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/*
* 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;
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);
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;
}
/* For non rpc-based layout drivers, retry-through-MDS */
if
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