Hi Trond/Anna,
I'd like your thoughts on this patch.
I have a customer whose NFS client occasionally gets into a state
where it spins indefinitely sending WRITE (or OPEN) and getting an
NFS4ERR_BAD_STATEID (or NFS4ERR_BAD_SEQID) error. The state manager
doesn't try any recovery as the open owner is no longer in the rbtree -
presumably due to an earlier NFS4ERR_BAD_SEQID. I've seen at least one
NFS: v4 server XXX returned a bad sequence-id error!
in the logs.
I don't know if this is a server problem or a client problem - client
didn't have
Commit: c7848f69ec4a ("NFSv4: OPEN must handle the NFS4ERR_IO return code correctly")
which cause cause BAD_SEQID errors.
However wherever the bug is we don't want the NFS client to spin like
that.
This patch removes the spinning when tested against a hacked NFS
server which can be convinced to return BAD_SEQID and BAD_STATED for a
given open owner.
My main concern is: is there some other reason to remove the open owner
from the rbtree other than to make sure it isn't used for new opens?
Thanks,
NeilBrown
When an NFS4ERR_BAD_SEQID is received the open-owner is removed from
the ->state_owners rbtree so that it will no longer be used.
If any stateids attached to this open-owner are still in use, and if a
request using one get an NFS4ERR_BAD_STATEID reply, this can for bad.
The state is marked as needing recovery and the nfs4_state_manager()
is scheduled to clean up. nfs4_state_manager() finds states to be
recovered by walking the state_owners rbtree. As the open-owner is
not in the rbtree, the bad state is not found so nfs4_state_manager()
completes having done nothing. The request is then retried, with a
predicatable result (indefinite retries).
This patch changes NFS4ERR_BAD_SEQID handling to leave the open-owner
in the rbtree but mark it a 'stale'. With this the indefinite retries
no longer happen. Errors get to user-space instead if recovery
doesn't work.
Signed-off-by: NeilBrown <neilb@xxxxxxxx>
---
fs/nfs/nfs4_fs.h | 3 ++-
fs/nfs/nfs4state.c | 18 +++++-------------
2 files changed, 7 insertions(+), 14 deletions(-)
diff --git a/fs/nfs/nfs4_fs.h b/fs/nfs/nfs4_fs.h
index 768456fa1b17..42244d1123f6 100644
--- a/fs/nfs/nfs4_fs.h
+++ b/fs/nfs/nfs4_fs.h
@@ -113,7 +113,8 @@ struct nfs4_state_owner {
enum {
NFS_OWNER_RECLAIM_REBOOT,
- NFS_OWNER_RECLAIM_NOGRACE
+ NFS_OWNER_RECLAIM_NOGRACE,
+ NFS_OWNER_STALE,
};
#define NFS_LOCK_NEW 0
diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
index 9679f4749364..abacaf521d29 100644
--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -400,6 +400,8 @@ nfs4_find_state_owner_locked(struct nfs_server *server, struct rpc_cred *cred)
p = &parent->rb_left;
else if (cred > sp->so_cred)
p = &parent->rb_right;
+ else if (test_bit(NFS_OWNER_STALE, &sp->so_flags))
+ p = &parent->rb_left;
else {
if (!list_empty(&sp->so_lru))
list_del_init(&sp->so_lru);
@@ -427,6 +429,8 @@ nfs4_insert_state_owner_locked(struct nfs4_state_owner *new)
p = &parent->rb_left;
else if (new->so_cred > sp->so_cred)
p = &parent->rb_right;
+ else if (test_bit(NFS_OWNER_STALE, &sp->so_flags))
+ p = &parent->rb_left;
else {
if (!list_empty(&sp->so_lru))
list_del_init(&sp->so_lru);
@@ -499,19 +503,7 @@ nfs4_alloc_state_owner(struct nfs_server *server,
static void
nfs4_drop_state_owner(struct nfs4_state_owner *sp)
{
- struct rb_node *rb_node = &sp->so_server_node;
-
- if (!RB_EMPTY_NODE(rb_node)) {
- struct nfs_server *server = sp->so_server;
- struct nfs_client *clp = server->nfs_client;
-
- spin_lock(&clp->cl_lock);
- if (!RB_EMPTY_NODE(rb_node)) {
- rb_erase(rb_node, &server->state_owners);
- RB_CLEAR_NODE(rb_node);
- }
- spin_unlock(&clp->cl_lock);
- }
+ set_bit(NFS_OWNER_STALE, &sp->so_flags);
}
static void nfs4_free_state_owner(struct nfs4_state_owner *sp)
--
2.8.3
Attachment:
signature.asc
Description: PGP signature
