- 根目录:
- fs
- nfs
- pagelist.c
/*
* linux/fs/nfs/pagelist.c
*
* A set of helper functions for managing NFS read and write requests.
* The main purpose of these routines is to provide support for the
* coalescing of several requests into a single RPC call.
*
* Copyright 2000, 2001 (c) Trond Myklebust <trond.myklebust@fys.uio.no>
*
*/
#include <linux/slab.h>
#include <linux/file.h>
#include <linux/sched.h>
#include <linux/sunrpc/clnt.h>
#include <linux/nfs.h>
#include <linux/nfs3.h>
#include <linux/nfs4.h>
#include <linux/nfs_page.h>
#include <linux/nfs_fs.h>
#include <linux/nfs_mount.h>
#include <linux/export.h>
#include "internal.h"
#include "pnfs.h"
#define NFSDBG_FACILITY NFSDBG_PAGECACHE
static struct kmem_cache *nfs_page_cachep;
static const struct rpc_call_ops nfs_pgio_common_ops;
static bool nfs_pgarray_set(struct nfs_page_array *p, unsigned int pagecount)
{
p->npages = pagecount;
if (pagecount <= ARRAY_SIZE(p->page_array))
p->pagevec = p->page_array;
else {
p->pagevec = kcalloc(pagecount, sizeof(struct page *), GFP_KERNEL);
if (!p->pagevec)
p->npages = 0;
}
return p->pagevec != NULL;
}
void nfs_pgheader_init(struct nfs_pageio_descriptor *desc,
struct nfs_pgio_header *hdr,
void (*release)(struct nfs_pgio_header *hdr))
{
hdr->req = nfs_list_entry(desc->pg_list.next);
hdr->inode = desc->pg_inode;
hdr->cred = hdr->req->wb_context->cred;
hdr->io_start = req_offset(hdr->req);
hdr->good_bytes = desc->pg_count;
hdr->dreq = desc->pg_dreq;
hdr->layout_private = desc->pg_layout_private;
hdr->release = release;
hdr->completion_ops = desc->pg_completion_ops;
if (hdr->completion_ops->init_hdr)
hdr->completion_ops->init_hdr(hdr);
}
EXPORT_SYMBOL_GPL(nfs_pgheader_init);
void nfs_set_pgio_error(struct nfs_pgio_header *hdr, int error, loff_t pos)
{
spin_lock(&hdr->lock);
if (pos < hdr->io_start + hdr->good_bytes) {
set_bit(NFS_IOHDR_ERROR, &hdr->flags);
clear_bit(NFS_IOHDR_EOF, &hdr->flags);
hdr->good_bytes = pos - hdr->io_start;
hdr->error = error;
}
spin_unlock(&hdr->lock);
}
static inline struct nfs_page *
nfs_page_alloc(void)
{
struct nfs_page *p = kmem_cache_zalloc(nfs_page_cachep, GFP_NOIO);
if (p)
INIT_LIST_HEAD(&p->wb_list);
return p;
}
static inline void
nfs_page_free(struct nfs_page *p)
{
kmem_cache_free(nfs_page_cachep, p);
}
static void
nfs_iocounter_inc(struct nfs_io_counter *c)
{
atomic_inc(&c->io_count);
}
static void
nfs_iocounter_dec(struct nfs_io_counter *c)
{
if (atomic_dec_and_test(&c->io_count)) {
clear_bit(NFS_IO_INPROGRESS, &c->flags);
smp_mb__after_atomic();
wake_up_bit(&c->flags, NFS_IO_INPROGRESS);
}
}
static int
__nfs_iocounter_wait(struct nfs_io_counter *c)
{
wait_queue_head_t *wq = bit_waitqueue(&c->flags, NFS_IO_INPROGRESS);
DEFINE_WAIT_BIT(q, &c->flags, NFS_IO_INPROGRESS);
int ret = 0;
do {
prepare_to_wait(wq, &q.wait, TASK_KILLABLE);
set_bit(NFS_IO_INPROGRESS, &c->flags);
if (atomic_read(&c->io_count) == 0)
break;
ret = nfs_wait_bit_killable(&q.key);
} while (atomic_read(&c->io_count) != 0 && !ret);
finish_wait(wq, &q.wait);
return ret;
}
/**
* nfs_iocounter_wait - wait for i/o to complete
* @c: nfs_io_counter to use
*
* returns -ERESTARTSYS if interrupted by a fatal signal.
