kernel_optimize_test/fs/nfs/pagelist.c
Fred Isaman a861a1e1c3 NFSv4.1: add generic layer hooks for pnfs COMMIT
We create three major hooks for the pnfs code.

pnfs_mark_request_commit() is called during writeback_done from
nfs_mark_request_commit, which gives the driver an opportunity to
claim it wants control over commiting a particular req.

pnfs_choose_commit_list() is called from nfs_scan_list
to choose which list a given req should be added to, based on
where we intend to send it for COMMIT.  It is up to the driver
to have preallocated list headers for each destination it may need.

pnfs_commit_list() is how the driver actually takes control, it is
used instead of nfs_commit_list().

In order to pass information between the above functions, we create
a union in nfs_page to hold a lseg (which is possible because the req is
not on any list while in transition), and add some flags to indicate
if we need to use the pnfs code.

Signed-off-by: Fred Isaman <iisaman@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2011-03-23 15:29:03 -04:00

455 lines
12 KiB
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/nfs3.h>
#include <linux/nfs4.h>
#include <linux/nfs_page.h>
#include <linux/nfs_fs.h>
#include <linux/nfs_mount.h>
#include "internal.h"
#include "pnfs.h"
static struct kmem_cache *nfs_page_cachep;
static inline struct nfs_page *
nfs_page_alloc(void)
{
struct nfs_page *p = kmem_cache_zalloc(nfs_page_cachep, GFP_KERNEL);
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);
}
/**
* nfs_create_request - Create an NFS read/write request.
* @file: file descriptor to use
* @inode: inode to which the request is attached
* @page: page to write
* @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 inode *inode,
struct page *page,
unsigned int offset, unsigned int count)
{
struct nfs_page *req;
/* 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 */
req->wb_lock_context = nfs_get_lock_context(ctx);
if (req->wb_lock_context == NULL) {
nfs_page_free(req);
return ERR_PTR(-ENOMEM);
}
/* 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;
atomic_set(&req->wb_complete, 0);
req->wb_index = page->index;
page_cache_get(page);
BUG_ON(PagePrivate(page));
BUG_ON(!PageLocked(page));
BUG_ON(page->mapping->host != inode);
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);
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_clear_bit();
clear_bit(PG_BUSY, &req->wb_flags);
smp_mb__after_clear_bit();
wake_up_bit(&req->wb_flags, PG_BUSY);
nfs_release_request(req);
}
/**
* nfs_set_page_tag_locked - Tag a request as locked
* @req:
*/
int nfs_set_page_tag_locked(struct nfs_page *req)
{
if (!nfs_lock_request_dontget(req))
return 0;
if (test_bit(PG_MAPPED, &req->wb_flags))
radix_tree_tag_set(&NFS_I(req->wb_context->path.dentry->d_inode)->nfs_page_tree, req->wb_index, NFS_PAGE_TAG_LOCKED);
return 1;
}
/**
* nfs_clear_page_tag_locked - Clear request tag and wake up sleepers
*/
void nfs_clear_page_tag_locked(struct nfs_page *req)
{
if (test_bit(PG_MAPPED, &req->wb_flags)) {
struct inode *inode = req->wb_context->path.dentry->d_inode;
struct nfs_inode *nfsi = NFS_I(inode);
spin_lock(&inode->i_lock);
radix_tree_tag_clear(&nfsi->nfs_page_tree, req->wb_index, NFS_PAGE_TAG_LOCKED);
nfs_unlock_request(req);
spin_unlock(&inode->i_lock);
} else
nfs_unlock_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.
*/
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_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!
*/
static void nfs_free_request(struct kref *kref)
{
struct nfs_page *req = container_of(kref, struct nfs_page, wb_kref);
/* 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_free_request);
}
static int nfs_wait_bit_uninterruptible(void *word)
{
io_schedule();
return 0;
}
/**
* 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(&req->wb_flags, PG_BUSY,
nfs_wait_bit_uninterruptible,
TASK_UNINTERRUPTIBLE);
}
/**
