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-rw-r--r--fs/nfs/read.c618
1 files changed, 618 insertions, 0 deletions
diff --git a/fs/nfs/read.c b/fs/nfs/read.c
new file mode 100644
index 0000000..a0042fb
--- /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");
+}
generated by cgit v1.1 at 2024-12-26 17:03:01 +0000