[PATCH v1 1/7] nfs: make nfs_page pin-aware
From: Pranjal Shrivastava
Date: Wed Jun 03 2026 - 01:31:14 EST
Modernizing the NFS Direct I/O path to use iov_iter_extract_pages()
introduces page pinning (GUP) instead of standard page referencing.
To handle this correctly, nfs_page must track whether it holds a
pin or a standard reference.
Introduce a new flag, PG_PINNED, to struct nfs_page. Update the creation
path (nfs_page_create_from_page and nfs_page_create_from_folio) to
accept a pinned bool and set the flag accordingly. If the page is pinned,
we skip the existing reference increment (get_page/folio_get) as the pin
itself acts as a reference.
Update nfs_clear_request() & nfs_direct_release_pages() to use
unpin_user_page() or unpin_user_folio() instead of only refcount
decrement (put_page) when PG_PINNED flag is set. Finally, ensure
subrequests inherit the pinning status from their parent request.
Signed-off-by: Pranjal Shrivastava <praan@xxxxxxxxxx>
---
fs/nfs/direct.c | 22 +++++++++++++++-------
fs/nfs/pagelist.c | 36 ++++++++++++++++++++++++++----------
fs/nfs/read.c | 2 +-
fs/nfs/write.c | 2 +-
include/linux/nfs_page.h | 3 +++
5 files changed, 46 insertions(+), 19 deletions(-)
diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
index 48d89716193a..80319c5eeed4 100644
--- a/fs/nfs/direct.c
+++ b/fs/nfs/direct.c
@@ -165,11 +165,17 @@ int nfs_swap_rw(struct kiocb *iocb, struct iov_iter *iter)
return 0;
}
-static void nfs_direct_release_pages(struct page **pages, unsigned int npages)
+static void nfs_direct_release_pages(struct page **pages, unsigned int npages,
+ bool pinned)
{
unsigned int i;
- for (i = 0; i < npages; i++)
- put_page(pages[i]);
+
+ if (pinned) {
+ unpin_user_pages(pages, npages);
+ } else {
+ for (i = 0; i < npages; i++)
+ put_page(pages[i]);
+ }
}
void nfs_init_cinfo_from_dreq(struct nfs_commit_info *cinfo,
@@ -371,7 +377,8 @@ static ssize_t nfs_direct_read_schedule_iovec(struct nfs_direct_req *dreq,
unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase);
/* XXX do we need to do the eof zeroing found in async_filler? */
req = nfs_page_create_from_page(dreq->ctx, pagevec[i],
- pgbase, pos, req_len);
+ false, pgbase, pos,
+ req_len);
if (IS_ERR(req)) {
result = PTR_ERR(req);
break;
@@ -386,7 +393,7 @@ static ssize_t nfs_direct_read_schedule_iovec(struct nfs_direct_req *dreq,
requested_bytes += req_len;
pos += req_len;
}
- nfs_direct_release_pages(pagevec, npages);
+ nfs_direct_release_pages(pagevec, npages, false);
kvfree(pagevec);
if (result < 0)
break;
@@ -899,7 +906,8 @@ static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq,
unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase);
req = nfs_page_create_from_page(dreq->ctx, pagevec[i],
- pgbase, pos, req_len);
+ false, pgbase, pos,
+ req_len);
if (IS_ERR(req)) {
result = PTR_ERR(req);
break;
@@ -942,7 +950,7 @@ static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq,
desc.pg_error = 0;
defer = true;
}
- nfs_direct_release_pages(pagevec, npages);
+ nfs_direct_release_pages(pagevec, npages, false);
kvfree(pagevec);
if (result < 0)
break;
diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
index 4a87b2fdb2e6..5c5601a27663 100644
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -404,20 +404,26 @@ static struct nfs_page *nfs_page_create(struct nfs_lock_context *l_ctx,
return req;
}
-static void nfs_page_assign_folio(struct nfs_page *req, struct folio *folio)
+static void nfs_page_assign_folio(struct nfs_page *req, struct folio *folio, bool pinned)
{
if (folio != NULL) {
req->wb_folio = folio;
- folio_get(folio);
+ if (pinned)
+ set_bit(PG_PINNED, &req->wb_flags);
+ else
+ folio_get(folio);
set_bit(PG_FOLIO, &req->wb_flags);
}
}
-static void nfs_page_assign_page(struct nfs_page *req, struct page *page)
+static void nfs_page_assign_page(struct nfs_page *req, struct page *page, bool pinned)
{
if (page != NULL) {
req->wb_page = page;
- get_page(page);
+ if (pinned)
+ set_bit(PG_PINNED, &req->wb_flags);
+ else
+ get_page(page);
