]> git.ipfire.org Git - people/ms/linux.git/blobdiff - fs/cifs/transport.c
Merge branch 'for-6.0/dax' into libnvdimm-fixes
[people/ms/linux.git] / fs / cifs / transport.c
index bfc9bd55870a0626005cf4adc7c10be58201cc95..9a2753e2117073666de3e3f0215dc7526bc8601a 100644 (file)
@@ -21,6 +21,7 @@
 #include <asm/processor.h>
 #include <linux/mempool.h>
 #include <linux/sched/signal.h>
+#include <linux/task_io_accounting_ops.h>
 #include "cifspdu.h"
 #include "cifsglob.h"
 #include "cifsproto.h"
@@ -37,13 +38,13 @@ cifs_wake_up_task(struct mid_q_entry *mid)
        wake_up_process(mid->callback_data);
 }
 
-struct mid_q_entry *
-AllocMidQEntry(const struct smb_hdr *smb_buffer, struct TCP_Server_Info *server)
+static struct mid_q_entry *
+alloc_mid(const struct smb_hdr *smb_buffer, struct TCP_Server_Info *server)
 {
        struct mid_q_entry *temp;
 
        if (server == NULL) {
-               cifs_dbg(VFS, "Null TCP session in AllocMidQEntry\n");
+               cifs_dbg(VFS, "%s: null TCP session\n", __func__);
                return NULL;
        }
 
@@ -68,12 +69,12 @@ AllocMidQEntry(const struct smb_hdr *smb_buffer, struct TCP_Server_Info *server)
        temp->callback = cifs_wake_up_task;
        temp->callback_data = current;
 
-       atomic_inc(&midCount);
+       atomic_inc(&mid_count);
        temp->mid_state = MID_REQUEST_ALLOCATED;
        return temp;
 }
 
-static void _cifs_mid_q_entry_release(struct kref *refcount)
+static void __release_mid(struct kref *refcount)
 {
        struct mid_q_entry *midEntry =
                        container_of(refcount, struct mid_q_entry, refcount);
@@ -91,7 +92,7 @@ static void _cifs_mid_q_entry_release(struct kref *refcount)
                server->ops->handle_cancelled_mid(midEntry, server);
 
        midEntry->mid_state = MID_FREE;
-       atomic_dec(&midCount);
+       atomic_dec(&mid_count);
        if (midEntry->large_buf)
                cifs_buf_release(midEntry->resp_buf);
        else
@@ -152,29 +153,26 @@ static void _cifs_mid_q_entry_release(struct kref *refcount)
        mempool_free(midEntry, cifs_mid_poolp);
 }
 
-void cifs_mid_q_entry_release(struct mid_q_entry *midEntry)
+void release_mid(struct mid_q_entry *mid)
 {
-       spin_lock(&GlobalMid_Lock);
-       kref_put(&midEntry->refcount, _cifs_mid_q_entry_release);
-       spin_unlock(&GlobalMid_Lock);
-}
+       struct TCP_Server_Info *server = mid->server;
 
-void DeleteMidQEntry(struct mid_q_entry *midEntry)
-{
-       cifs_mid_q_entry_release(midEntry);
+       spin_lock(&server->mid_lock);
+       kref_put(&mid->refcount, __release_mid);
+       spin_unlock(&server->mid_lock);
 }
 
 void
-cifs_delete_mid(struct mid_q_entry *mid)
+delete_mid(struct mid_q_entry *mid)
 {
-       spin_lock(&GlobalMid_Lock);
+       spin_lock(&mid->server->mid_lock);
        if (!(mid->mid_flags & MID_DELETED)) {
                list_del_init(&mid->qhead);
                mid->mid_flags |= MID_DELETED;
        }
-       spin_unlock(&GlobalMid_Lock);
+       spin_unlock(&mid->server->mid_lock);
 
-       DeleteMidQEntry(mid);
+       release_mid(mid);
 }
 
 /*
@@ -196,10 +194,6 @@ smb_send_kvec(struct TCP_Server_Info *server, struct msghdr *smb_msg,
 
        *sent = 0;
 
