File: [Development] / xfs-linux / linux-2.4 / Attic / xfs_buf.c (download)
Revision 1.98, Fri Feb 21 04:02:00 2003 UTC (14 years, 8 months ago) by nathans
Branch: MAIN
Changes since 1.97: +99 -181
lines
Rework how IO completion is handled in pagebuf, particularly the case of
blocksizes less than the pagesize. This makes more of an effort to set
pages uptodate in this case, and removes the page_sync_t structure from
the code entirely (previously we were allocating one of these per-page
for small IOs). Some of the functions no longer need to return errors
now, and some were doing bytes-written accounting unnecessarily - no more.
|
/*
* Copyright (c) 2000-2002 Silicon Graphics, Inc. All Rights Reserved.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of version 2 of the GNU General Public License as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it would be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
*
* Further, this software is distributed without any warranty that it is
* free of the rightful claim of any third person regarding infringement
* or the like. Any license provided herein, whether implied or
* otherwise, applies only to this software file. Patent licenses, if
* any, provided herein do not apply to combinations of this program with
* other software, or any other product whatsoever.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write the Free Software Foundation, Inc., 59
* Temple Place - Suite 330, Boston MA 02111-1307, USA.
*
* Contact information: Silicon Graphics, Inc., 1600 Amphitheatre Pkwy,
* Mountain View, CA 94043, or:
*
* http://www.sgi.com
*
* For further information regarding this notice, see:
*
* http://oss.sgi.com/projects/GenInfo/SGIGPLNoticeExplan/
*/
/*
* page_buf.c
*
* The page_buf module provides an abstract buffer cache model on top of
* the Linux page cache. Cached metadata blocks for a file system are
* hashed to the inode for the block device. The page_buf module
* assembles buffer (page_buf_t) objects on demand to aggregate such
* cached pages for I/O.
*
*
* Written by Steve Lord, Jim Mostek, Russell Cattelan
* and Rajagopal Ananthanarayanan ("ananth") at SGI.
*
*/
#include <linux/module.h>
#include <linux/stddef.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/pagemap.h>
#include <linux/init.h>
#include <linux/vmalloc.h>
#include <linux/blkdev.h>
#include <linux/locks.h>
#include <linux/sysctl.h>
#include <linux/proc_fs.h>
#include <support/debug.h>
#include <support/kmem.h>
#include "page_buf_internal.h"
#define NBBY 8
#define BBSHIFT 9
#define BN_ALIGN_MASK ((1 << (PAGE_CACHE_SHIFT - BBSHIFT)) - 1)
#ifndef GFP_READAHEAD
#define GFP_READAHEAD 0
#endif
/*
* A backport of the 2.5 scheduler is used by many vendors of 2.4-based
* distributions.
* We can only guess it's presences by the lack of the SCHED_YIELD flag.
* If the heuristic doesn't work, change this define by hand.
*/
#ifndef SCHED_YIELD
#define __HAVE_NEW_SCHEDULER 1
#endif
/*
* Debug code
*/
#ifdef PAGEBUF_TRACE
static spinlock_t pb_trace_lock = SPIN_LOCK_UNLOCKED;
struct pagebuf_trace_buf pb_trace;
EXPORT_SYMBOL(pb_trace);
EXPORT_SYMBOL(pb_trace_func);
#define CIRC_INC(i) (((i) + 1) & (PB_TRACE_BUFSIZE - 1))
void
pb_trace_func(
page_buf_t *pb,
int event,
void *misc,
void *ra)
{
int j;
unsigned long flags;
if (!pb_params.p_un.debug) return;
if (ra == NULL) ra = (void *)__builtin_return_address(0);
spin_lock_irqsave(&pb_trace_lock, flags);
j = pb_trace.start;
pb_trace.start = CIRC_INC(j);
spin_unlock_irqrestore(&pb_trace_lock, flags);
pb_trace.buf[j].pb = (unsigned long) pb;
pb_trace.buf[j].event = event;
pb_trace.buf[j].flags = pb->pb_flags;
pb_trace.buf[j].hold = pb->pb_hold.counter;
pb_trace.buf[j].lock_value = pb->pb_sema.count.counter;
pb_trace.buf[j].task = (void *)current;
pb_trace.buf[j].misc = misc;
pb_trace.buf[j].ra = ra;
pb_trace.buf[j].offset = pb->pb_file_offset;
pb_trace.buf[j].size = pb->pb_buffer_length;
}
#endif /* PAGEBUF_TRACE */
/*
* File wide globals
*/
STATIC kmem_cache_t *pagebuf_cache;
STATIC struct list_head pagebuf_iodone_tq[NR_CPUS];
STATIC wait_queue_head_t pagebuf_iodone_wait[NR_CPUS];
/*
* For pre-allocated buffer head pool
*/
#define NR_RESERVED_BH 64
static wait_queue_head_t pb_resv_bh_wait;
static spinlock_t pb_resv_bh_lock = SPIN_LOCK_UNLOCKED;
struct buffer_head *pb_resv_bh = NULL; /* list of bh */
int pb_resv_bh_cnt = 0; /* # of bh available */
STATIC void pagebuf_daemon_wakeup(int);
STATIC void _pagebuf_ioapply(page_buf_t *);
STATIC void pagebuf_delwri_queue(page_buf_t *, int);
/*
* Pagebuf module configuration parameters, exported via
* /proc/sys/vm/pagebuf
*/
unsigned long pagebuf_min[P_PARAM] = { HZ/2, 1*HZ, 0, 0 };
unsigned long pagebuf_max[P_PARAM] = { HZ*30, HZ*300, 1, 1 };
pagebuf_param_t pb_params = {{ HZ, 15 * HZ, 0, 0 }};
/*
* Pagebuf statistics variables
*/
struct pbstats pbstats;
/*
* Pagebuf allocation / freeing.
*/
#define pb_to_gfp(flags) \
(((flags) & PBF_READ_AHEAD) ? GFP_READAHEAD : \
((flags) & PBF_DONT_BLOCK) ? GFP_NOFS : GFP_KERNEL)
#define pagebuf_allocate(flags) \
kmem_cache_alloc(pagebuf_cache, pb_to_gfp(flags))
#define pagebuf_deallocate(pb) \
kmem_cache_free(pagebuf_cache, (pb));
/*
* Pagebuf hashing
*/
/* This structure must be a power of 2 long for the hash to work */
typedef struct {
struct list_head pb_hash;
int pb_count;
spinlock_t pb_hash_lock;
} pb_hash_t;
static pb_hash_t *pbhash;
static unsigned int pb_hash_mask;
static unsigned int pb_hash_shift;
static unsigned int pb_order;
#define pb_hash(pb) &pbhash[pb->pb_hash_index]
/*
* This hash is the same one as used on the Linux buffer cache,
* see fs/buffer.c
*/
#define _hashfn(dev,block) \
((((dev)<<(pb_hash_shift - 6)) ^ ((dev)<<(pb_hash_shift - 9))) ^ \
(((block)<<(pb_hash_shift - 6)) ^ ((block) >> 13) ^ \
((block) << (pb_hash_shift - 12))))
static inline int
_bhash(
dev_t dev,
loff_t base)
{
base >>= 9;
return (_hashfn(HASHDEV(dev),base) & pb_hash_mask);
}
/*
* Mapping of multi-page buffers into contingous virtual space
*/
STATIC void *pagebuf_mapout_locked(page_buf_t *);
STATIC spinlock_t as_lock = SPIN_LOCK_UNLOCKED;
typedef struct a_list {
void *vm_addr;
struct a_list *next;
} a_list_t;
STATIC a_list_t *as_free_head;
STATIC int as_list_len;
/*
* Try to batch vunmaps because they are costly.
*/
STATIC void
free_address(
void *addr)
{
a_list_t *aentry;
aentry = kmalloc(sizeof(a_list_t), GFP_ATOMIC);
if (aentry) {
spin_lock(&as_lock);
aentry->next = as_free_head;
aentry->vm_addr = addr;
as_free_head = aentry;
as_list_len++;
spin_unlock(&as_lock);
} else {
vunmap(addr);
}
}
STATIC void
purge_addresses(void)
{
a_list_t *aentry, *old;
if (as_free_head == NULL)
return;
spin_lock(&as_lock);
aentry = as_free_head;
as_free_head = NULL;
as_list_len = 0;
spin_unlock(&as_lock);
while ((old = aentry) != NULL) {
vunmap(aentry->vm_addr);
aentry = aentry->next;
kfree(old);
}
}
/*
* Locking model:
*
* Buffers associated with inodes for which buffer locking
* is not enabled are not protected by semaphores, and are
* assumed to be exclusively owned by the caller. There is
* spinlock in the buffer, for use by the caller when concurrent
* access is possible.