* Otherwise returns 0 once the io_count hits 0.
*/
int
nfs_iocounter_wait(struct nfs_io_counter *c)
{
if (atomic_read(&c->io_count) == 0)
return 0;
return __nfs_iocounter_wait(c);
}
/*
* nfs_page_group_lock - lock the head of the page group
* @req - request in group that is to be locked
* @nonblock - if true don't block waiting for lock
*
* this lock must be held if modifying the page group list
*
* return 0 on success, < 0 on error: -EDELAY if nonblocking or the
* result from wait_on_bit_lock
*
* NOTE: calling with nonblock=false should always have set the
* lock bit (see fs/buffer.c and other uses of wait_on_bit_lock
* with TASK_UNINTERRUPTIBLE), so there is no need to check the result.
*/
int
nfs_page_group_lock(struct nfs_page *req, bool nonblock)
{
struct nfs_page *head = req->wb_head;
WARN_ON_ONCE(head != head->wb_head);
if (!test_and_set_bit(PG_HEADLOCK, &head->wb_flags))
return 0;
if (!nonblock)
return wait_on_bit_lock(&head->wb_flags, PG_HEADLOCK,
TASK_UNINTERRUPTIBLE);
return -EAGAIN;
}
/*
* nfs_page_group_lock_wait - wait for the lock to clear, but don't grab it
* @req - a request in the group
*
* This is a blocking call to wait for the group lock to be cleared.
*/
void
nfs_page_group_lock_wait(struct nfs_page *req)
{
struct nfs_page *head = req->wb_head;
WARN_ON_ONCE(head != head->wb_head);
wait_on_bit(&head->wb_flags, PG_HEADLOCK,
TASK_UNINTERRUPTIBLE);
}
/*
* nfs_page_group_unlock - unlock the head of the page group
* @req - request in group that is to be unlocked
*/
void
nfs_page_group_unlock(struct nfs_page *req)
{
struct nfs_page *head = req->wb_head;
WARN_ON_ONCE(head != head->wb_head);
smp_mb__before_atomic();
clear_bit(PG_HEADLOCK, &head->wb_flags);
smp_mb__after_atomic();
wake_up_bit(&head->wb_flags, PG_HEADLOCK);
}
/*
* nfs_page_group_sync_on_bit_locked
*
* must be called with page group lock held
*/
static bool
nfs_page_group_sync_on_bit_locked(struct nfs_page *req, unsigned int bit)
{
struct nfs_page *head = req->wb_head;
struct nfs_page *tmp;
WARN_ON_ONCE(!test_bit(PG_HEADLOCK, &head->wb_flags));
WARN_ON_ONCE(test_and_set_bit(bit, &req->wb_flags));
tmp = req->wb_this_page;
while (tmp != req) {
if (!test_bit(bit, &tmp->wb_flags))
return false;
tmp = tmp->wb_this_page;
}
/* true! reset all bits */
tmp = req;
do {
clear_bit(bit, &tmp->wb_flags);
tmp = tmp->wb_this_page;
} while (tmp != req);
return true;
}
/*
* nfs_page_group_sync_on_bit - set bit on current request, but only
* return true if the bit is set for all requests in page group
* @req - request in page group
* @bit - PG_* bit that is used to sync page group
*/
bool nfs_page_group_sync_on_bit(struct nfs_page *req, unsigned int bit)
{
bool ret;
nfs_page_group_lock(req, false);
ret = nfs_page_group_sync_on_bit_locked(req, bit);
nfs_page_group_unlock(req);
return ret;
}
/*
* nfs_page_group_init - Initialize the page group linkage for @req
* @req - a new nfs request
* @prev - the previous request in page group, or NULL if @req is the first
* or only request in the group (the head).
*/
static inline void
nfs_page_group_init(struct nfs_page *req, struct nfs_page *prev)
{
WARN_ON_ONCE(prev == req);
if (!prev) {
/* a head request */
req->wb_head = req;
req->wb_this_page = req;
} else {
/* a subrequest */
WARN_ON_ONCE(prev->wb_this_page != prev->wb_head);
WARN_ON_ONCE(!test_bit(PG_HEADLOCK, &prev->wb_head->wb_flags));
req->wb_head = prev->wb_head;
req->wb_this_page = prev->wb_this_page;
prev->wb_this_page = req;
/* All subrequests take a ref on the head request until
* nfs_page_group_destroy is called */
kref_get(&req->wb_head->wb_kref);
/* grab extra ref if head request has extra ref from
* the write/commit path to handle handoff between write
* and commit lists */
if (test_bit(PG_INODE_REF, &prev->wb_head->wb_flags)) {
set_bit(PG_INODE_REF, &req->wb_flags);
kref_get(&req->wb_kref);
}
}
}
/*
* nfs_page_group_destroy - sync the destruction of page groups
* @req - request that no longer needs the page group
*
* releases the page group reference from each member once all
* members have called this function.