-       smb_msg->msg_name = (struct sockaddr *) &server->dstaddr;
-       smb_msg->msg_namelen = sizeof(struct sockaddr);
-       smb_msg->msg_control = NULL;
-       smb_msg->msg_controllen = 0;
        if (server->noblocksnd)
                smb_msg->msg_flags = MSG_DONTWAIT + MSG_NOSIGNAL;
        else
@@ -263,8 +257,8 @@ smb_rqst_len(struct TCP_Server_Info *server, struct smb_rqst *rqst)
        int nvec;
        unsigned long buflen = 0;
 
-       if (server->vals->header_preamble_size == 0 &&
-           rqst->rq_nvec >= 2 && rqst->rq_iov[0].iov_len == 4) {
+       if (!is_smb1(server) && rqst->rq_nvec >= 2 &&
+           rqst->rq_iov[0].iov_len == 4) {
                iov = &rqst->rq_iov[1];
                nvec = rqst->rq_nvec - 1;
        } else {
@@ -311,7 +305,7 @@ __smb_send_rqst(struct TCP_Server_Info *server, int num_rqst,
        sigset_t mask, oldmask;
        size_t total_len = 0, sent, size;
        struct socket *ssocket = server->ssocket;
-       struct msghdr smb_msg;
+       struct msghdr smb_msg = {};
        __be32 rfc1002_marker;
 
        if (cifs_rdma_enabled(server)) {
@@ -348,7 +342,7 @@ __smb_send_rqst(struct TCP_Server_Info *server, int num_rqst,
        sigprocmask(SIG_BLOCK, &mask, &oldmask);
 
        /* Generate a rfc1002 marker for SMB2+ */
-       if (server->vals->header_preamble_size == 0) {
+       if (!is_smb1(server)) {
                struct kvec hiov = {
                        .iov_base = &rfc1002_marker,
                        .iov_len  = 4
@@ -577,12 +571,12 @@ wait_for_free_credits(struct TCP_Server_Info *server, const int num_credits,
                } else {
                        spin_unlock(&server->req_lock);
 
-                       spin_lock(&cifs_tcp_ses_lock);
+                       spin_lock(&server->srv_lock);
                        if (server->tcpStatus == CifsExiting) {
-                               spin_unlock(&cifs_tcp_ses_lock);
+                               spin_unlock(&server->srv_lock);
                                return -ENOENT;
                        }
-                       spin_unlock(&cifs_tcp_ses_lock);
+                       spin_unlock(&server->srv_lock);
 
                        /*
                         * For normal commands, reserve the last MAX_COMPOUND
@@ -725,11 +719,11 @@ cifs_wait_mtu_credits(struct TCP_Server_Info *server, unsigned int size,
 static int allocate_mid(struct cifs_ses *ses, struct smb_hdr *in_buf,
                        struct mid_q_entry **ppmidQ)
 {
-       spin_lock(&cifs_tcp_ses_lock);
+       spin_lock(&ses->ses_lock);
        if (ses->ses_status == SES_NEW) {
                if ((in_buf->Command != SMB_COM_SESSION_SETUP_ANDX) &&
                        (in_buf->Command != SMB_COM_NEGOTIATE)) {
-                       spin_unlock(&cifs_tcp_ses_lock);
+                       spin_unlock(&ses->ses_lock);
                        return -EAGAIN;
                }
                /* else ok - we are setting up session */
@@ -738,19 +732,19 @@ static int allocate_mid(struct cifs_ses *ses, struct smb_hdr *in_buf,
        if (ses->ses_status == SES_EXITING) {
                /* check if SMB session is bad because we are setting it up */
                if (in_buf->Command != SMB_COM_LOGOFF_ANDX) {
-                       spin_unlock(&cifs_tcp_ses_lock);
+                       spin_unlock(&ses->ses_lock);
                        return -EAGAIN;
                }
                /* else ok - we are shutting down session */
        }
-       spin_unlock(&cifs_tcp_ses_lock);
+       spin_unlock(&ses->ses_lock);
 
-       *ppmidQ = AllocMidQEntry(in_buf, ses->server);
+       *ppmidQ = alloc_mid(in_buf, ses->server);
        if (*ppmidQ == NULL)
                return -ENOMEM;
-       spin_lock(&GlobalMid_Lock);
+       spin_lock(&ses->server->mid_lock);
        list_add_tail(&(*ppmidQ)->qhead, &ses->server->pending_mid_q);
-       spin_unlock(&GlobalMid_Lock);
+       spin_unlock(&ses->server->mid_lock);
        return 0;
 }
 