*/
/*
* Internal pagebuf object manipulation
*/
STATIC void
_pagebuf_initialize(
page_buf_t *pb,
pb_target_t *target,
loff_t range_base,
size_t range_length,
page_buf_flags_t flags)
{
/*
* We don't want certain flags to appear in pb->pb_flags.
*/
flags &= ~(PBF_LOCK|PBF_MAPPED|PBF_DONT_BLOCK|PBF_READ_AHEAD);
memset(pb, 0, sizeof(page_buf_t));
atomic_set(&pb->pb_hold, 1);
init_MUTEX_LOCKED(&pb->pb_iodonesema);
INIT_LIST_HEAD(&pb->pb_list);
INIT_LIST_HEAD(&pb->pb_hash_list);
init_MUTEX_LOCKED(&pb->pb_sema); /* held, no waiters */
PB_SET_OWNER(pb);
pb->pb_target = target;
pb->pb_file_offset = range_base;
/*
* Set buffer_length and count_desired to the same value initially.
* IO routines should use count_desired, which will be the same in
* most cases but may be reset (e.g. XFS recovery).
*/
pb->pb_buffer_length = pb->pb_count_desired = range_length;
pb->pb_flags = flags | PBF_NONE;
pb->pb_bn = PAGE_BUF_DADDR_NULL;
atomic_set(&pb->pb_pin_count, 0);
init_waitqueue_head(&pb->pb_waiters);
PB_STATS_INC(pbstats.pb_create);
PB_TRACE(pb, PB_TRACE_REC(get), target);
}
/*
* Allocate a page array capable of holding a specified number
* of pages, and point the page buf at it.
*/
STATIC int
_pagebuf_get_pages(
page_buf_t *pb,
int page_count,
page_buf_flags_t flags)
{
int gpf_mask = pb_to_gfp(flags);
/* Make sure that we have a page list */
if (pb->pb_pages == NULL) {
pb->pb_offset = page_buf_poff(pb->pb_file_offset);
pb->pb_page_count = page_count;
if (page_count <= PB_PAGES) {
pb->pb_pages = pb->pb_page_array;
} else {
pb->pb_pages = kmalloc(sizeof(struct page *) *
page_count, gpf_mask);
if (pb->pb_pages == NULL)
return -ENOMEM;
}
memset(pb->pb_pages, 0, sizeof(struct page *) * page_count);
}
return 0;
}
/*
* Walk a pagebuf releasing all the pages contained within it.
*/
STATIC inline void
_pagebuf_freepages(
page_buf_t *pb)
{
int buf_index;
for (buf_index = 0; buf_index < pb->pb_page_count; buf_index++) {
struct page *page = pb->pb_pages[buf_index];
if (page) {
pb->pb_pages[buf_index] = NULL;
page_cache_release(page);
}
}
if (pb->pb_pages != pb->pb_page_array)
kfree(pb->pb_pages);
}
/*
* _pagebuf_free_object
*
* _pagebuf_free_object releases the contents specified buffer.
* The modification state of any associated pages is left unchanged.
*/
void
_pagebuf_free_object(
pb_hash_t *hash, /* hash bucket for buffer */
page_buf_t *pb) /* buffer to deallocate */
{
page_buf_flags_t pb_flags = pb->pb_flags;
PB_TRACE(pb, PB_TRACE_REC(free_obj), 0);
pb->pb_flags |= PBF_FREED;
if (hash) {
if (!list_empty(&pb->pb_hash_list)) {
hash->pb_count--;
list_del_init(&pb->pb_hash_list);
}
spin_unlock(&hash->pb_hash_lock);
}
if (!(pb_flags & PBF_FREED)) {
/* release any virtual mapping */ ;
if (pb->pb_flags & _PBF_ADDR_ALLOCATED) {
void *vaddr = pagebuf_mapout_locked(pb);
if (vaddr) {
free_address(vaddr);
}
}
if (pb->pb_flags & _PBF_MEM_ALLOCATED) {
if (pb->pb_pages) {
/* release the pages in the address list */
if (pb->pb_pages[0] &&
PageSlab(pb->pb_pages[0])) {
/*
* This came from the slab
* allocator free it as such
*/
kfree(pb->pb_addr);
} else {
_pagebuf_freepages(pb);
}
pb->pb_pages = NULL;
}
pb->pb_flags &= ~_PBF_MEM_ALLOCATED;
}
}
pagebuf_deallocate(pb);
}
/*
* _pagebuf_lookup_pages
*
* _pagebuf_lookup_pages finds all pages which match the buffer
* in question and the range of file offsets supplied,
* and builds the page list for the buffer, if the
* page list is not already formed or if not all of the pages are
* already in the list. Invalid pages (pages which have not yet been
* read in from disk) are assigned for any pages which are not found.
*/
STATIC int
_pagebuf_lookup_pages(
page_buf_t *pb,
struct address_space *aspace,
page_buf_flags_t flags)
{
loff_t next_buffer_offset;
unsigned long page_count, pi, index;
struct page *page;
int gfp_mask, retry_count = 5, rval = 0;
int all_mapped, good_pages;
size_t blocksize;
/* For pagebufs where we want to map an address, do not use
* highmem pages - so that we do not need to use kmap resources
* to access the data.
*
* For pages where the caller has indicated there may be resource
* contention (e.g. called from a transaction) do not flush
* delalloc pages to obtain memory.
*/
if (flags & PBF_READ_AHEAD) {
gfp_mask = GFP_READAHEAD;
retry_count = 0;
} else if (flags & PBF_DONT_BLOCK) {
gfp_mask = GFP_NOFS;
} else if (flags & PBF_MAPPABLE) {
gfp_mask = GFP_KERNEL;
} else {
gfp_mask = GFP_HIGHUSER;
}
next_buffer_offset = pb->pb_file_offset + pb->pb_buffer_length;
good_pages = page_count = (page_buf_btoc(next_buffer_offset) -
page_buf_btoct(pb->pb_file_offset));
if (pb->pb_flags & _PBF_ALL_PAGES_MAPPED) {
/* Bring pages forward in cache */
for (pi = 0; pi < page_count; pi++) {
mark_page_accessed(pb->pb_pages[pi]);
}
if ((flags & PBF_MAPPED) && !(pb->pb_flags & PBF_MAPPED)) {
all_mapped = 1;
goto mapit;
}
return 0;
}
/* Ensure pb_pages field has been initialised */
rval = _pagebuf_get_pages(pb, page_count, flags);
if (rval)
return rval;
rval = pi = 0;
blocksize = pb->pb_target->pbr_bsize;
/* Enter the pages in the page list */
index = (pb->pb_file_offset - pb->pb_offset) >> PAGE_CACHE_SHIFT;
for (all_mapped = 1; pi < page_count; pi++, index++) {
if (pb->pb_pages[pi] == 0) {
retry:
page = find_or_create_page(aspace, index, gfp_mask);
if (!page) {
if (--retry_count > 0) {
PB_STATS_INC(pbstats.pb_page_retries);
pagebuf_daemon_wakeup(1);
current->state = TASK_UNINTERRUPTIBLE;
schedule_timeout(10);
goto retry;
}
rval = -ENOMEM;
all_mapped = 0;
continue;
}
PB_STATS_INC(pbstats.pb_page_found);
mark_page_accessed(page);
pb->pb_pages[pi] = page;
} else {
page = pb->pb_pages[pi];
lock_page(page);
}
/* If we need to do I/O on a page record the fact */
if (!Page_Uptodate(page)) {
good_pages--;
if ((blocksize == PAGE_CACHE_SIZE) &&
(flags & PBF_READ))
pb->pb_locked = 1;
}
}
if (!pb->pb_locked) {
for (pi = 0; pi < page_count; pi++) {
if (pb->pb_pages[pi])
unlock_page(pb->pb_pages[pi]);
}
}
mapit:
pb->pb_flags |= _PBF_MEM_ALLOCATED;
if (all_mapped) {
pb->pb_flags |= _PBF_ALL_PAGES_MAPPED;
/* A single page buffer is always mappable */
if (page_count == 1) {
pb->pb_addr = (caddr_t)
page_address(pb->pb_pages[0]) + pb->pb_offset;
pb->pb_flags |= PBF_MAPPED;
} else if (flags & PBF_MAPPED) {
if (as_list_len > 64)
purge_addresses();
pb->pb_addr = vmap(pb->pb_pages, page_count);
if (pb->pb_addr == NULL)
return -ENOMEM;
pb->pb_addr += pb->pb_offset;
pb->pb_flags |= PBF_MAPPED | _PBF_ADDR_ALLOCATED;
}
}
/* If some pages were found with data in them
* we are not in PBF_NONE state.
