linux/fs/nfs/read.c

687 lines
18 KiB
C

/*
* 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"
#define NFSDBG_FACILITY NFSDBG_PAGECACHE
static const struct nfs_pageio_ops nfs_pageio_read_ops;
static const struct rpc_call_ops nfs_read_common_ops;
static const struct nfs_pgio_completion_ops nfs_async_read_completion_ops;
static struct kmem_cache *nfs_rdata_cachep;
struct nfs_read_header *nfs_readhdr_alloc(void)
{
struct nfs_read_header *rhdr;
rhdr = kmem_cache_zalloc(nfs_rdata_cachep, GFP_KERNEL);
if (rhdr) {
struct nfs_pgio_header *hdr = &rhdr->header;
INIT_LIST_HEAD(&hdr->pages);
INIT_LIST_HEAD(&hdr->rpc_list);
spin_lock_init(&hdr->lock);
atomic_set(&hdr->refcnt, 0);
}
return rhdr;
}
EXPORT_SYMBOL_GPL(nfs_readhdr_alloc);
static struct nfs_read_data *nfs_readdata_alloc(struct nfs_pgio_header *hdr,
unsigned int pagecount)
{
struct nfs_read_data *data, *prealloc;
prealloc = &container_of(hdr, struct nfs_read_header, header)->rpc_data;
if (prealloc->header == NULL)
data = prealloc;
else
data = kzalloc(sizeof(*data), GFP_KERNEL);
if (!data)
goto out;
if (nfs_pgarray_set(&data->pages, pagecount)) {
data->header = hdr;
atomic_inc(&hdr->refcnt);
} else {
if (data != prealloc)
kfree(data);
data = NULL;
}
out:
return data;
}
void nfs_readhdr_free(struct nfs_pgio_header *hdr)
{
struct nfs_read_header *rhdr = container_of(hdr, struct nfs_read_header, header);
kmem_cache_free(nfs_rdata_cachep, rhdr);
}
EXPORT_SYMBOL_GPL(nfs_readhdr_free);
void nfs_readdata_release(struct nfs_read_data *rdata)
{
struct nfs_pgio_header *hdr = rdata->header;
struct nfs_read_header *read_header = container_of(hdr, struct nfs_read_header, header);
put_nfs_open_context(rdata->args.context);
if (rdata->pages.pagevec != rdata->pages.page_array)
kfree(rdata->pages.pagevec);
if (rdata == &read_header->rpc_data) {
rdata->header = NULL;
rdata = NULL;
}
if (atomic_dec_and_test(&hdr->refcnt))
hdr->completion_ops->completion(hdr);
/* Note: we only free the rpc_task after callbacks are done.
* See the comment in rpc_free_task() for why
*/
kfree(rdata);
}
EXPORT_SYMBOL_GPL(nfs_readdata_release);
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,
const struct nfs_pgio_completion_ops *compl_ops)
{
nfs_pageio_init(pgio, inode, &nfs_pageio_read_ops, compl_ops,
NFS_SERVER(inode)->rsize, 0);
}
EXPORT_SYMBOL_GPL(nfs_pageio_init_read);
void nfs_pageio_reset_read_mds(struct nfs_pageio_descriptor *pgio)
{
pgio->pg_ops = &nfs_pageio_read_ops;
pgio->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;
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_PROTO(inode)->read_pageio_init(&pgio, inode, &nfs_async_read_completion_ops);
nfs_pageio_add_request(&pgio, new);
nfs_pageio_complete(&pgio);
NFS_I(inode)->read_io += pgio.pg_bytes_written;
return 0;
}
static void nfs_readpage_release(struct nfs_page *req)
{
struct inode *d_inode = req->wb_context->dentry->d_inode;
if (PageUptodate(req->wb_page))
nfs_readpage_to_fscache(d_inode, req->wb_page, 0);
unlock_page(req->wb_page);
dprintk("NFS: read done (%s/%Lu %d@%Ld)\n",
req->wb_context->dentry->d_inode->i_sb->s_id,
(unsigned long long)NFS_FILEID(req->wb_context->dentry->d_inode),
req->wb_bytes,
(long long)req_offset(req));
nfs_release_request(req);
}
/* Note io was page aligned */
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;
if (test_bit(NFS_IOHDR_EOF, &hdr->flags)) {
if (bytes > hdr->good_bytes)
zero_user(page, 0, PAGE_SIZE);
else if (hdr->good_bytes - bytes < PAGE_SIZE)
zero_user_segment(page,
hdr->good_bytes & ~PAGE_MASK,
PAGE_SIZE);
}
bytes += req->wb_bytes;
if (test_bit(NFS_IOHDR_ERROR, &hdr->flags)) {
if (bytes <= hdr->good_bytes)
SetPageUptodate(page);
} else
SetPageUptodate(page);
