1 files changed, 469 insertions, 0 deletions

diff --git a/fs/nfs/read.c b/fs/nfs/read.c
new file mode 100644
index 000000000..6aad42fbf
--- /dev/null
+++ b/fs/nfs/read.c
@@ -0,0 +1,469 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * linux/fs/nfs/read.c
+ *
+ * Block I/O for NFS
+ *
+ * Partial copy of Linus' read cache modifications to fs/nfs/file.c
+ * modified for async RPC by okir@monad.swb.de
+ */
+
+#include <linux/time.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/fcntl.h>
+#include <linux/stat.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/task_io_accounting_ops.h>
+#include <linux/pagemap.h>
+#include <linux/sunrpc/clnt.h>
+#include <linux/nfs_fs.h>
+#include <linux/nfs_page.h>
+#include <linux/module.h>
+
+#include "nfs4_fs.h"
+#include "internal.h"
+#include "iostat.h"
+#include "fscache.h"
+#include "pnfs.h"
+#include "nfstrace.h"
+
+#define NFSDBG_FACILITY		NFSDBG_PAGECACHE
+
+static const struct nfs_pgio_completion_ops nfs_async_read_completion_ops;
+static const struct nfs_rw_ops nfs_rw_read_ops;
+
+static struct kmem_cache *nfs_rdata_cachep;
+
+static struct nfs_pgio_header *nfs_readhdr_alloc(void)
+{
+	struct nfs_pgio_header *p = kmem_cache_zalloc(nfs_rdata_cachep, GFP_KERNEL);
+
+	if (p)
+		p->rw_mode = FMODE_READ;
+	return p;
+}
+
+static void nfs_readhdr_free(struct nfs_pgio_header *rhdr)
+{
+	if (rhdr->res.scratch != NULL)
+		kfree(rhdr->res.scratch);
+	kmem_cache_free(nfs_rdata_cachep, rhdr);
+}
+
+static
+int nfs_return_empty_page(struct page *page)
+{
+	zero_user(page, 0, PAGE_SIZE);
+	SetPageUptodate(page);
+	unlock_page(page);
+	return 0;
+}
+
+void nfs_pageio_init_read(struct nfs_pageio_descriptor *pgio,
+			      struct inode *inode, bool force_mds,
+			      const struct nfs_pgio_completion_ops *compl_ops)
+{
+	struct nfs_server *server = NFS_SERVER(inode);
+	const struct nfs_pageio_ops *pg_ops = &nfs_pgio_rw_ops;
+
+#ifdef CONFIG_NFS_V4_1
+	if (server->pnfs_curr_ld && !force_mds)
+		pg_ops = server->pnfs_curr_ld->pg_read_ops;
+#endif
+	nfs_pageio_init(pgio, inode, pg_ops, compl_ops, &nfs_rw_read_ops,
+			server->rsize, 0);
+}
+EXPORT_SYMBOL_GPL(nfs_pageio_init_read);
+
+static void nfs_pageio_complete_read(struct nfs_pageio_descriptor *pgio)
+{
+	struct nfs_pgio_mirror *pgm;
+	unsigned long npages;
+
+	nfs_pageio_complete(pgio);
+
+	/* It doesn't make sense to do mirrored reads! */
+	WARN_ON_ONCE(pgio->pg_mirror_count != 1);
+
+	pgm = &pgio->pg_mirrors[0];
+	NFS_I(pgio->pg_inode)->read_io += pgm->pg_bytes_written;
+	npages = (pgm->pg_bytes_written + PAGE_SIZE - 1) >> PAGE_SHIFT;
+	nfs_add_stats(pgio->pg_inode, NFSIOS_READPAGES, npages);
+}
+
+
+void nfs_pageio_reset_read_mds(struct nfs_pageio_descriptor *pgio)
+{
+	struct nfs_pgio_mirror *mirror;
+
+	if (pgio->pg_ops && pgio->pg_ops->pg_cleanup)
+		pgio->pg_ops->pg_cleanup(pgio);
+
+	pgio->pg_ops = &nfs_pgio_rw_ops;
+
+	/* read path should never have more than one mirror */
+	WARN_ON_ONCE(pgio->pg_mirror_count != 1);
+
+	mirror = &pgio->pg_mirrors[0];
+	mirror->pg_bsize = NFS_SERVER(pgio->pg_inode)->rsize;
+}
+EXPORT_SYMBOL_GPL(nfs_pageio_reset_read_mds);
+
+bool nfs_read_alloc_scratch(struct nfs_pgio_header *hdr, size_t size)
+{
+	WARN_ON(hdr->res.scratch != NULL);