*/
if (good_pages != 0) {
pb->pb_flags &= ~(PBF_NONE);
if (good_pages != page_count) {
pb->pb_flags |= PBF_PARTIAL;
}
}
PB_TRACE(pb, PB_TRACE_REC(look_pg), good_pages);
return rval;
}
/*
* Pre-allocation of a pool of buffer heads for use in
* low-memory situations.
*/
/*
* _pagebuf_prealloc_bh
*
* Pre-allocate a pool of "count" buffer heads at startup.
* Puts them on a list at "pb_resv_bh"
* Returns number of bh actually allocated to pool.
*/
STATIC int
_pagebuf_prealloc_bh(
int count)
{
struct buffer_head *bh;
int i;
for (i = 0; i < count; i++) {
bh = kmem_cache_alloc(bh_cachep, SLAB_KERNEL);
if (!bh)
break;
bh->b_pprev = &pb_resv_bh;
bh->b_next = pb_resv_bh;
pb_resv_bh = bh;
pb_resv_bh_cnt++;
}
return i;
}
/*
* _pagebuf_get_prealloc_bh
*
* Get one buffer head from our pre-allocated pool.
* If pool is empty, sleep 'til one comes back in.
* Returns aforementioned buffer head.
*/
STATIC struct buffer_head *
_pagebuf_get_prealloc_bh(void)
{
unsigned long flags;
struct buffer_head *bh;
DECLARE_WAITQUEUE (wait, current);
spin_lock_irqsave(&pb_resv_bh_lock, flags);
if (pb_resv_bh_cnt < 1) {
add_wait_queue(&pb_resv_bh_wait, &wait);
do {
set_current_state(TASK_UNINTERRUPTIBLE);
spin_unlock_irqrestore(&pb_resv_bh_lock, flags);
pagebuf_run_queues(NULL);
schedule();
spin_lock_irqsave(&pb_resv_bh_lock, flags);
} while (pb_resv_bh_cnt < 1);
__set_current_state(TASK_RUNNING);
remove_wait_queue(&pb_resv_bh_wait, &wait);
}
BUG_ON(pb_resv_bh_cnt < 1);
BUG_ON(!pb_resv_bh);
bh = pb_resv_bh;
pb_resv_bh = bh->b_next;
pb_resv_bh_cnt--;
spin_unlock_irqrestore(&pb_resv_bh_lock, flags);
return bh;
}
/*
* _pagebuf_free_bh
*
* Take care of buffer heads that we're finished with.
* Call this instead of just kmem_cache_free(bh_cachep, bh)
* when you're done with a bh.
*
* If our pre-allocated pool is full, just free the buffer head.
* Otherwise, put it back in the pool, and wake up anybody
* waiting for one.
*/
STATIC inline void
_pagebuf_free_bh(
struct buffer_head *bh)
{
unsigned long flags;
int free;
if (! (free = pb_resv_bh_cnt >= NR_RESERVED_BH)) {
spin_lock_irqsave(&pb_resv_bh_lock, flags);
if (! (free = pb_resv_bh_cnt >= NR_RESERVED_BH)) {
bh->b_pprev = &pb_resv_bh;
bh->b_next = pb_resv_bh;
pb_resv_bh = bh;
pb_resv_bh_cnt++;
if (waitqueue_active(&pb_resv_bh_wait)) {
wake_up(&pb_resv_bh_wait);
}
}
spin_unlock_irqrestore(&pb_resv_bh_lock, flags);
}
if (free) {
kmem_cache_free(bh_cachep, bh);
}
}
/*
* Finding and Reading Buffers
*/
/*
* _pagebuf_find
*
* Looks up, and creates if absent, a lockable buffer for
* a given range of an inode. The buffer is returned
* locked. If other overlapping buffers exist, they are
* released before the new buffer is created and locked,
* which may imply that this call will block until those buffers
* are unlocked. No I/O is implied by this call.
*/
STATIC page_buf_t *
_pagebuf_find( /* find buffer for block */
pb_target_t *target,/* target for block */
loff_t ioff, /* starting offset of range */
size_t isize, /* length of range */
page_buf_flags_t flags, /* PBF_TRYLOCK */
page_buf_t *new_pb)/* newly allocated buffer */
{
loff_t range_base;
size_t range_length;
int hval;
pb_hash_t *h;
struct list_head *p;
page_buf_t *pb;
int not_locked;
range_base = (ioff << BBSHIFT);
range_length = (isize << BBSHIFT);
/* Ensure we never do IOs smaller than the sector size */
BUG_ON(range_length < (1 << target->pbr_sshift));
/* Ensure we never do IOs that are not sector aligned */
BUG_ON(range_base & (loff_t)target->pbr_smask);
hval = _bhash(target->pbr_bdev->bd_dev, range_base);
h = &pbhash[hval];
spin_lock(&h->pb_hash_lock);
list_for_each(p, &h->pb_hash) {
pb = list_entry(p, page_buf_t, pb_hash_list);
if ((target == pb->pb_target) &&
(pb->pb_file_offset == range_base) &&
(pb->pb_buffer_length == range_length)) {
if (pb->pb_flags & PBF_FREED)
break;
/* If we look at something bring it to the
* front of the list for next time
*/
list_del(&pb->pb_hash_list);
list_add(&pb->pb_hash_list, &h->pb_hash);
goto found;
}
}
/* No match found */
if (new_pb) {
_pagebuf_initialize(new_pb, target, range_base,
range_length, flags | _PBF_LOCKABLE);
new_pb->pb_hash_index = hval;
h->pb_count++;
list_add(&new_pb->pb_hash_list, &h->pb_hash);
} else {
PB_STATS_INC(pbstats.pb_miss_locked);
}
spin_unlock(&h->pb_hash_lock);
return (new_pb);
found:
atomic_inc(&pb->pb_hold);
spin_unlock(&h->pb_hash_lock);
/* Attempt to get the semaphore without sleeping,
* if this does not work then we need to drop the
* spinlock and do a hard attempt on the semaphore.
*/
not_locked = down_trylock(&pb->pb_sema);
if (not_locked) {
if (!(flags & PBF_TRYLOCK)) {
/* wait for buffer ownership */
PB_TRACE(pb, PB_TRACE_REC(get_lk), 0);
pagebuf_lock(pb);
PB_STATS_INC(pbstats.pb_get_locked_waited);
} else {
/* We asked for a trylock and failed, no need
* to look at file offset and length here, we
* know that this pagebuf at least overlaps our
* pagebuf and is locked, therefore our buffer
* either does not exist, or is this buffer
*/
pagebuf_rele(pb);
PB_STATS_INC(pbstats.pb_busy_locked);
return (NULL);
}
} else {
/* trylock worked */
PB_SET_OWNER(pb);
}
if (pb->pb_flags & PBF_STALE)
pb->pb_flags &= PBF_MAPPABLE | \
PBF_MAPPED | \
_PBF_LOCKABLE | \
_PBF_ALL_PAGES_MAPPED | \
_PBF_ADDR_ALLOCATED | \
_PBF_MEM_ALLOCATED;
PB_TRACE(pb, PB_TRACE_REC(got_lk), 0);
PB_STATS_INC(pbstats.pb_get_locked);
return (pb);
}
/*
* pagebuf_find
*
* pagebuf_find returns a buffer matching the specified range of
* data for the specified target, if any of the relevant blocks
* are in memory. The buffer may have unallocated holes, if
* some, but not all, of the blocks are in memory. Even where
* pages are present in the buffer, not all of every page may be
* valid.
*/
page_buf_t *
pagebuf_find( /* find buffer for block */
/* if the block is in memory */
pb_target_t *target,/* target for block */
loff_t ioff, /* starting offset of range */
size_t isize, /* length of range */
page_buf_flags_t flags) /* PBF_TRYLOCK */
{
return _pagebuf_find(target, ioff, isize, flags, NULL);
}
/*
* pagebuf_get
*
* pagebuf_get assembles a buffer covering the specified range.
* Some or all of the blocks in the range may be valid. Storage
* in memory for all portions of the buffer will be allocated,
* although backing storage may not be. If PBF_READ is set in
* flags, pagebuf_iostart is called also.
*/
page_buf_t *
pagebuf_get( /* allocate a buffer */
pb_target_t *target,/* target for buffer */
loff_t ioff, /* starting offset of range */
size_t isize, /* length of range */
page_buf_flags_t flags) /* PBF_TRYLOCK */
{
page_buf_t *pb, *new_pb;
int error;
new_pb = pagebuf_allocate(flags);
if (unlikely(!new_pb))
return (NULL);
pb = _pagebuf_find(target, ioff, isize, flags, new_pb);
if (pb != new_pb) {
pagebuf_deallocate(new_pb);
if (unlikely(!pb))
return (NULL);
}
PB_STATS_INC(pbstats.pb_get);
/* fill in any missing pages */
error = _pagebuf_lookup_pages(pb, pb->pb_target->pbr_mapping, flags);
if (unlikely(error)) {
pagebuf_free(pb);
return (NULL);
}
/*
* Always fill in the block number now, the mapped cases can do
* their own overlay of this later.