nfs_list_remove_request(req);
nfs_readpage_release(req);
}
out:
hdr->release(hdr);
}
int nfs_initiate_read(struct rpc_clnt *clnt,
struct nfs_read_data *data,
const struct rpc_call_ops *call_ops, int flags)
{
struct inode *inode = data->header->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 = data->header->cred,
};
struct rpc_task_setup task_setup_data = {
.task = &data->task,
.rpc_client = clnt,
.rpc_message = &msg,
.callback_ops = call_ops,
.callback_data = data,
.workqueue = nfsiod_workqueue,
.flags = RPC_TASK_ASYNC | swap_flags | flags,
};
/* Set up the initial task struct. */
NFS_PROTO(inode)->read_setup(data, &msg);
dprintk("NFS: %5u initiated read call (req %s/%llu, %u bytes @ "
"offset %llu)\n",
data->task.tk_pid,
inode->i_sb->s_id,
(unsigned long long)NFS_FILEID(inode),
data->args.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;
}
EXPORT_SYMBOL_GPL(nfs_initiate_read);
/*
* Set up the NFS read request struct
*/
static void nfs_read_rpcsetup(struct nfs_read_data *data,
unsigned int count, unsigned int offset)
{
struct nfs_page *req = data->header->req;
data->args.fh = NFS_FH(data->header->inode);
data->args.offset = req_offset(req) + offset;
data->args.pgbase = req->wb_pgbase + offset;
data->args.pages = data->pages.pagevec;
data->args.count = count;
data->args.context = get_nfs_open_context(req->wb_context);
data->args.lock_context = req->wb_lock_context;
data->res.fattr = &data->fattr;
data->res.count = count;
data->res.eof = 0;
nfs_fattr_init(&data->fattr);
}
static int nfs_do_read(struct nfs_read_data *data,
const struct rpc_call_ops *call_ops)
{
struct inode *inode = data->header->inode;
return nfs_initiate_read(NFS_CLIENT(inode), data, call_ops, 0);
}
static int
nfs_do_multiple_reads(struct list_head *head,
const struct rpc_call_ops *call_ops)
{
struct nfs_read_data *data;
int ret = 0;
while (!list_empty(head)) {
int ret2;
data = list_first_entry(head, struct nfs_read_data, list);
list_del_init(&data->list);
ret2 = nfs_do_read(data, call_ops);
if (ret == 0)
ret = ret2;
}
return ret;
}
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,
};
static void nfs_pagein_error(struct nfs_pageio_descriptor *desc,
struct nfs_pgio_header *hdr)
{
set_bit(NFS_IOHDR_REDO, &hdr->flags);
while (!list_empty(&hdr->rpc_list)) {
struct nfs_read_data *data = list_first_entry(&hdr->rpc_list,
struct nfs_read_data, list);
list_del(&data->list);
nfs_readdata_release(data);
}
desc->pg_completion_ops->error_cleanup(&desc->pg_list);
}
/*
* 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 nfs_pageio_descriptor *desc,
struct nfs_pgio_header *hdr)
{
struct nfs_page *req = hdr->req;
struct page *page = req->wb_page;
struct nfs_read_data *data;
size_t rsize = desc->pg_bsize, nbytes;
unsigned int offset;
offset = 0;
nbytes = desc->pg_count;
do {
size_t len = min(nbytes,rsize);
data = nfs_readdata_alloc(hdr, 1);
if (!data) {
nfs_pagein_error(desc, hdr);
return -ENOMEM;
}
data->pages.pagevec[0] = page;
nfs_read_rpcsetup(data, len, offset);
list_add(&data->list, &hdr->rpc_list);
nbytes -= len;
offset += len;
} while (nbytes != 0);
nfs_list_remove_request(req);
nfs_list_add_request(req, &hdr->pages);
desc->pg_rpc_callops = &nfs_read_common_ops;
return 0;
}
static int nfs_pagein_one(struct nfs_pageio_descriptor *desc,
struct nfs_pgio_header *hdr)
{
struct nfs_page *req;
struct page **pages;
struct nfs_read_data *data;
struct list_head *head = &desc->pg_list;
data = nfs_readdata_alloc(hdr, nfs_page_array_len(desc->pg_base,
desc->pg_count));
if (!data) {
nfs_pagein_error(desc, hdr);
return -ENOMEM;
}
pages = data->pages.pagevec;
while (!list_empty(head)) {
req = nfs_list_entry(head->next);
nfs_list_remove_request(req);
