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