+	hdr->res.scratch = kmalloc(size, GFP_KERNEL);
+	return hdr->res.scratch != NULL;
+}
+EXPORT_SYMBOL_GPL(nfs_read_alloc_scratch);
+
+static void nfs_readpage_release(struct nfs_page *req, int error)
+{
+	struct inode *inode = d_inode(nfs_req_openctx(req)->dentry);
+	struct page *page = req->wb_page;
+
+	dprintk("NFS: read done (%s/%llu %d@%lld)\n", inode->i_sb->s_id,
+		(unsigned long long)NFS_FILEID(inode), req->wb_bytes,
+		(long long)req_offset(req));
+
+	if (nfs_error_is_fatal_on_server(error) && error != -ETIMEDOUT)
+		SetPageError(page);
+	if (nfs_page_group_sync_on_bit(req, PG_UNLOCKPAGE)) {
+		if (PageUptodate(page))
+			nfs_fscache_write_page(inode, page);
+		unlock_page(page);
+	}
+	nfs_release_request(req);
+}
+
+struct nfs_readdesc {
+	struct nfs_pageio_descriptor pgio;
+	struct nfs_open_context *ctx;
+};
+
+static void nfs_page_group_set_uptodate(struct nfs_page *req)
+{
+	if (nfs_page_group_sync_on_bit(req, PG_UPTODATE))
+		SetPageUptodate(req->wb_page);
+}
+
+static void nfs_read_completion(struct nfs_pgio_header *hdr)
+{
+	unsigned long bytes = 0;
+	int error;
+
+	if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
+		goto out;
+	while (!list_empty(&hdr->pages)) {
+		struct nfs_page *req = nfs_list_entry(hdr->pages.next);
+		struct page *page = req->wb_page;
+		unsigned long start = req->wb_pgbase;
+		unsigned long end = req->wb_pgbase + req->wb_bytes;
+
+		if (test_bit(NFS_IOHDR_EOF, &hdr->flags)) {
+			/* note: regions of the page not covered by a
+			 * request are zeroed in readpage_async_filler */
+			if (bytes > hdr->good_bytes) {
+				/* nothing in this request was good, so zero
+				 * the full extent of the request */
+				zero_user_segment(page, start, end);
+
+			} else if (hdr->good_bytes - bytes < req->wb_bytes) {
+				/* part of this request has good bytes, but
+				 * not all. zero the bad bytes */
+				start += hdr->good_bytes - bytes;
+				WARN_ON(start < req->wb_pgbase);
+				zero_user_segment(page, start, end);
+			}
+		}
+		error = 0;
+		bytes += req->wb_bytes;
+		if (test_bit(NFS_IOHDR_ERROR, &hdr->flags)) {
+			if (bytes <= hdr->good_bytes)
+				nfs_page_group_set_uptodate(req);
+			else {
+				error = hdr->error;
+				xchg(&nfs_req_openctx(req)->error, error);
+			}
+		} else
+			nfs_page_group_set_uptodate(req);
+		nfs_list_remove_request(req);
+		nfs_readpage_release(req, error);
+	}
+out:
+	hdr->release(hdr);
+}
+
+static void nfs_initiate_read(struct nfs_pgio_header *hdr,
+			      struct rpc_message *msg,
+			      const struct nfs_rpc_ops *rpc_ops,
+			      struct rpc_task_setup *task_setup_data, int how)
+{
+	rpc_ops->read_setup(hdr, msg);
+	trace_nfs_initiate_read(hdr);
+}
+
+static void
+nfs_async_read_error(struct list_head *head, int error)
+{
+	struct nfs_page	*req;
+
+	while (!list_empty(head)) {
+		req = nfs_list_entry(head->next);
+		nfs_list_remove_request(req);
+		nfs_readpage_release(req, error);
+	}
+}
+
+static const struct nfs_pgio_completion_ops nfs_async_read_completion_ops = {
+	.error_cleanup = nfs_async_read_error,
+	.completion = nfs_read_completion,
+};
+
+/*
+ * This is the callback from RPC telling us whether a reply was
+ * received or some error occurred (timeout or socket shutdown).
