File: [Development] / xfs-linux / linux-2.4 / Attic / xfs_buf.c (download)
Revision 1.143, Fri Nov 21 21:31:49 2003 UTC (13 years, 11 months ago) by sandeen
Branch: MAIN
Changes since 1.142: +1 -1
lines
Fix the pb stats clear handler, value is
int but handler was using ulong
Merge of 2.4.x-xfs-kern:slinx:162287a by sandeen.
Set up pb clear handler properly for int value
|
/*
* Copyright (c) 2000-2003 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/ktrace.h>
#include <support/debug.h>
#include <support/kmem.h>
#include "page_buf.h"
#define NBBY 8
#define BBSHIFT 9
#define BBMASK ((1 << BBSHIFT) - 1)
#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
/*
* cpumask_t is used for supporting NR_CPUS > BITS_PER_LONG.
* If support for this is present, migrate_to_cpu exists and provides
* a wrapper around the set_cpus_allowed routine.
*/
#ifdef copy_cpumask
#define __HAVE_CPUMASK_T 1
#endif
#ifndef __HAVE_CPUMASK_T
# ifndef __HAVE_NEW_SCHEDULER
# define migrate_to_cpu(cpu) \
do { current->cpus_allowed = 1UL << (cpu); } while (0)
# else
# define migrate_to_cpu(cpu) \
set_cpus_allowed(current, 1UL << (cpu))
# endif
#endif
/*
* File wide globals
*/
STATIC kmem_cache_t *pagebuf_cache;
#define MAX_IO_DAEMONS NR_CPUS
#define CPU_TO_DAEMON(cpu) (cpu)
STATIC int pb_logio_daemons[MAX_IO_DAEMONS];
STATIC struct list_head pagebuf_logiodone_tq[MAX_IO_DAEMONS];
STATIC wait_queue_head_t pagebuf_logiodone_wait[MAX_IO_DAEMONS];
STATIC int pb_dataio_daemons[MAX_IO_DAEMONS];
STATIC struct list_head pagebuf_dataiodone_tq[MAX_IO_DAEMONS];
STATIC wait_queue_head_t pagebuf_dataiodone_wait[MAX_IO_DAEMONS];
/*
* 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);
STATIC void pagebuf_runall_queues(struct list_head[]);
/*
* Pagebuf module configuration parameters, exported via
* /proc/sys/vm/pagebuf
*/
typedef struct pb_sysctl_val {
int min;
int val;
int max;
} pb_sysctl_val_t;
struct {
pb_sysctl_val_t flush_interval; /* interval between runs of the
* delwri flush daemon. */
pb_sysctl_val_t age_buffer; /* time for buffer to age before
* we flush it. */
pb_sysctl_val_t stats_clear; /* clear the pagebuf stats */
pb_sysctl_val_t debug; /* debug tracing on or off */
} pb_params = {
/* MIN DFLT MAX */
.flush_interval = { HZ/2, HZ, 30*HZ },
.age_buffer = { 1*HZ, 15*HZ, 300*HZ },
.stats_clear = { 0, 0, 1 },
.debug = { 0, 0, 1 },
};
enum {
PB_FLUSH_INT = 1,
PB_FLUSH_AGE = 2,
PB_STATS_CLEAR = 3,
PB_DEBUG = 4,
};
/*
* Pagebuf statistics variables
*/
struct {
u_int32_t pb_get;
u_int32_t pb_create;
u_int32_t pb_get_locked;
u_int32_t pb_get_locked_waited;
u_int32_t pb_busy_locked;
u_int32_t pb_miss_locked;
u_int32_t pb_page_retries;
u_int32_t pb_page_found;
u_int32_t pb_get_read;
} pbstats;
#define PB_STATS_INC(count) ( pbstats.count++ )
/*
* Pagebuf debugging
*/
#ifdef PAGEBUF_TRACE
void
pagebuf_trace(
page_buf_t *pb,
char *id,
void *data,
void *ra)
{
if (!pb_params.debug.val)
return;
ktrace_enter(pagebuf_trace_buf,
pb, id,
(void *)(unsigned long)pb->pb_flags,
(void *)(unsigned long)pb->pb_hold.counter,
(void *)(unsigned long)pb->pb_sema.count.counter,
(void *)current,
data, ra,
(void *)(unsigned long)((pb->pb_file_offset>>32) & 0xffffffff),
(void *)(unsigned long)(pb->pb_file_offset & 0xffffffff),
(void *)(unsigned long)pb->pb_buffer_length,
NULL, NULL, NULL, NULL, NULL);
}
ktrace_t *pagebuf_trace_buf;
EXPORT_SYMBOL(pagebuf_trace_buf);
#define PAGEBUF_TRACE_SIZE 4096
