/* * linux/fs/nfs/read.c * * Block I/O for NFS * * Partial copy of Linus' read cache modifications to fs/nfs/file.c * modified for async RPC by okir@monad.swb.de */ #include <linux/time.h> #include <linux/kernel.h> #include <linux/errno.h> #include <linux/fcntl.h> #include <linux/stat.h> #include <linux/mm.h> #include <linux/slab.h> #include <linux/pagemap.h> #include <linux/sunrpc/clnt.h> #include <linux/nfs_fs.h> #include <linux/nfs_page.h> #include <linux/smp_lock.h> #include <asm/system.h> #include "internal.h" #include "iostat.h" #define NFSDBG_FACILITY NFSDBG_PAGECACHE static int nfs_pagein_multi(struct inode *, struct list_head *, unsigned int, size_t, int); static int nfs_pagein_one(struct inode *, struct list_head *, unsigned int, size_t, int); static const struct rpc_call_ops nfs_read_partial_ops; static const struct rpc_call_ops nfs_read_full_ops; static struct kmem_cache *nfs_rdata_cachep; static mempool_t *nfs_rdata_mempool; #define MIN_POOL_READ (32) struct nfs_read_data *nfs_readdata_alloc(unsigned int pagecount) { struct nfs_read_data *p = mempool_alloc(nfs_rdata_mempool, GFP_NOFS); if (p) { memset(p, 0, sizeof(*p)); INIT_LIST_HEAD(&p->pages); p->npages = pagecount; if (pagecount <= ARRAY_SIZE(p->page_array)) p->pagevec = p->page_array; else { p->pagevec = kcalloc(pagecount, sizeof(struct page *), GFP_NOFS); if (!p->pagevec) { mempool_free(p, nfs_rdata_mempool); p = NULL; } } } return p; } static void nfs_readdata_rcu_free(struct rcu_head *head) { struct nfs_read_data *p = container_of(head, struct nfs_read_data, task.u.tk_rcu); if (p && (p->pagevec != &p->page_array[0])) kfree(p->pagevec); mempool_free(p, nfs_rdata_mempool); } static void nfs_readdata_free(struct nfs_read_data *rdata) { call_rcu_bh(&rdata->task.u.tk_rcu, nfs_readdata_rcu_free); } void nfs_readdata_release(void *data) { nfs_readdata_free(data); } static int nfs_return_empty_page(struct page *page) { zero_user_page(page, 0, PAGE_CACHE_SIZE, KM_USER0); SetPageUptodate(page); unlock_page(page); return 0; } static void nfs_readpage_truncate_uninitialised_page(struct nfs_read_data *data) { unsigned int remainder = data->args.count - data->res.count; unsigned int base = data->args.pgbase + data->res.count; unsigned int pglen; struct page **pages; if (data->res.eof == 0 || remainder == 0) return; /* * Note: "remainder" can never be negative, since we check for * this in the XDR code. */ pages = &data->args.pages[base >> PAGE_CACHE_SHIFT]; base &= ~PAGE_CACHE_MASK; pglen = PAGE_CACHE_SIZE - base; for (;;) { if (remainder <= pglen) { zero_user_page(*pages, base, remainder, KM_USER0); break; } zero_user_page(*pages, base, pglen, KM_USER0); pages++; remainder -= pglen; pglen = PAGE_CACHE_SIZE; base = 0; } } static int nfs_readpage_async(struct nfs_open_context *ctx, struct inode *inode, struct page *page) { LIST_HEAD(one_request); struct nfs_page *new; unsigned int len; len = nfs_page_length(page); if (len == 0) return nfs_return_empty_page(page); new = nfs_create_request(ctx, inode, page, 0, len); if (IS_ERR(new)) { unlock_page(page); return PTR_ERR(new); } if (len < PAGE_CACHE_SIZE) zero_user_page(page, len, PAGE_CACHE_SIZE - len, KM_USER0); nfs_list_add_request(new, &one_request); if (NFS_SERVER(inode)->rsize < PAGE_CACHE_SIZE) nfs_pagein_multi(inode, &one_request, 1, len, 0); else nfs_pagein_one(inode, &one_request, 1, len, 0); return 0; } static void nfs_readpage_release(struct nfs_page *req) { unlock_page(req->wb_page); dprintk("NFS: read done (%s/%Ld %d@%Ld)\n", req->wb_context->path.dentry->d_inode->i_sb->s_id, (long long)NFS_FILEID(req->wb_context->path.dentry->d_inode), req->wb_bytes, (long long)req_offset(req)); nfs_clear_request(req); nfs_release_request(req); } /* * Set up the NFS read request struct */ static void nfs_read_rpcsetup(struct nfs_page *req, struct nfs_read_data *data, const struct rpc_call_ops *call_ops, unsigned int count, unsigned int