diff options
Diffstat (limited to 'fs/nfs/read.c')
| -rw-r--r-- | fs/nfs/read.c | 618 |
1 files changed, 618 insertions, 0 deletions
diff --git a/fs/nfs/read.c b/fs/nfs/read.c new file mode 100644 index 000000000000..a0042fb58634 --- /dev/null +++ b/fs/nfs/read.c @@ -0,0 +1,618 @@ +/* + * 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 + * + * We do an ugly hack here in order to return proper error codes to the + * user program when a read request failed: since generic_file_read + * only checks the return value of inode->i_op->readpage() which is always 0 + * for async RPC, we set the error bit of the page to 1 when an error occurs, + * and make nfs_readpage transmit requests synchronously when encountering this. + * This is only a small problem, though, since we now retry all operations + * within the RPC code when root squashing is suspected. + */ + +#include <linux/config.h> +#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> + +#define NFSDBG_FACILITY NFSDBG_PAGECACHE + +static int nfs_pagein_one(struct list_head *, struct inode *); +static void nfs_readpage_result_partial(struct nfs_read_data *, int); +static void nfs_readpage_result_full(struct nfs_read_data *, int); + +static kmem_cache_t *nfs_rdata_cachep; +mempool_t *nfs_rdata_mempool; + +#define MIN_POOL_READ (32) + +void nfs_readdata_release(struct rpc_task *task) +{ + struct nfs_read_data *data = (struct nfs_read_data *)task->tk_calldata; + nfs_readdata_free(data); +} + +static +unsigned int nfs_page_length(struct inode *inode, struct page *page) +{ + loff_t i_size = i_size_read(inode); + unsigned long idx; + + if (i_size <= 0) + return 0; + idx = (i_size - 1) >> PAGE_CACHE_SHIFT; + if (page->index > idx) + return 0; + if (page->index != idx) + return PAGE_CACHE_SIZE; + return 1 + ((i_size - 1) & (PAGE_CACHE_SIZE - 1)); +} + +static +int nfs_return_empty_page(struct page *page) +{ + memclear_highpage_flush(page, 0, PAGE_CACHE_SIZE); + SetPageUptodate(page); + unlock_page(page); + return 0; +} + +/* + * Read a page synchronously. + */ +static int nfs_readpage_sync(struct nfs_open_context *ctx, struct inode *inode, + struct page *page) +{ + unsigned int rsize = NFS_SERVER(inode)->rsize; + unsigned int count = PAGE_CACHE_SIZE; + int result; + struct nfs_read_data *rdata; + + rdata = nfs_readdata_alloc(); + if (!rdata) + return -ENOMEM; + + memset(rdata, 0, sizeof(*rdata)); + rdata->flags = (IS_SWAPFILE(inode)? NFS_RPC_SWAPFLAGS : 0); + rdata->cred = ctx->cred; + rdata->inode = inode; + INIT_LIST_HEAD(&rdata->pages); + rdata->args.fh = NFS_FH(inode); + rdata->args.context = ctx; + rdata->args.pages = &page; + rdata->args.pgbase = 0UL; + rdata->args.count = rsize; + rdata->res.fattr = &rdata->fattr; + + dprintk("NFS: nfs_readpage_sync(%p)\n", page); + + /* + * This works now because the socket layer never tries to DMA + * into this buffer directly. + */ + do { + if (count < rsize) + rdata->args.count = count; + rdata->res.count = rdata->args.count; + rdata->args.offset = page_offset(page) + rdata->args.pgbase; + + dprintk("NFS: nfs_proc_read(%s, (%s/%Ld), %Lu, %u)\n", + NFS_SERVER(inode)->hostname, + inode->i_sb->s_id, + (long long)NFS_FILEID(inode), + (unsigned long long)rdata->args.pgbase, + rdata->args.count); + + lock_kernel(); + result = NFS_PROTO(inode)->read(rdata); + unlock_kernel(); + + /* + * Even if we had a partial success we can't mark the page + * cache valid. + */ + if (result < 0) { + if (result == -EISDIR) + result = -EINVAL; + goto io_error; + } + count -= result; + rdata->args.pgbase += result; + /* Note: result == 0 should only happen if we're caching + * a write that extends the file and punches a hole. + */ + if (rdata->res.eof != 0 || result == 0) + break; + } while (count); + NFS_FLAGS(inode) |= NFS_INO_INVALID_ATIME; + + if (count) + memclear_highpage_flush(page, rdata->args.pgbase, count); + SetPageUptodate(page); + if (PageError(page)) + ClearPageError(page); + result = 0; + +io_error: + unlock_page(page); + nfs_readdata_free(rdata); + return result; +} + +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(inode, 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) + memclear_highpage_flush(page, len, PAGE_CACHE_SIZE - len); + + nfs_lock_request(new); + nfs_list_add_request(new, &one_request); + nfs_pagein_one(&one_request, inode); + return 