*/
static void
nfs_page_group_destroy(struct kref *kref)
{
struct nfs_page *req = container_of(kref, struct nfs_page, wb_kref);
struct nfs_page *tmp, *next;
/* subrequests must release the ref on the head request */
if (req->wb_head != req)
nfs_release_request(req->wb_head);
if (!nfs_page_group_sync_on_bit(req, PG_TEARDOWN))
return;
tmp = req;
do {
next = tmp->wb_this_page;
/* unlink and free */
tmp->wb_this_page = tmp;
tmp->wb_head = tmp;
nfs_free_request(tmp);
tmp = next;
} while (tmp != req);
}
/**
* nfs_create_request - Create an NFS read/write request.
* @ctx: open context to use
* @page: page to write
* @last: last nfs request created for this page group or NULL if head
* @offset: starting offset within the page for the write
* @count: number of bytes to read/write
*
* The page must be locked by the caller. This makes sure we never
* create two different requests for the same page.
* User should ensure it is safe to sleep in this function.
*/
struct nfs_page *
nfs_create_request(struct nfs_open_context *ctx, struct page *page,
struct nfs_page *last, unsigned int offset,
unsigned int count)
{
struct nfs_page *req;
struct nfs_lock_context *l_ctx;
if (test_bit(NFS_CONTEXT_BAD, &ctx->flags))
return ERR_PTR(-EBADF);
/* try to allocate the request struct */
req = nfs_page_alloc();
if (req == NULL)
return ERR_PTR(-ENOMEM);
/* get lock context early so we can deal with alloc failures */
l_ctx = nfs_get_lock_context(ctx);
if (IS_ERR(l_ctx)) {
nfs_page_free(req);
return ERR_CAST(l_ctx);
}
req->wb_lock_context = l_ctx;
nfs_iocounter_inc(&l_ctx->io_count);
/* Initialize the request struct. Initially, we assume a
* long write-back delay. This will be adjusted in
* update_nfs_request below if the region is not locked. */
req->wb_page = page;
req->wb_index = page_file_index(page);
page_cache_get(page);
req->wb_offset = offset;
req->wb_pgbase = offset;
req->wb_bytes = count;
req->wb_context = get_nfs_open_context(ctx);
kref_init(&req->wb_kref);
nfs_page_group_init(req, last);
return req;
}
/**
* nfs_unlock_request - Unlock request and wake up sleepers.
* @req:
*/
void nfs_unlock_request(struct nfs_page *req)
{
if (!NFS_WBACK_BUSY(req)) {
printk(KERN_ERR "NFS: Invalid unlock attempted\n");
BUG();
}
smp_mb__before_atomic();
clear_bit(PG_BUSY, &req->wb_flags);
smp_mb__after_atomic();
wake_up_bit(&req->wb_flags, PG_BUSY);
}
/**
* nfs_unlock_and_release_request - Unlock request and release the nfs_page
* @req:
*/
void nfs_unlock_and_release_request(struct nfs_page *req)
{
nfs_unlock_request(req);
nfs_release_request(req);
}
/*
* nfs_clear_request - Free up all resources allocated to the request
* @req:
*
* Release page and open context resources associated with a read/write
* request after it has completed.
*/
static void nfs_clear_request(struct nfs_page *req)
{
struct page *page = req->wb_page;
struct nfs_open_context *ctx = req->wb_context;
struct nfs_lock_context *l_ctx = req->wb_lock_context;
if (page != NULL) {
page_cache_release(page);
req->wb_page = NULL;
}
if (l_ctx != NULL) {
nfs_iocounter_dec(&l_ctx->io_count);
nfs_put_lock_context(l_ctx);
req->wb_lock_context = NULL;
}
if (ctx != NULL) {
put_nfs_open_context(ctx);
req->wb_context = NULL;
}
}
/**
* nfs_release_request - Release the count on an NFS read/write request
* @req: request to release
*
* Note: Should never be called with the spinlock held!
