cifs: Provide the capability to extract from ITER_FOLIOQ to RDMA SGEs

Make smb_extract_iter_to_rdma() extract page fragments from an ITER_FOLIOQ
iterator into RDMA SGEs.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Steve French <sfrench@samba.org>
cc: Paulo Alcantara <pc@manguebit.com>
cc: Tom Talpey <tom@talpey.com>
cc: Enzo Matsumiya <ematsumiya@suse.de>
cc: linux-cifs@vger.kernel.org
Link: https://lore.kernel.org/r/20240814203850.2240469-15-dhowells@redhat.com/
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/fs/smb/client/smbdirect.c b/fs/smb/client/smbdirect.c
index 7bcc379014cadd4e20415b6a06914e3ad33744f8..c946b38ca825dc01cd09a20c2d134bb4ad7fb55b 100644 (file)
--- a/fs/smb/client/smbdirect.c
+++ b/fs/smb/client/smbdirect.c
@@ -6,6 +6,7 @@
  */
 #include <linux/module.h>
 #include <linux/highmem.h>
+#include <linux/folio_queue.h>
 #include "smbdirect.h"
 #include "cifs_debug.h"
 #include "cifsproto.h"
@@ -2463,6 +2464,8 @@ static ssize_t smb_extract_bvec_to_rdma(struct iov_iter *iter,
                start = 0;
        }
 
+       if (ret > 0)
+               iov_iter_advance(iter, ret);
        return ret;
 }
 
@@ -2519,6 +2522,65 @@ static ssize_t smb_extract_kvec_to_rdma(struct iov_iter *iter,
                start = 0;
        }
 
+       if (ret > 0)
+               iov_iter_advance(iter, ret);
+       return ret;
+}
+
+/*
+ * Extract folio fragments from a FOLIOQ-class iterator and add them to an RDMA
+ * list.  The folios are not pinned.
+ */
+static ssize_t smb_extract_folioq_to_rdma(struct iov_iter *iter,
+                                         struct smb_extract_to_rdma *rdma,
+                                         ssize_t maxsize)
+{
+       const struct folio_queue *folioq = iter->folioq;
+       unsigned int slot = iter->folioq_slot;
+       ssize_t ret = 0;
+       size_t offset = iter->iov_offset;
+
+       BUG_ON(!folioq);
+
+       if (slot >= folioq_nr_slots(folioq)) {
+               folioq = folioq->next;
+               if (WARN_ON_ONCE(!folioq))
+                       return -EIO;
+               slot = 0;
+       }
+
+       do {
+               struct folio *folio = folioq_folio(folioq, slot);
+               size_t fsize = folioq_folio_size(folioq, slot);
+
+               if (offset < fsize) {
+                       size_t part = umin(maxsize - ret, fsize - offset);
+
+                       if (!smb_set_sge(rdma, folio_page(folio, 0), offset, part))
+                               return -EIO;
+
+                       offset += part;
+                       ret += part;
+               }
+
+               if (offset >= fsize) {
+                       offset = 0;
+                       slot++;
+                       if (slot >= folioq_nr_slots(folioq)) {
+                               if (!folioq->next) {
+                                       WARN_ON_ONCE(ret < iter->count);
+                                       break;
+                               }
+                               folioq = folioq->next;
+                               slot = 0;
+                       }
+               }
+       } while (rdma->nr_sge < rdma->max_sge || maxsize > 0);
+
+       iter->folioq = folioq;
+       iter->folioq_slot = slot;
+       iter->iov_offset = offset;
+       iter->count -= ret;
        return ret;
 }
 
@@ -2563,6 +2625,8 @@ static ssize_t smb_extract_xarray_to_rdma(struct iov_iter *iter,
        }
 
        rcu_read_unlock();
+       if (ret > 0)
+               iov_iter_advance(iter, ret);
        return ret;
 }
 
@@ -2590,6 +2654,9 @@ static ssize_t smb_extract_iter_to_rdma(struct iov_iter *iter, size_t len,
        case ITER_KVEC:
                ret = smb_extract_kvec_to_rdma(iter, rdma, len);
                break;
+       case ITER_FOLIOQ:
+               ret = smb_extract_folioq_to_rdma(iter, rdma, len);
+               break;
        case ITER_XARRAY:
                ret = smb_extract_xarray_to_rdma(iter, rdma, len);
                break;
@@ -2598,9 +2665,7 @@ static ssize_t smb_extract_iter_to_rdma(struct iov_iter *iter, size_t len,
                return -EIO;
        }
 
-       if (ret > 0) {
-               iov_iter_advance(iter, ret);
-       } else if (ret < 0) {
+       if (ret < 0) {
                while (rdma->nr_sge > before) {
                        struct ib_sge *sge = &rdma->sge[rdma->nr_sge--];