#define PB_TRACE(pb, id, data) \
pagebuf_trace(pb, id, (void *)data, (void *)__builtin_return_address(0))
#else
#define PB_TRACE(pb, id, data) do { } while (0)
#endif
#ifdef PAGEBUF_LOCK_TRACKING
# define PB_SET_OWNER(pb) ((pb)->pb_last_holder = current->pid)
# define PB_CLEAR_OWNER(pb) ((pb)->pb_last_holder = -1)
# define PB_GET_OWNER(pb) ((pb)->pb_last_holder)
#else
# define PB_SET_OWNER(pb) do { } while (0)
# define PB_CLEAR_OWNER(pb) do { } while (0)
# define PB_GET_OWNER(pb) do { } while (0)
#endif
/*
* 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
*/
#define NBITS 8
#define NHASH (1<<NBITS)
typedef struct {
struct list_head pb_hash;
int pb_count;
spinlock_t pb_hash_lock;
} pb_hash_t;
STATIC pb_hash_t pbhash[NHASH];
#define pb_hash(pb) &pbhash[pb->pb_hash_index]
STATIC int
_bhash(
struct block_device *bdev,
loff_t base)
{
int bit, hval;
base >>= 9;
base ^= (unsigned long)bdev / L1_CACHE_BYTES;
for (bit = hval = 0; base && bit < sizeof(base) * 8; bit += NBITS) {
hval ^= (int)base & (NHASH-1);
base >>= NBITS;
}
return hval;
}
/*
* Mapping of multi-page buffers into contiguous virtual space
*/
STATIC void *pagebuf_mapout_locked(page_buf_t *);
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;
STATIC spinlock_t as_lock = SPIN_LOCK_UNLOCKED;
/*
* 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);
}
}
/*
* 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(pb_create);
PB_TRACE(pb, "initialize", 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, "free_object", 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;
all_mapped = 1;
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 (pi = 0; 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(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(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,
VM_ALLOC, PAGE_KERNEL);
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, "lookup_pages", (long)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);
blk_run_queues();
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, 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(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, "get_lock", 0);
pagebuf_lock(pb);
PB_STATS_INC(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(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, "got_lock", 0);
PB_STATS_INC(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(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, "get_read", (unsigned long)flags);
PB_STATS_INC(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, "get_done", (unsigned long)flags);
return (pb);
}
/*
* Create a skeletal pagebuf (no pages associated with it).
*/
page_buf_t *
pagebuf_lookup(
struct pb_target *target,
loff_t ioff,
size_t isize,
page_buf_flags_t flags)
{
page_buf_t *pb;
flags |= _PBF_PRIVATE_BH | _PBF_LOCKABLE;
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(
size_t len,
pb_target_t *target)
{
page_buf_t *pb;
pb = pagebuf_allocate(_PBF_LOCKABLE);
if (pb)
_pagebuf_initialize(pb, target, 0, len, _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, "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, "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, "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);
}
}
/*
* Mutual exclusion on buffers. 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 a
* spinlock in the buffer, used by the caller when concurrent
* access is possible.
