_dentry = nfsd_client_mkdir(nn, &clp->cl_nfsdfs,
> - clp->cl_clientid.cl_id - nn->clientid_base,
> - client_files);
> + clp->cl_nfsd_dentry = nfsd_client_mkdir(
> + nn, &clp->cl_nfsdfs,
> + clp->cl_clientid.cl_id - nn->clientid_base,
> + client_files, dentries);
> + clp->cl_nfsd_info_dentry = dentries[0];
> if (!clp->cl_nfsd_dentry) {
> free_client(clp);
> return NULL;
> @@ -2798,7 +2806,10 @@ move_to_confirmed(struct nfs4_client *clp)
> list_move(&clp->cl_idhash, &nn->conf_id_hashtbl[idhashval]);
> rb_erase(&clp->cl_namenode, &nn->unconf_name_tree);
> add_clp_to_name_tree(clp, &nn->conf_name_tree);
> - set_bit(NFSD4_CLIENT_CONFIRMED, &clp->cl_flags);
> + if (!test_and_set_bit(NFSD4_CLIENT_CONFIRMED, &clp->cl_flags) &&
> + clp->cl_nfsd_dentry &&
> + clp->cl_nfsd_info_dentry)
> + fsnotify_dentry(clp->cl_nfsd_info_dentry, FS_MODIFY);
I hit a "sleep while spin-locked" splat and bisected it to this
commit. fsnotify() can allocate memory with GFP_KERNEL, so it
can't be called while &nn->client_lock is held, unfortunately.
> renew_client_locked(clp);
> }
>
> diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
> index ef86ed23af82..94ce1eabd9d1 100644
> --- a/fs/nfsd/nfsctl.c
> +++ b/fs/nfsd/nfsctl.c
> @@ -1266,7 +1266,8 @@ static void nfsdfs_remove_files(struct dentry *root)
> /* XXX: cut'n'paste from simple_fill_super; figure out if we could share
> * code instead. */
> static int nfsdfs_create_files(struct dentry *root,
> - const struct tree_descr *files)
> + const struct tree_descr *files,
> + struct dentry **fdentries)
> {
> struct inode *dir = d_inode(root);
> struct inode *inode;
> @@ -1275,8 +1276,6 @@ static int nfsdfs_create_files(struct dentry *root,
>
> inode_lock(dir);
> for (i = 0; files->name && files->name[0]; i++, files++) {
> - if (!files->name)
> - continue;
> dentry = d_alloc_name(root, files->name);
> if (!dentry)
> goto out;
> @@ -1290,6 +1289,8 @@ static int nfsdfs_create_files(struct dentry *root,
> inode->i_private = __get_nfsdfs_client(dir);
> d_add(dentry, inode);
> fsnotify_create(dir, dentry);
> + if (fdentries)
> + fdentries[i] = dentry;
> }
> inode_unlock(dir);
> return 0;
> @@ -1301,8 +1302,9 @@ static int nfsdfs_create_files(struct dentry *root,
>
> /* on success, returns positive number unique to that client. */
> struct dentry *nfsd_client_mkdir(struct nfsd_net *nn,
> - struct nfsdfs_client *ncl, u32 id,
> - const struct tree_descr *files)
> + struct nfsdfs_client *ncl, u32 id,
> + const struct tree_descr *files,
> + struct dentry **fdentries)
> {
> struct dentry *dentry;
> char name[11];
> @@ -1313,7 +1315,7 @@ struct dentry *nfsd_client_mkdir(struct nfsd_net *nn,
> dentry = nfsd_mkdir(nn->nfsd_client_dir, ncl, name);
> if (IS_ERR(dentry)) /* XXX: tossing errors? */
> return NULL;
> - ret = nfsdfs_create_files(dentry, files);
> + ret = nfsdfs_create_files(dentry, files, fdentries);
> if (ret) {
> nfsd_client_rmdir(dentry);
> return NULL;
> diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h
> index 8bdc37aa2c2e..9aee72f65330 100644
> --- a/fs/nfsd/nfsd.h
> +++ b/fs/nfsd/nfsd.h
> @@ -107,7 +107,9 @@ struct nfsdfs_client {
>
> struct nfsdfs_client *get_nfsdfs_client(struct inode *);
> struct dentry *nfsd_client_mkdir(struct nfsd_net *nn,
> - struct nfsdfs_client *ncl, u32 id, const struct tree_descr *);
> + struct nfsdfs_client *ncl, u32 id,
> + const struct tree_descr *,
> + struct dentry **fdentries);
> void nfsd_client_rmdir(struct dentry *dentry);
>
>
> diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h
> index 73deea353169..54cab651ac1d 100644
> --- a/fs/nfsd/state.h
> +++ b/fs/nfsd/state.h
> @@ -371,6 +371,10 @@ struct nfs4_client {
>
> /* debugging info directory under nfsd/clients/ : */
> struct dentry *cl_nfsd_dentry;
> + /* 'info' file within that directory. Ref is not counted,
> + * but will remain valid iff cl_nfsd_dentry != NULL
> + */
> + struct dentry *cl_nfsd_info_dentry;
>
> /* for nfs41 callbacks */
> /* We currently support a single back channel with a single slot */
> --
> 2.30.1
>
--
Chuck Lever
