1 files changed, 309 insertions, 0 deletions

diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
new file mode 100644
index 000000000000..4f1ba723848d
--- /dev/null
+++ b/fs/nfs/pagelist.c
@@ -0,0 +1,309 @@
+/*
+ * linux/fs/nfs/pagelist.c
+ *
+ * A set of helper functions for managing NFS read and write requests.
+ * The main purpose of these routines is to provide support for the
+ * coalescing of several requests into a single RPC call.
+ *
+ * Copyright 2000, 2001 (c) Trond Myklebust <trond.myklebust@fys.uio.no>
+ *
+ */
+
+#include <linux/config.h>
+#include <linux/slab.h>
+#include <linux/file.h>
+#include <linux/sunrpc/clnt.h>
+#include <linux/nfs3.h>
+#include <linux/nfs4.h>
+#include <linux/nfs_page.h>
+#include <linux/nfs_fs.h>
+#include <linux/nfs_mount.h>
+
+#define NFS_PARANOIA 1
+
+static kmem_cache_t *nfs_page_cachep;
+
+static inline struct nfs_page *
+nfs_page_alloc(void)
+{
+        struct nfs_page *p;
+        p = kmem_cache_alloc(nfs_page_cachep, SLAB_KERNEL);
+        if (p) {
+                memset(p, 0, sizeof(*p));
+                INIT_LIST_HEAD(&p->wb_list);
+        }
+        return p;
+}
+
+static inline void
+nfs_page_free(struct nfs_page *p)
+{
+        kmem_cache_free(nfs_page_cachep, p);
+}
+
+/**
+ * nfs_create_request - Create an NFS read/write request.
+ * @file: file descriptor to use
+ * @inode: inode to which the request is attached
+ * @page: page to write
+ * @offset: starting offset within the page for the write
+ * @count: number of bytes to read/write
+ *
+ * The page must be locked by the caller. This makes sure we never
+ * create two different requests for the same page, and avoids
+ * a possible deadlock when we reach the hard limit on the number
+ * of dirty pages.
+ * User should ensure it is safe to sleep in this function.
+ */
+struct nfs_page *
+nfs_create_request(struct nfs_open_context *ctx, struct inode *inode,
+                   struct page *page,
+                   unsigned int offset, unsigned int count)
+{
+        struct nfs_server *server = NFS_SERVER(inode);
+        struct nfs_page         *req;
+
+        /* Deal with hard limits.  */
+        for (;;) {
+                /* try to allocate the request struct */
+                req = nfs_page_alloc();
+                if (req != NULL)
+                        break;
+
+                /* Try to free up at least one request in order to stay
+                 * below the hard limit
+                 */
+                if (signalled() && (server->flags & NFS_MOUNT_INTR))
+                        return ERR_PTR(-ERESTARTSYS);
+                yield();
+        }
+
+        /* Initialize the request struct. Initially, we assume a
+         * long write-back delay. This will be adjusted in
+         * update_nfs_request below if the region is not locked. */
+        req->wb_page    = page;
+        atomic_set(&req->wb_complete, 0);
+        req->wb_index   = page->index;
+        page_cache_get(page);
+        req->wb_offset  = offset;
+        req->wb_pgbase  = offset;
+        req->wb_bytes   = count;
+        atomic_set(&req->wb_count, 1);
+        req->wb_context = get_nfs_open_context(ctx);
+
+        return req;
+}
+
+/**
+ * nfs_unlock_request - Unlock request and wake up sleepers.
+ * @req:
+ */
+void nfs_unlock_request(struct nfs_page *req)
+{
+        if (!NFS_WBACK_BUSY(req)) {
+                printk(KERN_ERR "NFS: Invalid unlock attempted\n");
+                BUG();
+        }
+        smp_mb__before_clear_bit();
+        clear_bit(PG_BUSY, &req->wb_flags);
+        smp_mb__after_clear_bit();
+        wake_up_all(&req->wb_context->waitq);
+        nfs_release_request(req);
+}
+
+/**
+ * nfs_clear_request - Free up all resources allocated to the request
+ * @req:
+ *
+ * Release page resources associated with a write request after it
+ * has completed.
+ */
+void nfs_clear_request(struct nfs_page *req)
+{
+        if (req->wb_page) {
+                page_cache_release(req->wb_page);
+                req->wb_page = NULL;
+        }
+}
+
+
+/**
+ * nfs_release_request - Release the count on an NFS read/write request
+ * @req: request to release
+ *
+ * Note: Should never be called with the spinlock held!
+ */
+void
+nfs_release_request(struct nfs_page *req)
+{
+        if (!atomic_dec_and_test(&req->wb_count))
+                return;
+
+#ifdef NFS_PARANOIA
+        BUG_ON (!list_empty(&req->wb_list));
+        BUG_ON (NFS_WBACK_BUSY(req));
+#endif
+
+        /* Release struct file or cached credential */
+        nfs_clear_request(req);
+        put_nfs_open_context(req->wb_context);
+        nfs_page_free(req);
+}
+
+/**
+ * nfs_list_add_request - Insert a request into a sorted list
+ * @req: request
+ * @head: head of list into which to insert the request.
