v4.19.13 snapshot.
diff --git a/include/linux/nfs_page.h b/include/linux/nfs_page.h
new file mode 100644
index 0000000..e27572d
--- /dev/null
+++ b/include/linux/nfs_page.h
@@ -0,0 +1,192 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * linux/include/linux/nfs_page.h
+ *
+ * Copyright (C) 2000 Trond Myklebust
+ *
+ * NFS page cache wrapper.
+ */
+
+#ifndef _LINUX_NFS_PAGE_H
+#define _LINUX_NFS_PAGE_H
+
+
+#include <linux/list.h>
+#include <linux/pagemap.h>
+#include <linux/wait.h>
+#include <linux/sunrpc/auth.h>
+#include <linux/nfs_xdr.h>
+
+#include <linux/kref.h>
+
+/*
+ * Valid flags for a dirty buffer
+ */
+enum {
+ PG_BUSY = 0, /* nfs_{un}lock_request */
+ PG_MAPPED, /* page private set for buffered io */
+ PG_CLEAN, /* write succeeded */
+ PG_COMMIT_TO_DS, /* used by pnfs layouts */
+ PG_INODE_REF, /* extra ref held by inode when in writeback */
+ PG_HEADLOCK, /* page group lock of wb_head */
+ PG_TEARDOWN, /* page group sync for destroy */
+ PG_UNLOCKPAGE, /* page group sync bit in read path */
+ PG_UPTODATE, /* page group sync bit in read path */
+ PG_WB_END, /* page group sync bit in write path */
+ 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? */
+};
+
+struct nfs_inode;
+struct nfs_page {
+ struct list_head wb_list; /* Defines state of page: */
+ struct page *wb_page; /* page to read in/write out */
+ struct nfs_open_context *wb_context; /* File state context info */
+ struct nfs_lock_context *wb_lock_context; /* lock context info */
+ pgoff_t wb_index; /* Offset >> PAGE_SHIFT */
+ unsigned int wb_offset, /* Offset & ~PAGE_MASK */
+ wb_pgbase, /* Start of page data */
+ wb_bytes; /* Length of request */
+ struct kref wb_kref; /* reference count */
+ unsigned long wb_flags;
+ struct nfs_write_verifier wb_verf; /* Commit cookie */
+ struct nfs_page *wb_this_page; /* list of reqs for this page */
+ struct nfs_page *wb_head; /* head pointer for req list */
+};
+
+struct nfs_pageio_descriptor;
+struct nfs_pageio_ops {
+ void (*pg_init)(struct nfs_pageio_descriptor *, struct nfs_page *);
+ size_t (*pg_test)(struct nfs_pageio_descriptor *, struct nfs_page *,
+ struct nfs_page *);
+ int (*pg_doio)(struct nfs_pageio_descriptor *);
+ unsigned int (*pg_get_mirror_count)(struct nfs_pageio_descriptor *,
+ struct nfs_page *);
+ void (*pg_cleanup)(struct nfs_pageio_descriptor *);
+};
+
+struct nfs_rw_ops {
+ struct nfs_pgio_header *(*rw_alloc_header)(void);
+ void (*rw_free_header)(struct nfs_pgio_header *);
+ int (*rw_done)(struct rpc_task *, struct nfs_pgio_header *,
+ struct inode *);
+ void (*rw_result)(struct rpc_task *, struct nfs_pgio_header *);
+ void (*rw_initiate)(struct nfs_pgio_header *, struct rpc_message *,
+ const struct nfs_rpc_ops *,
+ struct rpc_task_setup *, int);
+};
+
+struct nfs_pgio_mirror {
+ struct list_head pg_list;
+ unsigned long pg_bytes_written;
+ size_t pg_count;
+ size_t pg_bsize;
+ unsigned int pg_base;
+ unsigned char pg_recoalesce : 1;
+};
+
+struct nfs_pageio_descriptor {
+ unsigned char pg_moreio : 1;
+ struct inode *pg_inode;
+ const struct nfs_pageio_ops *pg_ops;