*/
/*
* pagebuf_cond_lock
*
* pagebuf_cond_lock locks a buffer object, if it is not already locked.
* Note that this in no way
* locks the underlying pages, so it is only useful for synchronizing
* concurrent use of page buffer objects, not for synchronizing independent
* access to the underlying pages.
*/
int
pagebuf_cond_lock( /* lock buffer, if not locked */
/* returns -EBUSY if locked) */
page_buf_t *pb)
{
int locked;
ASSERT(pb->pb_flags & _PBF_LOCKABLE);
locked = down_trylock(&pb->pb_sema) == 0;
if (locked) {
PB_SET_OWNER(pb);
}
PB_TRACE(pb, "cond_lock", (long)locked);
return(locked ? 0 : -EBUSY);
}
/*
* pagebuf_lock_value
*
* Return lock value for a pagebuf
*/
int
pagebuf_lock_value(
page_buf_t *pb)
{
ASSERT(pb->pb_flags & _PBF_LOCKABLE);
return(atomic_read(&pb->pb_sema.count));
}
/*
* pagebuf_lock
*
* pagebuf_lock locks a buffer object. Note that this in no way
* locks the underlying pages, so it is only useful for synchronizing
* concurrent use of page buffer objects, not for synchronizing independent
* access to the underlying pages.
*/
int
pagebuf_lock(
page_buf_t *pb)
{
ASSERT(pb->pb_flags & _PBF_LOCKABLE);
PB_TRACE(pb, "lock", 0);
if (atomic_read(&pb->pb_io_remaining))
blk_run_queues();
down(&pb->pb_sema);
PB_SET_OWNER(pb);
PB_TRACE(pb, "locked", 0);
return 0;
}
/*
* pagebuf_unlock
*
* pagebuf_unlock releases the lock on the buffer object created by
* pagebuf_lock or pagebuf_cond_lock (not any
* pinning of underlying pages created by pagebuf_pin).
*/
void
pagebuf_unlock( /* unlock buffer */
page_buf_t *pb) /* buffer to unlock */
{
ASSERT(pb->pb_flags & _PBF_LOCKABLE);
PB_CLEAR_OWNER(pb);
up(&pb->pb_sema);
PB_TRACE(pb, "unlock", 0);
}
/*
* 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, "pin", (long)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, "unpin", (long)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;
if (atomic_read(&pb->pb_io_remaining))
blk_run_queues();
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 dataio,
int schedule)
{
pb->pb_flags &= ~(PBF_READ | PBF_WRITE);
if (pb->pb_error == 0) {
pb->pb_flags &= ~(PBF_PARTIAL | PBF_NONE);
}
PB_TRACE(pb, "iodone", pb->pb_iodone);
if ((pb->pb_iodone) || (pb->pb_flags & PBF_ASYNC)) {
if (schedule) {
int daemon = CPU_TO_DAEMON(smp_processor_id());
INIT_TQUEUE(&pb->pb_iodone_sched,
pagebuf_iodone_sched, (void *)pb);
queue_task(&pb->pb_iodone_sched, dataio ?
&pagebuf_dataiodone_tq[daemon] :
&pagebuf_logiodone_tq[daemon]);
wake_up(dataio ?
&pagebuf_dataiodone_wait[daemon] :
&pagebuf_logiodone_wait[daemon]);
} 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, "ioerror", (unsigned long)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, "iostart", (unsigned long)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 | PBF_RUN_QUEUES);
pb->pb_flags |= flags & (PBF_READ | PBF_WRITE | PBF_ASYNC | \
PBF_SYNC | PBF_READ_AHEAD | PBF_RUN_QUEUES);
BUG_ON(pb->pb_bn == PAGE_BUF_DADDR_NULL);
/* For writes allow an alternate strategy routine to precede
* the actual I/O request (which may not be issued at all in
* a shutdown situation, for example).
*/
status = (flags & PBF_WRITE) ?
pagebuf_iostrategy(pb) : pagebuf_iorequest(pb);
/* Wait for I/O if we are not an async request.
