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DEFINITIONS
This source file includes following definitions.
- nfs_readdata_alloc
- nfs_readdata_free
- nfs_readdata_release
- nfs_return_empty_page
- nfs_readpage_truncate_uninitialised_page
- nfs_readpage_async
- nfs_readpage_release
- nfs_read_rpcsetup
- nfs_async_read_error
- nfs_pagein_multi
- nfs_pagein_one
- nfs_readpage_result
- nfs_readpage_retry
- nfs_readpage_result_partial
- nfs_readpage_release_partial
- nfs_readpage_set_pages_uptodate
- nfs_readpage_result_full
- nfs_readpage_release_full
- nfs_readpage
- readpage_async_filler
- nfs_readpages
- nfs_init_readpagecache
- nfs_destroy_readpagecache
/*
* 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/smp_lock.h>
#include <asm/system.h>
#include "internal.h"
#include "iostat.h"
#define NFSDBG_FACILITY NFSDBG_PAGECACHE
static int nfs_pagein_multi(struct inode *, struct list_head *, unsigned int, size_t, int);
static int nfs_pagein_one(struct inode *, struct list_head *, unsigned int, size_t, int);
static const struct rpc_call_ops nfs_read_partial_ops;
static const struct rpc_call_ops nfs_read_full_ops;
static struct kmem_cache *nfs_rdata_cachep;
static mempool_t *nfs_rdata_mempool;
#define MIN_POOL_READ (32)
struct nfs_read_data *nfs_readdata_alloc(unsigned int pagecount)
{
struct nfs_read_data *p = mempool_alloc(nfs_rdata_mempool, GFP_NOFS);
if (p) {
memset(p, 0, sizeof(*p));
INIT_LIST_HEAD(&p->pages);
p->npages = pagecount;
if (pagecount <= ARRAY_SIZE(p->page_array))
p->pagevec = p->page_array;
else {
p->pagevec = kcalloc(pagecount, sizeof(struct page *), GFP_NOFS);
if (!p->pagevec) {
mempool_free(p, nfs_rdata_mempool);
p = NULL;
}
}
}
return p;
}
static void nfs_readdata_free(struct nfs_read_data *p)
{
if (p && (p->pagevec != &p->page_array[0]))
kfree(p->pagevec);
mempool_free(p, nfs_rdata_mempool);
}
void nfs_readdata_release(void *data)
{
struct nfs_read_data *rdata = data;
put_nfs_open_context(rdata->args.context);
nfs_readdata_free(rdata);
}
static
int nfs_return_empty_page(struct page *page)
{
zero_user(page, 0, PAGE_CACHE_SIZE);
SetPageUptodate(page);
unlock_page(page);
return 0;
}
static void nfs_readpage_truncate_uninitialised_page(struct nfs_read_data *data)
{
unsigned int remainder = data->args.count - data->res.count;
unsigned int base = data->args.pgbase + data->res.count;
unsigned int pglen;
struct page **pages;
if (data->res.eof == 0 || remainder == 0)
return;
/*
* Note: "remainder" can never be negative, since we check for
* this in the XDR code.
*/
pages = &data->args.pages[base >> PAGE_CACHE_SHIFT];
base &= ~PAGE_CACHE_MASK;
pglen = PAGE_CACHE_SIZE - base;
for (;;) {
if (remainder <= pglen) {
zero_user(*pages, base, remainder);
break;
}
zero_user(*pages, base, pglen);
pages++;
remainder -= pglen;
pglen = PAGE_CACHE_SIZE;
base = 0;
}
}
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(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)
zero_user_segment(page, len, PAGE_CACHE_SIZE);
nfs_list_add_request(new, &one_request);
if (NFS_SERVER(inode)->rsize < PAGE_CACHE_SIZE)
nfs_pagein_multi(inode, &one_request, 1, len, 0);
else
nfs_pagein_one(inode, &one_request, 1, len, 0);
return 0;
}
static void nfs_readpage_release(struct nfs_page *req)
{
unlock_page(req->wb_page);
dprintk("NFS: read done (%s/%Ld %d@%Ld)\n",
req->wb_context->path.dentry->d_inode->i_sb->s_id,
(long long)NFS_FILEID(req->wb_context->path.dentry->d_inode),
req->wb_bytes,
(long long)req_offset(req));
nfs_clear_request(req);
nfs_release_request(req);
}
/*
* Set up the NFS read request struct
*/
static int nfs_read_rpcsetup(struct nfs_page *req, struct nfs_read_data *data,
const struct rpc_call_ops *call_ops,
unsigned int count, unsigned int offset)
