![Bryan Schumaker](/assets/img/avatar_default.png)
pNFS needs to select a read function based on the layout driver currently in use, so I let each NFS version decide how to best handle initializing reads. Signed-off-by: Bryan Schumaker <bjschuma@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
675 lines
17 KiB
C
675 lines
17 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 "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 const struct nfs_pageio_ops nfs_pageio_read_ops;
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static const struct rpc_call_ops nfs_read_common_ops;
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static const struct nfs_pgio_completion_ops nfs_async_read_completion_ops;
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static struct kmem_cache *nfs_rdata_cachep;
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struct nfs_read_header *nfs_readhdr_alloc(void)
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{
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struct nfs_read_header *rhdr;
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rhdr = kmem_cache_zalloc(nfs_rdata_cachep, GFP_KERNEL);
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if (rhdr) {
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struct nfs_pgio_header *hdr = &rhdr->header;
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INIT_LIST_HEAD(&hdr->pages);
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INIT_LIST_HEAD(&hdr->rpc_list);
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spin_lock_init(&hdr->lock);
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atomic_set(&hdr->refcnt, 0);
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}
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return rhdr;
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}
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static struct nfs_read_data *nfs_readdata_alloc(struct nfs_pgio_header *hdr,
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unsigned int pagecount)
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{
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struct nfs_read_data *data, *prealloc;
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prealloc = &container_of(hdr, struct nfs_read_header, header)->rpc_data;
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if (prealloc->header == NULL)
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data = prealloc;
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else
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data = kzalloc(sizeof(*data), GFP_KERNEL);
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if (!data)
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goto out;
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if (nfs_pgarray_set(&data->pages, pagecount)) {
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data->header = hdr;
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atomic_inc(&hdr->refcnt);
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} else {
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if (data != prealloc)
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kfree(data);
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data = NULL;
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}
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out:
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return data;
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}
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void nfs_readhdr_free(struct nfs_pgio_header *hdr)
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{
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struct nfs_read_header *rhdr = container_of(hdr, struct nfs_read_header, header);
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kmem_cache_free(nfs_rdata_cachep, rhdr);
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}
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void nfs_readdata_release(struct nfs_read_data *rdata)
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{
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struct nfs_pgio_header *hdr = rdata->header;
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struct nfs_read_header *read_header = container_of(hdr, struct nfs_read_header, header);
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put_nfs_open_context(rdata->args.context);
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if (rdata->pages.pagevec != rdata->pages.page_array)
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kfree(rdata->pages.pagevec);
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if (rdata != &read_header->rpc_data)
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kfree(rdata);
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else
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rdata->header = NULL;
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if (atomic_dec_and_test(&hdr->refcnt))
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hdr->completion_ops->completion(hdr);
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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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void nfs_pageio_init_read(struct nfs_pageio_descriptor *pgio,
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struct inode *inode,
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const struct nfs_pgio_completion_ops *compl_ops)
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{
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nfs_pageio_init(pgio, inode, &nfs_pageio_read_ops, compl_ops,
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NFS_SERVER(inode)->rsize, 0);
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}
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void nfs_pageio_reset_read_mds(struct nfs_pageio_descriptor *pgio)
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{
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pgio->pg_ops = &nfs_pageio_read_ops;
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pgio->pg_bsize = NFS_SERVER(pgio->pg_inode)->rsize;
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}
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EXPORT_SYMBOL_GPL(nfs_pageio_reset_read_mds);
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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_PROTO(inode)->read_pageio_init(&pgio, inode, &nfs_async_read_completion_ops);
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nfs_pageio_add_request(&pgio, new);
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nfs_pageio_complete(&pgio);
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NFS_I(inode)->read_io += pgio.pg_bytes_written;
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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->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->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_release_request(req);
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}
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/* Note io was page aligned */
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static void nfs_read_completion(struct nfs_pgio_header *hdr)
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{
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unsigned long bytes = 0;
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if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