+ */
+static int nfs_readpage_done(struct rpc_task *task,
+			     struct nfs_pgio_header *hdr,
+			     struct inode *inode)
+{
+	int status = NFS_PROTO(inode)->read_done(task, hdr);
+	if (status != 0)
+		return status;
+
+	nfs_add_stats(inode, NFSIOS_SERVERREADBYTES, hdr->res.count);
+	trace_nfs_readpage_done(task, hdr);
+
+	if (task->tk_status == -ESTALE) {
+		nfs_set_inode_stale(inode);
+		nfs_mark_for_revalidate(inode);
+	}
+	return 0;
+}
+
+static void nfs_readpage_retry(struct rpc_task *task,
+			       struct nfs_pgio_header *hdr)
+{
+	struct nfs_pgio_args *argp = &hdr->args;
+	struct nfs_pgio_res  *resp = &hdr->res;
+
+	/* This is a short read! */
+	nfs_inc_stats(hdr->inode, NFSIOS_SHORTREAD);
+	trace_nfs_readpage_short(task, hdr);
+
+	/* Has the server at least made some progress? */
+	if (resp->count == 0) {
+		nfs_set_pgio_error(hdr, -EIO, argp->offset);
+		return;
+	}
+
+	/* For non rpc-based layout drivers, retry-through-MDS */
+	if (!task->tk_ops) {
+		hdr->pnfs_error = -EAGAIN;
+		return;
+	}
+
+	/* Yes, so retry the read at the end of the hdr */
+	hdr->mds_offset += resp->count;
+	argp->offset += resp->count;
+	argp->pgbase += resp->count;
+	argp->count -= resp->count;
+	resp->count = 0;
+	resp->eof = 0;
+	rpc_restart_call_prepare(task);
+}
+
+static void nfs_readpage_result(struct rpc_task *task,
+				struct nfs_pgio_header *hdr)
+{
+	if (hdr->res.eof) {
+		loff_t pos = hdr->args.offset + hdr->res.count;
+		unsigned int new = pos - hdr->io_start;
+
+		if (hdr->good_bytes > new) {
+			hdr->good_bytes = new;
+			set_bit(NFS_IOHDR_EOF, &hdr->flags);
+			clear_bit(NFS_IOHDR_ERROR, &hdr->flags);
+		}
+	} else if (hdr->res.count < hdr->args.count)
+		nfs_readpage_retry(task, hdr);
+}
+
+static int
+readpage_async_filler(struct nfs_readdesc *desc, struct page *page)
+{
+	struct inode *inode = page_file_mapping(page)->host;
+	unsigned int rsize = NFS_SERVER(inode)->rsize;
+	struct nfs_page *new;
+	unsigned int len, aligned_len;
+	int error;
+
+	len = nfs_page_length(page);
+	if (len == 0)
+		return nfs_return_empty_page(page);
+
+	aligned_len = min_t(unsigned int, ALIGN(len, rsize), PAGE_SIZE);
+
+	if (!IS_SYNC(page->mapping->host)) {
+		error = nfs_fscache_read_page(page->mapping->host, page);
+		if (error == 0)
+			goto out_unlock;
+	}
+
+	new = nfs_create_request(desc->ctx, page, 0, aligned_len);
+	if (IS_ERR(new))
+		goto out_error;
+
+	if (len < PAGE_SIZE)
+		zero_user_segment(page, len, PAGE_SIZE);
+	if (!nfs_pageio_add_request(&desc->pgio, new)) {
+		nfs_list_remove_request(new);
+		error = desc->pgio.pg_error;
+		nfs_readpage_release(new, error);
+		goto out;
+	}
+	return 0;
+out_error:
+	error = PTR_ERR(new);
+out_unlock:
+	unlock_page(page);
+out:
+	return error;
+}
+
+/*
+ * Read a page over NFS.
+ * We read the page synchronously in the following case:
+ *  -	The error flag is set for this page. This happens only when a
+ *	previous async read operation failed.
