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![Trond Myklebust](/assets/img/avatar_default.png)
If we're resending a write due to a short read or write, ensure we reset the reply count to zero. Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
484 lines
12 KiB
C
484 lines
12 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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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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#include "pnfs.h"
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#include "nfstrace.h"
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#define NFSDBG_FACILITY NFSDBG_PAGECACHE
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static const struct nfs_pgio_completion_ops nfs_async_read_completion_ops;
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static const struct nfs_rw_ops nfs_rw_read_ops;
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static struct kmem_cache *nfs_rdata_cachep;
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static struct nfs_pgio_header *nfs_readhdr_alloc(void)
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{
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struct nfs_pgio_header *p = kmem_cache_zalloc(nfs_rdata_cachep, GFP_KERNEL);
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if (p)
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p->rw_mode = FMODE_READ;
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return p;
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}
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static void nfs_readhdr_free(struct nfs_pgio_header *rhdr)
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{
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kmem_cache_free(nfs_rdata_cachep, rhdr);
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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_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, bool force_mds,
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const struct nfs_pgio_completion_ops *compl_ops)
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{
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struct nfs_server *server = NFS_SERVER(inode);
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const struct nfs_pageio_ops *pg_ops = &nfs_pgio_rw_ops;
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#ifdef CONFIG_NFS_V4_1
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if (server->pnfs_curr_ld && !force_mds)
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pg_ops = server->pnfs_curr_ld->pg_read_ops;
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#endif
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nfs_pageio_init(pgio, inode, pg_ops, compl_ops, &nfs_rw_read_ops,
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server->rsize, 0);
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}
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EXPORT_SYMBOL_GPL(nfs_pageio_init_read);
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void nfs_pageio_reset_read_mds(struct nfs_pageio_descriptor *pgio)
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{
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struct nfs_pgio_mirror *mirror;
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if (pgio->pg_ops && pgio->pg_ops->pg_cleanup)
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pgio->pg_ops->pg_cleanup(pgio);
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pgio->pg_ops = &nfs_pgio_rw_ops;
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/* read path should never have more than one mirror */
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WARN_ON_ONCE(pgio->pg_mirror_count != 1);
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mirror = &pgio->pg_mirrors[0];
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mirror->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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static void nfs_readpage_release(struct nfs_page *req, int error)
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{
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struct inode *inode = d_inode(nfs_req_openctx(req)->dentry);
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struct page *page = req->wb_page;
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dprintk("NFS: read done (%s/%llu %d@%lld)\n", inode->i_sb->s_id,
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(unsigned long long)NFS_FILEID(inode), req->wb_bytes,
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(long long)req_offset(req));
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if (nfs_error_is_fatal_on_server(error) && error != -ETIMEDOUT)
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SetPageError(page);
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if (nfs_page_group_sync_on_bit(req, PG_UNLOCKPAGE)) {
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struct address_space *mapping = page_file_mapping(page);
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if (PageUptodate(page))
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nfs_readpage_to_fscache(inode, page, 0);
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else if (!PageError(page) && !PagePrivate(page))
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generic_error_remove_page(mapping, page);
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unlock_page(page);
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}
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nfs_release_request(req);
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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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struct nfs_pgio_mirror *pgm;
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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, 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_SIZE)
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zero_user_segment(page, len, PAGE_SIZE);
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nfs_pageio_init_read(&pgio, inode, false,
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&nfs_async_read_completion_ops);
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if (!nfs_pageio_add_request(&pgio, new)) {
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nfs_list_remove_request(new);
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nfs_readpage_release(new, pgio.pg_error);
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}
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nfs_pageio_complete(&pgio);
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/* It doesn't make sense to do mirrored reads! */
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WARN_ON_ONCE(pgio.pg_mirror_count != 1);
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pgm = &pgio.pg_mirrors[0];
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NFS_I(inode)->read_io += pgm->pg_bytes_written;
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return pgio.pg_error < 0 ? pgio.pg_error : 0;
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}
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static void nfs_page_group_set_uptodate(struct nfs_page *req)
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{
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if (nfs_page_group_sync_on_bit(req, PG_UPTODATE))
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SetPageUptodate(req->wb_page);
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}
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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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int error;
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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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unsigned long start = req->wb_pgbase;
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unsigned long end = req->wb_pgbase + req->wb_bytes;
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if (test_bit(NFS_IOHDR_EOF, &hdr->flags)) {
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/* note: regions of the page not covered by a
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* request are zeroed in nfs_readpage_async /
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* readpage_async_filler */
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if (bytes > hdr->good_bytes) {
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/* nothing in this request was good, so zero
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* the full extent of the request */
