| /* |
| * 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" |
| #include "nfstrace.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) |
| { |
| struct nfs_pgio_header *p = kmem_cache_zalloc(nfs_rdata_cachep, GFP_KERNEL); |
| |
| if (p) |
| p->rw_mode = FMODE_READ; |
| return p; |
| } |
| |
| 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_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) |
| { |
| struct nfs_pgio_mirror *mirror; |
| |
| if (pgio->pg_ops && pgio->pg_ops->pg_cleanup) |
| pgio->pg_ops->pg_cleanup(pgio); |
| |
| pgio->pg_ops = &nfs_pgio_rw_ops; |
| |
| /* read path should never have more than one mirror */ |
| WARN_ON_ONCE(pgio->pg_mirror_count != 1); |
| |
| mirror = &pgio->pg_mirrors[0]; |
| mirror->pg_bsize = NFS_SERVER(pgio->pg_inode)->rsize; |
| } |
| EXPORT_SYMBOL_GPL(nfs_pageio_reset_read_mds); |
| |
| static void nfs_readpage_release(struct nfs_page *req) |
| { |
| struct inode *inode = d_inode(req->wb_context->dentry); |
| |
| dprintk("NFS: read done (%s/%llu %d@%lld)\n", inode->i_sb->s_id, |
| (unsigned long long)NFS_FILEID(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(inode, req->wb_page, 0); |
| |
| unlock_page(req->wb_page); |
| } |
| nfs_release_request(req); |
| } |
| |
| 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; |
| struct nfs_pgio_mirror *pgm; |
| |
| 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_SIZE) |
| zero_user_segment(page, len, PAGE_SIZE); |
| |
| nfs_pageio_init_read(&pgio, inode, false, |
| &nfs_async_read_completion_ops); |
| if (!nfs_pageio_add_request(&pgio, new)) { |
| nfs_list_remove_request(new); |
| nfs_readpage_release(new); |
| } |
| nfs_pageio_complete(&pgio); |
| |
| /* It doesn't make sense to do mirrored reads! */ |
| WARN_ON_ONCE(pgio.pg_mirror_count != 1); |
| |
| pgm = &pgio.pg_mirrors[0]; |
| NFS_I(inode)->read_io += pgm->pg_bytes_written; |
| |
| return pgio.pg_error < 0 ? pgio.pg_error : 0; |
| } |
| |
| 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, |
| const struct nfs_rpc_ops *rpc_ops, |
| 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; |
| rpc_ops->read_setup(hdr, msg); |
| trace_nfs_initiate_read(inode, hdr->io_start, hdr->good_bytes); |
| } |
| |
| 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); |
| trace_nfs_readpage_done(inode, task->tk_status, |
| hdr->args.offset, hdr->res.eof); |
| |
| 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; |
| } |
| |
| /* For non rpc-based layout drivers, retry-through-MDS */ |
| if (!task->tk_ops) { |
| hdr->pnfs_error = -EAGAIN; |
| 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_SIZE, page_index(page)); |
| 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(struct file *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_SIZE) |
| zero_user_segment(page, len, PAGE_SIZE); |
| if (!nfs_pageio_add_request(desc->pgio, new)) { |
| nfs_list_remove_request(new); |
| nfs_readpage_release(new); |
| error = desc->pgio->pg_error; |
| goto out; |
| } |
| return 0; |
| out_error: |
| error = PTR_ERR(new); |
| unlock_page(page); |
| out: |
| 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_pgio_mirror *pgm; |
| 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); |
| |
| /* It doesn't make sense to do mirrored reads! */ |
| WARN_ON_ONCE(pgio.pg_mirror_count != 1); |
| |
| pgm = &pgio.pg_mirrors[0]; |
| NFS_I(inode)->read_io += pgm->pg_bytes_written; |
| npages = (pgm->pg_bytes_written + PAGE_SIZE - 1) >> |
| PAGE_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_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, |
| }; |