smb: smbdirect: fix MR registration for coalesced SG lists

ib_dma_map_sg() modifies the provided scatterlist and returns the
number of mapped entries, which can be fewer than the requested
mr->sgt.nents if the DMA controller coalesces contiguous memory
segments. Passing the original, uncoalesced count to ib_map_mr_sg()
causes memory registration failures if coalescing actually occurs.

Capture the actual mapped count returned by ib_dma_map_sg() and pass it
to ib_map_mr_sg() to ensure correct MR registration.

Also update the ib_dma_map_sg() error logging to drop the error
pointer formatting, since the return value is an integer count
rather than an error code.

Ensure a proper error code (-EIO) is assigned when DMA mapping or
MR registration fails.

Fixes: de5ef8ec3c46 ("smb: smbdirect: introduce smbdirect_mr.c with client mr code")
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=221408
Reviewed-by: Stefan Metzmacher <metze@samba.org>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Yi Kuo <yi@yikuo.dev>
Signed-off-by: Steve French <stfrench@microsoft.com>

diff --git a/fs/smb/smbdirect/mr.c b/fs/smb/smbdirect/mr.c
index 9e6ac9d8717ab8901e7814a406f8c5e00e857bd3..15c6363a2f97afd263455e80cbb3dd48b094a307 100644 (file)
--- a/fs/smb/smbdirect/mr.c
+++ b/fs/smb/smbdirect/mr.c
@@ -269,7 +269,7 @@ smbdirect_connection_register_mr_io(struct smbdirect_socket *sc,
 {
        const struct smbdirect_socket_parameters *sp = &sc->parameters;
        struct smbdirect_mr_io *mr;
-       int ret, num_pages;
+       int ret, num_pages, num_mapped;
        struct ib_reg_wr *reg_wr;
 
        num_pages = iov_iter_npages(iter, sp->max_frmr_depth + 1);
@@ -300,19 +300,22 @@ smbdirect_connection_register_mr_io(struct smbdirect_socket *sc,
                num_pages, iov_iter_count(iter), sp->max_frmr_depth);
        smbdirect_iter_to_sgt(iter, &mr->sgt, sp->max_frmr_depth);
 
-       ret = ib_dma_map_sg(sc->ib.dev, mr->sgt.sgl, mr->sgt.nents, mr->dir);
-       if (!ret) {
+       num_mapped = ib_dma_map_sg(sc->ib.dev, mr->sgt.sgl, mr->sgt.nents, mr->dir);
+       if (!num_mapped) {
                smbdirect_log_rdma_mr(sc, SMBDIRECT_LOG_ERR,
-                       "ib_dma_map_sg num_pages=%u dir=%x ret=%d (%1pe)\n",
-                       num_pages, mr->dir, ret, SMBDIRECT_DEBUG_ERR_PTR(ret));
+                       "ib_dma_map_sg num_pages=%u dir=%x num_mapped=%d\n",
+                       num_pages, mr->dir, num_mapped);
+               ret = -EIO;
                goto dma_map_error;
        }
 
-       ret = ib_map_mr_sg(mr->mr, mr->sgt.sgl, mr->sgt.nents, NULL, PAGE_SIZE);
-       if (ret != mr->sgt.nents) {
+       ret = ib_map_mr_sg(mr->mr, mr->sgt.sgl, num_mapped, NULL, PAGE_SIZE);
+       if (ret != num_mapped) {
                smbdirect_log_rdma_mr(sc, SMBDIRECT_LOG_ERR,
-                       "ib_map_mr_sg failed ret = %d nents = %u\n",
-                       ret, mr->sgt.nents);
+                       "ib_map_mr_sg failed ret = %d num_mapped = %u\n",
+                       ret, num_mapped);
+               if (ret >= 0)
+                       ret = -EIO;
                goto map_mr_error;
        }