+ *
+ * Note that the wb_list is sorted by page index in order to facilitate
+ * coalescing of requests.
+ * We use an insertion sort that is optimized for the case of appended
+ * writes.
+ */
+void
+nfs_list_add_request(struct nfs_page *req, struct list_head *head)
+{
+        struct list_head *pos;
+
+#ifdef NFS_PARANOIA
+        if (!list_empty(&req->wb_list)) {
+                printk(KERN_ERR "NFS: Add to list failed!\n");
+                BUG();
+        }
+#endif
+        list_for_each_prev(pos, head) {
+                struct nfs_page *p = nfs_list_entry(pos);
+                if (p->wb_index < req->wb_index)
+                        break;
+        }
+        list_add(&req->wb_list, pos);
+        req->wb_list_head = head;
+}
+
+/**
+ * nfs_wait_on_request - Wait for a request to complete.
+ * @req: request to wait upon.
+ *
+ * Interruptible by signals only if mounted with intr flag.
+ * The user is responsible for holding a count on the request.
+ */
+int
+nfs_wait_on_request(struct nfs_page *req)
+{
+        struct inode    *inode = req->wb_context->dentry->d_inode;
+        struct rpc_clnt *clnt = NFS_CLIENT(inode);
+
+        if (!NFS_WBACK_BUSY(req))
+                return 0;
+        return nfs_wait_event(clnt, req->wb_context->waitq, !NFS_WBACK_BUSY(req));
+}
+
+/**
+ * nfs_coalesce_requests - Split coalesced requests out from a list.
+ * @head: source list
+ * @dst: destination list
+ * @nmax: maximum number of requests to coalesce
+ *
+ * Moves a maximum of 'nmax' elements from one list to another.
+ * The elements are checked to ensure that they form a contiguous set
+ * of pages, and that the RPC credentials are the same.
+ */
+int
+nfs_coalesce_requests(struct list_head *head, struct list_head *dst,
+                      unsigned int nmax)
+{
+        struct nfs_page         *req = NULL;
+        unsigned int            npages = 0;
+
+        while (!list_empty(head)) {
+                struct nfs_page *prev = req;
+
+                req = nfs_list_entry(head->next);
+                if (prev) {
+                        if (req->wb_context->cred != prev->wb_context->cred)
+                                break;
+                        if (req->wb_context->lockowner != prev->wb_context->lockowner)
+                                break;
+                        if (req->wb_context->state != prev->wb_context->state)
+                                break;
+                        if (req->wb_index != (prev->wb_index + 1))
+                                break;
+
+                        if (req->wb_pgbase != 0)
+                                break;
+                }
+                nfs_list_remove_request(req);
+                nfs_list_add_request(req, dst);
+                npages++;
+                if (req->wb_pgbase + req->wb_bytes != PAGE_CACHE_SIZE)
+                        break;
+                if (npages >= nmax)
+                        break;
+        }
+        return npages;
+}
+
+/**
+ * nfs_scan_list - Scan a list for matching requests
+ * @head: One of the NFS inode request lists
+ * @dst: Destination list
+ * @idx_start: lower bound of page->index to scan
+ * @npages: idx_start + npages sets the upper bound to scan.
+ *
+ * Moves elements from one of the inode request lists.
+ * If the number of requests is set to 0, the entire address_space
+ * starting at index idx_start, is scanned.
+ * The requests are *not* checked to ensure that they form a contiguous set.
+ * You must be holding the inode's req_lock when calling this function
+ */
+int
+nfs_scan_list(struct list_head *head, struct list_head *dst,
+              unsigned long idx_start, unsigned int npages)
+{
+        struct list_head        *pos, *tmp;
+        struct nfs_page         *req;
+        unsigned long           idx_end;
+        int                     res;
+
+        res = 0;
+        if (npages == 0)
+                idx_end = ~0;
+        else
+                idx_end = idx_start + npages - 1;
+
+        list_for_each_safe(pos, tmp, head) {
+
+                req = nfs_list_entry(pos);
+
+                if (req->wb_index < idx_start)
+                        continue;
+                if (req->wb_index > idx_end)
+                        break;
+
+                if (!nfs_lock_request(req))
+                        continue;
+                nfs_list_remove_request(req);
+                nfs_list_add_request(req, dst);
+                res++;
+        }
+        return res;
+}
+
+int nfs_init_nfspagecache(void)
+{
+        nfs_page_cachep = kmem_cache_create("nfs_page",
+                                            sizeof(struct nfs_page),
+                                            0, SLAB_HWCACHE_ALIGN,
+                                            NULL, NULL);
+        if (nfs_page_cachep == NULL)
+                return -ENOMEM;
+
+        return 0;
+}
+
+void nfs_destroy_nfspagecache(void)
+{
+        if (kmem_cache_destroy(nfs_page_cachep))
+                printk(KERN_INFO "nfs_page: not all structures were freed\n");
+}
+