1 files changed, 486 insertions, 0 deletions

diff --git a/fs/nfs/read.c b/fs/nfs/read.c
new file mode 100644
index 000000000..eb854f1f8
--- /dev/null
+++ b/fs/nfs/read.c
@@ -0,0 +1,486 @@
+// 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/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)
+{
+	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);
+
+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);
+
+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)) {
+		struct address_space *mapping = page_file_mapping(page);
+
+		if (PageUptodate(page))
+			nfs_readpage_to_fscache(inode, page, 0);
+		else if (!PageError(page) && !PagePrivate(page))
+			generic_error_remove_page(mapping, page);
+		unlock_page(page);
+	}
+	nfs_release_request(req);
+}
+
+int nfs_readpage_async(struct nfs_open_context *ctx, struct inode *inode,
+		       struct page *page)
+{
+	struct nfs_page	*new;
+	unsigned int len;
+	struct nfs_pageio_descriptor pgio;
+	struct nfs_pgio_mirror *pgm;
+
+	len = nfs_page_length(page);
+	if (len == 0)
+		return nfs_return_empty_page(page);
+	new = nfs_create_request(ctx, page, 0, len);
+	if (IS_ERR(new)) {
+		unlock_page(page);
+		return PTR_ERR(new);
+	}
+	if (len < PAGE_SIZE)
+		zero_user_segment(page, len, PAGE_SIZE);
+
+	nfs_pageio_init_read(&pgio, inode, false,
+			     &nfs_async_read_completion_ops);
+	if (!nfs_pageio_add_request(&pgio, new)) {
+		nfs_list_remove_request(new);
+		nfs_readpage_release(new, pgio.pg_error);
+	}
+	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(inode)->read_io += pgm->pg_bytes_written;
+
+	return pgio.pg_error < 0 ? pgio.pg_error : 0;
+}
+
+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 nfs_readpage_async /
+			 * 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)
+{
+	struct inode *inode = hdr->inode;
+	int swap_flags = IS_SWAPFILE(inode) ? NFS_RPC_SWAPFLAGS : 0;
+
+	task_setup_data->flags |= swap_flags;
+	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);
+}
+
+/*
+ * 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_readpage(struct file *file, struct page *page)
+{
+	struct nfs_open_context *ctx;
+	struct inode *inode = page_file_mapping(page)->host;
+	int		error;
+
+	dprintk("NFS: nfs_readpage (%p %ld@%lu)\n",
+		page, PAGE_SIZE, page_index(page));
+	nfs_inc_stats(inode, NFSIOS_VFSREADPAGE);
+	nfs_add_stats(inode, NFSIOS_READPAGES, 1);
+
+	/*
+	 * 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).
+	 */
+	error = nfs_wb_page(inode, page);
+	if (error)
+		goto out_unlock;
+	if (PageUptodate(page))
+		goto out_unlock;
+
+	error = -ESTALE;
+	if (NFS_STALE(inode))
+		goto out_unlock;
+
+	if (file == NULL) {
+		error = -EBADF;
+		ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
+		if (ctx == NULL)
+			goto out_unlock;
+	} else
+		ctx = get_nfs_open_context(nfs_file_open_context(file));
+
+	if (!IS_SYNC(inode)) {
+		error = nfs_readpage_from_fscache(ctx, inode, page);
+		if (error == 0)
+			goto out;
+	}
+
+	xchg(&ctx->error, 0);
+	error = nfs_readpage_async(ctx, inode, page);
+	if (!error) {
+		error = wait_on_page_locked_killable(page);
+		if (!PageUptodate(page) && !error)
+			error = xchg(&ctx->error, 0);
+	}
+out:
+	put_nfs_open_context(ctx);
+	return error;
+out_unlock:
+	unlock_page(page);
+	return error;
+}
+
+struct nfs_readdesc {
+	struct nfs_pageio_descriptor *pgio;
+	struct nfs_open_context *ctx;
+};
+
+static int
+readpage_async_filler(void *data, struct page *page)
+{
+	struct nfs_readdesc *desc = (struct nfs_readdesc *)data;
+	struct nfs_page *new;
+	unsigned int len;
+	int error;
+
+	len = nfs_page_length(page);
+	if (len == 0)
+		return nfs_return_empty_page(page);
+
+	new = nfs_create_request(desc->ctx, page, 0, 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);
+	unlock_page(page);
+out:
+	return error;
+}
+
+int nfs_readpages(struct file *filp, struct address_space *mapping,
+		struct list_head *pages, unsigned nr_pages)
+{
+	struct nfs_pageio_descriptor pgio;
+	struct nfs_pgio_mirror *pgm;
+	struct nfs_readdesc desc = {
+		.pgio = &pgio,
+	};
+	struct inode *inode = mapping->host;
+	unsigned long npages;
+	int ret = -ESTALE;
+
+	dprintk("NFS: nfs_readpages (%s/%Lu %d)\n",
+			inode->i_sb->s_id,
+			(unsigned long long)NFS_FILEID(inode),
+			nr_pages);
+	nfs_inc_stats(inode, NFSIOS_VFSREADPAGES);
+
+	if (NFS_STALE(inode))
+		goto out;
+
+	if (filp == NULL) {
+		desc.ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
+		if (desc.ctx == NULL)
+			return -EBADF;
+	} else
+		desc.ctx = get_nfs_open_context(nfs_file_open_context(filp));
+
+	/* attempt to read as many of the pages as possible from the cache
+	 * - this returns -ENOBUFS immediately if the cookie is negative
+	 */
+	ret = nfs_readpages_from_fscache(desc.ctx, inode, mapping,
+					 pages, &nr_pages);
+	if (ret == 0)
+		goto read_complete; /* all pages were read */
+
+	nfs_pageio_init_read(&pgio, inode, false,
+			     &nfs_async_read_completion_ops);
+
+	ret = read_cache_pages(mapping, pages, readpage_async_filler, &desc);
+	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(inode)->read_io += pgm->pg_bytes_written;
+	npages = (pgm->pg_bytes_written + PAGE_SIZE - 1) >>
+		 PAGE_SHIFT;
+	nfs_add_stats(inode, NFSIOS_READPAGES, npages);
+read_complete:
+	put_nfs_open_context(desc.ctx);
+out:
+	return 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,
+};