}
}
@@ -435,6 +441,7 @@ static void nfs_page_assign_page(struct nfs_page *req, struct page *page)
*/
struct nfs_page *nfs_page_create_from_page(struct nfs_open_context *ctx,
struct page *page,
+ bool pinned,
unsigned int pgbase, loff_t offset,
unsigned int count)
{
@@ -446,7 +453,7 @@ struct nfs_page *nfs_page_create_from_page(struct nfs_open_context *ctx,
ret = nfs_page_create(l_ctx, pgbase, offset >> PAGE_SHIFT,
offset_in_page(offset), count);
if (!IS_ERR(ret)) {
- nfs_page_assign_page(ret, page);
+ nfs_page_assign_page(ret, page, pinned);
nfs_page_group_init(ret, NULL);
}
nfs_put_lock_context(l_ctx);
@@ -466,6 +473,7 @@ struct nfs_page *nfs_page_create_from_page(struct nfs_open_context *ctx,
*/
struct nfs_page *nfs_page_create_from_folio(struct nfs_open_context *ctx,
struct folio *folio,
+ bool pinned,
unsigned int offset,
unsigned int count)
{
@@ -476,7 +484,7 @@ struct nfs_page *nfs_page_create_from_folio(struct nfs_open_context *ctx,
return ERR_CAST(l_ctx);
ret = nfs_page_create(l_ctx, offset, folio->index, offset, count);
if (!IS_ERR(ret)) {
- nfs_page_assign_folio(ret, folio);
+ nfs_page_assign_folio(ret, folio, pinned);
nfs_page_group_init(ret, NULL);
}
nfs_put_lock_context(l_ctx);
@@ -498,9 +506,11 @@ nfs_create_subreq(struct nfs_page *req,
offset, count);
if (!IS_ERR(ret)) {
if (folio)
- nfs_page_assign_folio(ret, folio);
+ nfs_page_assign_folio(ret, folio,
+ test_bit(PG_PINNED, &req->wb_flags));
else
- nfs_page_assign_page(ret, page);
+ nfs_page_assign_page(ret, page,
+ test_bit(PG_PINNED, &req->wb_flags));
/* find the last request */
for (last = req->wb_head;
last->wb_this_page != req->wb_head;
@@ -552,11 +562,17 @@ static void nfs_clear_request(struct nfs_page *req)
struct nfs_open_context *ctx;
if (folio != NULL) {
- folio_put(folio);
+ if (test_and_clear_bit(PG_PINNED, &req->wb_flags))
+ unpin_user_folio(folio, 1);
+ else
+ folio_put(folio);
req->wb_folio = NULL;
clear_bit(PG_FOLIO, &req->wb_flags);
} else if (page != NULL) {
- put_page(page);
+ if (test_and_clear_bit(PG_PINNED, &req->wb_flags))
+ unpin_user_page(page);
+ else
+ put_page(page);
req->wb_page = NULL;
}
if (l_ctx != NULL) {
diff --git a/fs/nfs/read.c b/fs/nfs/read.c
index e1fe78d7b8d0..ebfebc47966d 100644
--- a/fs/nfs/read.c
+++ b/fs/nfs/read.c
@@ -301,7 +301,7 @@ int nfs_read_add_folio(struct nfs_pageio_descriptor *pgio,
aligned_len = min_t(unsigned int, ALIGN(len, rsize), fsize);
- new = nfs_page_create_from_folio(ctx, folio, 0, aligned_len);
+ new = nfs_page_create_from_folio(ctx, folio, false, 0, aligned_len);
if (IS_ERR(new)) {
error = PTR_ERR(new);
if (nfs_netfs_folio_unlock(folio))
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 3134bb17f3e3..cf56c07ae2ee 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -1086,7 +1086,7 @@ static struct nfs_page *nfs_setup_write_request(struct nfs_open_context *ctx,
req = nfs_try_to_update_request(folio, offset, bytes);
if (req != NULL)
goto out;
- req = nfs_page_create_from_folio(ctx, folio, offset, bytes);
+ req = nfs_page_create_from_folio(ctx, folio, false, offset, bytes);
if (IS_ERR(req))
goto out;
nfs_inode_add_request(req);
diff --git a/include/linux/nfs_page.h b/include/linux/nfs_page.h
index afe1d8f09d89..9ece78f1b788 100644
--- a/include/linux/nfs_page.h
+++ b/include/linux/nfs_page.h
@@ -37,6 +37,7 @@ enum {
PG_REMOVE, /* page group sync bit in write path */
PG_CONTENDED1, /* Is someone waiting for a lock? */
PG_CONTENDED2, /* Is someone waiting for a lock? */
+ PG_PINNED, /* page is pinned by GUP */
};
struct nfs_inode;
@@ -124,11 +125,13 @@ struct nfs_pageio_descriptor {
extern struct nfs_page *nfs_page_create_from_page(struct nfs_open_context *ctx,
struct page *page,
+ bool pinned,
unsigned int pgbase,
loff_t offset,
unsigned int count);
extern struct nfs_page *nfs_page_create_from_folio(struct nfs_open_context *ctx,
struct folio *folio,
+ bool pinned,
unsigned int offset,
unsigned int count);
extern void nfs_release_request(struct nfs_page *);
--
2.54.0.1013.g208068f2d8-goog