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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 Reviewed-by: Christoph Hellwig --- fs/nfs/direct.c | 22 +++++++++++++------- fs/nfs/pagelist.c | 44 +++++++++++++++++++++++++++++++--------- fs/nfs/read.c | 2 +- fs/nfs/write.c | 2 +- include/linux/nfs_page.h | 3 +++ 5 files changed, 54 insertions(+), 19 deletions(-) diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c index e626c72495e6..19792a38c924 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; @@ -907,7 +914,8 @@ 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; @@ -950,7 +958,7 @@ 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 7dd478ffc2fa..a562cfe2a126 100644 --- a/fs/nfs/pagelist.c +++ b/fs/nfs/pagelist.c @@ -404,20 +404,28 @@ 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); } } @@ -425,6 +433,7 @@ static void nfs_page_assign_page(struct nfs_page *req, struct page *page) * nfs_page_create_from_page - Create an NFS read/write request. * @ctx: open context to use * @page: page to write + * @pinned: true if page is pinned * @pgbase: starting offset within the page for the write * @offset: file offset for the write * @count: number of bytes to read/write @@ -435,6 +444,7 @@ 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 +456,7 @@ 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); @@ -457,6 +467,7 @@ struct nfs_page *nfs_page_create_from_page(struct nfs_open_context *ctx, * nfs_page_create_from_folio - Create an NFS read/write request. * @ctx: open context to use * @folio: folio to write + * @pinned: true if folio is pinned * @offset: starting offset within the folio for the write * @count: number of bytes to read/write * @@ -466,6 +477,7 @@ 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 +488,7 @@ 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 +510,11 @@ 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 +566,21 @@ 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)) { + if (req == req->wb_head) + 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)) { + if (req == req->wb_head) + 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 2b70bd2b934b..e7497b029d6c 100644 --- a/fs/nfs/read.c +++ b/fs/nfs/read.c @@ -324,7 +324,7 @@ 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 d2b03ceaeb4f..e565b811d8b7 100644 --- a/fs/nfs/write.c +++ b/fs/nfs/write.c @@ -1088,7 +1088,7 @@ 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 4b9a35dbc062..fd7aafe7cb54 100644 --- a/include/linux/nfs_page.h +++ b/include/linux/nfs_page.h @@ -38,6 +38,7 @@ 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; @@ -125,11 +126,13 @@ 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 *); -- 2.55.0.691.gc56d675ccc-goog