*/
void nfs_free_request(struct nfs_page *req)
{
WARN_ON_ONCE(req->wb_this_page != req);
/* extra debug: make sure no sync bits are still set */
WARN_ON_ONCE(test_bit(PG_TEARDOWN, &req->wb_flags));
WARN_ON_ONCE(test_bit(PG_UNLOCKPAGE, &req->wb_flags));
WARN_ON_ONCE(test_bit(PG_UPTODATE, &req->wb_flags));
WARN_ON_ONCE(test_bit(PG_WB_END, &req->wb_flags));
WARN_ON_ONCE(test_bit(PG_REMOVE, &req->wb_flags));
/* Release struct file and open context */
nfs_clear_request(req);
nfs_page_free(req);
}
void nfs_release_request(struct nfs_page *req)
{
kref_put(&req->wb_kref, nfs_page_group_destroy);
}
/**
* nfs_wait_on_request - Wait for a request to complete.
* @req: request to wait upon.
*
* Interruptible by fatal signals only.
* The user is responsible for holding a count on the request.
*/
int
nfs_wait_on_request(struct nfs_page *req)
{
return wait_on_bit_io(&req->wb_flags, PG_BUSY,
TASK_UNINTERRUPTIBLE);
}
/*
* nfs_generic_pg_test - determine if requests can be coalesced
* @desc: pointer to descriptor
* @prev: previous request in desc, or NULL
* @req: this request
*
* Returns zero if @req can be coalesced into @desc, otherwise it returns
* the size of the request.
*/
size_t nfs_generic_pg_test(struct nfs_pageio_descriptor *desc,
struct nfs_page *prev, struct nfs_page *req)
{
if (desc->pg_count > desc->pg_bsize) {
/* should never happen */
WARN_ON_ONCE(1);
return 0;
}
/*
* Limit the request size so that we can still allocate a page array
* for it without upsetting the slab allocator.
*/
if (((desc->pg_count + req->wb_bytes) >> PAGE_SHIFT) *
sizeof(struct page) > PAGE_SIZE)
return 0;
return min(desc->pg_bsize - desc->pg_count, (size_t)req->wb_bytes);
}
EXPORT_SYMBOL_GPL(nfs_generic_pg_test);
struct nfs_pgio_header *nfs_pgio_header_alloc(const struct nfs_rw_ops *ops)
{
struct nfs_pgio_header *hdr = ops->rw_alloc_header();
if (hdr) {
INIT_LIST_HEAD(&hdr->pages);
spin_lock_init(&hdr->lock);
hdr->rw_ops = ops;
}
return hdr;
}
EXPORT_SYMBOL_GPL(nfs_pgio_header_alloc);
/*
* nfs_pgio_header_free - Free a read or write header
* @hdr: The header to free
*/
void nfs_pgio_header_free(struct nfs_pgio_header *hdr)
{
hdr->rw_ops->rw_free_header(hdr);
}
EXPORT_SYMBOL_GPL(nfs_pgio_header_free);
/**
* nfs_pgio_data_destroy - make @hdr suitable for reuse
*
* Frees memory and releases refs from nfs_generic_pgio, so that it may
* be called again.