offset) { struct inode *inode = req->wb_context->path.dentry->d_inode; int swap_flags = IS_SWAPFILE(inode) ? NFS_RPC_SWAPFLAGS : 0; struct rpc_task *task; struct rpc_message msg = { .rpc_argp = &data->args, .rpc_resp = &data->res, .rpc_cred = req->wb_context->cred, }; struct rpc_task_setup task_setup_data = { .task = &data->task, .rpc_client = NFS_CLIENT(inode), .rpc_message = &msg, .callback_ops = call_ops, .callback_data = data, .flags = RPC_TASK_ASYNC | swap_flags, }; data->req = req; data->inode = inode; data->cred = msg.rpc_cred; data->args.fh = NFS_FH(inode); data->args.offset = req_offset(req) + offset; data->args.pgbase = req->wb_pgbase + offset; data->args.pages = data->pagevec; data->args.count = count; data->args.context = req->wb_context; data->res.fattr = &data->fattr; data->res.count = count; data->res.eof = 0; nfs_fattr_init(&data->fattr); /* Set up the initial task struct. */ NFS_PROTO(inode)->read_setup(data, &msg); dprintk("NFS: %5u initiated read call (req %s/%Ld, %u bytes @ offset %Lu)\n", data->task.tk_pid, inode->i_sb->s_id, (long long)NFS_FILEID(inode), count, (unsigned long long)data->args.offset); task = rpc_run_task(&task_setup_data); if (!IS_ERR(task)) rpc_put_task(task); } static void nfs_async_read_error(struct list_head *head) { struct nfs_page *req; while (!list_empty(head)) { req = nfs_list_entry(head->next); nfs_list_remove_request(req); SetPageError(req->wb_page); nfs_readpage_release(req); } } /* * Generate multiple requests to fill a single page. * * We optimize to reduce the number of read operations on the wire. If we * detect that we're reading a page, or an area of a page, that is past the * end of file, we do not generate NFS read operations but just clear the * parts of the page that would have come back zero from the server anyway. * * We rely on the cached value of i_size to make this determination; another * client can fill pages on the server past our cached end-of-file, but we * won't see the new data until our attribute cache is updated. This is more * or less conventional NFS client behavior. */ static int nfs_pagein_multi(struct inode *inode, struct list_head *head, unsigned int npages, size_t count, int flags) { struct nfs_page *req = nfs_list_entry(head->next); struct page *page = req->wb_page; struct nfs_read_data *data; size_t rsize = NFS_SERVER(inode)->rsize, nbytes; unsigned int offset; int requests = 0; LIST_HEAD(list); nfs_list_remove_request(req); nbytes = count; do { size_t len = min(nbytes,rsize); data = nfs_readdata_alloc(1); if (!data) goto out_bad; INIT_LIST_HEAD(&data->pages); list_add(&data->pages, &list); requests++; nbytes -= len; } while(nbytes != 0); atomic_set(&req->wb_complete, requests); ClearPageError(page); offset = 0; nbytes = count; do { data = list_entry(list.next, struct nfs_read_data, pages); list_del_init(&data->pages); data->pagevec[0] = page; if (nbytes < rsize) rsize = nbytes; nfs_read_rpcsetup(req, data, &nfs_read_partial_ops, rsize, offset); offset += rsize; nbytes -= rsize; } while (nbytes != 0); return 0; out_bad: while (!list_empty(&list)) { data = list_entry(list.next, struct nfs_read_data, pages); list_del(&data->pages); nfs_readdata_free(data); } SetPageError(page); nfs_readpage_release(req); return -ENOMEM; } static int nfs_pagein_one(struct inode *inode, struct list_head *head, unsigned int npages, size_t count, int flags) { struct nfs_page *req; struct page **pages; struct nfs_read_data *data; data = nfs_readdata_alloc(npages); if (!data) goto out_bad; INIT_LIST_HEAD(&data->pages); pages = data->pagevec; while (!list_empty(head)) { req = nfs_list_entry(head->next); nfs_list_remove_request(req); nfs_list_add_request(req, &data->pages); ClearPageError(req->wb_page); *pages++ = req->wb_page; } req = nfs_list_entry(data->pages.next); nfs_read_rpcsetup(req, data, &nfs_read_full_ops, count, 0); return 0; out_bad: nfs_async_read_error(head); return -ENOMEM; } /* * This is the callback from RPC telling us whether a reply was * received or some error occurred (timeout or socket shutdown). */ int nfs_readpage_result(struct rpc_task *task, struct nfs_read_data *data) { int status; dprintk("NFS: %s: %5u, (status %d)\n", __FUNCTION__, task->tk_pid, task->tk_status); status = NFS_PROTO(data->inode)->read_done(task, data); if (status != 0) return status; nfs_add_stats(data->inode, NFSIOS_SERVERREADBYTES, data->res.count); if (task->tk_status == -ESTALE) { set_bit(NFS_INO_STALE, &NFS_FLAGS(data->inode)); nfs_mark_for_revalidate(data->inode); } return 0; } static int nfs_readpage_retry(struct rpc_task *task, struct nfs_read_data *data) { struct nfs_readargs *argp = &data->args; struct nfs_readres *resp = &data->res; if (resp->eof || resp->count == argp->count) return 0; /* This is a short read! */ nfs_inc_stats(data->inode, NFSIOS_SHORTREAD); /* Has the server at least made some progress? */ if (resp->count == 0) return 0; /* Yes, so retry the read at the end of the data */ argp->offset += resp->count; argp->pgbase += resp->count; argp->count -= resp->count; rpc_restart_call(task); return -EAGAIN; } /* * Handle a read reply that fills part of a page. */ static void nfs_readpage_result_partial(struct rpc_task *task, void *calldata) { struct nfs_read_data *data = calldata; struct nfs_page *req = data->req; struct page *page = req->wb_page; if (nfs_readpage_result(task, data) != 0) return; if (likely(task->tk_status >= 0)) { nfs_readpage_truncate_uninitialised_page(data); if (nfs_readpage_retry(task, data) != 0) return; } if (unlikely(task->tk_status < 0)) SetPageError(page); if (atomic_dec_and_test(&req->wb_complete)) { if (!PageError(page)) SetPageUptodate(page); nfs_readpage_release(req); } } static const struct rpc_call_ops nfs_read_partial_ops = { .rpc_call_done = nfs_readpage_result_partial, .rpc_release = nfs_readdata_release, }; static void nfs_readpage_set_pages_uptodate(struct nfs_read_data *data) { unsigned int count = data->res.count; unsigned int base = data->args.pgbase; struct page **pages; if (data->res.eof) count = data->args.count; if (unlikely(count == 0)) return; pages = &data->args.pages[base >> PAGE_CACHE_SHIFT]; 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; /* * 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. */ if (likely(task->tk_status >= 0)) { nfs_readpage_truncate_uninitialised_page(data); nfs_readpage_set_pages_uptodate(data); if (nfs_readpage_retry(task, data) != 0) return; } while (!list_empty(&data->pages)) { struct nfs_page *req = nfs_list_entry(data->pages.next); nfs_list_remove_request(req); nfs_readpage_release(req); } } static const struct rpc_call_ops nfs_read_full_ops = { .rpc_call_done = nfs_readpage_result_full, .rpc_release = nfs_readdata_release, }; /* * 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)); error = nfs_readpage_async(ctx, inode, page); 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; error = nfs_wb_page(inode, page); if (error) goto out_unlock; if (PageUptodate(page)) goto out_unlock; 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_page(page, len, PAGE_CACHE_SIZE - len, KM_USER0); nfs_pageio_add_request(desc->pgio, new); 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)); if (rsize < PAGE_CACHE_SIZE) nfs_pageio_init(&pgio, inode, nfs_pagein_multi, rsize, 0); else nfs_pageio_init(&pgio, inode, nfs_pagein_one, rsize, 0); ret = read_cache_pages(mapping, pages, readpage_async_filler, &desc); nfs_pageio_complete(&pgio); npages = (pgio.pg_bytes_written + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; nfs_add_stats(inode, NFSIOS_READPAGES, npages); put_nfs_open_context(desc.ctx); out: return ret; } int __init nfs_init_readpagecache(void) { nfs_rdata_cachep = kmem_cache_create("nfs_read_data", sizeof(struct nfs_read_data), 0, SLAB_HWCACHE_ALIGN, NULL); 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); }