[PATCH 13/24] cifs: Provide the capability to extract from ITER_FOLIOQ to RDMA SGEs

David Howells
2024-07-29T16:22:04Z

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
---
fs/smb/client/smbdirect.c | 71 +++++++++++++++++++++++++++++++++++++--
1 file changed, 68 insertions(+), 3 deletions(-)

diff --git a/fs/smb/client/smbdirect.c b/fs/smb/client/smbdirect.c
index d74e829de51c..52acead63d9d 100644
--- 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--];