*/
pb->pb_bn = ioff;
pb->pb_count_desired = pb->pb_buffer_length;
if (flags & PBF_READ) {
if (PBF_NOT_DONE(pb)) {
PB_TRACE(pb, PB_TRACE_REC(get_read), flags);
PB_STATS_INC(pbstats.pb_get_read);
pagebuf_iostart(pb, flags);
} else if (flags & PBF_ASYNC) {
/*
* Read ahead call which is already satisfied,
* drop the buffer
*/
if (flags & (PBF_LOCK | PBF_TRYLOCK))
pagebuf_unlock(pb);
pagebuf_rele(pb);
return NULL;
} else {
/* We do not want read in the flags */
pb->pb_flags &= ~PBF_READ;
}
}
PB_TRACE(pb, PB_TRACE_REC(get_obj), flags);
return (pb);
}
/*
* Create a pagebuf and populate it with pages from the address
* space of the passed in inode.
*/
page_buf_t *
pagebuf_lookup(
struct pb_target *target,
struct inode *inode,
loff_t ioff,
size_t isize,
page_buf_flags_t flags)
{
page_buf_t *pb = NULL;
flags |= _PBF_PRIVATE_BH;
pb = pagebuf_allocate(flags);
if (pb) {
_pagebuf_initialize(pb, target, ioff, isize, flags);
}
return pb;
}
/*
* If we are not low on memory then do the readahead in a deadlock
* safe manner.
*/
void
pagebuf_readahead(
pb_target_t *target,
loff_t ioff,
size_t isize,
page_buf_flags_t flags)
{
flags |= (PBF_TRYLOCK|PBF_READ|PBF_ASYNC|PBF_MAPPABLE|PBF_READ_AHEAD);
pagebuf_get(target, ioff, isize, flags);
}
page_buf_t *
pagebuf_get_empty(
pb_target_t *target)
{
page_buf_t *pb;
pb = pagebuf_allocate(_PBF_LOCKABLE);
if (pb)
_pagebuf_initialize(pb, target, 0, 0, _PBF_LOCKABLE);
return pb;
}
static inline struct page *
mem_to_page(
void *addr)
{
if (((unsigned long)addr < VMALLOC_START) ||
((unsigned long)addr >= VMALLOC_END)) {
return virt_to_page(addr);
} else {
return vmalloc_to_page(addr);
}
}
int
pagebuf_associate_memory(
page_buf_t *pb,
void *mem,
size_t len)
{
int rval;
int i = 0;
size_t ptr;
size_t end, end_cur;
off_t offset;
int page_count;
page_count = PAGE_CACHE_ALIGN(len) >> PAGE_CACHE_SHIFT;
offset = (off_t) mem - ((off_t)mem & PAGE_CACHE_MASK);
if (offset && (len > PAGE_CACHE_SIZE))
page_count++;
/* Free any previous set of page pointers */
if (pb->pb_pages && (pb->pb_pages != pb->pb_page_array)) {
kfree(pb->pb_pages);
}
pb->pb_pages = NULL;
pb->pb_addr = mem;
rval = _pagebuf_get_pages(pb, page_count, 0);
if (rval)
return rval;
pb->pb_offset = offset;
ptr = (size_t) mem & PAGE_CACHE_MASK;
end = PAGE_CACHE_ALIGN((size_t) mem + len);
end_cur = end;
/* set up first page */
pb->pb_pages[0] = mem_to_page(mem);
ptr += PAGE_CACHE_SIZE;
pb->pb_page_count = ++i;
while (ptr < end) {
pb->pb_pages[i] = mem_to_page((void *)ptr);
pb->pb_page_count = ++i;
ptr += PAGE_CACHE_SIZE;
}
pb->pb_locked = 0;
pb->pb_count_desired = pb->pb_buffer_length = len;
pb->pb_flags |= PBF_MAPPED | _PBF_PRIVATE_BH;
return 0;
}
page_buf_t *
pagebuf_get_no_daddr(
size_t len,
pb_target_t *target)
{
int rval;
void *rmem = NULL;
page_buf_flags_t flags = _PBF_LOCKABLE | PBF_FORCEIO;
page_buf_t *pb;
size_t tlen = 0;
if (len > 0x20000)
return(NULL);
pb = pagebuf_allocate(flags);
if (!pb)
return NULL;
_pagebuf_initialize(pb, target, 0, len, flags);
do {
if (tlen == 0) {
tlen = len; /* first time */
} else {
kfree(rmem); /* free the mem from the previous try */
tlen <<= 1; /* double the size and try again */
}
if ((rmem = kmalloc(tlen, GFP_KERNEL)) == 0) {
pagebuf_free(pb);
return NULL;
}
} while ((size_t)rmem != ((size_t)rmem & ~target->pbr_smask));
if ((rval = pagebuf_associate_memory(pb, rmem, len)) != 0) {
kfree(rmem);
pagebuf_free(pb);
return NULL;
}
/* otherwise pagebuf_free just ignores it */
pb->pb_flags |= _PBF_MEM_ALLOCATED;
PB_CLEAR_OWNER(pb);
up(&pb->pb_sema); /* Return unlocked pagebuf */
PB_TRACE(pb, PB_TRACE_REC(no_daddr), rmem);
return pb;
}
/*
* pagebuf_hold
*
* Increment reference count on buffer, to hold the buffer concurrently
* with another thread which may release (free) the buffer asynchronously.
*
* Must hold the buffer already to call this function.
*/
void
pagebuf_hold(
page_buf_t *pb)
{
atomic_inc(&pb->pb_hold);
PB_TRACE(pb, PB_TRACE_REC(hold), 0);
}
/*
* pagebuf_free
*
* pagebuf_free releases the specified buffer. The modification
* state of any associated pages is left unchanged.
*/
void
pagebuf_free(
page_buf_t *pb)
{
if (pb->pb_flags & _PBF_LOCKABLE) {
pb_hash_t *h = pb_hash(pb);
spin_lock(&h->pb_hash_lock);
_pagebuf_free_object(h, pb);
} else {
_pagebuf_free_object(NULL, pb);
}
}
/*
* pagebuf_rele
*
* pagebuf_rele releases a hold on the specified buffer. If the
* the hold count is 1, pagebuf_rele calls pagebuf_free.
*/
void
pagebuf_rele(
page_buf_t *pb)
{
pb_hash_t *h;
PB_TRACE(pb, PB_TRACE_REC(rele), pb->pb_relse);
if (pb->pb_flags & _PBF_LOCKABLE) {
h = pb_hash(pb);
spin_lock(&h->pb_hash_lock);
} else {
h = NULL;
}
if (atomic_dec_and_test(&pb->pb_hold)) {
int do_free = 1;
if (pb->pb_relse) {
atomic_inc(&pb->pb_hold);
if (h)
spin_unlock(&h->pb_hash_lock);
(*(pb->pb_relse)) (pb);
do_free = 0;
}
if (pb->pb_flags & PBF_DELWRI) {
pb->pb_flags |= PBF_ASYNC;
atomic_inc(&pb->pb_hold);
if (h && do_free)
spin_unlock(&h->pb_hash_lock);
pagebuf_delwri_queue(pb, 0);
do_free = 0;
} else if (pb->pb_flags & PBF_FS_MANAGED) {
if (h)
spin_unlock(&h->pb_hash_lock);
do_free = 0;
}
if (do_free) {
_pagebuf_free_object(h, pb);
}
} else if (h) {
spin_unlock(&h->pb_hash_lock);
}
}
/*
* Pinning Buffer Storage in Memory
*/
/*
* pagebuf_pin
*
* pagebuf_pin locks all of the memory represented by a buffer in
* memory. Multiple calls to pagebuf_pin and pagebuf_unpin, for
* the same or different buffers affecting a given page, will
* properly count the number of outstanding "pin" requests. The
* buffer may be released after the pagebuf_pin and a different
* buffer used when calling pagebuf_unpin, if desired.
* pagebuf_pin should be used by the file system when it wants be
* assured that no attempt will be made to force the affected
* memory to disk. It does not assure that a given logical page
* will not be moved to a different physical page.
*/
void
pagebuf_pin(
page_buf_t *pb)
{
atomic_inc(&pb->pb_pin_count);
PB_TRACE(pb, PB_TRACE_REC(pin), pb->pb_pin_count.counter);
}
/*
* pagebuf_unpin
*
* pagebuf_unpin reverses the locking of memory performed by
* pagebuf_pin. Note that both functions affected the logical
* pages associated with the buffer, not the buffer itself.