*
* @hdr: A header that has had nfs_generic_pgio called
*/
void nfs_pgio_data_destroy(struct nfs_pgio_header *hdr)
{
if (hdr->args.context)
put_nfs_open_context(hdr->args.context);
if (hdr->page_array.pagevec != hdr->page_array.page_array)
kfree(hdr->page_array.pagevec);
}
EXPORT_SYMBOL_GPL(nfs_pgio_data_destroy);
/**
* nfs_pgio_rpcsetup - Set up arguments for a pageio call
* @hdr: The pageio hdr
* @count: Number of bytes to read
* @offset: Initial offset
* @how: How to commit data (writes only)
* @cinfo: Commit information for the call (writes only)
*/
static void nfs_pgio_rpcsetup(struct nfs_pgio_header *hdr,
unsigned int count, unsigned int offset,
int how, struct nfs_commit_info *cinfo)
{
struct nfs_page *req = hdr->req;
/* Set up the RPC argument and reply structs
* NB: take care not to mess about with hdr->commit et al. */
hdr->args.fh = NFS_FH(hdr->inode);
hdr->args.offset = req_offset(req) + offset;
/* pnfs_set_layoutcommit needs this */
hdr->mds_offset = hdr->args.offset;
hdr->args.pgbase = req->wb_pgbase + offset;
hdr->args.pages = hdr->page_array.pagevec;
hdr->args.count = count;
hdr->args.context = get_nfs_open_context(req->wb_context);
hdr->args.lock_context = req->wb_lock_context;
hdr->args.stable = NFS_UNSTABLE;
switch (how & (FLUSH_STABLE | FLUSH_COND_STABLE)) {
case 0:
break;
case FLUSH_COND_STABLE:
if (nfs_reqs_to_commit(cinfo))
break;
default:
hdr->args.stable = NFS_FILE_SYNC;
}
hdr->res.fattr = &hdr->fattr;
hdr->res.count = count;
hdr->res.eof = 0;
hdr->res.verf = &hdr->verf;
nfs_fattr_init(&hdr->fattr);
}
/**
* nfs_pgio_prepare - Prepare pageio hdr to go over the wire
* @task: The current task
* @calldata: pageio header to prepare
*/
static void nfs_pgio_prepare(struct rpc_task *task, void *calldata)
{
struct nfs_pgio_header *hdr = calldata;
int err;
err = NFS_PROTO(hdr->inode)->pgio_rpc_prepare(task, hdr);
if (err)
rpc_exit(task, err);
}
int nfs_initiate_pgio(struct rpc_clnt *clnt, struct nfs_pgio_header *hdr,
const struct rpc_call_ops *call_ops, int how, int flags)
{
struct rpc_task *task;
struct rpc_message msg = {
.rpc_argp = &hdr->args,
.rpc_resp = &hdr->res,
.rpc_cred = hdr->cred,
};
struct rpc_task_setup task_setup_data = {
.rpc_client = clnt,
.task = &hdr->task,
.rpc_message = &msg,
.callback_ops = call_ops,
.callback_data = hdr,
.workqueue = nfsiod_workqueue,
.flags = RPC_TASK_ASYNC | flags,
};
int ret = 0;
hdr->rw_ops->rw_initiate(hdr, &msg, &task_setup_data, how);
dprintk("NFS: %5u initiated pgio call "
"(req %s/%llu, %u bytes @ offset %llu)\n",
hdr->task.tk_pid,
hdr->inode->i_sb->s_id,
(unsigned long long)NFS_FILEID(hdr->inode),
hdr->args.count,
(unsigned long long)hdr->args.offset);
task = rpc_run_task(&task_setup_data);
if (IS_ERR(task)) {
ret = PTR_ERR(task);
goto out;
}
if (how & FLUSH_SYNC) {
ret = rpc_wait_for_completion_task(task);
if (ret == 0)
ret = task->tk_status;
}
rpc_put_task(task);
out:
return ret;
}
EXPORT_SYMBOL_GPL(nfs_initiate_pgio);
/**
* nfs_pgio_error - Clean up from a pageio error
* @desc: IO descriptor
* @hdr: pageio header
*/
static int nfs_pgio_error(struct nfs_pageio_descriptor *desc,
struct nfs_pgio_header *hdr)
{
set_bit(NFS_IOHDR_REDO, &hdr->flags);
nfs_pgio_data_destroy(hdr);
hdr->completion_ops->completion(hdr);
desc->pg_completion_ops->error_cleanup(&desc->pg_list);
return -ENOMEM;
}
/**
* nfs_pgio_release - Release pageio data
* @calldata: The pageio header to release
*/
static void nfs_pgio_release(void *calldata)
{
struct nfs_pgio_header *hdr = calldata;
if (hdr->rw_ops->rw_release)
hdr->rw_ops->rw_release(hdr);
nfs_pgio_data_destroy(hdr);
hdr->completion_ops->completion(hdr);
}
/**
* nfs_pageio_init - initialise a page io descriptor
* @desc: pointer to descriptor
* @inode: pointer to inode
* @doio: pointer to io function
* @bsize: io block size
* @io_flags: extra parameters for the io function
*/
void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
struct inode *inode,
const struct nfs_pageio_ops *pg_ops,
const struct nfs_pgio_completion_ops *compl_ops,
const struct nfs_rw_ops *rw_ops,
size_t bsize,
int io_flags)
{
INIT_LIST_HEAD(&desc->pg_list);
desc->pg_bytes_written = 0;
desc->pg_count = 0;
desc->pg_bsize = bsize;
desc->pg_base = 0;
desc->pg_moreio = 0;
desc->pg_recoalesce = 0;
desc->pg_inode = inode;
desc->pg_ops = pg_ops;
desc->pg_completion_ops = compl_ops;
desc->pg_rw_ops = rw_ops;
desc->pg_ioflags = io_flags;
desc->pg_error = 0;
desc->pg_lseg = NULL;
desc->pg_dreq = NULL;
desc->pg_layout_private = NULL;
}
EXPORT_SYMBOL_GPL(nfs_pageio_init);
/**
* nfs_pgio_result - Basic pageio error handling
* @task: The task that ran
* @calldata: Pageio header to check
*/
static void nfs_pgio_result(struct rpc_task *task, void *calldata)
{
struct nfs_pgio_header *hdr = calldata;
struct inode *inode = hdr->inode;
dprintk("NFS: %s: %5u, (status %d)\n", __func__,
task->tk_pid, task->tk_status);
if (hdr->rw_ops->rw_done(task, hdr, inode) != 0)
return;
if (task->tk_status < 0)
nfs_set_pgio_error(hdr, task->tk_status, hdr->args.offset);
else
hdr->rw_ops->rw_result(task, hdr);
}
/*
* Create an RPC task for the given read or write request and kick it.