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goto out;
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while (!list_empty(&hdr->pages)) {
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struct nfs_page *req = nfs_list_entry(hdr->pages.next);
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struct page *page = req->wb_page;
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if (test_bit(NFS_IOHDR_EOF, &hdr->flags)) {
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if (bytes > hdr->good_bytes)
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zero_user(page, 0, PAGE_SIZE);
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else if (hdr->good_bytes - bytes < PAGE_SIZE)
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zero_user_segment(page,
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hdr->good_bytes & ~PAGE_MASK,
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PAGE_SIZE);
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}
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bytes += req->wb_bytes;
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if (test_bit(NFS_IOHDR_ERROR, &hdr->flags)) {
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if (bytes <= hdr->good_bytes)
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SetPageUptodate(page);
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} else
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SetPageUptodate(page);
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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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out:
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hdr->release(hdr);
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}
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int nfs_initiate_read(struct rpc_clnt *clnt,
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struct nfs_read_data *data,
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const struct rpc_call_ops *call_ops, int flags)
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{
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struct inode *inode = data->header->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->header->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 | 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 void nfs_read_rpcsetup(struct nfs_read_data *data,
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unsigned int count, unsigned int offset)
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{
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struct nfs_page *req = data->header->req;
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data->args.fh = NFS_FH(data->header->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->pages.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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}
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static int nfs_do_read(struct nfs_read_data *data,
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const struct rpc_call_ops *call_ops)
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{
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struct inode *inode = data->header->inode;
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return nfs_initiate_read(NFS_CLIENT(inode), data, call_ops, 0);
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}
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static int
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nfs_do_multiple_reads(struct list_head *head,
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const struct rpc_call_ops *call_ops)
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{
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struct nfs_read_data *data;
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int ret = 0;
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while (!list_empty(head)) {
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int ret2;
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data = list_first_entry(head, struct nfs_read_data, list);
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list_del_init(&data->list);
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ret2 = nfs_do_read(data, call_ops);
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if (ret == 0)
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ret = ret2;
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}
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return ret;
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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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nfs_readpage_release(req);
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}
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}
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static const struct nfs_pgio_completion_ops nfs_async_read_completion_ops = {
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.error_cleanup = nfs_async_read_error,
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.completion = nfs_read_completion,
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};
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static void nfs_pagein_error(struct nfs_pageio_descriptor *desc,
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struct nfs_pgio_header *hdr)
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{
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set_bit(NFS_IOHDR_REDO, &hdr->flags);
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while (!list_empty(&hdr->rpc_list)) {
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struct nfs_read_data *data = list_first_entry(&hdr->rpc_list,
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struct nfs_read_data, list);
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list_del(&data->list);
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nfs_readdata_release(data);
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}
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desc->pg_completion_ops->error_cleanup(&desc->pg_list);
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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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struct nfs_pgio_header *hdr)
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{
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struct nfs_page *req = hdr->req;
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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 = desc->pg_bsize, nbytes;
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unsigned int offset;
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offset = 0;
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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(hdr, 1);
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if (!data) {
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nfs_pagein_error(desc, hdr);
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return -ENOMEM;
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}
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data->pages.pagevec[0] = page;
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nfs_read_rpcsetup(data, len, offset);
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list_add(&data->list, &hdr->rpc_list);
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nbytes -= len;
