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![Trond Myklebust](/assets/img/avatar_default.png)
When a nfs_page is freed, nfs_free_request is called which also calls nfs_clear_request to clean out the lock and open contexts and free the pagecache page. However, a couple of places in the nfs code call nfs_clear_request themselves. What happens here if the refcount on the request is still high? We'll be releasing contexts and freeing pointers while the request is possibly still in use. Remove those bare calls to nfs_clear_context. That should only be done when the request is being freed. Note that when doing this, we need to watch out for tests of req->wb_page. Previously, nfs_set_page_tag_locked() and nfs_clear_page_tag_locked() would check the value of req->wb_page to figure out if the page is mapped into the nfsi->nfs_page_tree. We now indicate the page is mapped using the new bit PG_MAPPED in req->wb_flags . Reported-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
666 lines
16 KiB
C
666 lines
16 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 <asm/system.h>
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#include "nfs4_fs.h"
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#include "internal.h"
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#include "iostat.h"
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#include "fscache.h"
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#include "pnfs.h"
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#define NFSDBG_FACILITY NFSDBG_PAGECACHE
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static int nfs_pagein_multi(struct inode *, struct list_head *, unsigned int, size_t, int);
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static int nfs_pagein_one(struct inode *, struct list_head *, unsigned int, 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(unsigned int pagecount)
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{
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struct nfs_read_data *p = mempool_alloc(nfs_rdata_mempool, GFP_KERNEL);
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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_KERNEL);
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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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void nfs_readdata_free(struct nfs_read_data *p)
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{
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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_release(struct nfs_read_data *rdata)
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{
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put_nfs_open_context(rdata->args.context);
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nfs_readdata_free(rdata);
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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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zero_user(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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zero_user(*pages, base, remainder);
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break;
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}
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zero_user(*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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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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pnfs_update_layout(inode, ctx, IOMODE_READ);
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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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zero_user_segment(page, len, PAGE_CACHE_SIZE);
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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, 1, len, 0);
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else
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nfs_pagein_one(inode, &one_request, 1, 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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struct inode *d_inode = req->wb_context->path.dentry->d_inode;
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if (PageUptodate(req->wb_page))
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nfs_readpage_to_fscache(d_inode, req->wb_page, 0);
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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->path.dentry->d_inode->i_sb->s_id,
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(long long)NFS_FILEID(req->wb_context->path.dentry->d_inode),
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req->wb_bytes,
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(long long)req_offset(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 int 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 = req->wb_context->path.dentry->d_inode;
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int swap_flags = IS_SWAPFILE(inode) ? NFS_RPC_SWAPFLAGS : 0;
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struct rpc_task *task;
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struct rpc_message msg = {
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.rpc_argp = &data->args,
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.rpc_resp = &data->res,
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.rpc_cred = req->wb_context->cred,
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};
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struct rpc_task_setup task_setup_data = {
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.task = &data->task,
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.rpc_client = NFS_CLIENT(inode),
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.rpc_message = &msg,
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.callback_ops = call_ops,
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.callback_data = data,
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.workqueue = nfsiod_workqueue,
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.flags = RPC_TASK_ASYNC | swap_flags,
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};
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data->req = req;
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data->inode = inode;
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data->cred = msg.rpc_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 = get_nfs_open_context(req->wb_context);
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data->args.lock_context = req->wb_lock_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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NFS_PROTO(inode)->read_setup(data, &msg);
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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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task = rpc_run_task(&task_setup_data);
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if (IS_ERR(task))
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return PTR_ERR(task);
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rpc_put_task(task);
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return 0;
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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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* 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, unsigned int npages, 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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int ret = 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(1);
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if (!data)
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goto out_bad;
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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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int ret2;
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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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ret2 = nfs_read_rpcsetup(req, data, &nfs_read_partial_ops,
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rsize, offset);
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if (ret == 0)
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ret = ret2;