nfs_list_add_request(req, &hdr->pages);
*pages++ = req->wb_page;
}
nfs_read_rpcsetup(data, desc->pg_count, 0);
list_add(&data->list, &hdr->rpc_list);
desc->pg_rpc_callops = &nfs_read_common_ops;
return 0;
}
int nfs_generic_pagein(struct nfs_pageio_descriptor *desc,
struct nfs_pgio_header *hdr)
{
if (desc->pg_bsize < PAGE_CACHE_SIZE)
return nfs_pagein_multi(desc, hdr);
return nfs_pagein_one(desc, hdr);
}
EXPORT_SYMBOL_GPL(nfs_generic_pagein);
static int nfs_generic_pg_readpages(struct nfs_pageio_descriptor *desc)
{
struct nfs_read_header *rhdr;
struct nfs_pgio_header *hdr;
int ret;
rhdr = nfs_readhdr_alloc();
if (!rhdr) {
desc->pg_completion_ops->error_cleanup(&desc->pg_list);
return -ENOMEM;
}
hdr = &rhdr->header;
nfs_pgheader_init(desc, hdr, nfs_readhdr_free);
atomic_inc(&hdr->refcnt);
ret = nfs_generic_pagein(desc, hdr);
if (ret == 0)
ret = nfs_do_multiple_reads(&hdr->rpc_list,
desc->pg_rpc_callops);
if (atomic_dec_and_test(&hdr->refcnt))
hdr->completion_ops->completion(hdr);
return ret;
}
static const struct nfs_pageio_ops nfs_pageio_read_ops = {
.pg_test = nfs_generic_pg_test,
.pg_doio = nfs_generic_pg_readpages,
};
/*
* 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 inode *inode = data->header->inode;
int status;
dprintk("NFS: %s: %5u, (status %d)\n", __func__, task->tk_pid,
task->tk_status);
status = NFS_PROTO(inode)->read_done(task, data);
if (status != 0)
return status;
nfs_add_stats(inode, NFSIOS_SERVERREADBYTES, data->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_read_data *data)
{
struct nfs_readargs *argp = &data->args;
struct nfs_readres *resp = &data->res;
/* This is a short read! */
nfs_inc_stats(data->header->inode, NFSIOS_SHORTREAD);
/* Has the server at least made some progress? */
if (resp->count == 0) {
nfs_set_pgio_error(data->header, -EIO, argp->offset);
return;
}
/* Yes, so retry the read at the end of the data */
data->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_common(struct rpc_task *task, void *calldata)
{
struct nfs_read_data *data = calldata;
struct nfs_pgio_header *hdr = data->header;
/* Note the only returns of nfs_readpage_result are 0 and -EAGAIN */
if (nfs_readpage_result(task, data) != 0)
return;
if (task->tk_status < 0)
nfs_set_pgio_error(hdr, task->tk_status, data->args.offset);
else if (data->res.eof) {
loff_t bound;
bound = data->args.offset + data->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 (data->res.count != data->args.count)
nfs_readpage_retry(task, data);
}
static void nfs_readpage_release_common(void *calldata)
{
nfs_readdata_release(calldata);
}
void nfs_read_prepare(struct rpc_task *task, void *calldata)
{
struct nfs_read_data *data = calldata;
int err;
err = NFS_PROTO(data->header->inode)->read_rpc_prepare(task, data);
if (err)
rpc_exit(task, err);
}
static const struct rpc_call_ops nfs_read_common_ops = {
.rpc_call_prepare = nfs_read_prepare,
.rpc_call_done = nfs_readpage_result_common,
.rpc_release = nfs_readpage_release_common,
};
/*
* 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 inode *inode = page_file_mapping(page)->host;
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, 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);
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;
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_PROTO(inode)->read_pageio_init(&pgio, inode, &nfs_async_read_completion_ops);
ret = read_cache_pages(mapping, pages, readpage_async_filler, &desc);
nfs_pageio_complete(&pgio);
NFS_I(inode)->read_io += pgio.pg_bytes_written;
npages = (pgio.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_read_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);
}