* Note: async I/O request completion will release the buffer,
* and that can already be done by this point. So using the
* buffer pointer from here on, after async I/O, is invalid.
*/
if (!status && !(flags & PBF_ASYNC))
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_target->pbr_bsize < PAGE_CACHE_SIZE)
return pb->pb_locked;
if (pb->pb_flags & PBF_READ)
return pb->pb_locked;
return (!(pb->pb_flags & _PBF_LOCKABLE));
}
STATIC void
_pagebuf_iodone(
page_buf_t *pb,
int schedule)
{
int i;
if (atomic_dec_and_test(&pb->pb_io_remaining) != 1)
return;
if (_pagebuf_iolocked(pb))
for (i = 0; i < pb->pb_page_count; i++)
unlock_page(pb->pb_pages[i]);
pb->pb_locked = 0;
pagebuf_iodone(pb, (pb->pb_flags & PBF_FS_DATAIOD), 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);
if (!PageError(page))
SetPageUptodate(page);
} else {
static spinlock_t page_uptodate_lock = SPIN_LOCK_UNLOCKED;
struct buffer_head *bp;
unsigned long flags;
ASSERT(PageLocked(page));
spin_lock_irqsave(&page_uptodate_lock, flags);
clear_buffer_async(bh);
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, 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 int
_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 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;
sector = 1 << sector_shift;
ASSERT(PageLocked(page));
if (!page_has_buffers(page))
create_empty_buffers(page, pbr->pbr_kdev, sector);
i = sector >> BBSHIFT;
bn -= (pg_offset >> BBSHIFT);
/* Find buffer_heads belonging to just this pagebuf */
bh = head = page_buffers(page);
do {
if (buffer_uptodate(bh) && cache_ok)
continue;
if (blk_length < pg_offset)
continue;
if (blk_length >= pg_offset + pg_length)
break;
lock_buffer(bh);
get_bh(bh);
bh->b_size = sector;
bh->b_blocknr = bn;
bufferlist[cnt++] = bh;
} while ((bn += i),
(blk_length += sector),
(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 > ((1ULL << NBBY * sizeof(bh->b_size)) - 1)) {
sector >>= 1;
blk_length++;
}
multi_ok = (blk_length != 1);
i = sector >> BBSHIFT;
for (; blk_length > 0; bn += i, 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_blocknr = bn;
bh->b_size = sector;
bh->b_dev = pbr->pbr_kdev;
set_buffer_locked(bh);
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_buffer_mapped(bh);
set_buffer_async(bh);
set_buffer_req(bh);
if (rw == WRITE)
set_buffer_uptodate(bh);
generic_make_request(rw, bh);
}
return 0;
}
/*
* We have no I/O to submit, let the caller know that
* we have skipped over this page entirely.
*/
return 1;
}
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 status, 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 >> BBSHIFT);
pg_offset = 0;
pg_length = PAGE_CACHE_SIZE;
} else {
pb_offset = offset - pb->pb_file_offset;
if (pb_offset) {
bn += (pb_offset + BBMASK) >> BBSHIFT;
}
}
locking = _pagebuf_iolocked(pb);
if (pb->pb_flags & PBF_WRITE) {
if (locking && !pb->pb_locked)
lock_page(page);
status = _pagebuf_page_io(page, pbr, pb, bn,
pg_offset, pg_length, WRITE,
last && (pb->pb_flags & PBF_FLUSH));
} else {
status = _pagebuf_page_io(page, pbr, pb, bn,
pg_offset, pg_length, READ, 0);
}
if (status && locking && !(pb->pb_target->pbr_bsize < PAGE_CACHE_SIZE))
unlock_page(page);
}
/*
* 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, "iorequest", 0);
if (pb->pb_flags & PBF_DELWRI) {
pagebuf_delwri_queue(pb, 1);
return 0;
}
if (pb->pb_flags & PBF_WRITE) {
_pagebuf_wait_unpin(pb);
}
pagebuf_hold(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);
pagebuf_rele(pb);
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, "iowait", 0);
if (atomic_read(&pb->pb_io_remaining))
blk_run_queues();
if ((pb->pb_flags & PBF_FS_DATAIOD))
pagebuf_runall_queues(pagebuf_dataiodone_tq);
down(&pb->pb_iodonesema);
PB_TRACE(pb, "iowaited", (long)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 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;
cur_offset = pb->pb_offset;
cur_len = buffer_len;
if (!pb->pb_locked &&
(pb->pb_target->pbr_bsize < PAGE_CACHE_SIZE)) {
for (index = 0; index < pb->pb_page_count; index++)
lock_page(pb->pb_pages[index]);
pb->pb_locked = 1;
}
for (index = 0; index < pb->pb_page_count; 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[index], page_offset, len,
index + 1 == pb->pb_page_count);
buffer_offset += len;
buffer_len -= len;
}
/*
* Run the block device task queue here, while we have
* a hold on the pagebuf (important to have that hold).
