From: Chuck Lever <chuck.lever@xxxxxxxxxx> We've found that there are cases where a transport disconnection results in the loss of callback RPCs. NFS servers typically do not retransmit callback operations after a disconnect. This can be a problem for the Linux NFS client's current implementation of asynchronous COPY, which waits indefinitely for a CB_OFFLOAD callback. If a transport disconnect occurs while an async COPY is running, there's a good chance the client will never get the completing CB_OFFLOAD. Fix this by implementing the OFFLOAD_STATUS operation so that the Linux NFS client can probe the NFS server if it doesn't see a CB_OFFLOAD in a reasonable amount of time. This patch implements a simplistic check. As future work, the client might also be able to detect whether there is no forward progress on the request asynchronous COPY operation, and CANCEL it. Suggested-by: Olga Kornievskaia <kolga@xxxxxxxxxx> Link: https://bugzilla.kernel.org/show_bug.cgi?id=218735 Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx> --- fs/nfs/nfs42proc.c | 68 +++++++++++++++++++++++++++++++++++++++------- 1 file changed, 58 insertions(+), 10 deletions(-) diff --git a/fs/nfs/nfs42proc.c b/fs/nfs/nfs42proc.c index fa180ce7c803..5f2bfca00416 100644 --- a/fs/nfs/nfs42proc.c +++ b/fs/nfs/nfs42proc.c @@ -175,6 +175,25 @@ int nfs42_proc_deallocate(struct file *filep, loff_t offset, loff_t len) return err; } +/* Wait this long before checking progress on a COPY operation */ +enum { + NFS42_COPY_TIMEOUT = 3 * HZ, +}; + +static void nfs4_copy_dequeue_callback(struct nfs_server *dst_server, + struct nfs_server *src_server, + struct nfs4_copy_state *copy) +{ + spin_lock(&dst_server->nfs_client->cl_lock); + list_del_init(©->copies); + spin_unlock(&dst_server->nfs_client->cl_lock); + if (dst_server != src_server) { + spin_lock(&src_server->nfs_client->cl_lock); + list_del_init(©->src_copies); + spin_unlock(&src_server->nfs_client->cl_lock); + } +} + static int handle_async_copy(struct nfs42_copy_res *res, struct nfs_server *dst_server, struct nfs_server *src_server, @@ -184,9 +203,10 @@ static int handle_async_copy(struct nfs42_copy_res *res, bool *restart) { struct nfs4_copy_state *copy, *tmp_copy = NULL, *iter; - int status = NFS4_OK; struct nfs_open_context *dst_ctx = nfs_file_open_context(dst); struct nfs_open_context *src_ctx = nfs_file_open_context(src); + int status = NFS4_OK; + u64 copied; copy = kzalloc(sizeof(struct nfs4_copy_state), GFP_KERNEL); if (!copy) @@ -224,15 +244,12 @@ static int handle_async_copy(struct nfs42_copy_res *res, spin_unlock(&src_server->nfs_client->cl_lock); } - status = wait_for_completion_interruptible(©->completion); - spin_lock(&dst_server->nfs_client->cl_lock); - list_del_init(©->copies); - spin_unlock(&dst_server->nfs_client->cl_lock); - if (dst_server != src_server) { - spin_lock(&src_server->nfs_client->cl_lock); - list_del_init(©->src_copies); - spin_unlock(&src_server->nfs_client->cl_lock); - } +wait: + status = wait_for_completion_interruptible_timeout(©->completion, + NFS42_COPY_TIMEOUT); + if (!status) + goto timeout; + nfs4_copy_dequeue_callback(dst_server, src_server, copy); if (status == -ERESTARTSYS) { goto out_cancel; } else if (copy->flags || copy->error == NFS4ERR_PARTNER_NO_AUTH) { @@ -242,6 +259,7 @@ static int handle_async_copy(struct nfs42_copy_res *res, } out: res->write_res.count = copy->count; + /* Copy out the updated write verifier provided by CB_OFFLOAD. */ memcpy(&res->write_res.verifier, ©->verf, sizeof(copy->verf)); status = -copy->error; @@ -253,6 +271,36 @@ static int handle_async_copy(struct nfs42_copy_res *res, if (!nfs42_files_from_same_server(src, dst)) nfs42_do_offload_cancel_async(src, src_stateid); goto out_free; +timeout: + status = nfs42_proc_offload_status(dst, ©->stateid, &copied); + if (status == -EINPROGRESS) + goto wait; + nfs4_copy_dequeue_callback(dst_server, src_server, copy); + switch (status) { + case 0: + /* The server recognized the copy stateid, so it hasn't + * rebooted. Don't overwrite the verifier returned in the + * COPY result. */ + res->write_res.count = copied; + goto out_free; + case -EREMOTEIO: + /* COPY operation failed on the server. */ + status = -EOPNOTSUPP; + res->write_res.count = copied; + goto out_free; + case -EBADF: + /* Server did not recognize the copy stateid. It has + * probably restarted and lost the plot. */ + res->write_res.count = 0; + status = -EOPNOTSUPP; + break; + case -EOPNOTSUPP: + /* RFC 7862 REQUIREs server to support OFFLOAD_STATUS when + * it has signed up for an async COPY, so server is not + * spec-compliant. */ + res->write_res.count = 0; + } + goto out_free; } static int process_copy_commit(struct file *dst, loff_t pos_dst, -- 2.47.0