*/
void
pagebuf_unpin(
page_buf_t *pb)
{
if (atomic_dec_and_test(&pb->pb_pin_count)) {
wake_up_all(&pb->pb_waiters);
}
PB_TRACE(pb, PB_TRACE_REC(unpin), pb->pb_pin_count.counter);
}
int
pagebuf_ispin(
page_buf_t *pb)
{
return atomic_read(&pb->pb_pin_count);
}
/*
* pagebuf_wait_unpin
*
* pagebuf_wait_unpin waits until all of the memory associated
* with the buffer is not longer locked in memory. It returns
* immediately if none of the affected pages are locked.
*/
static inline void
_pagebuf_wait_unpin(
page_buf_t *pb)
{
DECLARE_WAITQUEUE (wait, current);
if (atomic_read(&pb->pb_pin_count) == 0)
return;
add_wait_queue(&pb->pb_waiters, &wait);
for (;;) {
current->state = TASK_UNINTERRUPTIBLE;
if (atomic_read(&pb->pb_pin_count) == 0) {
break;
}
pagebuf_run_queues(pb);
schedule();
}
remove_wait_queue(&pb->pb_waiters, &wait);
current->state = TASK_RUNNING;
}
/*
* Buffer Utility Routines
*/
/*
* pagebuf_iodone
*
* pagebuf_iodone marks a buffer for which I/O is in progress
* done with respect to that I/O. The pb_iodone routine, if
* present, will be called as a side-effect.
*/
void
pagebuf_iodone_sched(
void *v)
{
page_buf_t *pb = (page_buf_t *)v;
if (pb->pb_iodone) {
(*(pb->pb_iodone)) (pb);
return;
}
if (pb->pb_flags & PBF_ASYNC) {
if ((pb->pb_flags & _PBF_LOCKABLE) && !pb->pb_relse)
pagebuf_unlock(pb);
pagebuf_rele(pb);
}
}
void
pagebuf_iodone(
page_buf_t *pb,
int schedule)
{
pb->pb_flags &= ~(PBF_READ | PBF_WRITE);
if (pb->pb_error == 0) {
pb->pb_flags &= ~(PBF_PARTIAL | PBF_NONE);
}
PB_TRACE(pb, PB_TRACE_REC(done), pb->pb_iodone);
if ((pb->pb_iodone) || (pb->pb_flags & PBF_ASYNC)) {
if (schedule) {
INIT_TQUEUE(&pb->pb_iodone_sched,
pagebuf_iodone_sched, (void *)pb);
queue_task(&pb->pb_iodone_sched,
&pagebuf_iodone_tq[smp_processor_id()]);
wake_up(&pagebuf_iodone_wait[smp_processor_id()]);
} else {
pagebuf_iodone_sched(pb);
}
} else {
up(&pb->pb_iodonesema);
}
}
/*
* pagebuf_ioerror
*
* pagebuf_ioerror sets the error code for a buffer.
*/
void
pagebuf_ioerror( /* mark/clear buffer error flag */
page_buf_t *pb, /* buffer to mark */
unsigned int error) /* error to store (0 if none) */
{
pb->pb_error = error;
PB_TRACE(pb, PB_TRACE_REC(ioerror), error);
}
/*
* pagebuf_iostart
*
* pagebuf_iostart initiates I/O on a buffer, based on the flags supplied.
* If necessary, it will arrange for any disk space allocation required,
* and it will break up the request if the block mappings require it.
* The pb_iodone routine in the buffer supplied will only be called
* when all of the subsidiary I/O requests, if any, have been completed.
* pagebuf_iostart calls the pagebuf_ioinitiate routine or
* pagebuf_iorequest, if the former routine is not defined, to start
* the I/O on a given low-level request.
*/
int
pagebuf_iostart( /* start I/O on a buffer */
page_buf_t *pb, /* buffer to start */
page_buf_flags_t flags) /* PBF_LOCK, PBF_ASYNC, PBF_READ, */
/* PBF_WRITE, PBF_DELWRI, */
/* PBF_SYNC, PBF_DONT_BLOCK */
{
int status = 0;
PB_TRACE(pb, PB_TRACE_REC(iostart), flags);
if (flags & PBF_DELWRI) {
pb->pb_flags &= ~(PBF_READ | PBF_WRITE | PBF_ASYNC);
pb->pb_flags |= flags &
(PBF_DELWRI | PBF_ASYNC | PBF_SYNC);
pagebuf_delwri_queue(pb, 1);
return status;
}
pb->pb_flags &=
~(PBF_READ|PBF_WRITE|PBF_ASYNC|PBF_DELWRI|PBF_READ_AHEAD);
pb->pb_flags |= flags &
(PBF_READ|PBF_WRITE|PBF_ASYNC|PBF_SYNC|PBF_READ_AHEAD);
BUG_ON(pb->pb_bn == PAGE_BUF_DADDR_NULL);
/* For writes call internal function which checks for
* filesystem specific callout function and execute it.
*/
if (flags & PBF_WRITE) {
status = __pagebuf_iorequest(pb);
} else {
status = pagebuf_iorequest(pb);
}
/* Wait for I/O if we are not an async request */
if ((status == 0) && (flags & PBF_ASYNC) == 0) {
status = pagebuf_iowait(pb);
}
return status;
}
/*
* Helper routines for pagebuf_iorequest (pagebuf I/O completion)
*/
STATIC __inline__ int
_pagebuf_iolocked(
page_buf_t *pb)
{
ASSERT(pb->pb_flags & (PBF_READ|PBF_WRITE));
if (pb->pb_flags & PBF_READ)
return pb->pb_locked;
return ((pb->pb_flags & _PBF_LOCKABLE) == 0);
}
STATIC void
_pagebuf_iodone(
page_buf_t *pb,
int fullpage,
int schedule)
{
if (atomic_dec_and_test(&pb->pb_io_remaining) == 1) {
struct page *page;
int i;
for (i = 0; i < pb->pb_page_count; i++) {
page = pb->pb_pages[i];
if (fullpage && !PageError(page))
SetPageUptodate(page);
if (_pagebuf_iolocked(pb))
unlock_page(page);
}
pb->pb_locked = 0;
pagebuf_iodone(pb, schedule);
}
}
STATIC void
_end_io_pagebuf(
struct buffer_head *bh,
int uptodate,
int fullpage)
{
struct page *page = bh->b_page;
page_buf_t *pb = (page_buf_t *)bh->b_private;
mark_buffer_uptodate(bh, uptodate);
put_bh(bh);
if (!uptodate) {
SetPageError(page);
pb->pb_error = EIO;
}
if (fullpage) {
unlock_buffer(bh);
_pagebuf_free_bh(bh);
} else {
static spinlock_t page_uptodate_lock = SPIN_LOCK_UNLOCKED;
struct buffer_head *bp;
unsigned long flags;
spin_lock_irqsave(&page_uptodate_lock, flags);
clear_bit(BH_Async, &bh->b_state);
unlock_buffer(bh);
for (bp = bh->b_this_page; bp != bh; bp = bp->b_this_page) {
if (buffer_locked(bp)) {
if (buffer_async(bp))
break;
} else if (!buffer_uptodate(bp))
break;
}
spin_unlock_irqrestore(&page_uptodate_lock, flags);
if (bp == bh && !PageError(page))
SetPageUptodate(page);
}
_pagebuf_iodone(pb, fullpage, 1);
}
STATIC void
_pagebuf_end_io_complete_pages(
struct buffer_head *bh,
int uptodate)
{
_end_io_pagebuf(bh, uptodate, 1);
}
STATIC void
_pagebuf_end_io_partial_pages(
struct buffer_head *bh,
int uptodate)
{
_end_io_pagebuf(bh, uptodate, 0);
}
/*
* Initiate I/O on part of a page we are interested in
*/
STATIC void
_pagebuf_page_io(
struct page *page, /* Page structure we are dealing with */
pb_target_t *pbr, /* device parameters (bsz, ssz, dev) */
page_buf_t *pb, /* pagebuf holding it, can be NULL */
page_buf_daddr_t bn, /* starting block number */
size_t pg_offset, /* starting offset in page */
size_t pg_length, /* count of data to process */
int locking, /* page locking in use */
int rw, /* read/write operation */
int flush)
{
size_t sector;
size_t blk_length = 0;
struct buffer_head *bh, *head, *bufferlist[MAX_BUF_PER_PAGE];
int sector_shift = pbr->pbr_sshift;
int i = 0, cnt = 0;
int public_bh = 0;
int multi_ok;
if ((pbr->pbr_bsize < PAGE_CACHE_SIZE) &&
!(pb->pb_flags & _PBF_PRIVATE_BH)) {
int cache_ok;
cache_ok = !((pb->pb_flags & PBF_FORCEIO) || (rw == WRITE));
public_bh = multi_ok = 1;
if (!page_has_buffers(page)) {
if (!locking) {
lock_page(page);
if (!page_has_buffers(page))
create_empty_buffers(page,
pbr->pbr_kdev,
1 << sector_shift);
unlock_page(page);
} else {
create_empty_buffers(page, pbr->pbr_kdev,
1 << sector_shift);
}
}
/* Find buffer_heads belonging to just this pagebuf */
bh = head = page_buffers(page);
do {
if (buffer_uptodate(bh) && cache_ok)
continue;
blk_length = i << sector_shift;
if (blk_length < pg_offset)
continue;
if (blk_length >= pg_offset + pg_length)
break;
lock_buffer(bh);
get_bh(bh);
bh->b_size = 1 << sector_shift;
bh->b_blocknr = bn + (i - (pg_offset >> sector_shift));
bufferlist[cnt++] = bh;
} while (i++, (bh = bh->b_this_page) != head);
goto request;
}
/* Calculate the block offsets and length we will be using */
if (pg_offset) {
size_t block_offset;
block_offset = pg_offset >> sector_shift;
block_offset = pg_offset - (block_offset << sector_shift);
blk_length = (pg_length + block_offset + pbr->pbr_smask) >>
sector_shift;
} else {
blk_length = (pg_length + pbr->pbr_smask) >> sector_shift;
}
/* This will attempt to make a request bigger than the sector
* size if we are well aligned.
