nfsd: Revert "nfsd: release svc_expkey/svc_export with rcu_work"

This reverts commit f8c989a0c89a75d30f899a7cabdc14d72522bb8d.

Before this commit, svc_export_put or expkey_put will call path_put with
sync mode. After this commit, path_put will be called with async mode.
And this can lead the unexpected results show as follow.

mkfs.xfs -f /dev/sda
echo "/ *(rw,no_root_squash,fsid=0)" > /etc/exports
echo "/mnt *(rw,no_root_squash,fsid=1)" >> /etc/exports
exportfs -ra
service nfs-server start
mount -t nfs -o vers=4.0 127.0.0.1:/mnt /mnt1
mount /dev/sda /mnt/sda
touch /mnt1/sda/file
exportfs -r
umount /mnt/sda # failed unexcepted

The touch will finally call nfsd_cross_mnt, add refcount to mount, and
then add cache_head. Before this commit, exportfs -r will call
cache_flush to cleanup all cache_head, and path_put in
svc_export_put/expkey_put will be finished with sync mode. So, the
latter umount will always success. However, after this commit, path_put
will be called with async mode, the latter umount may failed, and if
we add some delay, umount will success too. Personally I think this bug
and should be fixed. We first revert before bugfix patch, and then fix
the original bug with a different way.

Fixes: f8c989a0c89a ("nfsd: release svc_expkey/svc_export with rcu_work")
Signed-off-by: Yang Erkun <yangerkun@huawei.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

diff --git a/fs/nfsd/export.c b/fs/nfsd/export.c
index eacafe46e3b673cb306bd3c7caabd3283a1e54b1..aa4712362b3b3d5823eb4211887c3d7e45960cee 100644 (file)
--- a/fs/nfsd/export.c
+++ b/fs/nfsd/export.c
@@ -40,24 +40,15 @@
 #define        EXPKEY_HASHMAX          (1 << EXPKEY_HASHBITS)
 #define        EXPKEY_HASHMASK         (EXPKEY_HASHMAX -1)
 
-static void expkey_put_work(struct work_struct *work)
+static void expkey_put(struct kref *ref)
 {
-       struct svc_expkey *key =
-               container_of(to_rcu_work(work), struct svc_expkey, ek_rcu_work);
+       struct svc_expkey *key = container_of(ref, struct svc_expkey, h.ref);
 
        if (test_bit(CACHE_VALID, &key->h.flags) &&
            !test_bit(CACHE_NEGATIVE, &key->h.flags))
                path_put(&key->ek_path);
        auth_domain_put(key->ek_client);
-       kfree(key);
-}
-
-static void expkey_put(struct kref *ref)
-{
-       struct svc_expkey *key = container_of(ref, struct svc_expkey, h.ref);
-
-       INIT_RCU_WORK(&key->ek_rcu_work, expkey_put_work);
-       queue_rcu_work(system_wq, &key->ek_rcu_work);
+       kfree_rcu(key, ek_rcu);
 }
 
 static int expkey_upcall(struct cache_detail *cd, struct cache_head *h)
@@ -364,26 +355,16 @@ static void export_stats_destroy(struct export_stats *stats)
                                            EXP_STATS_COUNTERS_NUM);
 }
 
-static void svc_export_put_work(struct work_struct *work)
+static void svc_export_put(struct kref *ref)
 {
-       struct svc_export *exp =
-               container_of(to_rcu_work(work), struct svc_export, ex_rcu_work);
-
+       struct svc_export *exp = container_of(ref, struct svc_export, h.ref);
        path_put(&exp->ex_path);
        auth_domain_put(exp->ex_client);
        nfsd4_fslocs_free(&exp->ex_fslocs);
        export_stats_destroy(exp->ex_stats);
        kfree(exp->ex_stats);
        kfree(exp->ex_uuid);
-       kfree(exp);
-}
-
-static void svc_export_put(struct kref *ref)
-{
-       struct svc_export *exp = container_of(ref, struct svc_export, h.ref);
-
-       INIT_RCU_WORK(&exp->ex_rcu_work, svc_export_put_work);
-       queue_rcu_work(system_wq, &exp->ex_rcu_work);
+       kfree_rcu(exp, ex_rcu);
 }
 
 static int svc_export_upcall(struct cache_detail *cd, struct cache_head *h)

diff --git a/fs/nfsd/export.h b/fs/nfsd/export.h
index 6f2fbaae01fa2814232a910cf830e7476fc9bf3f..4d92b99c1ffdd9d4656c2548fc672b7f58a0ec23 100644 (file)
--- a/fs/nfsd/export.h
+++ b/fs/nfsd/export.h
@@ -75,7 +75,7 @@ struct svc_export {
        u32                     ex_layout_types;
        struct nfsd4_deviceid_map *ex_devid_map;
        struct cache_detail     *cd;
-       struct rcu_work         ex_rcu_work;
+       struct rcu_head         ex_rcu;
        unsigned long           ex_xprtsec_modes;
        struct export_stats     *ex_stats;
 };
@@ -92,7 +92,7 @@ struct svc_expkey {
        u32                     ek_fsid[6];
 
        struct path             ek_path;
-       struct rcu_work         ek_rcu_work;
+       struct rcu_head         ek_rcu;
 };
 
 #define EX_ISSYNC(exp)         (!((exp)->ex_flags & NFSEXP_ASYNC))