smb: client: call ib_dma_unmap_sg if mr->sgt.nents is not 0

This seems to be the more reliable way to check if we need to
call ib_dma_unmap_sg().

Fixes: c7398583340a ("CIFS: SMBD: Implement RDMA memory registration")
Cc: Steve French <smfrench@gmail.com>
Cc: Tom Talpey <tom@talpey.com>
Cc: Long Li <longli@microsoft.com>
Cc: Namjae Jeon <linkinjeon@kernel.org>
Cc: linux-cifs@vger.kernel.org
Cc: samba-technical@lists.samba.org
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

diff --git a/fs/smb/client/smbdirect.c b/fs/smb/client/smbdirect.c
index af0642e94d7ef6e15e8d0b740368508388a6a2e5..21dcd326af3df4d28f0bd0d0515690200a3a1542 100644 (file)
--- a/fs/smb/client/smbdirect.c
+++ b/fs/smb/client/smbdirect.c
@@ -2365,9 +2365,8 @@ static void destroy_mr_list(struct smbdirect_socket *sc)
        spin_unlock_irqrestore(&sc->mr_io.all.lock, flags);
 
        list_for_each_entry_safe(mr, tmp, &all_list, list) {
-               if (mr->state == SMBDIRECT_MR_INVALIDATED)
-                       ib_dma_unmap_sg(sc->ib.dev, mr->sgt.sgl,
-                               mr->sgt.nents, mr->dir);
+               if (mr->sgt.nents)
+                       ib_dma_unmap_sg(sc->ib.dev, mr->sgt.sgl, mr->sgt.nents, mr->dir);
                ib_dereg_mr(mr->mr);
                kfree(mr->sgt.sgl);
                list_del(&mr->list);
@@ -2589,6 +2588,7 @@ map_mr_error:
        ib_dma_unmap_sg(sc->ib.dev, mr->sgt.sgl, mr->sgt.nents, mr->dir);
 
 dma_map_error:
+       mr->sgt.nents = 0;
        mr->state = SMBDIRECT_MR_ERROR;
        if (atomic_dec_and_test(&sc->mr_io.used.count))
                wake_up(&sc->mr_io.cleanup.wait_queue);
@@ -2651,8 +2651,12 @@ void smbd_deregister_mr(struct smbdirect_mr_io *mr)
                 */
                mr->state = SMBDIRECT_MR_INVALIDATED;
 
-       if (mr->state == SMBDIRECT_MR_INVALIDATED) {
+       if (mr->sgt.nents) {
                ib_dma_unmap_sg(sc->ib.dev, mr->sgt.sgl, mr->sgt.nents, mr->dir);
+               mr->sgt.nents = 0;
+       }
+
+       if (mr->state == SMBDIRECT_MR_INVALIDATED) {
                mr->state = SMBDIRECT_MR_READY;
                if (atomic_inc_return(&sc->mr_io.ready.count) == 1)
                        wake_up(&sc->mr_io.ready.wait_queue);