![Trond Myklebust](/assets/img/avatar_default.png)
Do the coalescing of read requests into block sized requests at start of I/O as we scan through the pages instead of going through a second pass. Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
607 lines
15 KiB
C
607 lines
15 KiB
C
/*
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* linux/fs/nfs/read.c
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*
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* Block I/O for NFS
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*
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* Partial copy of Linus' read cache modifications to fs/nfs/file.c
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* modified for async RPC by okir@monad.swb.de
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*/
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#include <linux/time.h>
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#include <linux/kernel.h>
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#include <linux/errno.h>
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#include <linux/fcntl.h>
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#include <linux/stat.h>
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#include <linux/mm.h>
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#include <linux/slab.h>
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#include <linux/pagemap.h>
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#include <linux/sunrpc/clnt.h>
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#include <linux/nfs_fs.h>
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#include <linux/nfs_page.h>
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#include <linux/smp_lock.h>
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#include <asm/system.h>
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#include "internal.h"
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#include "iostat.h"
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#define NFSDBG_FACILITY NFSDBG_PAGECACHE
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static int nfs_pagein_multi(struct inode *, struct list_head *, size_t, int);
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static int nfs_pagein_one(struct inode *, struct list_head *, size_t, int);
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static const struct rpc_call_ops nfs_read_partial_ops;
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static const struct rpc_call_ops nfs_read_full_ops;
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static struct kmem_cache *nfs_rdata_cachep;
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static mempool_t *nfs_rdata_mempool;
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#define MIN_POOL_READ (32)
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struct nfs_read_data *nfs_readdata_alloc(size_t len)
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{
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unsigned int pagecount = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
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struct nfs_read_data *p = mempool_alloc(nfs_rdata_mempool, GFP_NOFS);
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if (p) {
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memset(p, 0, sizeof(*p));
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INIT_LIST_HEAD(&p->pages);
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p->npages = pagecount;
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if (pagecount <= ARRAY_SIZE(p->page_array))
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p->pagevec = p->page_array;
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else {
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p->pagevec = kcalloc(pagecount, sizeof(struct page *), GFP_NOFS);
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if (!p->pagevec) {
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mempool_free(p, nfs_rdata_mempool);
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p = NULL;
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}
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}
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}
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return p;
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}
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static void nfs_readdata_rcu_free(struct rcu_head *head)
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{
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struct nfs_read_data *p = container_of(head, struct nfs_read_data, task.u.tk_rcu);
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if (p && (p->pagevec != &p->page_array[0]))
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kfree(p->pagevec);
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mempool_free(p, nfs_rdata_mempool);
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}
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static void nfs_readdata_free(struct nfs_read_data *rdata)
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{
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call_rcu_bh(&rdata->task.u.tk_rcu, nfs_readdata_rcu_free);
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}
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void nfs_readdata_release(void *data)
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{
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nfs_readdata_free(data);
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}
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static
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int nfs_return_empty_page(struct page *page)
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{
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memclear_highpage_flush(page, 0, PAGE_CACHE_SIZE);
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SetPageUptodate(page);
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unlock_page(page);
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return 0;
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}
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static void nfs_readpage_truncate_uninitialised_page(struct nfs_read_data *data)
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{
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unsigned int remainder = data->args.count - data->res.count;
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unsigned int base = data->args.pgbase + data->res.count;
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unsigned int pglen;
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struct page **pages;
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if (data->res.eof == 0 || remainder == 0)
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return;
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/*
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* Note: "remainder" can never be negative, since we check for
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* this in the XDR code.