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offset += rsize;
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nbytes -= rsize;
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} while (nbytes != 0);
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return ret;
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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, unsigned int npages, 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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int ret = -ENOMEM;
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data = nfs_readdata_alloc(npages);
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if (!data)
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goto out_bad;
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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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return nfs_read_rpcsetup(req, data, &nfs_read_full_ops, count, 0);
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out_bad:
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nfs_async_read_error(head);
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return ret;
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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", __func__, 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_I(data->inode)->flags);
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nfs_mark_for_revalidate(data->inode);
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}
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return 0;
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}
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static void 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;
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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;
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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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nfs_restart_rpc(task, NFS_SERVER(data->inode)->nfs_client);
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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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if (nfs_readpage_result(task, data) != 0)
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return;
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if (task->tk_status < 0)
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return;
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nfs_readpage_truncate_uninitialised_page(data);
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nfs_readpage_retry(task, data);
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}
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static void nfs_readpage_release_partial(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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int status = data->task.tk_status;
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if (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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nfs_readdata_release(calldata);
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}
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#if defined(CONFIG_NFS_V4_1)
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void nfs_read_prepare(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 (nfs4_setup_sequence(NFS_SERVER(data->inode),
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&data->args.seq_args, &data->res.seq_res,
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0, task))
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return;
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rpc_call_start(task);
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}
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#endif /* CONFIG_NFS_V4_1 */
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static const struct rpc_call_ops nfs_read_partial_ops = {
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#if defined(CONFIG_NFS_V4_1)
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.rpc_call_prepare = nfs_read_prepare,
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#endif /* CONFIG_NFS_V4_1 */
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.rpc_call_done = nfs_readpage_result_partial,
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.rpc_release = nfs_readpage_release_partial,
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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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if (task->tk_status < 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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nfs_readpage_truncate_uninitialised_page(data);
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nfs_readpage_set_pages_uptodate(data);
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nfs_readpage_retry(task, data);
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}
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static void nfs_readpage_release_full(void *calldata)
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{
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struct nfs_read_data *data = calldata;
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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);
|
|
}
|
|
nfs_readdata_release(calldata);
|
|
}
|
|
|
|
static const struct rpc_call_ops nfs_read_full_ops = {
|
|
#if defined(CONFIG_NFS_V4_1)
|
|
.rpc_call_prepare = nfs_read_prepare,
|
|
#endif /* CONFIG_NFS_V4_1 */
|
|
.rpc_call_done = nfs_readpage_result_full,
|
|
.rpc_release = nfs_readpage_release_full,
|
|
};
|
|
|
|
/*
|
|
* Read a page over NFS.
|
|
* We read the page synchronously in the following case:
|
|
* - The error flag is set for this page. This happens only when a
|
|
* previous async read operation failed.
|
|
*/
|
|
int nfs_readpage(struct file *file, struct page *page)
|
|
{
|
|
struct nfs_open_context *ctx;
|
|
struct inode *inode = page->mapping->host;
|
|
int error;
|
|
|
|
dprintk("NFS: nfs_readpage (%p %ld@%lu)\n",
|
|
page, PAGE_CACHE_SIZE, page->index);
|
|
nfs_inc_stats(inode, NFSIOS_VFSREADPAGE);
|
|
nfs_add_stats(inode, NFSIOS_READPAGES, 1);
|
|
|
|
/*
|
|
* Try to flush any pending writes to the file..
|
|
*
|
|
* NOTE! Because we own the page lock, there cannot
|
|
* be any new pending writes generated at this point
|
|
* for this page (other pages can be written to).
|
|
*/
|
|
error = nfs_wb_page(inode, page);
|
|
if (error)
|
|
goto out_unlock;
|
|
if (PageUptodate(page))
|
|
goto out_unlock;
|
|
|
|
error = -ESTALE;
|
|
if (NFS_STALE(inode))
|
|
goto out_unlock;
|
|
|
|
if (file == NULL) {
|
|
error = -EBADF;
|
|
ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
|
|
if (ctx == NULL)
|
|
goto out_unlock;
|
|
} else
|
|
ctx = get_nfs_open_context(nfs_file_open_context(file));
|
|
|
|
if (!IS_SYNC(inode)) {
|
|
error = nfs_readpage_from_fscache(ctx, inode, page);
|
|
if (error == 0)
|
|
goto out;
|
|
}
|
|
|
|
error = nfs_readpage_async(ctx, inode, page);
|
|
|
|
out:
|
|
put_nfs_open_context(ctx);
|
|
return error;
|
|
out_unlock:
|
|
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;
|
|
int error;
|
|
|
|
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))
|
|
goto out_error;
|
|
|
|
if (len < PAGE_CACHE_SIZE)
|
|
zero_user_segment(page, len, PAGE_CACHE_SIZE);
|
|
if (!nfs_pageio_add_request(desc->pgio, new)) {
|
|
error = desc->pgio->pg_error;
|
|
goto out_unlock;
|
|
}
|
|
return 0;
|
|
out_error:
|
|
error = PTR_ERR(new);
|
|
SetPageError(page);
|
|
out_unlock:
|
|
unlock_page(page);
|
|
return error;
|
|
}
|
|
|
|
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(nfs_file_open_context(filp));
|
|
|
|
/* attempt to read as many of the pages as possible from the cache
|
|
* - this returns -ENOBUFS immediately if the cookie is negative
|
|
*/
|
|
ret = nfs_readpages_from_fscache(desc.ctx, inode, mapping,
|
|
pages, &nr_pages);
|
|
if (ret == 0)
|
|
goto read_complete; /* all pages were read */
|
|
|
|
pnfs_update_layout(inode, desc.ctx, IOMODE_READ);
|
|
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);
|
|
read_complete:
|
|
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);
|
|
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);
|
|
}
|