* The page must have been locked by the caller.
*
* It may happen that the page we're passed is not marked dirty.
* This is the case if nfs_updatepage detects a conflicting request
* that has been written but not committed.
*/
int nfs_generic_pgio(struct nfs_pageio_descriptor *desc,
struct nfs_pgio_header *hdr)
{
struct nfs_page *req;
struct page **pages,
*last_page;
struct list_head *head = &desc->pg_list;
struct nfs_commit_info cinfo;
unsigned int pagecount, pageused;
pagecount = nfs_page_array_len(desc->pg_base, desc->pg_count);
if (!nfs_pgarray_set(&hdr->page_array, pagecount))
return nfs_pgio_error(desc, hdr);
nfs_init_cinfo(&cinfo, desc->pg_inode, desc->pg_dreq);
pages = hdr->page_array.pagevec;
last_page = NULL;
pageused = 0;
while (!list_empty(head)) {
req = nfs_list_entry(head->next);
nfs_list_remove_request(req);
nfs_list_add_request(req, &hdr->pages);
if (!last_page || last_page != req->wb_page) {
pageused++;
if (pageused > pagecount)
break;
*pages++ = last_page = req->wb_page;
}
}
if (WARN_ON_ONCE(pageused != pagecount))
return nfs_pgio_error(desc, hdr);
if ((desc->pg_ioflags & FLUSH_COND_STABLE) &&
(desc->pg_moreio || nfs_reqs_to_commit(&cinfo)))
desc->pg_ioflags &= ~FLUSH_COND_STABLE;
/* Set up the argument struct */
nfs_pgio_rpcsetup(hdr, desc->pg_count, 0, desc->pg_ioflags, &cinfo);
desc->pg_rpc_callops = &nfs_pgio_common_ops;
return 0;
}
EXPORT_SYMBOL_GPL(nfs_generic_pgio);
static int nfs_generic_pg_pgios(struct nfs_pageio_descriptor *desc)
{
struct nfs_pgio_header *hdr;
int ret;
hdr = nfs_pgio_header_alloc(desc->pg_rw_ops);
if (!hdr) {
desc->pg_completion_ops->error_cleanup(&desc->pg_list);
return -ENOMEM;
}
nfs_pgheader_init(desc, hdr, nfs_pgio_header_free);
ret = nfs_generic_pgio(desc, hdr);
if (ret == 0)
ret = nfs_initiate_pgio(NFS_CLIENT(hdr->inode),
hdr, desc->pg_rpc_callops,
desc->pg_ioflags, 0);
return ret;
}
static bool nfs_match_open_context(const struct nfs_open_context *ctx1,
const struct nfs_open_context *ctx2)
{
return ctx1->cred == ctx2->cred && ctx1->state == ctx2->state;
}
static bool nfs_match_lock_context(const struct nfs_lock_context *l1,
const struct nfs_lock_context *l2)
{
return l1->lockowner.l_owner == l2->lockowner.l_owner
&& l1->lockowner.l_pid == l2->lockowner.l_pid;
}
/**
* nfs_can_coalesce_requests - test two requests for compatibility
* @prev: pointer to nfs_page
* @req: pointer to nfs_page
*
* The nfs_page structures 'prev' and 'req' are compared to ensure that the
* page data area they describe is contiguous, and that their RPC
* credentials, NFSv4 open state, and lockowners are the same.
