From 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sat, 16 Apr 2005 15:20:36 -0700 Subject: Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip! --- fs/nfs/pagelist.c | 309 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 309 insertions(+) create mode 100644 fs/nfs/pagelist.c (limited to 'fs/nfs/pagelist.c') 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 + * + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#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"); +} + -- cgit v1.2.3