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67d0338edd
Operations that modify state for a whole page must be syncronized across all requests within a page group. In the read path, this is calling unlock_page and SetPageUptodate. Both of these functions should not be called until all requests in a page group have reached the point where they would call them. This patch should have no effect yet since all page groups currently have one request, but will come into play when pg_test functions are modified to split pages into sub-page regions. Signed-off-by: Weston Andros Adamson <dros@primarydata.com> Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
419 lines
10 KiB
C
419 lines
10 KiB
C
/*
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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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#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_rw_header *nfs_readhdr_alloc(void)
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{
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return kmem_cache_zalloc(nfs_rdata_cachep, GFP_KERNEL);
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}
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static void nfs_readhdr_free(struct nfs_rw_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_CACHE_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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pgio->pg_ops = &nfs_pgio_rw_ops;
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pgio->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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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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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, NULL, 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_CACHE_SIZE)
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zero_user_segment(page, len, PAGE_CACHE_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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nfs_pageio_add_request(&pgio, new);
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nfs_pageio_complete(&pgio);
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NFS_I(inode)->read_io += pgio.pg_bytes_written;
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return 0;
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}
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static void nfs_readpage_release(struct nfs_page *req)
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{
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struct inode *d_inode = req->wb_context->dentry->d_inode;
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dprintk("NFS: read done (%s/%llu %d@%lld)\n", d_inode->i_sb->s_id,
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(unsigned long long)NFS_FILEID(d_inode), req->wb_bytes,
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(long long)req_offset(req));
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if (nfs_page_group_sync_on_bit(req, PG_UNLOCKPAGE)) {
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if (PageUptodate(req->wb_page))
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nfs_readpage_to_fscache(d_inode, req->wb_page, 0);
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unlock_page(req->wb_page);
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}
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dprintk("NFS: read done (%s/%Lu %d@%Ld)\n",
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req->wb_context->dentry->d_inode->i_sb->s_id,
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(unsigned long long)NFS_FILEID(req->wb_context->dentry->d_inode),
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req->wb_bytes,
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(long long)req_offset(req));
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nfs_release_request(req);
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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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/* Note io was page aligned */
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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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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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if (test_bit(NFS_IOHDR_EOF, &hdr->flags)) {
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if (bytes > hdr->good_bytes)
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zero_user(page, 0, PAGE_SIZE);
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else if (hdr->good_bytes - bytes < PAGE_SIZE)
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zero_user_segment(page,
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hdr->good_bytes & ~PAGE_MASK,
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PAGE_SIZE);
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}
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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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nfs_page_group_set_uptodate(req);
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nfs_list_remove_request(req);
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nfs_readpage_release(req);
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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_data *data, struct rpc_message *msg,
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struct rpc_task_setup *task_setup_data, int how)
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{
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struct inode *inode = data->header->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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NFS_PROTO(inode)->read_setup(data, msg);
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}
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static void
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nfs_async_read_error(struct list_head *head)
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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);
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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, struct nfs_pgio_data *data,
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struct inode *inode)
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{
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int status = NFS_PROTO(inode)->read_done(task, data);
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if (status != 0)
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return status;
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nfs_add_stats(inode, NFSIOS_SERVERREADBYTES, data->res.count);
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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, struct nfs_pgio_data *data)
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{
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struct nfs_pgio_args *argp = &data->args;
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struct nfs_pgio_res *resp = &data->res;
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/* This is a short read! */
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nfs_inc_stats(data->header->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(data->header, -EIO, argp->offset);
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return;
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}
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/* Yes, so retry the read at the end of the data */
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data->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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rpc_restart_call_prepare(task);
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}
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static void nfs_readpage_result(struct rpc_task *task, struct nfs_pgio_data *data)
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{
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struct nfs_pgio_header *hdr = data->header;
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if (data->res.eof) {
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loff_t bound;
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bound = data->args.offset + data->res.count;
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spin_lock(&hdr->lock);
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if (bound < hdr->io_start + hdr->good_bytes) {
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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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hdr->good_bytes = bound - hdr->io_start;
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}
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spin_unlock(&hdr->lock);
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} else if (data->res.count != data->args.count)
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nfs_readpage_retry(task, data);
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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_CACHE_SIZE, page_file_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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error = nfs_readpage_async(ctx, inode, page);
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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, NULL, 0, len);
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if (IS_ERR(new))
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goto out_error;
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if (len < PAGE_CACHE_SIZE)
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zero_user_segment(page, len, PAGE_CACHE_SIZE);
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if (!nfs_pageio_add_request(desc->pgio, new)) {
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error = desc->pgio->pg_error;
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goto out_unlock;
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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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out_unlock:
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unlock_page(page);
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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_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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NFS_I(inode)->read_io += pgio.pg_bytes_written;
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npages = (pgio.pg_bytes_written + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_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_rw_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_mode = FMODE_READ,
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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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