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OpenCloudOS-Kernel/fs/nfs/read.c

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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
*
* 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/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 "iostat.h"
#define NFSDBG_FACILITY NFSDBG_PAGECACHE
static int nfs_pagein_one(struct list_head *, struct inode *);
static const struct rpc_call_ops nfs_read_partial_ops;
static const struct rpc_call_ops nfs_read_full_ops;
static kmem_cache_t *nfs_rdata_cachep;
static mempool_t *nfs_rdata_mempool;
#define MIN_POOL_READ (32)
struct nfs_read_data *nfs_readdata_alloc(size_t len)
{
unsigned int pagecount = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
struct nfs_read_data *p = mempool_alloc(nfs_rdata_mempool, SLAB_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)
{
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;
}
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) {
memclear_highpage_flush(*pages, base, remainder);
break;
}
memclear_highpage_flush(*pages, base, pglen);
pages++;
remainder -= pglen;
pglen = PAGE_CACHE_SIZE;
base = 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(count);
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)->nfs_client->cl_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;
nfs_add_stats(inode, NFSIOS_SERVERREADBYTES, 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);
spin_lock(&inode->i_lock);
NFS_I(inode)->cache_validity |= NFS_INO_INVALID_ATIME;
spin_unlock(&inode->i_lock);
if (rdata->res.eof || rdata->res.count == rdata->args.count) {
SetPageUptodate(page);
if (rdata->res.eof && count != 0)
memclear_highpage_flush(page, rdata->args.pgbase, count);
}
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_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);
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));
nfs_clear_request(req);
nfs_release_request(req);
}
/*
* Set up the NFS read request struct
*/
static void 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;
int flags;
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_fattr_init(&data->fattr);
/* Set up the initial task struct. */
flags = RPC_TASK_ASYNC | (IS_SWAPFILE(inode)? NFS_RPC_SWAPFLAGS : 0);
rpc_init_task(&data->task, NFS_CLIENT(inode), flags, call_ops, data);
NFS_PROTO(inode)->read_setup(data);
data->task.tk_cookie = (unsigned long)inode;
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;
size_t rsize = NFS_SERVER(inode)->rsize, nbytes;
unsigned int offset;
int requests = 0;
LIST_HEAD(list);
nfs_list_remove_request(req);
nbytes = req->wb_bytes;
do {
size_t len = min(nbytes,rsize);
data = nfs_readdata_alloc(len);
if (!data)
goto out_bad;
INIT_LIST_HEAD(&data->pages);
list_add(&data->pages, &list);
requests++;
nbytes -= len;
} while(nbytes != 0);
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;
if (nbytes > rsize) {
nfs_read_rpcsetup(req, data, &nfs_read_partial_ops,
rsize, offset);
offset += rsize;
nbytes -= rsize;
} else {
nfs_read_rpcsetup(req, data, &nfs_read_partial_ops,
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(NFS_SERVER(inode)->rsize);
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);
nfs_read_rpcsetup(req, data, &nfs_read_full_ops, 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 rpc_task *task, void *calldata)
{
struct nfs_read_data *data = calldata;
struct nfs_page *req = data->req;
struct page *page = req->wb_page;
if (likely(task->tk_status >= 0))
nfs_readpage_truncate_uninitialised_page(data);
else
SetPageError(page);
if (nfs_readpage_result(task, data) != 0)
return;
if (atomic_dec_and_test(&req->wb_complete)) {
if (!PageError(page))
SetPageUptodate(page);
nfs_readpage_release(req);
}
}
static const struct rpc_call_ops nfs_read_partial_ops = {
.rpc_call_done = nfs_readpage_result_partial,
.rpc_release = nfs_readdata_release,
};
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)
SetPageUptodate(*pages);
}
static void nfs_readpage_set_pages_error(struct nfs_read_data *data)
{
unsigned int count = data->args.count;
unsigned int base = data->args.pgbase;
struct page **pages;
pages = &data->args.pages[base >> PAGE_CACHE_SHIFT];
base &= ~PAGE_CACHE_MASK;
count += base;
for (;count >= PAGE_CACHE_SIZE; count -= PAGE_CACHE_SIZE, pages++)
SetPageError(*pages);
if (count != 0)
SetPageError(*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;
/*
* Note: nfs_readpage_result may change the values of
* data->args. In the multi-page case, we therefore need
* to ensure that we call the next nfs_readpage_set_page_uptodate()
* first in the multi-page case.
*/
if (likely(task->tk_status >= 0)) {
nfs_readpage_truncate_uninitialised_page(data);
nfs_readpage_set_pages_uptodate(data);
} else
nfs_readpage_set_pages_error(data);
if (nfs_readpage_result(task, data) != 0)
return;
while (!list_empty(&data->pages)) {
struct nfs_page *req = nfs_list_entry(data->pages.next);
nfs_list_remove_request(req);
nfs_readpage_release(req);
}
}
static const struct rpc_call_ops nfs_read_full_ops = {
.rpc_call_done = nfs_readpage_result_full,
.rpc_release = nfs_readdata_release,
};
/*
* 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)
{
struct nfs_readargs *argp = &data->args;
struct nfs_readres *resp = &data->res;
int status;
dprintk("NFS: %4d nfs_readpage_result, (status %d)\n",
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, resp->count);
/* Is this a short read? */
if (task->tk_status >= 0 && resp->count < argp->count && !resp->eof) {
nfs_inc_stats(data->inode, NFSIOS_SHORTREAD);
/* 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 -EAGAIN;
}
task->tk_status = -EIO;
}
spin_lock(&data->inode->i_lock);
NFS_I(data->inode)->cache_validity |= NFS_INO_INVALID_ATIME;
spin_unlock(&data->inode->i_lock);
return 0;
}
/*
* 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_error;
if (file == NULL) {
ctx = nfs_find_open_context(inode, NULL, 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_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);
nfs_inc_stats(inode, NFSIOS_VFSREADPAGES);
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((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)
nfs_add_stats(inode, NFSIOS_READPAGES, err);
ret = err;
}
put_nfs_open_context(desc.ctx);
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, 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);
if (kmem_cache_destroy(nfs_rdata_cachep))
printk(KERN_INFO "nfs_read_data: not all structures were freed\n");
}
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