*/
switch (pb->pb_target->pbr_flags) {
case 0:
sector = blk_length << sector_shift;
blk_length = 1;
break;
case PBR_ALIGNED_ONLY:
if ((pg_offset == 0) && (pg_length == PAGE_CACHE_SIZE) &&
(((unsigned int) bn) & BN_ALIGN_MASK) == 0) {
sector = blk_length << sector_shift;
blk_length = 1;
break;
}
case PBR_SECTOR_ONLY:
/* Fallthrough, same as default */
default:
sector = 1 << sector_shift;
}
/* If we are doing I/O larger than the bh->b_size field then
* we need to split this request up.
*/
while (sector > ((1 << NBBY * sizeof(bh->b_size)) - 1)) {
sector >>= 1;
blk_length++;
}
multi_ok = (blk_length != 1);
for (; blk_length > 0; blk_length--, pg_offset += sector) {
bh = kmem_cache_alloc(bh_cachep, SLAB_NOFS);
if (!bh)
bh = _pagebuf_get_prealloc_bh();
memset(bh, 0, sizeof(*bh));
bh->b_size = sector;
bh->b_blocknr = bn++;
bh->b_dev = pbr->pbr_kdev;
set_bit(BH_Lock, &bh->b_state);
set_bh_page(bh, page, pg_offset);
init_waitqueue_head(&bh->b_wait);
atomic_set(&bh->b_count, 1);
bufferlist[cnt++] = bh;
}
request:
if (cnt) {
void (*callback)(struct buffer_head *, int);
callback = (multi_ok && public_bh) ?
_pagebuf_end_io_partial_pages :
_pagebuf_end_io_complete_pages;
/* Account for additional buffers in progress */
atomic_add(cnt, &pb->pb_io_remaining);
#ifdef RQ_WRITE_ORDERED
if (flush)
set_bit(BH_Ordered_Flush, &bufferlist[cnt-1]->b_state);
#endif
for (i = 0; i < cnt; i++) {
bh = bufferlist[i];
init_buffer(bh, callback, pb);
bh->b_rdev = bh->b_dev;
bh->b_rsector = bh->b_blocknr;
set_bit(BH_Mapped, &bh->b_state);
set_bit(BH_Async, &bh->b_state);
set_bit(BH_Req, &bh->b_state);
if (rw == WRITE)
set_bit(BH_Uptodate, &bh->b_state);
generic_make_request(rw, bh);
}
} else {
if (locking)
unlock_page(page);
}
}
STATIC void
_pagebuf_page_apply(
page_buf_t *pb,
loff_t offset,
struct page *page,
size_t pg_offset,
size_t pg_length,
int last)
{
page_buf_daddr_t bn = pb->pb_bn;
pb_target_t *pbr = pb->pb_target;
loff_t pb_offset;
int locking;
ASSERT(page);
ASSERT(pb->pb_flags & (PBF_READ|PBF_WRITE));
if ((pbr->pbr_bsize == PAGE_CACHE_SIZE) &&
(pb->pb_buffer_length < PAGE_CACHE_SIZE) &&
(pb->pb_flags & PBF_READ) && pb->pb_locked) {
bn -= (pb->pb_offset >> pbr->pbr_sshift);
pg_offset = 0;
pg_length = PAGE_CACHE_SIZE;
} else {
pb_offset = offset - pb->pb_file_offset;
if (pb_offset) {
bn += (pb_offset + pbr->pbr_smask) >> pbr->pbr_sshift;
}
}
locking = _pagebuf_iolocked(pb);
if (pb->pb_flags & PBF_WRITE) {
if (locking && (pb->pb_locked == 0))
lock_page(page);
_pagebuf_page_io(page, pbr, pb, bn,
pg_offset, pg_length, locking, WRITE,
last && (pb->pb_flags & PBF_FLUSH));
} else {
_pagebuf_page_io(page, pbr, pb, bn,
pg_offset, pg_length, locking, READ, 0);
}
}
/*
* pagebuf_iorequest
*
* pagebuf_iorequest is the core I/O request routine.
* It assumes that the buffer is well-formed and
* mapped and ready for physical I/O, unlike
* pagebuf_iostart() and pagebuf_iophysio(). Those
* routines call the pagebuf_ioinitiate routine to start I/O,
* if it is present, or else call pagebuf_iorequest()
* directly if the pagebuf_ioinitiate routine is not present.
*
* This function will be responsible for ensuring access to the
* pages is restricted whilst I/O is in progress - for locking
* pagebufs the pagebuf lock is the mediator, for non-locking
* pagebufs the pages will be locked. In the locking case we
* need to use the pagebuf lock as multiple meta-data buffers
* will reference the same page.
*/
int
pagebuf_iorequest( /* start real I/O */
page_buf_t *pb) /* buffer to convey to device */
{
PB_TRACE(pb, PB_TRACE_REC(ioreq), 0);
if (pb->pb_flags & PBF_DELWRI) {
pagebuf_delwri_queue(pb, 1);
return 0;
}
if (pb->pb_flags & PBF_WRITE) {
_pagebuf_wait_unpin(pb);
}
/* Set the count to 1 initially, this will stop an I/O
* completion callout which happens before we have started
* all the I/O from calling pagebuf_iodone too early.
*/
atomic_set(&pb->pb_io_remaining, 1);
_pagebuf_ioapply(pb);
_pagebuf_iodone(pb, 0, 0);
return 0;
}
/*
* pagebuf_iowait
*
* pagebuf_iowait waits for I/O to complete on the buffer supplied.
* It returns immediately if no I/O is pending. In any case, it returns
* the error code, if any, or 0 if there is no error.
*/
int
pagebuf_iowait(
page_buf_t *pb)
{
PB_TRACE(pb, PB_TRACE_REC(iowait), 0);
pagebuf_run_queues(pb);
down(&pb->pb_iodonesema);
PB_TRACE(pb, PB_TRACE_REC(iowaited), (int)pb->pb_error);
return pb->pb_error;
}
STATIC void *
pagebuf_mapout_locked(
page_buf_t *pb)
{
void *old_addr = NULL;
if (pb->pb_flags & PBF_MAPPED) {
if (pb->pb_flags & _PBF_ADDR_ALLOCATED)
old_addr = pb->pb_addr - pb->pb_offset;
pb->pb_addr = NULL;
pb->pb_flags &= ~(PBF_MAPPED | _PBF_ADDR_ALLOCATED);
}
return old_addr; /* Caller must free the address space,
* we are under a spin lock, probably
* not safe to do vfree here
*/
}
caddr_t
pagebuf_offset(
page_buf_t *pb,
size_t offset)
{
struct page *page;
offset += pb->pb_offset;
page = pb->pb_pages[offset >> PAGE_CACHE_SHIFT];
return (caddr_t) page_address(page) + (offset & (PAGE_CACHE_SIZE - 1));
}
/*
* pagebuf_iomove
*
* Move data into or out of a buffer.
*/
void
pagebuf_iomove(
page_buf_t *pb, /* buffer to process */
size_t boff, /* starting buffer offset */
size_t bsize, /* length to copy */
caddr_t data, /* data address */
page_buf_rw_t mode) /* read/write flag */
{
size_t bend, cpoff, csize;
struct page *page;
bend = boff + bsize;
while (boff < bend) {
page = pb->pb_pages[page_buf_btoct(boff + pb->pb_offset)];
cpoff = page_buf_poff(boff + pb->pb_offset);
csize = min_t(size_t,
PAGE_CACHE_SIZE-cpoff, pb->pb_count_desired-boff);
ASSERT(((csize + cpoff) <= PAGE_CACHE_SIZE));
switch (mode) {
case PBRW_ZERO:
memset(page_address(page) + cpoff, 0, csize);
break;
case PBRW_READ:
memcpy(data, page_address(page) + cpoff, csize);
break;
case PBRW_WRITE:
memcpy(page_address(page) + cpoff, data, csize);
}
boff += csize;
data += csize;
}
}
/*
* _pagebuf_ioapply
*
* Applies _pagebuf_page_apply to each page of the page_buf_t.
