diff options
Diffstat (limited to '')
-rw-r--r-- | fs/nfs/read.c | 486 |
1 files changed, 486 insertions, 0 deletions
diff --git a/fs/nfs/read.c b/fs/nfs/read.c new file mode 100644 index 000000000..eb854f1f8 --- /dev/null +++ b/fs/nfs/read.c @@ -0,0 +1,486 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * 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, int error) +{ + struct inode *inode = d_inode(nfs_req_openctx(req)->dentry); + struct page *page = req->wb_page; + + 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_error_is_fatal_on_server(error) && error != -ETIMEDOUT) + SetPageError(page); + if (nfs_page_group_sync_on_bit(req, PG_UNLOCKPAGE)) { + struct address_space *mapping = page_file_mapping(page); + + if (PageUptodate(page)) + nfs_readpage_to_fscache(inode, page, 0); + else if (!PageError(page) && !PagePrivate(page)) + generic_error_remove_page(mapping, page); + unlock_page(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, 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, pgio.pg_error); + } + 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; + int error; + + 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); + } + } + error = 0; + bytes += req->wb_bytes; + if (test_bit(NFS_IOHDR_ERROR, &hdr->flags)) { + if (bytes <= hdr->good_bytes) + nfs_page_group_set_uptodate(req); + else { + error = hdr->error; + xchg(&nfs_req_openctx(req)->error, error); + } + } else + nfs_page_group_set_uptodate(req); + nfs_list_remove_request(req); + nfs_readpage_release(req, error); + } +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(hdr); +} + +static void +nfs_async_read_error(struct list_head *head, int error) +{ + struct nfs_page *req; + + while (!list_empty(head)) { + req = nfs_list_entry(head->next); + nfs_list_remove_request(req); + nfs_readpage_release(req, error); + } +} + +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(task, hdr); + + if (task->tk_status == -ESTALE) { + nfs_set_inode_stale(inode); + 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); + trace_nfs_readpage_short(task, hdr); + + /* 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; + resp->count = 0; + resp->eof = 0; + 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 pos = hdr->args.offset + hdr->res.count; + unsigned int new = pos - hdr->io_start; + + if (hdr->good_bytes > new) { + hdr->good_bytes = new; + set_bit(NFS_IOHDR_EOF, &hdr->flags); + clear_bit(NFS_IOHDR_ERROR, &hdr->flags); + } + } 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; + } + + xchg(&ctx->error, 0); + error = nfs_readpage_async(ctx, inode, page); + if (!error) { + error = wait_on_page_locked_killable(page); + if (!PageUptodate(page) && !error) + error = xchg(&ctx->error, 0); + } +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, 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); + error = desc->pgio->pg_error; + nfs_readpage_release(new, 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, +}; |