Re: [PATCH v3 5/5] nfs: introduce nfs_direct_extract_pages helper
From: Shivaji Kant
Date: Mon Jul 20 2026 - 06:40:35 EST
On Wed, Jul 15, 2026 at 8:05 PM Pranjal Shrivastava <praan@xxxxxxxxxx> wrote:
>
> Introduce nfs_direct_extract_pages() in direct.c to centralize page
> extraction and request creation for the Direct I/O path. The helper
> manages extraction from the iters and builds a list of nfs_page requests
>
> Refactor nfs_direct_read_schedule_iovec() and
> nfs_direct_write_schedule_iovec() to utilize the new helper, unifying
> the extraction logic on both paths.
>
> Signed-off-by: Pranjal Shrivastava <praan@xxxxxxxxxx>
> ---
> fs/nfs/direct.c | 127 ++++++++++++++++++++++++------------------------
> 1 file changed, 64 insertions(+), 63 deletions(-)
>
> diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
> index b9ac0a67693c..d31e4720ffff 100644
> --- a/fs/nfs/direct.c
> +++ b/fs/nfs/direct.c
> @@ -178,6 +178,50 @@ static void nfs_direct_release_pages(struct page **pages, unsigned int npages,
> }
> }
>
> +static ssize_t nfs_direct_extract_pages(struct nfs_direct_req *dreq,
> + struct iov_iter *iter,
> + size_t size, loff_t *pos,
> + struct list_head *list)
> +{
> + bool pinned = iov_iter_extract_will_pin(iter);
> + struct page **pagevec = NULL;
> + ssize_t result, bytes = 0;
> + unsigned int npages, i;
> + size_t pgbase;
> +
> + result = iov_iter_extract_pages(iter, &pagevec, size, ~0U, 0, &pgbase);
> + if (result <= 0)
> + return result;
> +
> + npages = (result + pgbase + PAGE_SIZE - 1) >> PAGE_SHIFT;
> + for (i = 0; i < npages; i++) {
> + struct nfs_page *req;
> + unsigned int req_len = min_t(size_t, result - bytes, PAGE_SIZE - pgbase);
> +
> + req = nfs_page_create_from_page(dreq->ctx, pagevec[i],
> + pinned, pgbase, *pos,
> + req_len);
> + if (IS_ERR(req)) {
> + if (!bytes)
> + bytes = PTR_ERR(req);
> + break;
> + }
> +
> + list_add_tail(&req->wb_list, list);
> + pgbase = 0;
> + bytes += req_len;
> + *pos += req_len;
> + }
> +
> + if (i < npages) {
> + iov_iter_revert(iter, result - bytes);
> + nfs_direct_release_pages(pagevec + i, npages - i, pinned);
> + }
> +
> + kvfree(pagevec);
> + return bytes;
> +}
> +
> void nfs_init_cinfo_from_dreq(struct nfs_commit_info *cinfo,
> struct nfs_direct_req *dreq)
> {
> @@ -346,6 +390,7 @@ static ssize_t nfs_direct_read_schedule_iovec(struct nfs_direct_req *dreq,
> ssize_t result = -EINVAL;
> size_t requested_bytes = 0;
> size_t rsize = max_t(size_t, NFS_SERVER(inode)->rsize, PAGE_SIZE);
> + LIST_HEAD(nfs_page_list);
>
> nfs_pageio_init_read(&desc, dreq->inode, false,
> &nfs_direct_read_completion_ops);
> @@ -354,43 +399,23 @@ static ssize_t nfs_direct_read_schedule_iovec(struct nfs_direct_req *dreq,
> inode_dio_begin(inode);
>
> while (iov_iter_count(iter)) {
> - struct page **pagevec = NULL;
> - size_t bytes;
> - size_t pgbase;
> - unsigned npages, i;
> - bool pinned = iov_iter_extract_will_pin(iter);
> -
> - result = iov_iter_extract_pages(iter, &pagevec,
> - rsize, ~0U, 0, &pgbase);
> + result = nfs_direct_extract_pages(dreq, iter, rsize, &pos, &nfs_page_list);
> if (result < 0)
> break;
>
> - bytes = result;
> - npages = (result + pgbase + PAGE_SIZE - 1) / PAGE_SIZE;
> - for (i = 0; i < npages; i++) {
> - struct nfs_page *req;
> - 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],
> - pinned, pgbase, pos,
