--- /dev/null
+/*
+ * 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"
+
+#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)
+{
+ return kmem_cache_zalloc(nfs_rdata_cachep, GFP_KERNEL);
+}
+
+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_CACHE_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;
+
+ 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);
+
+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_CACHE_SIZE)
+ zero_user_segment(page, len, PAGE_CACHE_SIZE);
+
+ nfs_pageio_init_read(&pgio, inode, false,
+ &nfs_async_read_completion_ops);
+ nfs_pageio_add_request(&pgio, 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 0;
+}
+
+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);
+}
+
+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);
+}
+
+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);
+
+ 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;
+ }
+ /* 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_CACHE_SIZE, page_file_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(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, NULL, 0, len);
+ if (IS_ERR(new))
+ goto out_error;
+
+ if (len < PAGE_CACHE_SIZE)
+ zero_user_segment(page, len, PAGE_CACHE_SIZE);
+ if (!nfs_pageio_add_request(desc->pgio, new)) {
+ error = desc->pgio->pg_error;
+ goto out_unlock;
+ }
+ return 0;
+out_error:
+ error = PTR_ERR(new);
+out_unlock:
+ unlock_page(page);
+ 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_CACHE_SIZE - 1) >>
+ PAGE_CACHE_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_mode = FMODE_READ,
+ .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,
+};
Code Review / kvmfornfv.git / blobdiff