*/
STATIC void
_pagebuf_ioapply( /* apply function to pages */
page_buf_t *pb) /* buffer to examine */
{
int buf_index;
loff_t buffer_offset = pb->pb_file_offset;
size_t buffer_len = pb->pb_count_desired;
size_t page_offset, len;
size_t cur_offset, cur_len;
pagebuf_hold(pb);
cur_offset = pb->pb_offset;
cur_len = buffer_len;
for (buf_index = 0; buf_index < pb->pb_page_count; buf_index++) {
if (cur_len == 0)
break;
if (cur_offset >= PAGE_CACHE_SIZE) {
cur_offset -= PAGE_CACHE_SIZE;
continue;
}
page_offset = cur_offset;
cur_offset = 0;
len = PAGE_CACHE_SIZE - page_offset;
if (len > cur_len)
len = cur_len;
cur_len -= len;
_pagebuf_page_apply(pb, buffer_offset,
pb->pb_pages[buf_index], page_offset, len,
buf_index+1 == pb->pb_page_count);
buffer_offset += len;
buffer_len -= len;
}
pagebuf_rele(pb);
}
/*
* Pagebuf delayed write buffer handling
*/
STATIC int pbd_active = 1;
STATIC LIST_HEAD(pbd_delwrite_queue);
STATIC spinlock_t pbd_delwrite_lock = SPIN_LOCK_UNLOCKED;
STATIC void
pagebuf_delwri_queue(
page_buf_t *pb,
int unlock)
{
PB_TRACE(pb, PB_TRACE_REC(delwri_q), unlock);
spin_lock(&pbd_delwrite_lock);
/* If already in the queue, dequeue and place at tail */
if (!list_empty(&pb->pb_list)) {
if (unlock) {
atomic_dec(&pb->pb_hold);
}
list_del(&pb->pb_list);
}
list_add_tail(&pb->pb_list, &pbd_delwrite_queue);
pb->pb_flushtime = jiffies + pb_params.p_un.age_buffer;
spin_unlock(&pbd_delwrite_lock);
if (unlock && (pb->pb_flags & _PBF_LOCKABLE)) {
pagebuf_unlock(pb);
}
}
void
pagebuf_delwri_dequeue(
page_buf_t *pb)
{
PB_TRACE(pb, PB_TRACE_REC(delwri_uq), 0);
spin_lock(&pbd_delwrite_lock);
list_del_init(&pb->pb_list);
pb->pb_flags &= ~PBF_DELWRI;
spin_unlock(&pbd_delwrite_lock);
}
/*
* The pagebuf iodone daemon
*/
STATIC int pb_daemons[NR_CPUS];
STATIC int
pagebuf_iodone_daemon(
void *__bind_cpu)
{
int bind_cpu = (int) (long) __bind_cpu;
int cpu = cpu_logical_map(bind_cpu);
DECLARE_WAITQUEUE (wait, current);
/* Set up the thread */
daemonize();
/* Avoid signals */
spin_lock_irq(¤t->sigmask_lock);
sigfillset(¤t->blocked);
recalc_sigpending(current);
spin_unlock_irq(¤t->sigmask_lock);
/* Migrate to the right CPU */
#ifdef __HAVE_NEW_SCHEDULER
set_cpus_allowed(current, 1UL << cpu);
if (smp_processor_id() != cpu)
BUG();
#else
current->cpus_allowed = 1UL << cpu;
while (smp_processor_id() != cpu)
schedule();
#endif
sprintf(current->comm, "pagebuf/%d", bind_cpu);
INIT_LIST_HEAD(&pagebuf_iodone_tq[cpu]);
init_waitqueue_head(&pagebuf_iodone_wait[cpu]);
__set_current_state(TASK_INTERRUPTIBLE);
mb();
pb_daemons[cpu] = 1;
for (;;) {
add_wait_queue(&pagebuf_iodone_wait[cpu],
&wait);
if (TQ_ACTIVE(pagebuf_iodone_tq[cpu]))
__set_task_state(current, TASK_RUNNING);
schedule();
remove_wait_queue(&pagebuf_iodone_wait[cpu],
&wait);
run_task_queue(&pagebuf_iodone_tq[cpu]);
if (pb_daemons[cpu] == 0)
break;
__set_current_state(TASK_INTERRUPTIBLE);
}
pb_daemons[cpu] = -1;
wake_up_interruptible(&pagebuf_iodone_wait[cpu]);
return 0;
}
/* Defines for pagebuf daemon */
DECLARE_WAIT_QUEUE_HEAD(pbd_waitq);
STATIC int force_flush;
STATIC void
pagebuf_daemon_wakeup(
int flag)
{
force_flush = flag;
if (waitqueue_active(&pbd_waitq)) {
wake_up_interruptible(&pbd_waitq);
}
}
typedef void (*timeout_fn)(unsigned long);
STATIC int
pagebuf_daemon(
void *data)
{
int count;
page_buf_t *pb;
struct list_head *curr, *next, tmp;
struct timer_list pb_daemon_timer =
{ {NULL, NULL}, 0, 0, (timeout_fn)pagebuf_daemon_wakeup };
/* Set up the thread */
daemonize();
/* Avoid signals */
spin_lock_irq(¤t->sigmask_lock);
sigfillset(¤t->blocked);
recalc_sigpending(current);
spin_unlock_irq(¤t->sigmask_lock);
strcpy(current->comm, "pagebufd");
current->flags |= PF_MEMALLOC;
INIT_LIST_HEAD(&tmp);
do {
if (pbd_active == 1) {
del_timer(&pb_daemon_timer);
pb_daemon_timer.expires = jiffies +
pb_params.p_un.flush_interval;
add_timer(&pb_daemon_timer);
interruptible_sleep_on(&pbd_waitq);
}
if (pbd_active == 0) {
del_timer(&pb_daemon_timer);
}
spin_lock(&pbd_delwrite_lock);
count = 0;
list_for_each_safe(curr, next, &pbd_delwrite_queue) {
pb = list_entry(curr, page_buf_t, pb_list);
PB_TRACE(pb, PB_TRACE_REC(walkq1), pagebuf_ispin(pb));
if ((pb->pb_flags & PBF_DELWRI) && !pagebuf_ispin(pb) &&
(((pb->pb_flags & _PBF_LOCKABLE) == 0) ||
!pagebuf_cond_lock(pb))) {
if (!force_flush &&
time_before(jiffies, pb->pb_flushtime)) {
pagebuf_unlock(pb);
break;
}
list_del(&pb->pb_list);
list_add(&pb->pb_list, &tmp);
count++;
}
}
spin_unlock(&pbd_delwrite_lock);
while (!list_empty(&tmp)) {
pb = list_entry(tmp.next, page_buf_t, pb_list);
list_del_init(&pb->pb_list);
pb->pb_flags &= ~PBF_DELWRI;
pb->pb_flags |= PBF_WRITE;
__pagebuf_iorequest(pb);
}
if (as_list_len > 0)
purge_addresses();
if (count)
pagebuf_run_queues(NULL);
force_flush = 0;
} while (pbd_active == 1);
pbd_active = -1;
wake_up_interruptible(&pbd_waitq);
return 0;
}
void
pagebuf_delwri_flush(
pb_target_t *target,
u_long flags,
int *pinptr)
{
page_buf_t *pb;
struct list_head *curr, *next, tmp;
int pincount = 0;
spin_lock(&pbd_delwrite_lock);
INIT_LIST_HEAD(&tmp);
list_for_each_safe(curr, next, &pbd_delwrite_queue) {
pb = list_entry(curr, page_buf_t, pb_list);
/*
* Skip other targets, markers and in progress buffers
*/
if ((pb->pb_flags == 0) || (pb->pb_target != target) ||
!(pb->pb_flags & PBF_DELWRI)) {
continue;
}
PB_TRACE(pb, PB_TRACE_REC(walkq2), pagebuf_ispin(pb));
if (pagebuf_ispin(pb)) {
pincount++;
continue;
}
if (flags & PBDF_TRYLOCK) {
if (!pagebuf_cond_lock(pb)) {
pincount++;
continue;
}
}
list_del_init(&pb->pb_list);
if (flags & PBDF_WAIT) {
list_add(&pb->pb_list, &tmp);
pb->pb_flags &= ~PBF_ASYNC;
}
spin_unlock(&pbd_delwrite_lock);
if ((flags & PBDF_TRYLOCK) == 0) {
pagebuf_lock(pb);
}
pb->pb_flags &= ~PBF_DELWRI;
pb->pb_flags |= PBF_WRITE;
__pagebuf_iorequest(pb);
spin_lock(&pbd_delwrite_lock);
}
spin_unlock(&pbd_delwrite_lock);
pagebuf_run_queues(NULL);
if (pinptr)
*pinptr = pincount;
if ((flags & PBDF_WAIT) == 0)
return;
while (!list_empty(&tmp)) {
pb = list_entry(tmp.next, page_buf_t, pb_list);
list_del_init(&pb->pb_list);
pagebuf_iowait(pb);
if (!pb->pb_relse)
pagebuf_unlock(pb);
pagebuf_rele(pb);
}
}
STATIC int
pagebuf_daemon_start(void)
{
int cpu;
kernel_thread(pagebuf_daemon, NULL,
CLONE_FS|CLONE_FILES|CLONE_VM);
for (cpu = 0; cpu < smp_num_cpus; cpu++) {
if (kernel_thread(pagebuf_iodone_daemon,
(void *)(long) cpu,
CLONE_FS|CLONE_FILES|CLONE_VM) < 0) {
printk("pagebuf_daemon_start failed\n");
} else {
while (!pb_daemons[cpu_logical_map(cpu)])
yield();
}
}
return 0;
}
/*
* pagebuf_daemon_stop
*
* Note: do not mark as __exit, it is called from pagebuf_terminate.
