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@xxxxxxxxxx>
---
fs/nfsd/export.c | 31 ++++++-------------------------
fs/nfsd/export.h | 4 ++--
2 files changed, 8 insertions(+), 27 deletions(-)
diff --git a/fs/nfsd/export.c b/fs/nfsd/export.c
index eacafe46e3b6..aa4712362b3b 100644
--- 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 6f2fbaae01fa..4d92b99c1ffd 100644
--- 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))