@@ -782,13 +776,13 @@ cifs_setup_async_request(struct TCP_Server_Info *server, struct smb_rqst *rqst)
        if (server->sign)
                hdr->Flags2 |= SMBFLG2_SECURITY_SIGNATURE;
 
-       mid = AllocMidQEntry(hdr, server);
+       mid = alloc_mid(hdr, server);
        if (mid == NULL)
                return ERR_PTR(-ENOMEM);
 
        rc = cifs_sign_rqst(rqst, server, &mid->sequence_number);
        if (rc) {
-               DeleteMidQEntry(mid);
+               release_mid(mid);
                return ERR_PTR(rc);
        }
 
@@ -849,9 +843,9 @@ cifs_call_async(struct TCP_Server_Info *server, struct smb_rqst *rqst,
        mid->mid_state = MID_REQUEST_SUBMITTED;
 
        /* put it on the pending_mid_q */
-       spin_lock(&GlobalMid_Lock);
+       spin_lock(&server->mid_lock);
        list_add_tail(&mid->qhead, &server->pending_mid_q);
-       spin_unlock(&GlobalMid_Lock);
+       spin_unlock(&server->mid_lock);
 
        /*
         * Need to store the time in mid before calling I/O. For call_async,
@@ -865,7 +859,7 @@ cifs_call_async(struct TCP_Server_Info *server, struct smb_rqst *rqst,
        if (rc < 0) {
                revert_current_mid(server, mid->credits);
                server->sequence_number -= 2;
-               cifs_delete_mid(mid);
+               delete_mid(mid);
        }
 
        cifs_server_unlock(server);
@@ -912,10 +906,10 @@ cifs_sync_mid_result(struct mid_q_entry *mid, struct TCP_Server_Info *server)
        cifs_dbg(FYI, "%s: cmd=%d mid=%llu state=%d\n",
                 __func__, le16_to_cpu(mid->command), mid->mid, mid->mid_state);
 
-       spin_lock(&GlobalMid_Lock);
+       spin_lock(&server->mid_lock);
        switch (mid->mid_state) {
        case MID_RESPONSE_RECEIVED:
-               spin_unlock(&GlobalMid_Lock);
+               spin_unlock(&server->mid_lock);
                return rc;
        case MID_RETRY_NEEDED:
                rc = -EAGAIN;
@@ -935,9 +929,9 @@ cifs_sync_mid_result(struct mid_q_entry *mid, struct TCP_Server_Info *server)
                         __func__, mid->mid, mid->mid_state);
                rc = -EIO;
        }
-       spin_unlock(&GlobalMid_Lock);
+       spin_unlock(&server->mid_lock);
 
-       DeleteMidQEntry(mid);
+       release_mid(mid);
        return rc;
 }
 
@@ -997,7 +991,7 @@ cifs_setup_request(struct cifs_ses *ses, struct TCP_Server_Info *ignored,
                return ERR_PTR(rc);
        rc = cifs_sign_rqst(rqst, ses->server, &mid->sequence_number);
        if (rc) {
-               cifs_delete_mid(mid);
+               delete_mid(mid);
                return ERR_PTR(rc);
        }
        return mid;
@@ -1026,7 +1020,7 @@ static void
 cifs_cancelled_callback(struct mid_q_entry *mid)
 {
        cifs_compound_callback(mid);
-       DeleteMidQEntry(mid);
+       release_mid(mid);
 }
 
 /*
@@ -1078,12 +1072,12 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses,
                return -EIO;
        }
 
-       spin_lock(&cifs_tcp_ses_lock);
+       spin_lock(&server->srv_lock);
        if (server->tcpStatus == CifsExiting) {
-               spin_unlock(&cifs_tcp_ses_lock);
+               spin_unlock(&server->srv_lock);
                return -ENOENT;
        }
-       spin_unlock(&cifs_tcp_ses_lock);
+       spin_unlock(&server->srv_lock);
 
        /*
         * Wait for all the requests to become available.
@@ -1130,7 +1124,7 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses,
                if (IS_ERR(midQ[i])) {
                        revert_current_mid(server, i);
                        for (j = 0; j < i; j++)
-                               cifs_delete_mid(midQ[j]);
+                               delete_mid(midQ[j]);
                        cifs_server_unlock(server);
 