{
struct inode *inode = req->wb_context->path.dentry->d_inode;
int swap_flags = IS_SWAPFILE(inode) ? NFS_RPC_SWAPFLAGS : 0;
struct rpc_task *task;
struct rpc_message msg = {
.rpc_argp = &data->args,
.rpc_resp = &data->res,
.rpc_cred = req->wb_context->cred,
};
struct rpc_task_setup task_setup_data = {
.task = &data->task,
.rpc_client = NFS_CLIENT(inode),
.rpc_message = &msg,
.callback_ops = call_ops,
.callback_data = data,
.workqueue = nfsiod_workqueue,
.flags = RPC_TASK_ASYNC | swap_flags,
};
data->req = req;
data->inode = inode;
data->cred = msg.rpc_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 = get_nfs_open_context(req->wb_context);
data->res.fattr = &data->fattr;
data->res.count = count;
data->res.eof = 0;
nfs_fattr_init(&data->fattr);
/* Set up the initial task struct. */
NFS_PROTO(inode)->read_setup(data, &msg);
dprintk("NFS: %5u 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);
task = rpc_run_task(&task_setup_data);
if (IS_ERR(task))
return PTR_ERR(task);
rpc_put_task(task);
return 0;
}
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);
}
}
/*
* 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 inode *inode, struct list_head *head, unsigned int npages, size_t count, int flags)
{
struct nfs_page *req = nfs_list_entry(head->next);
struct page *page = req->wb_page;
struct nfs_read_data *data;
size_t rsize = NFS_SERVER(inode)->rsize, nbytes;
unsigned int offset;
int requests = 0;
int ret = 0;
LIST_HEAD(list);
nfs_list_remove_request(req);
nbytes = count;
do {
size_t len = min(nbytes,rsize);
data = nfs_readdata_alloc(1);
if (!data)
goto out_bad;
list_add(&data->pages, &list);
requests++;
nbytes -= len;
} while(nbytes != 0);
atomic_set(&req->wb_complete, requests);
ClearPageError(page);
offset = 0;
nbytes = count;
do {
int ret2;
data = list_entry(list.next, struct nfs_read_data, pages);
list_del_init(&data->pages);
data->pagevec[0] = page;
if (nbytes < rsize)
rsize = nbytes;
ret2 = nfs_read_rpcsetup(req, data, &nfs_read_partial_ops,
rsize, offset);
if (ret == 0)
ret = ret2;
offset += rsize;
nbytes -= rsize;
} while (nbytes != 0);
return ret;
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 inode *inode, struct list_head *head, unsigned int npages, size_t count, int flags)
{
struct nfs_page *req;
struct page **pages;
struct nfs_read_data *data;
int ret = -ENOMEM;
data = nfs_readdata_alloc(npages);
if (!data)
goto out_bad;
pages = data->pagevec;
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;
}
req = nfs_list_entry(data->pages.next);
return nfs_read_rpcsetup(req, data, &nfs_read_full_ops, count, 0);
out_bad:
nfs_async_read_error(head);
return ret;
}
/*
* This is the callback from RPC telling us whether a reply was
* received or some error occurred (timeout or socket shutdown).
*/
int nfs_readpage_result(struct rpc_task *task, struct nfs_read_data *data)
{
int status;
dprintk("NFS: %s: %5u, (status %d)\n", __func__, task->tk_pid,
task->tk_status);
status = NFS_PROTO(data->inode)->read_done(task, data);
if (status != 0)
return status;
nfs_add_stats(data->inode, NFSIOS_SERVERREADBYTES, data->res.count);
if (task->tk_status == -ESTALE) {
set_bit(NFS_INO_STALE, &NFS_I(data->inode)->flags);
nfs_mark_for_revalidate(data->inode);
}
return 0;
}
static void nfs_readpage_retry(struct rpc_task *task, struct nfs_read_data *data)
{
struct nfs_readargs *argp = &data->args;
struct nfs_readres *resp = &data->res;
if (resp->eof || resp->count == argp->count)
return;
/* This is a short read! */
nfs_inc_stats(data->inode, NFSIOS_SHORTREAD);
/* Has the server at least made some progress? */
if (resp->count == 0)
return;
/* 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);
}
/*
* Handle a read reply that fills part of a page.
