![Trond Myklebust](/assets/img/avatar_default.png)
Ensure that we always get a layout before setting up the i/o request. Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
718 lines
18 KiB
C
718 lines
18 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/module.h>
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#include <asm/system.h>
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#include "pnfs.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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#define NFSDBG_FACILITY NFSDBG_PAGECACHE
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static int nfs_pagein_multi(struct nfs_pageio_descriptor *desc);
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static int nfs_pagein_one(struct nfs_pageio_descriptor *desc);
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static const struct nfs_pageio_ops nfs_pageio_read_ops;
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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_lseg(rdata->lseg);
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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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static void nfs_pageio_init_read_mds(struct nfs_pageio_descriptor *pgio,
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struct inode *inode)
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{
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nfs_pageio_init(pgio, inode, &nfs_pageio_read_ops,
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NFS_SERVER(inode)->rsize, 0);
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}
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static void nfs_pageio_init_read(struct nfs_pageio_descriptor *pgio,
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struct inode *inode)
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{
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if (!pnfs_pageio_init_read(pgio, inode))
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nfs_pageio_init_read_mds(pgio, inode);
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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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struct nfs_page *new;
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unsigned int len;
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struct nfs_pageio_descriptor pgio;
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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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zero_user_segment(page, len, PAGE_CACHE_SIZE);
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nfs_pageio_init_read(&pgio, inode);
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nfs_pageio_add_request(&pgio, new);
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nfs_pageio_complete(&pgio);
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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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int nfs_initiate_read(struct nfs_read_data *data, struct rpc_clnt *clnt,
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const struct rpc_call_ops *call_ops)
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{
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struct inode *inode = data->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 = data->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 = clnt,
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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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/* 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/%lld, %u bytes @ "
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"offset %llu)\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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data->args.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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EXPORT_SYMBOL_GPL(nfs_initiate_read);
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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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struct pnfs_layout_segment *lseg)
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{
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struct inode *inode = req->wb_context->path.dentry->d_inode;
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data->req = req;
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data->inode = inode;
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data->cred = req->wb_context->cred;
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data->lseg = get_lseg(lseg);
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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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if (data->lseg &&
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(pnfs_try_to_read_data(data, call_ops) == PNFS_ATTEMPTED))
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return 0;
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return nfs_initiate_read(data, NFS_CLIENT(inode), call_ops);
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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 nfs_pageio_descriptor *desc)
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{
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struct nfs_page *req = nfs_list_entry(desc->pg_list.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(desc->pg_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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struct pnfs_layout_segment *lseg = desc->pg_lseg;
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LIST_HEAD(list);
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nfs_list_remove_request(req);
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nbytes = desc->pg_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 = desc->pg_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, lseg);
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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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put_lseg(lseg);
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desc->pg_lseg = NULL;
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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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put_lseg(lseg);
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desc->pg_lseg = NULL;
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return -ENOMEM;
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}
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static int nfs_pagein_one(struct nfs_pageio_descriptor *desc)
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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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struct list_head *head = &desc->pg_list;
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struct pnfs_layout_segment *lseg = desc->pg_lseg;
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int ret = -ENOMEM;
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data = nfs_readdata_alloc(nfs_page_array_len(desc->pg_base,
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desc->pg_count));
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if (!data) {
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nfs_async_read_error(head);
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goto out;
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}
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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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ret = nfs_read_rpcsetup(req, data, &nfs_read_full_ops, desc->pg_count,
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0, lseg);
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out:
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put_lseg(lseg);
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desc->pg_lseg = NULL;
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return ret;
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}
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int nfs_generic_pg_readpages(struct nfs_pageio_descriptor *desc)
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{
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if (desc->pg_bsize < PAGE_CACHE_SIZE)
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return nfs_pagein_multi(desc);
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return nfs_pagein_one(desc);
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}
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EXPORT_SYMBOL_GPL(nfs_generic_pg_readpages);
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static const struct nfs_pageio_ops nfs_pageio_read_ops = {
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.pg_test = nfs_generic_pg_test,
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.pg_doio = nfs_generic_pg_readpages,
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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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data->mds_offset += resp->count;
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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;
|
|
count += base;
|
|
for (;count >= PAGE_CACHE_SIZE; count -= PAGE_CACHE_SIZE, pages++)
|
|
SetPageUptodate(*pages);
|
|
if (count == 0)
|
|
return;
|
|
/* Was this a short read? */
|
|
if (data->res.eof || data->res.count == data->args.count)
|
|
SetPageUptodate(*pages);
|
|
}
|
|
|
|
/*
|
|
* This is the callback from RPC telling us whether a reply was
|
|
* received or some error occurred (timeout or socket shutdown).
|
|
*/
|
|
static void nfs_readpage_result_full(struct rpc_task *task, void *calldata)
|
|
{
|
|
struct nfs_read_data *data = calldata;
|
|
|
|
if (nfs_readpage_result(task, data) != 0)
|
|
return;
|
|
if (task->tk_status < 0)
|
|
return;
|
|
/*
|
|
* Note: nfs_readpage_retry may change the values of
|
|
* data->args. In the multi-page case, we therefore need
|
|
* to ensure that we call nfs_readpage_set_pages_uptodate()
|
|
* first.
|
|
*/
|
|
nfs_readpage_truncate_uninitialised_page(data);
|
|
nfs_readpage_set_pages_uptodate(data);
|
|
nfs_readpage_retry(task, data);
|
|
}
|
|
|
|
static void nfs_readpage_release_full(void *calldata)
|
|
{
|
|
struct nfs_read_data *data = calldata;
|
|
|
|
while (!list_empty(&data->pages)) {
|
|
struct nfs_page *req = nfs_list_entry(data->pages.next);
|
|
|
|
nfs_list_remove_request(req);
|
|
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;
|
|
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 */
|
|
|
|
nfs_pageio_init_read(&pgio, inode);
|
|
|
|
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);
|
|
}
|