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zero_user_segment(page, start, end);
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} else if (hdr->good_bytes - bytes < req->wb_bytes) {
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/* part of this request has good bytes, but
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* not all. zero the bad bytes */
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start += hdr->good_bytes - bytes;
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WARN_ON(start < req->wb_pgbase);
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zero_user_segment(page, start, end);
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}
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}
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error = 0;
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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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nfs_page_group_set_uptodate(req);
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else {
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error = hdr->error;
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xchg(&nfs_req_openctx(req)->error, error);
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}
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} else
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nfs_page_group_set_uptodate(req);
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nfs_list_remove_request(req);
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nfs_readpage_release(req, error);
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}
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out:
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hdr->release(hdr);
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}
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static void nfs_initiate_read(struct nfs_pgio_header *hdr,
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struct rpc_message *msg,
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const struct nfs_rpc_ops *rpc_ops,
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struct rpc_task_setup *task_setup_data, int how)
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{
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struct inode *inode = hdr->inode;
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int swap_flags = IS_SWAPFILE(inode) ? NFS_RPC_SWAPFLAGS : 0;
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task_setup_data->flags |= swap_flags;
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rpc_ops->read_setup(hdr, msg);
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trace_nfs_initiate_read(hdr);
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}
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static void
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nfs_async_read_error(struct list_head *head, int error)
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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, error);
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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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/*
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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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static int nfs_readpage_done(struct rpc_task *task,
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struct nfs_pgio_header *hdr,
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struct inode *inode)
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{
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int status = NFS_PROTO(inode)->read_done(task, hdr);
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if (status != 0)
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return status;
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nfs_add_stats(inode, NFSIOS_SERVERREADBYTES, hdr->res.count);
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trace_nfs_readpage_done(task, hdr);
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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,
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struct nfs_pgio_header *hdr)
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{
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struct nfs_pgio_args *argp = &hdr->args;
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struct nfs_pgio_res *resp = &hdr->res;
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/* This is a short read! */
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nfs_inc_stats(hdr->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(hdr, -EIO, argp->offset);
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return;
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}
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/* For non rpc-based layout drivers, retry-through-MDS */
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if (!task->tk_ops) {
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hdr->pnfs_error = -EAGAIN;
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return;
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}
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/* Yes, so retry the read at the end of the hdr */
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hdr->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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resp->count = 0;
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resp->eof = 0;
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rpc_restart_call_prepare(task);
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}
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static void nfs_readpage_result(struct rpc_task *task,
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struct nfs_pgio_header *hdr)
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{
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if (hdr->res.eof) {
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loff_t pos = hdr->args.offset + hdr->res.count;
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unsigned int new = pos - hdr->io_start;
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if (hdr->good_bytes > new) {
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hdr->good_bytes = new;
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set_bit(NFS_IOHDR_EOF, &hdr->flags);
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clear_bit(NFS_IOHDR_ERROR, &hdr->flags);
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}
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} else if (hdr->res.count < hdr->args.count)
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nfs_readpage_retry(task, hdr);
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}
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/*
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* Read a page over NFS.
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* We read the page synchronously in the following case:
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* - The error flag is set for this page. This happens only when a
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* previous async read operation failed.
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*/
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int nfs_readpage(struct file *file, struct page *page)
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{
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struct nfs_open_context *ctx;
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struct inode *inode = page_file_mapping(page)->host;
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int error;
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dprintk("NFS: nfs_readpage (%p %ld@%lu)\n",
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page, PAGE_SIZE, page_index(page));
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nfs_inc_stats(inode, NFSIOS_VFSREADPAGE);
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nfs_add_stats(inode, NFSIOS_READPAGES, 1);
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/*
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* Try to flush any pending writes to the file..
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*
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* NOTE! Because we own the page lock, there cannot
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* be any new pending writes generated at this point
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* for this page (other pages can be written to).