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*/
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pages = &data->args.pages[base >> PAGE_CACHE_SHIFT];
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base &= ~PAGE_CACHE_MASK;
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pglen = PAGE_CACHE_SIZE - base;
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for (;;) {
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if (remainder <= pglen) {
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memclear_highpage_flush(*pages, base, remainder);
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break;
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}
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memclear_highpage_flush(*pages, base, pglen);
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pages++;
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remainder -= pglen;
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pglen = PAGE_CACHE_SIZE;
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base = 0;
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}
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}
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static int nfs_readpage_async(struct nfs_open_context *ctx, struct inode *inode,
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struct page *page)
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{
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LIST_HEAD(one_request);
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struct nfs_page *new;
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unsigned int len;
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len = nfs_page_length(page);
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if (len == 0)
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return nfs_return_empty_page(page);
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new = nfs_create_request(ctx, inode, page, 0, len);
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if (IS_ERR(new)) {
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unlock_page(page);
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return PTR_ERR(new);
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}
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if (len < PAGE_CACHE_SIZE)
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memclear_highpage_flush(page, len, PAGE_CACHE_SIZE - len);
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nfs_list_add_request(new, &one_request);
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if (NFS_SERVER(inode)->rsize < PAGE_CACHE_SIZE)
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nfs_pagein_multi(inode, &one_request, len, 0);
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else
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nfs_pagein_one(inode, &one_request, len, 0);
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return 0;
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}
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static void nfs_readpage_release(struct nfs_page *req)
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{
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unlock_page(req->wb_page);
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dprintk("NFS: read done (%s/%Ld %d@%Ld)\n",
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req->wb_context->dentry->d_inode->i_sb->s_id,
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(long long)NFS_FILEID(req->wb_context->dentry->d_inode),
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req->wb_bytes,
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(long long)req_offset(req));
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nfs_clear_request(req);
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nfs_release_request(req);
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}
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/*
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* Set up the NFS read request struct
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*/
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static void nfs_read_rpcsetup(struct nfs_page *req, struct nfs_read_data *data,
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const struct rpc_call_ops *call_ops,
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unsigned int count, unsigned int offset)
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{
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struct inode *inode;
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int flags;
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data->req = req;
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data->inode = inode = req->wb_context->dentry->d_inode;
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data->cred = req->wb_context->cred;
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data->args.fh = NFS_FH(inode);
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data->args.offset = req_offset(req) + offset;
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data->args.pgbase = req->wb_pgbase + offset;
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data->args.pages = data->pagevec;
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data->args.count = count;
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data->args.context = req->wb_context;
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data->res.fattr = &data->fattr;
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data->res.count = count;
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data->res.eof = 0;
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nfs_fattr_init(&data->fattr);
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/* Set up the initial task struct. */
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flags = RPC_TASK_ASYNC | (IS_SWAPFILE(inode)? NFS_RPC_SWAPFLAGS : 0);
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rpc_init_task(&data->task, NFS_CLIENT(inode), flags, call_ops, data);
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NFS_PROTO(inode)->read_setup(data);
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data->task.tk_cookie = (unsigned long)inode;
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dprintk("NFS: %5u initiated read call (req %s/%Ld, %u bytes @ offset %Lu)\n",
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data->task.tk_pid,
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inode->i_sb->s_id,
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(long long)NFS_FILEID(inode),
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count,
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(unsigned long long)data->args.offset);
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}
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static void
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nfs_async_read_error(struct list_head *head)
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{
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struct nfs_page *req;
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while (!list_empty(head)) {
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req = nfs_list_entry(head->next);
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nfs_list_remove_request(req);
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SetPageError(req->wb_page);
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nfs_readpage_release(req);
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}
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}
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/*
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* Start an async read operation
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*/
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static void nfs_execute_read(struct nfs_read_data *data)
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{
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struct rpc_clnt *clnt = NFS_CLIENT(data->inode);
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sigset_t oldset;
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rpc_clnt_sigmask(clnt, &oldset);
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rpc_execute(&data->task);
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rpc_clnt_sigunmask(clnt, &oldset);
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}
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/*
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* Generate multiple requests to fill a single page.
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*
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* We optimize to reduce the number of read operations on the wire. If we
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* detect that we're reading a page, or an area of a page, that is past the
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* end of file, we do not generate NFS read operations but just clear the
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* parts of the page that would have come back zero from the server anyway.
