/* * 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/module.h> #include "nfs4_fs.h" #include "internal.h" #include "iostat.h" #include "fscache.h" #include "pnfs.h" #define NFSDBG_FACILITY NFSDBG_PAGECACHE static const struct nfs_pgio_completion_ops nfs_async_read_completion_ops; static const struct nfs_rw_ops nfs_rw_read_ops; static struct kmem_cache *nfs_rdata_cachep; static struct nfs_pgio_header *nfs_readhdr_alloc(void) { return kmem_cache_zalloc(nfs_rdata_cachep, GFP_KERNEL); } static void nfs_readhdr_free(struct nfs_pgio_header *rhdr) { kmem_cache_free(nfs_rdata_cachep, rhdr); } static int nfs_return_empty_page(struct page *page) { zero_user(page, 0, PAGE_CACHE_SIZE); SetPageUptodate(page); unlock_page(page); return 0; } void nfs_pageio_init_read(struct nfs_pageio_descriptor *pgio, struct inode *inode, bool force_mds, const struct nfs_pgio_completion_ops *compl_ops) { struct nfs_server *server = NFS_SERVER(inode); const struct nfs_pageio_ops *pg_ops = &nfs_pgio_rw_ops; #ifdef CONFIG_NFS_V4_1 if (server->pnfs_curr_ld && !force_mds) pg_ops = server->pnfs_curr_ld->pg_read_ops; #endif nfs_pageio_init(pgio, inode, pg_ops, compl_ops, &nfs_rw_read_ops, server->rsize, 0); } EXPORT_SYMBOL_GPL(nfs_pageio_init_read); void nfs_pageio_reset_read_mds(struct nfs_pageio_descriptor *pgio) { pgio->pg_ops = &nfs_pgio_rw_ops; pgio->pg_bsize = NFS_SERVER(pgio->pg_inode)->rsize; } EXPORT_SYMBOL_GPL(nfs_pageio_reset_read_mds); int nfs_readpage_async(struct nfs_open_context *ctx, struct inode *inode, struct page *page) { struct nfs_page *new; unsigned int len; struct nfs_pageio_descriptor pgio; len = nfs_page_length(page); if (len == 0) return nfs_return_empty_page(page); new = nfs_create_request(ctx, page, NULL, 0, len); if (IS_ERR(new)) { unlock_page(page); return PTR_ERR(new); } if (len < PAGE_CACHE_SIZE) zero_user_segment(page, len, PAGE_CACHE_SIZE); nfs_pageio_init_read(&pgio, inode, false, &nfs_async_read_completion_ops); nfs_pageio_add_request(&pgio, new); nfs_pageio_complete(&pgio); NFS_I(inode)->read_io += pgio.pg_bytes_written; return 0; } static void nfs_readpage_release(struct nfs_page *req) { struct inode *d_inode = req->wb_context->dentry->d_inode; dprintk("NFS: read done (%s/%llu %d@%lld)\n", d_inode->i_sb->s_id, (unsigned long long)NFS_FILEID(d_inode), req->wb_bytes, (long long)req_offset(req)); if (nfs_page_group_sync_on_bit(req, PG_UNLOCKPAGE)) { if (PageUptodate(req->wb_page)) nfs_readpage_to_fscache(d_inode, req->wb_page, 0); unlock_page(req->wb_page); } nfs_release_request(req); } static void nfs_page_group_set_uptodate(struct nfs_page *req) { if (nfs_page_group_sync_on_bit(req, PG_UPTODATE)) SetPageUptodate(req->wb_page); } static void nfs_read_completion(struct nfs_pgio_header *hdr) { unsigned long bytes = 0; if (test_bit(NFS_IOHDR_REDO, &hdr->flags)) goto out; while (!list_empty(&hdr->pages)) { struct nfs_page *req = nfs_list_entry(hdr->pages.next); struct page *page = req->wb_page; unsigned long start = req->wb_pgbase; unsigned long end = req->wb_pgbase + req->wb_bytes; if (test_bit(NFS_IOHDR_EOF, &hdr->flags)) { /* note: regions of the page not covered by a * request are zeroed in nfs_readpage_async / * readpage_async_filler */ if (bytes > hdr->good_bytes) { /* nothing in this request was good, so zero * the full extent of the request */ zero_user_segment(page, start, end); } else