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authorTrond Myklebust <trond.myklebust@hammerspace.com>2021-06-01 11:10:05 -0400
committerTrond Myklebust <trond.myklebust@hammerspace.com>2021-06-03 10:14:42 -0400
commitdfe1fe75e00e4c724ede7b9e593f6f680e446c5f (patch)
tree2a74d5f01498891b11d85c89085737df12838413
parentd1b5c230e9cb6dddeab23f0f0c808e2b1c28d1b6 (diff)
NFSv4: Fix deadlock between nfs4_evict_inode() and nfs4_opendata_get_inode()
If the inode is being evicted, but has to return a delegation first, then it can cause a deadlock in the corner case where the server reboots before the delegreturn completes, but while the call to iget5_locked() in nfs4_opendata_get_inode() is waiting for the inode free to complete. Since the open call still holds a session slot, the reboot recovery cannot proceed. In order to break the logjam, we can turn the delegation return into a privileged operation for the case where we're evicting the inode. We know that in that case, there can be no other state recovery operation that conflicts. Reported-by: zhangxiaoxu (A) <zhangxiaoxu5@huawei.com> Fixes: 5fcdfacc01f3 ("NFSv4: Return delegations synchronously in evict_inode") Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
-rw-r--r--fs/nfs/nfs4_fs.h1
-rw-r--r--fs/nfs/nfs4proc.c12
2 files changed, 12 insertions, 1 deletions
diff --git a/fs/nfs/nfs4_fs.h b/fs/nfs/nfs4_fs.h
index 065cb04222a1..543d916f79ab 100644
--- a/fs/nfs/nfs4_fs.h
+++ b/fs/nfs/nfs4_fs.h
@@ -205,6 +205,7 @@ struct nfs4_exception {
struct inode *inode;
nfs4_stateid *stateid;
long timeout;
+ unsigned char task_is_privileged : 1;
unsigned char delay : 1,
recovering : 1,
retry : 1;
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 7e63fbe253f0..cf85f0ed1e06 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -589,6 +589,8 @@ int nfs4_handle_exception(struct nfs_server *server, int errorcode, struct nfs4_
goto out_retry;
}
if (exception->recovering) {
+ if (exception->task_is_privileged)
+ return -EDEADLOCK;
ret = nfs4_wait_clnt_recover(clp);
if (test_bit(NFS_MIG_FAILED, &server->mig_status))
return -EIO;
@@ -614,6 +616,8 @@ nfs4_async_handle_exception(struct rpc_task *task, struct nfs_server *server,
goto out_retry;
}
if (exception->recovering) {
+ if (exception->task_is_privileged)
+ return -EDEADLOCK;
rpc_sleep_on(&clp->cl_rpcwaitq, task, NULL);
if (test_bit(NFS4CLNT_MANAGER_RUNNING, &clp->cl_state) == 0)
rpc_wake_up_queued_task(&clp->cl_rpcwaitq, task);
@@ -6417,6 +6421,7 @@ static void nfs4_delegreturn_done(struct rpc_task *task, void *calldata)
struct nfs4_exception exception = {
.inode = data->inode,
.stateid = &data->stateid,
+ .task_is_privileged = data->args.seq_args.sa_privileged,
};
if (!nfs4_sequence_done(task, &data->res.seq_res))
@@ -6540,7 +6545,6 @@ static int _nfs4_proc_delegreturn(struct inode *inode, const struct cred *cred,
data = kzalloc(sizeof(*data), GFP_NOFS);
if (data == NULL)
return -ENOMEM;
- nfs4_init_sequence(&data->args.seq_args, &data->res.seq_res, 1, 0);
nfs4_state_protect(server->nfs_client,
NFS_SP4_MACH_CRED_CLEANUP,
@@ -6571,6 +6575,12 @@ static int _nfs4_proc_delegreturn(struct inode *inode, const struct cred *cred,
}
}
+ if (!data->inode)
+ nfs4_init_sequence(&data->args.seq_args, &data->res.seq_res, 1,
+ 1);
+ else
+ nfs4_init_sequence(&data->args.seq_args, &data->res.seq_res, 1,
+ 0);
task_setup_data.callback_data = data;
msg.rpc_argp = &data->args;
msg.rpc_resp = &data->res;