                        /* Update # of requests on wire to server */
@@ -1186,17 +1180,17 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses,
        /*
         * Compounding is never used during session establish.
         */
-       spin_lock(&cifs_tcp_ses_lock);
+       spin_lock(&ses->ses_lock);
        if ((ses->ses_status == SES_NEW) || (optype & CIFS_NEG_OP) || (optype & CIFS_SESS_OP)) {
-               spin_unlock(&cifs_tcp_ses_lock);
+               spin_unlock(&ses->ses_lock);
 
                cifs_server_lock(server);
                smb311_update_preauth_hash(ses, server, rqst[0].rq_iov, rqst[0].rq_nvec);
                cifs_server_unlock(server);
 
-               spin_lock(&cifs_tcp_ses_lock);
+               spin_lock(&ses->ses_lock);
        }
-       spin_unlock(&cifs_tcp_ses_lock);
+       spin_unlock(&ses->ses_lock);
 
        for (i = 0; i < num_rqst; i++) {
                rc = wait_for_response(server, midQ[i]);
@@ -1208,14 +1202,14 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses,
                        cifs_server_dbg(FYI, "Cancelling wait for mid %llu cmd: %d\n",
                                 midQ[i]->mid, le16_to_cpu(midQ[i]->command));
                        send_cancel(server, &rqst[i], midQ[i]);
-                       spin_lock(&GlobalMid_Lock);
+                       spin_lock(&server->mid_lock);
                        midQ[i]->mid_flags |= MID_WAIT_CANCELLED;
                        if (midQ[i]->mid_state == MID_REQUEST_SUBMITTED) {
                                midQ[i]->callback = cifs_cancelled_callback;
                                cancelled_mid[i] = true;
                                credits[i].value = 0;
                        }
-                       spin_unlock(&GlobalMid_Lock);
+                       spin_unlock(&server->mid_lock);
                }
        }
 
@@ -1240,7 +1234,7 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses,
                buf = (char *)midQ[i]->resp_buf;
                resp_iov[i].iov_base = buf;
                resp_iov[i].iov_len = midQ[i]->resp_buf_size +
-                       server->vals->header_preamble_size;
+                       HEADER_PREAMBLE_SIZE(server);
 
                if (midQ[i]->large_buf)
                        resp_buf_type[i] = CIFS_LARGE_BUFFER;
@@ -1250,7 +1244,7 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses,
                rc = server->ops->check_receive(midQ[i], server,
                                                     flags & CIFS_LOG_ERROR);
 
-               /* mark it so buf will not be freed by cifs_delete_mid */
+               /* mark it so buf will not be freed by delete_mid */
                if ((flags & CIFS_NO_RSP_BUF) == 0)
                        midQ[i]->resp_buf = NULL;
 
@@ -1259,19 +1253,19 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses,
        /*
         * Compounding is never used during session establish.
         */
-       spin_lock(&cifs_tcp_ses_lock);
+       spin_lock(&ses->ses_lock);
        if ((ses->ses_status == SES_NEW) || (optype & CIFS_NEG_OP) || (optype & CIFS_SESS_OP)) {
                struct kvec iov = {
                        .iov_base = resp_iov[0].iov_base,
                        .iov_len = resp_iov[0].iov_len
                };
-               spin_unlock(&cifs_tcp_ses_lock);
+               spin_unlock(&ses->ses_lock);
                cifs_server_lock(server);
                smb311_update_preauth_hash(ses, server, &iov, 1);
                cifs_server_unlock(server);
-               spin_lock(&cifs_tcp_ses_lock);
+               spin_lock(&ses->ses_lock);
        }
-       spin_unlock(&cifs_tcp_ses_lock);
+       spin_unlock(&ses->ses_lock);
 
 out:
        /*
@@ -1282,7 +1276,7 @@ out:
         */
        for (i = 0; i < num_rqst; i++) {
                if (!cancelled_mid[i])
-                       cifs_delete_mid(midQ[i]);
+                       delete_mid(midQ[i]);
        }
 
        return rc;
@@ -1360,12 +1354,12 @@ SendReceive(const unsigned int xid, struct cifs_ses *ses,
                return -EIO;
        }
 