*
* Return 'true' if this is the case, else return 'false'.
*/
static bool nfs_can_coalesce_requests(struct nfs_page *prev,
struct nfs_page *req,
struct nfs_pageio_descriptor *pgio)
{
size_t size;
if (prev) {
if (!nfs_match_open_context(req->wb_context, prev->wb_context))
return false;
if (req->wb_context->dentry->d_inode->i_flock != NULL &&
!nfs_match_lock_context(req->wb_lock_context,
prev->wb_lock_context))
return false;
if (req_offset(req) != req_offset(prev) + prev->wb_bytes)
return false;
if (req->wb_page == prev->wb_page) {
if (req->wb_pgbase != prev->wb_pgbase + prev->wb_bytes)
return false;
} else {
if (req->wb_pgbase != 0 ||
prev->wb_pgbase + prev->wb_bytes != PAGE_CACHE_SIZE)
return false;
}
}
size = pgio->pg_ops->pg_test(pgio, prev, req);
WARN_ON_ONCE(size > req->wb_bytes);
if (size && size < req->wb_bytes)
req->wb_bytes = size;
return size > 0;
}
/**
* nfs_pageio_do_add_request - Attempt to coalesce a request into a page list.
* @desc: destination io descriptor
* @req: request
*
* Returns true if the request 'req' was successfully coalesced into the
* existing list of pages 'desc'.
*/
static int nfs_pageio_do_add_request(struct nfs_pageio_descriptor *desc,
struct nfs_page *req)
{
struct nfs_page *prev = NULL;
if (desc->pg_count != 0) {
prev = nfs_list_entry(desc->pg_list.prev);
} else {
if (desc->pg_ops->pg_init)
desc->pg_ops->pg_init(desc, req);
desc->pg_base = req->wb_pgbase;
}
if (!nfs_can_coalesce_requests(prev, req, desc))
return 0;
nfs_list_remove_request(req);
nfs_list_add_request(req, &desc->pg_list);
desc->pg_count += req->wb_bytes;
return 1;
}
/*
* Helper for nfs_pageio_add_request and nfs_pageio_complete
*/
static void nfs_pageio_doio(struct nfs_pageio_descriptor *desc)
{
if (!list_empty(&desc->pg_list)) {
int error = desc->pg_ops->pg_doio(desc);
if (error < 0)
desc->pg_error = error;
else
desc->pg_bytes_written += desc->pg_count;
}
if (list_empty(&desc->pg_list)) {
desc->pg_count = 0;
desc->pg_base = 0;
}
}
/**
* nfs_pageio_add_request - Attempt to coalesce a request into a page list.
* @desc: destination io descriptor
* @req: request
*
* This may split a request into subrequests which are all part of the
* same page group.
*
* Returns true if the request 'req' was successfully coalesced into the
* existing list of pages 'desc'.
*/
static int __nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
struct nfs_page *req)
{
struct nfs_page *subreq;
unsigned int bytes_left = 0;
unsigned int offset, pgbase;
nfs_page_group_lock(req, false);
subreq = req;
bytes_left = subreq->wb_bytes;
offset = subreq->wb_offset;
pgbase = subreq->wb_pgbase;
do {
if (!nfs_pageio_do_add_request(desc, subreq)) {
/* make sure pg_test call(s) did nothing */
WARN_ON_ONCE(subreq->wb_bytes != bytes_left);
WARN_ON_ONCE(subreq->wb_offset != offset);
WARN_ON_ONCE(subreq->wb_pgbase != pgbase);
nfs_page_group_unlock(req);
desc->pg_moreio = 1;
nfs_pageio_doio(desc);
if (desc->pg_error < 0)
return 0;
if (desc->pg_recoalesce)
return 0;
/* retry add_request for this subreq */
nfs_page_group_lock(req, false);
continue;
}
/* check for buggy pg_test call(s) */
WARN_ON_ONCE(subreq->wb_bytes + subreq->wb_pgbase > PAGE_SIZE);
WARN_ON_ONCE(subreq->wb_bytes > bytes_left);
WARN_ON_ONCE(subreq->wb_bytes == 0);
bytes_left -= subreq->wb_bytes;
offset += subreq->wb_bytes;
pgbase += subreq->wb_bytes;
if (bytes_left) {
subreq = nfs_create_request(req->wb_context,