if (hdr->good_bytes - bytes < req->wb_bytes) { /* part of this request has good bytes, but * not all. zero the bad bytes */ start += hdr->good_bytes - bytes; WARN_ON(start < req->wb_pgbase); zero_user_segment(page, start, end); } } bytes += req->wb_bytes; if (test_bit(NFS_IOHDR_ERROR, &hdr->flags)) { if (bytes <= hdr->good_bytes) nfs_page_group_set_uptodate(req); } else nfs_page_group_set_uptodate(req); nfs_list_remove_request(req); nfs_readpage_release(req); } out: hdr->release(hdr); } static void nfs_initiate_read(struct nfs_pgio_header *hdr, struct rpc_message *msg, struct rpc_task_setup *task_setup_data, int how) { struct inode *inode = hdr->inode; int swap_flags = IS_SWAPFILE(inode) ? NFS_RPC_SWAPFLAGS : 0; task_setup_data->flags |= swap_flags; NFS_PROTO(inode)->read_setup(hdr, msg); } 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); nfs_readpage_release(req); } } static const struct nfs_pgio_completion_ops nfs_async_read_completion_ops = { .error_cleanup = nfs_async_read_error, .completion = nfs_read_completion, }; /* * This is the callback from RPC telling us whether a reply was * received or some error occurred (timeout or socket shutdown). */ static int nfs_readpage_done(struct rpc_task *task, struct nfs_pgio_header *hdr, struct inode *inode) { int status = NFS_PROTO(inode)->read_done(task, hdr); if (status != 0) return status; nfs_add_stats(inode, NFSIOS_SERVERREADBYTES, hdr->res.count); if (task->tk_status == -ESTALE) { set_bit(NFS_INO_STALE, &NFS_I(inode)->flags); nfs_mark_for_revalidate(inode); } return 0; } static void nfs_readpage_retry(struct rpc_task *task, struct nfs_pgio_header *hdr) { struct nfs_pgio_args *argp = &hdr->args; struct nfs_pgio_res *resp = &hdr->res; /* This is a short read! */ nfs_inc_stats(hdr->inode, NFSIOS_SHORTREAD); /* Has the server at least made some progress? */ if (resp->count == 0) { nfs_set_pgio_error(hdr, -EIO, argp->offset); return; } /* Yes, so retry the read at the end of the hdr */ hdr->mds_offset += resp->count; argp->offset += resp->count; argp->pgbase += resp->count; argp->count -= resp->count; rpc_restart_call_prepare(task); } static void nfs_readpage_result(struct rpc_task *task, struct nfs_pgio_header *hdr) { if (hdr->res.eof) { loff_t bound; bound = hdr->args.offset + hdr->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 (hdr->res.count != hdr->args.count) nfs_readpage_retry(task, hdr); } /* * 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_file_mapping(page)->host; int error; dprintk("NFS: nfs_readpage (%p %ld@%lu)\n", page, PAGE_CACHE_SIZE, page_file_index(page)); nfs_inc_stats(inode, NFSIOS_VFSREADPAGE); nfs_inc_stats(inode, NFSIOS_READPAGES); /* * 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 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, page, NULL, 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/%Lu %d)\n", inode->i_sb->s_id, (unsigned 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, false, &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_pgio_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); } static const struct nfs_rw_ops nfs_rw_read_ops = { .rw_mode = FMODE_READ, .rw_alloc_header = nfs_readhdr_alloc, .rw_free_header = nfs_readhdr_free, .rw_done = nfs_readpage_done, .rw_result = nfs_readpage_result, .rw_initiate = nfs_initiate_read, };