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*
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* We rely on the cached value of i_size to make this determination; another
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* client can fill pages on the server past our cached end-of-file, but we
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* won't see the new data until our attribute cache is updated. This is more
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* or less conventional NFS client behavior.
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*/
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static int nfs_pagein_multi(struct inode *inode, struct list_head *head, size_t count, int flags)
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{
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struct nfs_page *req = nfs_list_entry(head->next);
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struct page *page = req->wb_page;
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struct nfs_read_data *data;
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size_t rsize = NFS_SERVER(inode)->rsize, nbytes;
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unsigned int offset;
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int requests = 0;
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LIST_HEAD(list);
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nfs_list_remove_request(req);
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nbytes = count;
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do {
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size_t len = min(nbytes,rsize);
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data = nfs_readdata_alloc(len);
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if (!data)
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goto out_bad;
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INIT_LIST_HEAD(&data->pages);
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list_add(&data->pages, &list);
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requests++;
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nbytes -= len;
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} while(nbytes != 0);
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atomic_set(&req->wb_complete, requests);
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ClearPageError(page);
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offset = 0;
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nbytes = count;
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do {
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data = list_entry(list.next, struct nfs_read_data, pages);
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list_del_init(&data->pages);
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data->pagevec[0] = page;
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if (nbytes < rsize)
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rsize = nbytes;
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nfs_read_rpcsetup(req, data, &nfs_read_partial_ops,
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rsize, offset);
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offset += rsize;
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nbytes -= rsize;
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nfs_execute_read(data);
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} while (nbytes != 0);
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return 0;
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out_bad:
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while (!list_empty(&list)) {
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data = list_entry(list.next, struct nfs_read_data, pages);
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list_del(&data->pages);
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nfs_readdata_free(data);
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}
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SetPageError(page);
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nfs_readpage_release(req);
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return -ENOMEM;
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}
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static int nfs_pagein_one(struct inode *inode, struct list_head *head, size_t count, int flags)
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{
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struct nfs_page *req;
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struct page **pages;
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struct nfs_read_data *data;
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data = nfs_readdata_alloc(count);
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if (!data)
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goto out_bad;
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INIT_LIST_HEAD(&data->pages);
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pages = data->pagevec;
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while (!list_empty(head)) {
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req = nfs_list_entry(head->next);
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nfs_list_remove_request(req);
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nfs_list_add_request(req, &data->pages);
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ClearPageError(req->wb_page);
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*pages++ = req->wb_page;
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}
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req = nfs_list_entry(data->pages.next);
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nfs_read_rpcsetup(req, data, &nfs_read_full_ops, count, 0);
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nfs_execute_read(data);
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return 0;
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out_bad:
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nfs_async_read_error(head);
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return -ENOMEM;
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}
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/*
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* This is the callback from RPC telling us whether a reply was
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* received or some error occurred (timeout or socket shutdown).
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*/
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int nfs_readpage_result(struct rpc_task *task, struct nfs_read_data *data)
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{
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int status;
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dprintk("NFS: %s: %5u, (status %d)\n", __FUNCTION__, task->tk_pid,
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task->tk_status);
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status = NFS_PROTO(data->inode)->read_done(task, data);
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if (status != 0)
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return status;
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nfs_add_stats(data->inode, NFSIOS_SERVERREADBYTES, data->res.count);
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if (task->tk_status == -ESTALE) {
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set_bit(NFS_INO_STALE, &NFS_FLAGS(data->inode));
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nfs_mark_for_revalidate(data->inode);
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}
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spin_lock(&data->inode->i_lock);
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NFS_I(data->inode)->cache_validity |= NFS_INO_INVALID_ATIME;
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spin_unlock(&data->inode->i_lock);
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return 0;
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}
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static int nfs_readpage_retry(struct rpc_task *task, struct nfs_read_data *data)
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{
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struct nfs_readargs *argp = &data->args;
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struct nfs_readres *resp = &data->res;
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if (resp->eof || resp->count == argp->count)
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return 0;
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/* This is a short read! */
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nfs_inc_stats(data->inode, NFSIOS_SHORTREAD);
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/* Has the server at least made some progress? */
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if (resp->count == 0)
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return 0;
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/* Yes, so retry the read at the end of the data */
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argp->offset += resp->count;
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argp->pgbase += resp->count;
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argp->count -= resp->count;
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rpc_restart_call(task);
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return -EAGAIN;
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}
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/*
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* Handle a read reply that fills part of a page.