-       spin_lock(&cifs_tcp_ses_lock);
+       spin_lock(&server->srv_lock);
        if (server->tcpStatus == CifsExiting) {
-               spin_unlock(&cifs_tcp_ses_lock);
+               spin_unlock(&server->srv_lock);
                return -ENOENT;
        }
-       spin_unlock(&cifs_tcp_ses_lock);
+       spin_unlock(&server->srv_lock);
 
        /* Ensure that we do not send more than 50 overlapping requests
           to the same server. We may make this configurable later or
@@ -1419,15 +1413,15 @@ SendReceive(const unsigned int xid, struct cifs_ses *ses,
        rc = wait_for_response(server, midQ);
        if (rc != 0) {
                send_cancel(server, &rqst, midQ);
-               spin_lock(&GlobalMid_Lock);
+               spin_lock(&server->mid_lock);
                if (midQ->mid_state == MID_REQUEST_SUBMITTED) {
                        /* no longer considered to be "in-flight" */
-                       midQ->callback = DeleteMidQEntry;
-                       spin_unlock(&GlobalMid_Lock);
+                       midQ->callback = release_mid;
+                       spin_unlock(&server->mid_lock);
                        add_credits(server, &credits, 0);
                        return rc;
                }
-               spin_unlock(&GlobalMid_Lock);
+               spin_unlock(&server->mid_lock);
        }
 
        rc = cifs_sync_mid_result(midQ, server);
@@ -1447,7 +1441,7 @@ SendReceive(const unsigned int xid, struct cifs_ses *ses,
        memcpy(out_buf, midQ->resp_buf, *pbytes_returned + 4);
        rc = cifs_check_receive(midQ, server, 0);
 out:
-       cifs_delete_mid(midQ);
+       delete_mid(midQ);
        add_credits(server, &credits, 0);
 
        return rc;
@@ -1505,12 +1499,12 @@ SendReceiveBlockingLock(const unsigned int xid, struct cifs_tcon *tcon,
                return -EIO;
        }
 
-       spin_lock(&cifs_tcp_ses_lock);
+       spin_lock(&server->srv_lock);
        if (server->tcpStatus == CifsExiting) {
-               spin_unlock(&cifs_tcp_ses_lock);
+               spin_unlock(&server->srv_lock);
                return -ENOENT;
        }
-       spin_unlock(&cifs_tcp_ses_lock);
+       spin_unlock(&server->srv_lock);
 
        /* Ensure that we do not send more than 50 overlapping requests
           to the same server. We may make this configurable later or
@@ -1540,7 +1534,7 @@ SendReceiveBlockingLock(const unsigned int xid, struct cifs_tcon *tcon,
 
        rc = cifs_sign_smb(in_buf, server, &midQ->sequence_number);
        if (rc) {
-               cifs_delete_mid(midQ);
+               delete_mid(midQ);
                cifs_server_unlock(server);
                return rc;
        }
@@ -1557,7 +1551,7 @@ SendReceiveBlockingLock(const unsigned int xid, struct cifs_tcon *tcon,
        cifs_server_unlock(server);
 
        if (rc < 0) {
-               cifs_delete_mid(midQ);
+               delete_mid(midQ);
                return rc;
        }
 
@@ -1568,19 +1562,19 @@ SendReceiveBlockingLock(const unsigned int xid, struct cifs_tcon *tcon,
                 (server->tcpStatus != CifsNew)));
 
        /* Were we interrupted by a signal ? */
-       spin_lock(&cifs_tcp_ses_lock);
+       spin_lock(&server->srv_lock);
        if ((rc == -ERESTARTSYS) &&
                (midQ->mid_state == MID_REQUEST_SUBMITTED) &&
                ((server->tcpStatus == CifsGood) ||
                 (server->tcpStatus == CifsNew))) {
-               spin_unlock(&cifs_tcp_ses_lock);
+               spin_unlock(&server->srv_lock);
 