*/
STATIC void
pagebuf_daemon_stop(void)
{
int cpu, pcpu;
pbd_active = 0;
wake_up_interruptible(&pbd_waitq);
wait_event_interruptible(pbd_waitq, pbd_active);
for (pcpu = 0; pcpu < smp_num_cpus; pcpu++) {
cpu = cpu_logical_map(pcpu);
pb_daemons[cpu] = 0;
wake_up(&pagebuf_iodone_wait[cpu]);
wait_event_interruptible(pagebuf_iodone_wait[cpu],
pb_daemons[cpu] == -1);
}
}
/*
* Pagebuf sysctl interface
*/
STATIC int
pb_stats_clear_handler(
ctl_table *ctl,
int write,
struct file *filp,
void *buffer,
size_t *lenp)
{
int ret;
int *valp = ctl->data;
ret = proc_doulongvec_minmax(ctl, write, filp, buffer, lenp);
if (!ret && write && *valp) {
printk("XFS Clearing pbstats\n");
memset(&pbstats, 0, sizeof(pbstats));
pb_params.p_un.stats_clear = 0;
}
return ret;
}
STATIC struct ctl_table_header *pagebuf_table_header;
STATIC ctl_table pagebuf_table[] = {
{PB_FLUSH_INT, "flush_int", &pb_params.data[0],
sizeof(ulong), 0644, NULL, &proc_doulongvec_ms_jiffies_minmax,
&sysctl_intvec, NULL, &pagebuf_min[0], &pagebuf_max[0]},
{PB_FLUSH_AGE, "flush_age", &pb_params.data[1],
sizeof(ulong), 0644, NULL, &proc_doulongvec_ms_jiffies_minmax,
&sysctl_intvec, NULL, &pagebuf_min[1], &pagebuf_max[1]},
{PB_STATS_CLEAR, "stats_clear", &pb_params.data[2],
sizeof(ulong), 0644, NULL, &pb_stats_clear_handler,
&sysctl_intvec, NULL, &pagebuf_min[2], &pagebuf_max[2]},
#ifdef PAGEBUF_TRACE
{PB_DEBUG, "debug", &pb_params.data[3],
sizeof(ulong), 0644, NULL, &proc_doulongvec_minmax,
&sysctl_intvec, NULL, &pagebuf_min[3], &pagebuf_max[3]},
#endif
{0}
};
STATIC ctl_table pagebuf_dir_table[] = {
{VM_PAGEBUF, "pagebuf", NULL, 0, 0555, pagebuf_table},
{0}
};
STATIC ctl_table pagebuf_root_table[] = {
{CTL_VM, "vm", NULL, 0, 0555, pagebuf_dir_table},
{0}
};
#ifdef CONFIG_PROC_FS
STATIC int
pagebuf_readstats(
char *buffer,
char **start,
off_t offset,
int count,
int *eof,
void *data)
{
int i, len;
len = 0;
len += sprintf(buffer + len, "pagebuf");
for (i = 0; i < sizeof(pbstats) / sizeof(u_int32_t); i++) {
len += sprintf(buffer + len, " %u",
*(((u_int32_t*)&pbstats) + i));
}
buffer[len++] = '\n';
if (offset >= len) {
*start = buffer;
*eof = 1;
return 0;
}
*start = buffer + offset;
if ((len -= offset) > count)
return count;
*eof = 1;
return len;
}
#endif /* CONFIG_PROC_FS */
STATIC void
pagebuf_shaker(void)
{
pagebuf_daemon_wakeup(1);
}
/*
* Initialization and Termination
*/
int __init
pagebuf_init(void)
{
int order, mempages, i;
unsigned int nr_hash;
extern int xfs_physmem;
mempages = xfs_physmem >>= 16;
mempages *= sizeof(pb_hash_t);
for (order = 0; (1 << order) < mempages; order++)
;
if (order > 3) order = 3; /* cap us at 2K buckets */
do {
unsigned long tmp;
nr_hash = (PAGE_SIZE << order) / sizeof(pb_hash_t);
nr_hash = 1 << (ffs(nr_hash) - 1);
pb_hash_mask = (nr_hash - 1);
tmp = nr_hash;
pb_hash_shift = 0;
while((tmp >>= 1UL) != 0UL)
pb_hash_shift++;
pbhash = (pb_hash_t *)
__get_free_pages(GFP_KERNEL, order);
pb_order = order;
} while (pbhash == NULL && --order > 0);
printk("pagebuf cache hash table entries: %d (order: %d, %ld bytes)\n",
nr_hash, order, (PAGE_SIZE << order));
for(i = 0; i < nr_hash; i++) {
spin_lock_init(&pbhash[i].pb_hash_lock);
INIT_LIST_HEAD(&pbhash[i].pb_hash);
}
pagebuf_table_header = register_sysctl_table(pagebuf_root_table, 1);
#ifdef CONFIG_PROC_FS
if (proc_mkdir("fs/pagebuf", 0))
create_proc_read_entry(
"fs/pagebuf/stat", 0, 0, pagebuf_readstats, NULL);
#endif
pagebuf_cache = kmem_cache_create("page_buf_t", sizeof(page_buf_t), 0,
SLAB_HWCACHE_ALIGN, NULL, NULL);
if (pagebuf_cache == NULL) {
printk("pagebuf: couldn't init pagebuf cache\n");
pagebuf_terminate();
return -ENOMEM;
}
if (_pagebuf_prealloc_bh(NR_RESERVED_BH) < NR_RESERVED_BH) {
printk("pagebuf: couldn't pre-allocate %d buffer heads\n",
NR_RESERVED_BH);
pagebuf_terminate();
return -ENOMEM;
}
init_waitqueue_head(&pb_resv_bh_wait);
#ifdef PAGEBUF_TRACE
pb_trace.buf = (pagebuf_trace_t *)kmalloc(
PB_TRACE_BUFSIZE * sizeof(pagebuf_trace_t), GFP_KERNEL);
memset(pb_trace.buf, 0, PB_TRACE_BUFSIZE * sizeof(pagebuf_trace_t));
pb_trace.start = 0;
pb_trace.end = PB_TRACE_BUFSIZE - 1;
#endif
pagebuf_daemon_start();
kmem_shake_register(pagebuf_shaker);
return 0;
}
/*
* pagebuf_terminate.
*
* Note: do not mark as __exit, this is also called from the __init code.
*/
void
pagebuf_terminate(void)
{
pagebuf_daemon_stop();
kmem_cache_destroy(pagebuf_cache);
kmem_shake_deregister(pagebuf_shaker);
free_pages((unsigned long)pbhash, pb_order);
unregister_sysctl_table(pagebuf_table_header);
#ifdef CONFIG_PROC_FS
remove_proc_entry("fs/pagebuf/stat", NULL);
remove_proc_entry("fs/pagebuf", NULL);
#endif
}
/*
* Module management (for kernel debugger module)
*/
EXPORT_SYMBOL(pagebuf_offset);
![[BACK]](/icons/back.gif){kind=icon}
Return to xfs_buf.c CVS log ![[TXT]](/icons/text.gif){kind=icon}
![[DIR]](/icons/dir.gif){kind=icon}
Up to [Development] / xfs-linux / linux-2.4