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offset += len;
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} while (nbytes != 0);
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nfs_list_remove_request(req);
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nfs_list_add_request(req, &hdr->pages);
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desc->pg_rpc_callops = &nfs_read_common_ops;
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return 0;
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}
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static int nfs_pagein_one(struct nfs_pageio_descriptor *desc,
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struct nfs_pgio_header *hdr)
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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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data = nfs_readdata_alloc(hdr, 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_pagein_error(desc, hdr);
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return -ENOMEM;
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}
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pages = data->pages.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, &hdr->pages);
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*pages++ = req->wb_page;
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}
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nfs_read_rpcsetup(data, desc->pg_count, 0);
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list_add(&data->list, &hdr->rpc_list);
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desc->pg_rpc_callops = &nfs_read_common_ops;
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return 0;
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}
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int nfs_generic_pagein(struct nfs_pageio_descriptor *desc,
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struct nfs_pgio_header *hdr)
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{
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if (desc->pg_bsize < PAGE_CACHE_SIZE)
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return nfs_pagein_multi(desc, hdr);
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return nfs_pagein_one(desc, hdr);
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}
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static int nfs_generic_pg_readpages(struct nfs_pageio_descriptor *desc)
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{
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struct nfs_read_header *rhdr;
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struct nfs_pgio_header *hdr;
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int ret;
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rhdr = nfs_readhdr_alloc();
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if (!rhdr) {
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desc->pg_completion_ops->error_cleanup(&desc->pg_list);
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return -ENOMEM;
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}
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hdr = &rhdr->header;
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nfs_pgheader_init(desc, hdr, nfs_readhdr_free);
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atomic_inc(&hdr->refcnt);
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ret = nfs_generic_pagein(desc, hdr);
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if (ret == 0)
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ret = nfs_do_multiple_reads(&hdr->rpc_list,
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desc->pg_rpc_callops);
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if (atomic_dec_and_test(&hdr->refcnt))
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hdr->completion_ops->completion(hdr);
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return ret;
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}
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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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struct inode *inode = data->header->inode;
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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(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(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(inode)->flags);
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nfs_mark_for_revalidate(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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/* This is a short read! */
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nfs_inc_stats(data->header->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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nfs_set_pgio_error(data->header, -EIO, argp->offset);
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return;
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}
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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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rpc_restart_call_prepare(task);
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}
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static void nfs_readpage_result_common(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_pgio_header *hdr = data->header;
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/* Note the only returns of nfs_readpage_result are 0 and -EAGAIN */
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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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nfs_set_pgio_error(hdr, task->tk_status, data->args.offset);
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else if (data->res.eof) {
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loff_t bound;
|
|
|
|
bound = data->args.offset + data->res.count;
|
|
spin_lock(&hdr->lock);
|
|
if (bound < hdr->io_start + hdr->good_bytes) {
|
|
set_bit(NFS_IOHDR_EOF, &hdr->flags);
|
|
clear_bit(NFS_IOHDR_ERROR, &hdr->flags);
|
|
hdr->good_bytes = bound - hdr->io_start;
|
|
}
|
|
spin_unlock(&hdr->lock);
|
|
} else if (data->res.count != data->args.count)
|
|
nfs_readpage_retry(task, data);
|
|
}
|
|
|
|
static void nfs_readpage_release_common(void *calldata)
|
|
{
|
|
nfs_readdata_release(calldata);
|
|
}
|
|
|
|
void nfs_read_prepare(struct rpc_task *task, void *calldata)
|
|
{
|
|
struct nfs_read_data *data = calldata;
|
|
NFS_PROTO(data->header->inode)->read_rpc_prepare(task, data);
|
|
}
|
|
|
|
static const struct rpc_call_ops nfs_read_common_ops = {
|
|
.rpc_call_prepare = nfs_read_prepare,
|
|
.rpc_call_done = nfs_readpage_result_common,
|
|
.rpc_release = nfs_readpage_release_common,
|
|
};
|
|
|
|
/*
|
|
* 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);
|
|
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_PROTO(inode)->read_pageio_init(&pgio, inode, &nfs_async_read_completion_ops);
|
|
|
|
ret = read_cache_pages(mapping, pages, readpage_async_filler, &desc);
|
|
|
|
nfs_pageio_complete(&pgio);
|
|
NFS_I(inode)->read_io += pgio.pg_bytes_written;
|
|
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_header),
|
|
0, SLAB_HWCACHE_ALIGN,
|
|
NULL);
|
|
if (nfs_rdata_cachep == NULL)
|
|
return -ENOMEM;
|
|
|
|
return 0;
|
|
}
|
|
|
|
void nfs_destroy_readpagecache(void)
|
|
{
|
|
kmem_cache_destroy(nfs_rdata_cachep);
|
|
}
|