6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Yang Erkun yangerkun@huawei.com
[ Upstream commit 69d803c40edeaf94089fbc8751c9b746cdc35044 ]
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 Signed-off-by: Sasha Levin sashal@kernel.org --- 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 d4d3ec58047e..4b5d998cbc2f 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) @@ -360,26 +351,16 @@ 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 9d895570ceba..ca9dc230ae3d 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))