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*/
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error = nfs_wb_page(inode, page);
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if (error)
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goto out_unlock;
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if (PageUptodate(page))
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goto out_unlock;
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error = -ESTALE;
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if (NFS_STALE(inode))
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goto out_unlock;
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if (file == NULL) {
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error = -EBADF;
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ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
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if (ctx == NULL)
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goto out_unlock;
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} else
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ctx = get_nfs_open_context(nfs_file_open_context(file));
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if (!IS_SYNC(inode)) {
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error = nfs_readpage_from_fscache(ctx, inode, page);
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if (error == 0)
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goto out;
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}
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xchg(&ctx->error, 0);
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error = nfs_readpage_async(ctx, inode, page);
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if (!error) {
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error = wait_on_page_locked_killable(page);
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if (!PageUptodate(page) && !error)
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error = xchg(&ctx->error, 0);
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}
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out:
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put_nfs_open_context(ctx);
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return error;
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out_unlock:
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unlock_page(page);
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return error;
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}
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struct nfs_readdesc {
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struct nfs_pageio_descriptor *pgio;
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struct nfs_open_context *ctx;
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};
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static int
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readpage_async_filler(void *data, struct page *page)
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{
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struct nfs_readdesc *desc = (struct nfs_readdesc *)data;
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struct nfs_page *new;
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unsigned int len;
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int error;
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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(desc->ctx, page, 0, len);
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if (IS_ERR(new))
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goto out_error;
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if (len < PAGE_SIZE)
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zero_user_segment(page, len, PAGE_SIZE);
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if (!nfs_pageio_add_request(desc->pgio, new)) {
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nfs_list_remove_request(new);
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error = desc->pgio->pg_error;
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nfs_readpage_release(new, error);
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goto out;
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}
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return 0;
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out_error:
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error = PTR_ERR(new);
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unlock_page(page);
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out:
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return error;
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}
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int nfs_readpages(struct file *filp, struct address_space *mapping,
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struct list_head *pages, unsigned nr_pages)
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{
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struct nfs_pageio_descriptor pgio;
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struct nfs_pgio_mirror *pgm;
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struct nfs_readdesc desc = {
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.pgio = &pgio,
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};
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struct inode *inode = mapping->host;
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unsigned long npages;
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int ret = -ESTALE;
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dprintk("NFS: nfs_readpages (%s/%Lu %d)\n",
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inode->i_sb->s_id,
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(unsigned long long)NFS_FILEID(inode),
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nr_pages);
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nfs_inc_stats(inode, NFSIOS_VFSREADPAGES);
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if (NFS_STALE(inode))
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goto out;
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if (filp == NULL) {
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desc.ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
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if (desc.ctx == NULL)
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return -EBADF;
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} else
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desc.ctx = get_nfs_open_context(nfs_file_open_context(filp));
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/* attempt to read as many of the pages as possible from the cache
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* - this returns -ENOBUFS immediately if the cookie is negative
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*/
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ret = nfs_readpages_from_fscache(desc.ctx, inode, mapping,
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pages, &nr_pages);
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if (ret == 0)
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goto read_complete; /* all pages were read */
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nfs_pageio_init_read(&pgio, inode, false,
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&nfs_async_read_completion_ops);
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ret = read_cache_pages(mapping, pages, readpage_async_filler, &desc);
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nfs_pageio_complete(&pgio);
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/* It doesn't make sense to do mirrored reads! */
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WARN_ON_ONCE(pgio.pg_mirror_count != 1);
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pgm = &pgio.pg_mirrors[0];
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NFS_I(inode)->read_io += pgm->pg_bytes_written;
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npages = (pgm->pg_bytes_written + PAGE_SIZE - 1) >>
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PAGE_SHIFT;
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nfs_add_stats(inode, NFSIOS_READPAGES, npages);
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read_complete:
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put_nfs_open_context(desc.ctx);
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out:
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return ret;
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}
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int __init nfs_init_readpagecache(void)
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{
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nfs_rdata_cachep = kmem_cache_create("nfs_read_data",
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sizeof(struct nfs_pgio_header),
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0, SLAB_HWCACHE_ALIGN,
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NULL);
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if (nfs_rdata_cachep == NULL)
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return -ENOMEM;
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return 0;
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}
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void nfs_destroy_readpagecache(void)
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{
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kmem_cache_destroy(nfs_rdata_cachep);
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}
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static const struct nfs_rw_ops nfs_rw_read_ops = {
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.rw_alloc_header = nfs_readhdr_alloc,
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.rw_free_header = nfs_readhdr_free,
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.rw_done = nfs_readpage_done,
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.rw_result = nfs_readpage_result,
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.rw_initiate = nfs_initiate_read,
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};
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