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*/
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static void nfs_readpage_result_partial(struct rpc_task *task, void *calldata)
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{
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struct nfs_read_data *data = calldata;
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struct nfs_page *req = data->req;
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struct page *page = req->wb_page;
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if (nfs_readpage_result(task, data) != 0)
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return;
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if (likely(task->tk_status >= 0)) {
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nfs_readpage_truncate_uninitialised_page(data);
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if (nfs_readpage_retry(task, data) != 0)
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return;
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}
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if (unlikely(task->tk_status < 0))
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SetPageError(page);
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if (atomic_dec_and_test(&req->wb_complete)) {
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if (!PageError(page))
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SetPageUptodate(page);
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nfs_readpage_release(req);
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}
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}
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static const struct rpc_call_ops nfs_read_partial_ops = {
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.rpc_call_done = nfs_readpage_result_partial,
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.rpc_release = nfs_readdata_release,
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};
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static void nfs_readpage_set_pages_uptodate(struct nfs_read_data *data)
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{
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unsigned int count = data->res.count;
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unsigned int base = data->args.pgbase;
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struct page **pages;
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if (data->res.eof)
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count = data->args.count;
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if (unlikely(count == 0))
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return;
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pages = &data->args.pages[base >> PAGE_CACHE_SHIFT];
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base &= ~PAGE_CACHE_MASK;
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count += base;
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for (;count >= PAGE_CACHE_SIZE; count -= PAGE_CACHE_SIZE, pages++)
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SetPageUptodate(*pages);
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if (count == 0)
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return;
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/* Was this a short read? */
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if (data->res.eof || data->res.count == data->args.count)
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SetPageUptodate(*pages);
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}
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/*
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* This is the callback from RPC telling us whether a reply was
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* received or some error occurred (timeout or socket shutdown).
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*/
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static void nfs_readpage_result_full(struct rpc_task *task, void *calldata)
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{
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struct nfs_read_data *data = calldata;
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if (nfs_readpage_result(task, data) != 0)
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return;
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/*
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* Note: nfs_readpage_retry may change the values of
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* data->args. In the multi-page case, we therefore need
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* to ensure that we call nfs_readpage_set_pages_uptodate()
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* first.
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*/
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if (likely(task->tk_status >= 0)) {
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nfs_readpage_truncate_uninitialised_page(data);
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nfs_readpage_set_pages_uptodate(data);
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if (nfs_readpage_retry(task, data) != 0)
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return;
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}
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while (!list_empty(&data->pages)) {
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struct nfs_page *req = nfs_list_entry(data->pages.next);
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nfs_list_remove_request(req);
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nfs_readpage_release(req);
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}
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}
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static const struct rpc_call_ops nfs_read_full_ops = {
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.rpc_call_done = nfs_readpage_result_full,
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.rpc_release = nfs_readdata_release,
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};
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/*
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* Read a page over NFS.
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* We read the page synchronously in the following case:
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* - The error flag is set for this page. This happens only when a
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* previous async read operation failed.