0; +} + +static void nfs_readpage_release(struct nfs_page *req) +{ + unlock_page(req->wb_page); + + nfs_clear_request(req); + nfs_release_request(req); + nfs_unlock_request(req); + + dprintk("NFS: read done (%s/%Ld %d@%Ld)\n", + req->wb_context->dentry->d_inode->i_sb->s_id, + (long long)NFS_FILEID(req->wb_context->dentry->d_inode), + req->wb_bytes, + (long long)req_offset(req)); +} + +/* + * Set up the NFS read request struct + */ +static void nfs_read_rpcsetup(struct nfs_page *req, struct nfs_read_data *data, + unsigned int count, unsigned int offset) +{ + struct inode *inode; + + data->req = req; + data->inode = inode = req->wb_context->dentry->d_inode; + data->cred = req->wb_context->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_PROTO(inode)->read_setup(data); + + data->task.tk_cookie = (unsigned long)inode; + data->task.tk_calldata = data; + /* Release requests */ + data->task.tk_release = nfs_readdata_release; + + dprintk("NFS: %4d 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); +} + +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); + } +} + +/* + * Start an async read operation + */ +static void nfs_execute_read(struct nfs_read_data *data) +{ + struct rpc_clnt *clnt = NFS_CLIENT(data->inode); + sigset_t oldset; + + rpc_clnt_sigmask(clnt, &oldset); + lock_kernel(); + rpc_execute(&data->task); + unlock_kernel(); + rpc_clnt_sigunmask(clnt, &oldset); +} + +/* + * 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 list_head *head, struct inode *inode) +{ + struct nfs_page *req = nfs_list_entry(head->next); + struct page *page = req->wb_page; + struct nfs_read_data *data; + unsigned int rsize = NFS_SERVER(inode)->rsize; + unsigned int nbytes, offset; + int requests = 0; + LIST_HEAD(list); + + nfs_list_remove_request(req); + + nbytes = req->wb_bytes; + for(;;) { + data = nfs_readdata_alloc(); + if (!data) + goto out_bad; + INIT_LIST_HEAD(&data->pages); + list_add(&data->pages, &list); + requests++; + if (nbytes <= rsize) + break; + nbytes -= rsize; + } + atomic_set(&req->wb_complete, requests); + + ClearPageError(page); + offset = 0; + nbytes = req->wb_bytes; + do { + data = list_entry(list.next, struct nfs_read_data, pages); + list_del_init(&data->pages); + + data->pagevec[0] = page; + data->complete = nfs_readpage_result_partial; + + if (nbytes > rsize) { + nfs_read_rpcsetup(req, data, rsize, offset); + offset += rsize; + nbytes -= rsize; + } else { + nfs_read_rpcsetup(req, data, nbytes, offset); + nbytes = 0; + } + nfs_execute_read(data); + } 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 list_head *head, struct inode *inode) +{ + struct nfs_page *req; + struct page **pages; + struct nfs_read_data *data; + unsigned int count; + + if (NFS_SERVER(inode)->rsize < PAGE_CACHE_SIZE) + return nfs_pagein_multi(head, inode); + + data = nfs_readdata_alloc(); + if (!data) + goto out_bad; + + INIT_LIST_HEAD(&data->pages); + pages = data->pagevec; + count = 0; + 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; + count += req->wb_bytes; + } + req = nfs_list_entry(data->pages.next); + + data->complete = nfs_readpage_result_full; + nfs_read_rpcsetup(req, data, count, 0); + + nfs_execute_read(data); + return 0; +out_bad: + nfs_async_read_error(head); + return -ENOMEM; +} + +static int +nfs_pagein_list(struct list_head *head, int rpages) +{ + LIST_HEAD(one_request); + struct nfs_page *req; + int error = 0; + unsigned int pages = 0; + + while (!list_empty(head)) { + pages += nfs_coalesce_requests(head, &one_request, rpages); + req = nfs_list_entry(one_request.next); + error = nfs_pagein_one(&one_request, req->wb_context->dentry->d_inode); + if (error < 0) + break; + } + if (error >= 0) + return pages; + + nfs_async_read_error(head); + return error; +} + +/* + * Handle a read reply that fills part of a page. + */ +static void nfs_readpage_result_partial(struct nfs_read_data *data, int status) +{ + struct nfs_page *req = data->req; + struct page *page = req->wb_page; + + if (status >= 0) { + unsigned int request = data->args.count; + unsigned int result = data->res.count; + + if (result < request) { + memclear_highpage_flush(page, + data->args.pgbase + result, + request - result); + } + } else + SetPageError(page); + + if (atomic_dec_and_test(&req->wb_complete)) { + if (!PageError(page)) + SetPageUptodate(page); + nfs_readpage_release(req); + } +} + +/* + * 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 nfs_read_data *data, int status) +{ + unsigned int count = data->res.count; + + while (!list_empty(&data->pages)) { + struct nfs_page *req = nfs_list_entry(data->pages.next); + struct page *page = req->wb_page; + nfs_list_remove_request(req); + + if (status >= 0) { + if (count < PAGE_CACHE_SIZE) { + if (count < req->wb_bytes) + memclear_highpage_flush(page, + req->wb_pgbase + count, + req->wb_bytes - count); + count = 0; + } else + count -= PAGE_CACHE_SIZE; + SetPageUptodate(page); + } else + SetPageError(page); + nfs_readpage_release(req); + } +} + +/* + * This is the callback from RPC telling us whether a reply was + * received or some error occurred (timeout or socket shutdown). + */ +void nfs_readpage_result(struct rpc_task *task) +{ + struct nfs_read_data *data = (struct nfs_read_data *)task->tk_calldata; + struct nfs_readargs *argp = &data->args; + struct nfs_readres *resp = &data->res; + int status = task->tk_status; + + dprintk("NFS: %4d nfs_readpage_result, (status %d)\n", + task->tk_pid, status); + + /* Is this a short read? */ + if (task->tk_status >= 0 && resp->count < argp->count && !resp->eof) { + /* Has the server at least made some progress? */ + if (resp->count != 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; + } + task->tk_status = -EIO; + } + NFS_FLAGS(data->inode) |= NFS_INO_INVALID_ATIME; + data->complete(data, status); +} + +/* + * 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); + /* + * 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_error; + + if (file == NULL) { + ctx = nfs_find_open_context(inode, FMODE_READ); + if (ctx == NULL) + return -EBADF; + } else + ctx = get_nfs_open_context((struct nfs_open_context *) + file->private_data); + if (!IS_SYNC(inode)) { + error = nfs_readpage_async(ctx, inode, page); + goto out; + } + + error = nfs_readpage_sync(ctx, inode, page); + if (error < 0 && IS_SWAPFILE(inode)) + printk("Aiee.. nfs swap-in of page failed!\n"); +out: + put_nfs_open_context(ctx); + return error; + +out_error: + unlock_page(page); + return error; +} + +struct nfs_readdesc { + struct list_head *head; + 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; + + nfs_wb_page(inode, page); + len = nfs_page_length(inode, page); + if (len == 0) + return nfs_return_empty_page(page); + new = nfs_create_request(desc->ctx, inode, page, 0, len); + if (IS_ERR(new)) { + SetPageError(page); + unlock_page(page); + return PTR_ERR(new); + } + if (len < PAGE_CACHE_SIZE) + memclear_highpage_flush(page, len, PAGE_CACHE_SIZE - len); + nfs_lock_request(new); + nfs_list_add_request(new, desc->head); + return 0; +} + +int nfs_readpages(struct file *filp, struct address_space *mapping, + struct list_head *pages, unsigned nr_pages) +{ + LIST_HEAD(head); + struct nfs_readdesc desc = { + .head = &head, + }; + struct inode *inode = mapping->host; + struct nfs_server *server = NFS_SERVER(inode); + int ret; + + dprintk("NFS: nfs_readpages (%s/%Ld %d)\n", + inode->i_sb->s_id, + (long long)NFS_FILEID(inode), + nr_pages); + + if (filp == NULL) { + desc.ctx = nfs_find_open_context(inode, FMODE_READ); + if (desc.ctx == NULL) + return -EBADF; + } else + desc.ctx = get_nfs_open_context((struct nfs_open_context *) + filp->private_data); + ret = read_cache_pages(mapping, pages, readpage_async_filler, &desc); + if (!list_empty(&head)) { + int err = nfs_pagein_list(&head, server->rpages); + if (!ret) + ret = err; + } + put_nfs_open_context(desc.ctx); + return ret; +} + +int nfs_init_readpagecache(void) +{ + nfs_rdata_cachep = kmem_cache_create("nfs_read_data", + sizeof(struct nfs_read_data), + 0, SLAB_HWCACHE_ALIGN, + NULL, NULL); + if (nfs_rdata_cachep == NULL) + return -ENOMEM; + + nfs_rdata_mempool = mempool_create(MIN_POOL_READ, + mempool_alloc_slab, + mempool_free_slab, + nfs_rdata_cachep); + if (nfs_rdata_mempool == NULL) + return -ENOMEM; + + return 0; +} + +void nfs_destroy_readpagecache(void) +{ + mempool_destroy(nfs_rdata_mempool); + if (kmem_cache_destroy(nfs_rdata_cachep)) + printk(KERN_INFO "nfs_read_data: not all structures were freed\n"); +} |