> - req_len);
> - if (IS_ERR(req)) {
> - result = PTR_ERR(req);
> - break;
> - }
> + while (!list_empty(&nfs_page_list)) {
> + struct nfs_page *req = nfs_list_entry(nfs_page_list.next);
> + size_t req_len = req->wb_bytes;
> +
> + nfs_list_remove_request(req);
> if (!nfs_pageio_add_request(&desc, req)) {
> result = desc.pg_error;
> nfs_release_request(req);
> + nfs_release_request_list(&nfs_page_list);
> break;
> }
> - pgbase = 0;
> - bytes -= req_len;
> requested_bytes += req_len;
> - pos += req_len;
> }
> - if (i < npages)
> - nfs_direct_release_pages(pagevec + i, npages - i, pinned);
> - kvfree(pagevec);
> if (result < 0)
> break;
> }
> @@ -881,6 +906,7 @@ static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq,
> ssize_t result = 0;
> size_t requested_bytes = 0;
> size_t wsize = max_t(size_t, NFS_SERVER(inode)->wsize, PAGE_SIZE);
> + LIST_HEAD(nfs_page_list);
> bool defer = false;
>
> trace_nfs_direct_write_schedule_iovec(dreq);
> @@ -893,55 +919,32 @@ static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq,
>
> NFS_I(inode)->write_io += iov_iter_count(iter);
> while (iov_iter_count(iter)) {
> - struct page **pagevec = NULL;
> - size_t bytes;
> - size_t pgbase;
> - unsigned npages, i;
> - bool pinned = iov_iter_extract_will_pin(iter);
> -
> - result = iov_iter_extract_pages(iter, &pagevec,
> - wsize, ~0U, 0, &pgbase);
> + result = nfs_direct_extract_pages(dreq, iter, wsize, &pos, &nfs_page_list);
> if (result < 0)
> break;
>
> - bytes = result;
> - npages = (result + pgbase + PAGE_SIZE - 1) / PAGE_SIZE;
> - for (i = 0; i < npages; i++) {
> - struct nfs_page *req;
> - unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase);
> -
> - req = nfs_page_create_from_page(dreq->ctx, pagevec[i],
> - pinned, pgbase, pos,
> - req_len);
> - if (IS_ERR(req)) {
> - result = PTR_ERR(req);
> - break;
> - }
> -
> - if (desc.pg_error < 0) {
> - nfs_free_request(req);
> - result = desc.pg_error;
> - break;
> - }
> -
> - pgbase = 0;
> - bytes -= req_len;
> - requested_bytes += req_len;
> - pos += req_len;
> + while (!list_empty(&nfs_page_list)) {
> + struct nfs_page *req = nfs_list_entry(nfs_page_list.next);
> + size_t req_len = req->wb_bytes;
>
> + nfs_list_remove_request(req);
> if (defer) {
> nfs_mark_request_commit(req, NULL, &cinfo, 0);
> + requested_bytes += req_len;
> continue;
> }
>
> nfs_lock_request(req);
> - if (nfs_pageio_add_request(&desc, req))
> + if (nfs_pageio_add_request(&desc, req)) {
> + requested_bytes += req_len;
> continue;
> + }
>
> /* Exit on hard errors */
> if (desc.pg_error < 0 && desc.pg_error != -EAGAIN) {
> result = desc.pg_error;
> nfs_unlock_and_release_request(req);
> + nfs_release_request_list(&nfs_page_list);
> break;
> }
>
> @@ -952,12 +955,10 @@ static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq,
> spin_unlock(&dreq->lock);
> nfs_unlock_request(req);
> nfs_mark_request_commit(req, NULL, &cinfo, 0);
> + requested_bytes += req_len;
> desc.pg_error = 0;
> defer = true;
> }
> - if (i < npages)
> - nfs_direct_release_pages(pagevec + i, npages - i, pinned);
> - kvfree(pagevec);
> if (result < 0)
> break;
> }
> --
> 2.55.0.229.g6434b31f56-goog
>
Refactoring looks good. Consolidates extraction, error handling, and
iov_iter_revert() into a single helper shared by both read and write
paths.
Reviewed-by: Shivaji Kant <shivajikant@xxxxxxxxxx>