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*/
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int nfs_readpage(struct file *file, struct page *page)
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{
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struct nfs_open_context *ctx;
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struct inode *inode = page->mapping->host;
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int error;
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dprintk("NFS: nfs_readpage (%p %ld@%lu)\n",
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page, PAGE_CACHE_SIZE, page->index);
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nfs_inc_stats(inode, NFSIOS_VFSREADPAGE);
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nfs_add_stats(inode, NFSIOS_READPAGES, 1);
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/*
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* Try to flush any pending writes to the file..
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*
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* NOTE! Because we own the page lock, there cannot
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* be any new pending writes generated at this point
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* for this page (other pages can be written to).
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*/
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error = nfs_wb_page(inode, page);
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if (error)
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goto out_error;
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error = -ESTALE;
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if (NFS_STALE(inode))
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goto out_error;
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if (file == NULL) {
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error = -EBADF;
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ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
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if (ctx == NULL)
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goto out_error;
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} else
|
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ctx = get_nfs_open_context((struct nfs_open_context *)
|
|
file->private_data);
|
|
|
|
error = nfs_readpage_async(ctx, inode, page);
|
|
|
|
put_nfs_open_context(ctx);
|
|
return error;
|
|
|
|
out_error:
|
|
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 inode *inode = page->mapping->host;
|
|
struct nfs_page *new;
|
|
unsigned int len;
|
|
|
|
nfs_wb_page(inode, page);
|
|
len = nfs_page_length(page);
|
|
if (len == 0)
|
|
return nfs_return_empty_page(page);
|
|
new = nfs_create_request(desc->ctx, inode, page, 0, len);
|
|
if (IS_ERR(new)) {
|
|
SetPageError(page);
|
|
unlock_page(page);
|
|
return PTR_ERR(new);
|
|
}
|
|
if (len < PAGE_CACHE_SIZE)
|
|
memclear_highpage_flush(page, len, PAGE_CACHE_SIZE - len);
|
|
nfs_pageio_add_request(desc->pgio, new);
|
|
return 0;
|
|
}
|
|
|
|
int nfs_readpages(struct file *filp, struct address_space *mapping,
|
|
struct list_head *pages, unsigned nr_pages)
|
|
{
|
|
struct nfs_pageio_descriptor pgio;
|
|
struct nfs_readdesc desc = {
|
|
.pgio = &pgio,
|
|
};
|
|
struct inode *inode = mapping->host;
|
|
struct nfs_server *server = NFS_SERVER(inode);
|
|
size_t rsize = server->rsize;
|
|
unsigned long npages;
|
|
int ret = -ESTALE;
|
|
|
|
dprintk("NFS: nfs_readpages (%s/%Ld %d)\n",
|
|
inode->i_sb->s_id,
|
|
(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((struct nfs_open_context *)
|
|
filp->private_data);
|
|
if (rsize < PAGE_CACHE_SIZE)
|
|
nfs_pageio_init(&pgio, inode, nfs_pagein_multi, rsize, 0);
|
|
else
|
|
nfs_pageio_init(&pgio, inode, nfs_pagein_one, rsize, 0);
|
|
|
|
ret = read_cache_pages(mapping, pages, readpage_async_filler, &desc);
|
|
|
|
nfs_pageio_complete(&pgio);
|
|
npages = (pgio.pg_bytes_written + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
|
|
nfs_add_stats(inode, NFSIOS_READPAGES, npages);
|
|
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_read_data),
|
|
0, SLAB_HWCACHE_ALIGN,
|
|
NULL, NULL);
|
|
if (nfs_rdata_cachep == NULL)
|
|
return -ENOMEM;
|
|
|
|
nfs_rdata_mempool = mempool_create_slab_pool(MIN_POOL_READ,
|
|
nfs_rdata_cachep);
|
|
if (nfs_rdata_mempool == NULL)
|
|
return -ENOMEM;
|
|
|
|
return 0;
|
|
}
|
|
|
|
void nfs_destroy_readpagecache(void)
|
|
{
|
|
mempool_destroy(nfs_rdata_mempool);
|
|
kmem_cache_destroy(nfs_rdata_cachep);
|
|
}
|