+ const struct nfs_rw_ops *pg_rw_ops;
+ int pg_ioflags;
+ int pg_error;
+ const struct rpc_call_ops *pg_rpc_callops;
+ const struct nfs_pgio_completion_ops *pg_completion_ops;
+ struct pnfs_layout_segment *pg_lseg;
+ struct nfs_io_completion *pg_io_completion;
+ struct nfs_direct_req *pg_dreq;
+ unsigned int pg_bsize; /* default bsize for mirrors */
+
+ u32 pg_mirror_count;
+ struct nfs_pgio_mirror *pg_mirrors;
+ struct nfs_pgio_mirror pg_mirrors_static[1];
+ struct nfs_pgio_mirror *pg_mirrors_dynamic;
+ u32 pg_mirror_idx; /* current mirror */
+};
+
+/* arbitrarily selected limit to number of mirrors */
+#define NFS_PAGEIO_DESCRIPTOR_MIRROR_MAX 16
+
+#define NFS_WBACK_BUSY(req) (test_bit(PG_BUSY,&(req)->wb_flags))
+
+extern struct nfs_page *nfs_create_request(struct nfs_open_context *ctx,
+ struct page *page,
+ struct nfs_page *last,
+ unsigned int offset,
+ unsigned int count);
+extern void nfs_release_request(struct nfs_page *);
+
+
+extern void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
+ struct inode *inode,
+ const struct nfs_pageio_ops *pg_ops,
+ const struct nfs_pgio_completion_ops *compl_ops,
+ const struct nfs_rw_ops *rw_ops,
+ size_t bsize,
+ int how);
+extern int nfs_pageio_add_request(struct nfs_pageio_descriptor *,
+ struct nfs_page *);
+extern int nfs_pageio_resend(struct nfs_pageio_descriptor *,
+ struct nfs_pgio_header *);
+extern void nfs_pageio_complete(struct nfs_pageio_descriptor *desc);
+extern void nfs_pageio_cond_complete(struct nfs_pageio_descriptor *, pgoff_t);
+extern size_t nfs_generic_pg_test(struct nfs_pageio_descriptor *desc,
+ struct nfs_page *prev,
+ struct nfs_page *req);
+extern int nfs_wait_on_request(struct nfs_page *);
+extern void nfs_unlock_request(struct nfs_page *req);
+extern void nfs_unlock_and_release_request(struct nfs_page *);
+extern int nfs_page_group_lock(struct nfs_page *);
+extern void nfs_page_group_unlock(struct nfs_page *);
+extern bool nfs_page_group_sync_on_bit(struct nfs_page *, unsigned int);
+extern bool nfs_async_iocounter_wait(struct rpc_task *, struct nfs_lock_context *);
+
+/*
+ * Lock the page of an asynchronous request
+ */
+static inline int
+nfs_lock_request(struct nfs_page *req)
+{
+ return !test_and_set_bit(PG_BUSY, &req->wb_flags);
+}
+
+/**
+ * nfs_list_add_request - Insert a request into a list
+ * @req: request
+ * @head: head of list into which to insert the request.
+ */
+static inline void
+nfs_list_add_request(struct nfs_page *req, struct list_head *head)
+{
+ list_add_tail(&req->wb_list, head);
+}
+
+
+/**
+ * nfs_list_remove_request - Remove a request from its wb_list
+ * @req: request
+ */
+static inline void
+nfs_list_remove_request(struct nfs_page *req)
+{
+ if (list_empty(&req->wb_list))
+ return;
+ list_del_init(&req->wb_list);
+}
+
+static inline struct nfs_page *
+nfs_list_entry(struct list_head *head)
+{
+ return list_entry(head, struct nfs_page, wb_list);
+}
+
+static inline
+loff_t req_offset(struct nfs_page *req)
+{
+ return (((loff_t)req->wb_index) << PAGE_SHIFT) + req->wb_offset;
+}
+
+#endif /* _LINUX_NFS_PAGE_H */