req->wb_page,
subreq, pgbase, bytes_left);
if (IS_ERR(subreq))
goto err_ptr;
nfs_lock_request(subreq);
subreq->wb_offset = offset;
subreq->wb_index = req->wb_index;
}
} while (bytes_left > 0);
nfs_page_group_unlock(req);
return 1;
err_ptr:
desc->pg_error = PTR_ERR(subreq);
nfs_page_group_unlock(req);
return 0;
}
static int nfs_do_recoalesce(struct nfs_pageio_descriptor *desc)
{
LIST_HEAD(head);
do {
list_splice_init(&desc->pg_list, &head);
desc->pg_bytes_written -= desc->pg_count;
desc->pg_count = 0;
desc->pg_base = 0;
desc->pg_recoalesce = 0;
desc->pg_moreio = 0;
while (!list_empty(&head)) {
struct nfs_page *req;
req = list_first_entry(&head, struct nfs_page, wb_list);
nfs_list_remove_request(req);
if (__nfs_pageio_add_request(desc, req))
continue;
if (desc->pg_error < 0)
return 0;
break;
}
} while (desc->pg_recoalesce);
return 1;
}
int nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
struct nfs_page *req)
{
int ret;
do {
ret = __nfs_pageio_add_request(desc, req);
if (ret)
break;
if (desc->pg_error < 0)
break;
ret = nfs_do_recoalesce(desc);
} while (ret);
return ret;
}
/*
* nfs_pageio_resend - Transfer requests to new descriptor and resend
* @hdr - the pgio header to move request from
* @desc - the pageio descriptor to add requests to
*
* Try to move each request (nfs_page) from @hdr to @desc then attempt
* to send them.
*
* Returns 0 on success and < 0 on error.
*/
int nfs_pageio_resend(struct nfs_pageio_descriptor *desc,
struct nfs_pgio_header *hdr)
{
LIST_HEAD(failed);
desc->pg_dreq = hdr->dreq;
while (!list_empty(&hdr->pages)) {
struct nfs_page *req = nfs_list_entry(hdr->pages.next);
nfs_list_remove_request(req);
if (!nfs_pageio_add_request(desc, req))
nfs_list_add_request(req, &failed);
}
nfs_pageio_complete(desc);
if (!list_empty(&failed)) {
list_move(&failed, &hdr->pages);
return -EIO;
}
return 0;
}
EXPORT_SYMBOL_GPL(nfs_pageio_resend);
/**
* nfs_pageio_complete - Complete I/O on an nfs_pageio_descriptor
* @desc: pointer to io descriptor
*/
void nfs_pageio_complete(struct nfs_pageio_descriptor *desc)
{
for (;;) {
nfs_pageio_doio(desc);
if (!desc->pg_recoalesce)
break;
if (!nfs_do_recoalesce(desc))
break;
}
}
/**
* nfs_pageio_cond_complete - Conditional I/O completion
* @desc: pointer to io descriptor
* @index: page index
*
* It is important to ensure that processes don't try to take locks
* on non-contiguous ranges of pages as that might deadlock. This
* function should be called before attempting to wait on a locked
* nfs_page. It will complete the I/O if the page index 'index'
* is not contiguous with the existing list of pages in 'desc'.
*/
void nfs_pageio_cond_complete(struct nfs_pageio_descriptor *desc, pgoff_t index)
{
if (!list_empty(&desc->pg_list)) {
struct nfs_page *prev = nfs_list_entry(desc->pg_list.prev);
if (index != prev->wb_index + 1)
nfs_pageio_complete(desc);
}
}
int __init nfs_init_nfspagecache(void)
{
nfs_page_cachep = kmem_cache_create("nfs_page",
sizeof(struct nfs_page),
0, SLAB_HWCACHE_ALIGN,
NULL);
if (nfs_page_cachep == NULL)
return -ENOMEM;
return 0;
}
void nfs_destroy_nfspagecache(void)
{
kmem_cache_destroy(nfs_page_cachep);
}
static const struct rpc_call_ops nfs_pgio_common_ops = {
.rpc_call_prepare = nfs_pgio_prepare,
.rpc_call_done = nfs_pgio_result,
.rpc_release = nfs_pgio_release,
};
const struct nfs_pageio_ops nfs_pgio_rw_ops = {
.pg_test = nfs_generic_pg_test,
.pg_doio = nfs_generic_pg_pgios,
};