*/
static void nfs_readpage_result_partial(struct rpc_task *task, void *calldata)
{
struct nfs_read_data *data = calldata;
if (nfs_readpage_result(task, data) != 0)
return;
if (task->tk_status < 0)
return;
nfs_readpage_truncate_uninitialised_page(data);
nfs_readpage_retry(task, data);
}
static void nfs_readpage_release_partial(void *calldata)
{
struct nfs_read_data *data = calldata;
struct nfs_page *req = data->req;
struct page *page = req->wb_page;
int status = data->task.tk_status;
if (status < 0)
SetPageError(page);
if (atomic_dec_and_test(&req->wb_complete)) {
if (!PageError(page))
SetPageUptodate(page);
nfs_readpage_release(req);
}
nfs_readdata_release(calldata);
}
static const struct rpc_call_ops nfs_read_partial_ops = {
.rpc_call_done = nfs_readpage_result_partial,
.rpc_release = nfs_readpage_release_partial,
};
static void nfs_readpage_set_pages_uptodate(struct nfs_read_data *data)
{
unsigned int count = data->res.count;
unsigned int base = data->args.pgbase;
struct page **pages;
if (data->res.eof)
count = data->args.count;
if (unlikely(count == 0))
return;
pages = &data->args.pages[base >> PAGE_CACHE_SHIFT];
base &= ~PAGE_CACHE_MASK;
count += base;
for (;count >= PAGE_CACHE_SIZE; count -= PAGE_CACHE_SIZE, pages++)
SetPageUptodate(*pages);
if (count == 0)
return;
/* Was this a short read? */
if (data->res.eof || data->res.count == data->args.count)
SetPageUptodate(*pages);
}
/*
* 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 rpc_task *task, void *calldata)
{
struct nfs_read_data *data = calldata;
if (nfs_readpage_result(task, data) != 0)
return;
if (task->tk_status < 0)
return;
/*
* Note: nfs_readpage_retry may change the values of
* data->args. In the multi-page case, we therefore need
* to ensure that we call nfs_readpage_set_pages_uptodate()
* first.
*/
nfs_readpage_truncate_uninitialised_page(data);
nfs_readpage_set_pages_uptodate(data);
nfs_readpage_retry(task, data);
}
static void nfs_readpage_release_full(void *calldata)
{
struct nfs_read_data *data = calldata;
while (!list_empty(&data->pages)) {
struct nfs_page *req = nfs_list_entry(data->pages.next);
nfs_list_remove_request(req);
nfs_readpage_release(req);
}
nfs_readdata_release(calldata);
}
static const struct rpc_call_ops nfs_read_full_ops = {
.rpc_call_done = nfs_readpage_result_full,
.rpc_release = nfs_readpage_release_full,
};
/*
* 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);
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));
error = nfs_readpage_async(ctx, inode, page);
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 inode *inode = page->mapping->host;
struct nfs_page *new;
unsigned int len;
int error;
error = nfs_wb_page(inode, page);
if (error)
goto out_unlock;
if (PageUptodate(page))
goto out_unlock;
len = nfs_page_length(page);
if (len == 0)
return nfs_return_empty_page(page);
new = nfs_create_request(desc->ctx, inode, page, 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);
SetPageError(page);
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_readdesc desc = {
.pgio = &pgio,
};
struct inode *inode = mapping->host;
struct nfs_server *server = NFS_SERVER(inode);
size_t rsize = server->rsize;
unsigned long npages;
int ret = -ESTALE;
dprintk("NFS: nfs_readpages (%s/%Ld %d)\n",
inode->i_sb->s_id,
(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));
if (rsize < PAGE_CACHE_SIZE)
nfs_pageio_init(&pgio, inode, nfs_pagein_multi, rsize, 0);
else
nfs_pageio_init(&pgio, inode, nfs_pagein_one, rsize, 0);
ret = read_cache_pages(mapping, pages, readpage_async_filler, &desc);
nfs_pageio_complete(&pgio);
npages = (pgio.pg_bytes_written + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
nfs_add_stats(inode, NFSIOS_READPAGES, npages);
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_read_data),
0, SLAB_HWCACHE_ALIGN,
NULL);
if (nfs_rdata_cachep == NULL)
return -ENOMEM;
nfs_rdata_mempool = mempool_create_slab_pool(MIN_POOL_READ,
nfs_rdata_cachep);
if (nfs_rdata_mempool == NULL)
return -ENOMEM;
return 0;
}
void nfs_destroy_readpagecache(void)
{
mempool_destroy(nfs_rdata_mempool);
kmem_cache_destroy(nfs_rdata_cachep);
}