                if (in_buf->Command == SMB_COM_TRANSACTION2) {
                        /* POSIX lock. We send a NT_CANCEL SMB to cause the
                           blocking lock to return. */
                        rc = send_cancel(server, &rqst, midQ);
                        if (rc) {
-                               cifs_delete_mid(midQ);
+                               delete_mid(midQ);
                                return rc;
                        }
                } else {
@@ -1592,7 +1586,7 @@ SendReceiveBlockingLock(const unsigned int xid, struct cifs_tcon *tcon,
                        /* If we get -ENOLCK back the lock may have
                           already been removed. Don't exit in this case. */
                        if (rc && rc != -ENOLCK) {
-                               cifs_delete_mid(midQ);
+                               delete_mid(midQ);
                                return rc;
                        }
                }
@@ -1600,21 +1594,21 @@ SendReceiveBlockingLock(const unsigned int xid, struct cifs_tcon *tcon,
                rc = wait_for_response(server, midQ);
                if (rc) {
                        send_cancel(server, &rqst, midQ);
-                       spin_lock(&GlobalMid_Lock);
+                       spin_lock(&server->mid_lock);
                        if (midQ->mid_state == MID_REQUEST_SUBMITTED) {
                                /* no longer considered to be "in-flight" */
-                               midQ->callback = DeleteMidQEntry;
-                               spin_unlock(&GlobalMid_Lock);
+                               midQ->callback = release_mid;
+                               spin_unlock(&server->mid_lock);
                                return rc;
                        }
-                       spin_unlock(&GlobalMid_Lock);
+                       spin_unlock(&server->mid_lock);
                }
 
                /* We got the response - restart system call. */
                rstart = 1;
-               spin_lock(&cifs_tcp_ses_lock);
+               spin_lock(&server->srv_lock);
        }
-       spin_unlock(&cifs_tcp_ses_lock);
+       spin_unlock(&server->srv_lock);
 