* 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,
int (*doio)(struct nfs_pageio_descriptor *),
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_inode = inode;
desc->pg_doio = doio;
desc->pg_ioflags = io_flags;
desc->pg_error = 0;
desc->pg_lseg = NULL;
}
/**
* 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 int nfs_can_coalesce_requests(struct nfs_page *prev,
struct nfs_page *req,
struct nfs_pageio_descriptor *pgio)
{
if (req->wb_context->cred != prev->wb_context->cred)
return 0;
if (req->wb_lock_context->lockowner != prev->wb_lock_context->lockowner)
return 0;
if (req->wb_context->state != prev->wb_context->state)
return 0;
if (req->wb_index != (prev->wb_index + 1))
return 0;
if (req->wb_pgbase != 0)
return 0;
if (prev->wb_pgbase + prev->wb_bytes != PAGE_CACHE_SIZE)
return 0;
/*
* Non-whole file layouts need to check that req is inside of
* pgio->pg_lseg.
*/
if (pgio->pg_test && !pgio->pg_test(pgio, prev, req))
return 0;
return 1;
}
/**
* 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)
{
size_t newlen = req->wb_bytes;
if (desc->pg_count != 0) {
struct nfs_page *prev;
/*
* FIXME: ideally we should be able to coalesce all requests
* that are not block boundary aligned, but currently this
* is problematic for the case of bsize < PAGE_CACHE_SIZE,
* since nfs_flush_multi and nfs_pagein_multi assume you
* can have only one struct nfs_page.
*/
if (desc->pg_bsize < PAGE_SIZE)
return 0;
newlen += desc->pg_count;
if (newlen > desc->pg_bsize)
return 0;
prev = nfs_list_entry(desc->pg_list.prev);
if (!nfs_can_coalesce_requests(prev, req, desc))
return 0;
} else
desc->pg_base = req->wb_pgbase;
nfs_list_remove_request(req);
nfs_list_add_request(req, &desc->pg_list);
desc->pg_count = newlen;
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_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
*
* Returns true if the request 'req' was successfully coalesced into the
* existing list of pages 'desc'.
*/
int nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
struct nfs_page *req)
{
while (!nfs_pageio_do_add_request(desc, req)) {
desc->pg_moreio = 1;
nfs_pageio_doio(desc);
if (desc->pg_error < 0)
return 0;
desc->pg_moreio = 0;
}
return 1;
}
/**
* 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)
{
nfs_pageio_doio(desc);
}
/**
* 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_doio(desc);
}
}
#define NFS_SCAN_MAXENTRIES 16
/**
* nfs_scan_list - Scan a list for matching requests
* @nfsi: NFS inode
* @dst: Destination list
* @idx_start: lower bound of page->index to scan
* @npages: idx_start + npages sets the upper bound to scan.
* @tag: tag to scan for
*
* Moves elements from one of the inode request lists.
* If the number of requests is set to 0, the entire address_space
* starting at index idx_start, is scanned.
* The requests are *not* checked to ensure that they form a contiguous set.
* You must be holding the inode's i_lock when calling this function
*/
int nfs_scan_list(struct nfs_inode *nfsi,
struct list_head *dst, pgoff_t idx_start,
unsigned int npages, int tag)
{
struct nfs_page *pgvec[NFS_SCAN_MAXENTRIES];
struct nfs_page *req;
pgoff_t idx_end;
int found, i;
int res;
struct list_head *list;
res = 0;
if (npages == 0)
idx_end = ~0;
else
idx_end = idx_start + npages - 1;
for (;;) {
found = radix_tree_gang_lookup_tag(&nfsi->nfs_page_tree,
(void **)&pgvec[0], idx_start,
NFS_SCAN_MAXENTRIES, tag);
if (found <= 0)
break;
for (i = 0; i < found; i++) {
req = pgvec[i];
if (req->wb_index > idx_end)
goto out;
idx_start = req->wb_index + 1;
if (nfs_set_page_tag_locked(req)) {
kref_get(&req->wb_kref);
radix_tree_tag_clear(&nfsi->nfs_page_tree,
req->wb_index, tag);
list = pnfs_choose_commit_list(req, dst);
nfs_list_add_request(req, list);
res++;
if (res == INT_MAX)
goto out;
}
}
/* for latency reduction */
cond_resched_lock(&nfsi->vfs_inode.i_lock);
}
out:
return res;
}
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);
}