+ */
+int nfs_read_folio(struct file *file, struct folio *folio)
+{
+	struct page *page = &folio->page;
+	struct nfs_readdesc desc;
+	struct inode *inode = page_file_mapping(page)->host;
+	int ret;
+
+	trace_nfs_aop_readpage(inode, page);
+	nfs_inc_stats(inode, NFSIOS_VFSREADPAGE);
+	task_io_account_read(folio_size(folio));
+
+	/*
+	 * Try to flush any pending writes to the file..
+	 *
+	 * NOTE! Because we own the page lock, there cannot
+	 * be any new pending writes generated at this point
+	 * for this page (other pages can be written to).
+	 */
+	ret = nfs_wb_page(inode, page);
+	if (ret)
+		goto out_unlock;
+	if (PageUptodate(page))
+		goto out_unlock;
+
+	ret = -ESTALE;
+	if (NFS_STALE(inode))
+		goto out_unlock;
+
+	if (file == NULL) {
+		ret = -EBADF;
+		desc.ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
+		if (desc.ctx == NULL)
+			goto out_unlock;
+	} else
+		desc.ctx = get_nfs_open_context(nfs_file_open_context(file));
+
+	xchg(&desc.ctx->error, 0);
+	nfs_pageio_init_read(&desc.pgio, inode, false,
+			     &nfs_async_read_completion_ops);
+
+	ret = readpage_async_filler(&desc, page);
+	if (ret)
+		goto out;
+
+	nfs_pageio_complete_read(&desc.pgio);
+	ret = desc.pgio.pg_error < 0 ? desc.pgio.pg_error : 0;
+	if (!ret) {
+		ret = wait_on_page_locked_killable(page);
+		if (!PageUptodate(page) && !ret)
+			ret = xchg(&desc.ctx->error, 0);
+	}
+out:
+	put_nfs_open_context(desc.ctx);
+	trace_nfs_aop_readpage_done(inode, page, ret);
+	return ret;
+out_unlock:
+	unlock_page(page);
+	trace_nfs_aop_readpage_done(inode, page, ret);
+	return ret;
+}
+
+void nfs_readahead(struct readahead_control *ractl)
+{
+	unsigned int nr_pages = readahead_count(ractl);
+	struct file *file = ractl->file;
+	struct nfs_readdesc desc;
+	struct inode *inode = ractl->mapping->host;
+	struct page *page;
+	int ret;
+
+	trace_nfs_aop_readahead(inode, readahead_pos(ractl), nr_pages);
+	nfs_inc_stats(inode, NFSIOS_VFSREADPAGES);
+	task_io_account_read(readahead_length(ractl));
+
+	ret = -ESTALE;
+	if (NFS_STALE(inode))
+		goto out;
+
+	if (file == NULL) {
+		ret = -EBADF;
+		desc.ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
+		if (desc.ctx == NULL)
+			goto out;
+	} else
+		desc.ctx = get_nfs_open_context(nfs_file_open_context(file));
+
+	nfs_pageio_init_read(&desc.pgio, inode, false,
+			     &nfs_async_read_completion_ops);
+
+	while ((page = readahead_page(ractl)) != NULL) {
+		ret = readpage_async_filler(&desc, page);
+		put_page(page);
+		if (ret)
+			break;
+	}
+
+	nfs_pageio_complete_read(&desc.pgio);
+
+	put_nfs_open_context(desc.ctx);
+out:
+	trace_nfs_aop_readahead_done(inode, nr_pages, ret);
+}
+
+int __init nfs_init_readpagecache(void)
+{
+	nfs_rdata_cachep = kmem_cache_create("nfs_read_data",
+					     sizeof(struct nfs_pgio_header),
+					     0, SLAB_HWCACHE_ALIGN,
+					     NULL);
+	if (nfs_rdata_cachep == NULL)
+		return -ENOMEM;
+
+	return 0;
+}
+
+void nfs_destroy_readpagecache(void)
+{
+	kmem_cache_destroy(nfs_rdata_cachep);
+}
+
+static const struct nfs_rw_ops nfs_rw_read_ops = {
+	.rw_alloc_header	= nfs_readhdr_alloc,
+	.rw_free_header		= nfs_readhdr_free,
+	.rw_done		= nfs_readpage_done,
+	.rw_result		= nfs_readpage_result,
+	.rw_initiate		= nfs_initiate_read,
+};