        rc = cifs_sync_mid_result(midQ, server);
        if (rc != 0)
@@ -1631,8 +1625,185 @@ SendReceiveBlockingLock(const unsigned int xid, struct cifs_tcon *tcon,
        memcpy(out_buf, midQ->resp_buf, *pbytes_returned + 4);
        rc = cifs_check_receive(midQ, server, 0);
 out:
-       cifs_delete_mid(midQ);
+       delete_mid(midQ);
        if (rstart && rc == -EACCES)
                return -ERESTARTSYS;
        return rc;
 }
+
+/*
+ * Discard any remaining data in the current SMB. To do this, we borrow the
+ * current bigbuf.
+ */
+int
+cifs_discard_remaining_data(struct TCP_Server_Info *server)
+{
+       unsigned int rfclen = server->pdu_size;
+       int remaining = rfclen + HEADER_PREAMBLE_SIZE(server) -
+               server->total_read;
+
+       while (remaining > 0) {
+               int length;
+
+               length = cifs_discard_from_socket(server,
+                               min_t(size_t, remaining,
+                                     CIFSMaxBufSize + MAX_HEADER_SIZE(server)));
+               if (length < 0)
+                       return length;
+               server->total_read += length;
+               remaining -= length;
+       }
+
+       return 0;
+}
+
+static int
+__cifs_readv_discard(struct TCP_Server_Info *server, struct mid_q_entry *mid,
+                    bool malformed)
+{
+       int length;
+
+       length = cifs_discard_remaining_data(server);
+       dequeue_mid(mid, malformed);
+       mid->resp_buf = server->smallbuf;
+       server->smallbuf = NULL;
+       return length;
+}
+
+static int
+cifs_readv_discard(struct TCP_Server_Info *server, struct mid_q_entry *mid)
+{
+       struct cifs_readdata *rdata = mid->callback_data;
+
+       return  __cifs_readv_discard(server, mid, rdata->result);
+}
+
+int
+cifs_readv_receive(struct TCP_Server_Info *server, struct mid_q_entry *mid)
+{
+       int length, len;
+       unsigned int data_offset, data_len;
+       struct cifs_readdata *rdata = mid->callback_data;
+       char *buf = server->smallbuf;
+       unsigned int buflen = server->pdu_size + HEADER_PREAMBLE_SIZE(server);
+       bool use_rdma_mr = false;
+
+       cifs_dbg(FYI, "%s: mid=%llu offset=%llu bytes=%u\n",
+                __func__, mid->mid, rdata->offset, rdata->bytes);
+
+       /*
+        * read the rest of READ_RSP header (sans Data array), or whatever we
+        * can if there's not enough data. At this point, we've read down to
+        * the Mid.
+        */
+       len = min_t(unsigned int, buflen, server->vals->read_rsp_size) -
+                                                       HEADER_SIZE(server) + 1;
+
+       length = cifs_read_from_socket(server,
+                                      buf + HEADER_SIZE(server) - 1, len);
+       if (length < 0)
+               return length;
+       server->total_read += length;
+
+       if (server->ops->is_session_expired &&
+           server->ops->is_session_expired(buf)) {
+               cifs_reconnect(server, true);
+               return -1;
+       }
+
+       if (server->ops->is_status_pending &&
+           server->ops->is_status_pending(buf, server)) {
+               cifs_discard_remaining_data(server);
+               return -1;
+       }
+
+       /* set up first two iov for signature check and to get credits */
+       rdata->iov[0].iov_base = buf;
+       rdata->iov[0].iov_len = HEADER_PREAMBLE_SIZE(server);
+       rdata->iov[1].iov_base = buf + HEADER_PREAMBLE_SIZE(server);
+       rdata->iov[1].iov_len =
+               server->total_read - HEADER_PREAMBLE_SIZE(server);
+       cifs_dbg(FYI, "0: iov_base=%p iov_len=%zu\n",
+                rdata->iov[0].iov_base, rdata->iov[0].iov_len);
+       cifs_dbg(FYI, "1: iov_base=%p iov_len=%zu\n",
+                rdata->iov[1].iov_base, rdata->iov[1].iov_len);
+
+       /* Was the SMB read successful? */
+       rdata->result = server->ops->map_error(buf, false);
+       if (rdata->result != 0) {
+               cifs_dbg(FYI, "%s: server returned error %d\n",
+                        __func__, rdata->result);
+               /* normal error on read response */
+               return __cifs_readv_discard(server, mid, false);
+       }
+
+       /* Is there enough to get to the rest of the READ_RSP header? */
+       if (server->total_read < server->vals->read_rsp_size) {
+               cifs_dbg(FYI, "%s: server returned short header. got=%u expected=%zu\n",
+                        __func__, server->total_read,
+                        server->vals->read_rsp_size);
+               rdata->result = -EIO;
+               return cifs_readv_discard(server, mid);
+       }
+
+       data_offset = server->ops->read_data_offset(buf) +
+               HEADER_PREAMBLE_SIZE(server);
+       if (data_offset < server->total_read) {
+               /*
+                * win2k8 sometimes sends an offset of 0 when the read
+                * is beyond the EOF. Treat it as if the data starts just after
+                * the header.
+                */
+               cifs_dbg(FYI, "%s: data offset (%u) inside read response header\n",
+                        __func__, data_offset);
+               data_offset = server->total_read;
+       } else if (data_offset > MAX_CIFS_SMALL_BUFFER_SIZE) {
+               /* data_offset is beyond the end of smallbuf */
+               cifs_dbg(FYI, "%s: data offset (%u) beyond end of smallbuf\n",
+                        __func__, data_offset);
+               rdata->result = -EIO;
+               return cifs_readv_discard(server, mid);
+       }
+
+       cifs_dbg(FYI, "%s: total_read=%u data_offset=%u\n",
+                __func__, server->total_read, data_offset);
+
+       len = data_offset - server->total_read;
+       if (len > 0) {
+               /* read any junk before data into the rest of smallbuf */
+               length = cifs_read_from_socket(server,
+                                              buf + server->total_read, len);
+               if (length < 0)
+                       return length;
+               server->total_read += length;
+       }
+
+       /* how much data is in the response? */
+#ifdef CONFIG_CIFS_SMB_DIRECT
+       use_rdma_mr = rdata->mr;
+#endif
+       data_len = server->ops->read_data_length(buf, use_rdma_mr);
+       if (!use_rdma_mr && (data_offset + data_len > buflen)) {
+               /* data_len is corrupt -- discard frame */
+               rdata->result = -EIO;
+               return cifs_readv_discard(server, mid);
+       }
+
+       length = rdata->read_into_pages(server, rdata, data_len);
+       if (length < 0)
+               return length;
+
+       server->total_read += length;
+
+       cifs_dbg(FYI, "total_read=%u buflen=%u remaining=%u\n",
+                server->total_read, buflen, data_len);
+
+       /* discard anything left over */
+       if (server->total_read < buflen)
+               return cifs_readv_discard(server, mid);
+
+       dequeue_mid(mid, false);
+       mid->resp_buf = server->smallbuf;
+       server->smallbuf = NULL;
+       return length;
+}