[PATCH v2 2/8] nfsd: make max_blksize a per-namespace setting

[Jeff Layton]

nfsd_max_blksize is module-scope, but /proc/fs/nfsd/max_block_size is a
per-netns file. A container writing it therefore changes the payload size
that every other namespace's next server start will use.

Move it into struct nfsd_net as ->max_blksize. The lazy
nfsd_get_default_max_blksize() fill-in now happens per namespace on first
nfsd_create_serv().

User-visible change: max_block_size no longer leaks across namespaces.

Fixes: 11f779421a39 ("nfsd: containerize NFSd filesystem")
Assisted-by: LLM
Signed-off-by: Jeff Layton <jlay...@kernel.org>
---
 fs/nfsd/netns.h  | 6 ++++++
 fs/nfsd/nfsctl.c | 8 +++-----
 fs/nfsd/nfsd.h   | 2 --
 fs/nfsd/nfssvc.c | 6 +++---
 4 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/fs/nfsd/netns.h b/fs/nfsd/netns.h
index 0ce7da20aba3..374ce83e2ba0 100644
--- a/fs/nfsd/netns.h
+++ b/fs/nfsd/netns.h
@@ -154,6 +154,12 @@ struct nfsd_net {
         */
        unsigned int min_threads;
 
+       /*
+        * Maximum size of an NFS READ or WRITE payload.  Zero until the
+        * first server start in this namespace picks a default.
+        */
+       unsigned int max_blksize;
+
        u32 clientid_base;
        u32 clientid_counter;
        u32 clverifier_counter;
diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
index f32311f2d7cf..330d0f12e199 100644
--- a/fs/nfsd/nfsctl.c
+++ b/fs/nfsd/nfsctl.c
@@ -885,8 +885,6 @@ static ssize_t write_ports(struct file *file, char *buf, 
size_t size)
 }
 
 
-int nfsd_max_blksize;
-
 /*
  * write_maxblksize - Set or report the current NFS blksize
  *
@@ -931,12 +929,12 @@ static ssize_t write_maxblksize(struct file *file, char 
*buf, size_t size)
                        mutex_unlock(&nfsd_mutex);
                        return -EBUSY;
                }
-               nfsd_max_blksize = bsize;
+               nn->max_blksize = bsize;
                mutex_unlock(&nfsd_mutex);
        }
 
-       return scnprintf(buf, SIMPLE_TRANSACTION_LIMIT, "%d\n",
-                                                       nfsd_max_blksize);
+       return scnprintf(buf, SIMPLE_TRANSACTION_LIMIT, "%u\n",
+                                                       nn->max_blksize);
 }
 
 #ifdef CONFIG_NFSD_V4
diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h
index d1e413d21e76..0864d6d564e2 100644
--- a/fs/nfsd/nfsd.h
+++ b/fs/nfsd/nfsd.h
@@ -143,8 +143,6 @@ enum {
 extern u64 nfsd_io_cache_read __read_mostly;
 extern u64 nfsd_io_cache_write __read_mostly;
 
-extern int nfsd_max_blksize;
-
 bool nfsd_v4client(struct svc_rqst *rqstp);
 
 /*
diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c
index d75fe1523436..77e1e6ba686d 100644
--- a/fs/nfsd/nfssvc.c
+++ b/fs/nfsd/nfssvc.c
@@ -630,12 +630,12 @@ int nfsd_create_serv(struct net *net, bool no_rpcbind)
        init_completion(&nn->nfsd_net_free_done);
        init_completion(&nn->nfsd_net_confirm_done);
 
-       if (nfsd_max_blksize == 0)
-               nfsd_max_blksize = nfsd_get_default_max_blksize();
+       if (nn->max_blksize == 0)
+               nn->max_blksize = nfsd_get_default_max_blksize();
        nfsd_reset_versions(nn);
        serv = svc_create_pooled(nfsd_programs, ARRAY_SIZE(nfsd_programs),
                                 &nn->nfsd_svcstats,
-                                nfsd_max_blksize, nfsd);
+                                nn->max_blksize, nfsd);
        if (serv == NULL) {
                percpu_ref_exit(&nn->nfsd_net_ref);
                return -ENOMEM;

-- 
2.55.0