*/
if (pb->pb_flags & PBF_RUN_QUEUES) {
pb->pb_flags &= ~PBF_RUN_QUEUES;
if (atomic_read(&pb->pb_io_remaining) > 1)
blk_run_queues();
}
}
/*
* 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, "delwri_q", (long)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.age_buffer.val;
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, "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 daemons
*/
STATIC int
pagebuf_iodone_daemon(
void *__bind_cpu,
const char *name,
int pagebuf_daemons[],
struct list_head pagebuf_iodone_tq[],
wait_queue_head_t pagebuf_iodone_wait[])
{
int bind_cpu, cpu;
DECLARE_WAITQUEUE (wait, current);
bind_cpu = (int) (long)__bind_cpu;
cpu = CPU_TO_DAEMON(cpu_logical_map(bind_cpu));
/* 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 */
migrate_to_cpu(cpu);
#ifdef __HAVE_NEW_SCHEDULER
if (smp_processor_id() != cpu)
BUG();
#else
while (smp_processor_id() != cpu)
schedule();
#endif
sprintf(current->comm, "%s/%d", name, bind_cpu);
INIT_LIST_HEAD(&pagebuf_iodone_tq[cpu]);
init_waitqueue_head(&pagebuf_iodone_wait[cpu]);
__set_current_state(TASK_INTERRUPTIBLE);
mb();
pagebuf_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 (pagebuf_daemons[cpu] == 0)
break;
__set_current_state(TASK_INTERRUPTIBLE);
}
pagebuf_daemons[cpu] = -1;
wake_up_interruptible(&pagebuf_iodone_wait[cpu]);
return 0;
}
STATIC void
pagebuf_runall_queues(
struct list_head pagebuf_iodone_tq[])
{
int pcpu, cpu;
for (cpu = 0; cpu < min(smp_num_cpus, MAX_IO_DAEMONS); cpu++) {
pcpu = CPU_TO_DAEMON(cpu_logical_map(cpu));
run_task_queue(&pagebuf_iodone_tq[pcpu]);
}
}
STATIC int
pagebuf_logiodone_daemon(
void *__bind_cpu)
{
return pagebuf_iodone_daemon(__bind_cpu, "xfslogd", pb_logio_daemons,
pagebuf_logiodone_tq, pagebuf_logiodone_wait);
}
STATIC int
pagebuf_dataiodone_daemon(
void *__bind_cpu)
{
return pagebuf_iodone_daemon(__bind_cpu, "xfsdatad", pb_dataio_daemons,
pagebuf_dataiodone_tq, pagebuf_dataiodone_wait);
}
/* 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) {
mod_timer(&pb_daemon_timer,
jiffies + pb_params.flush_interval.val);
interruptible_sleep_on(&pbd_waitq);
}
if (pbd_active == 0) {
del_timer_sync(&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, "walkq1", (long)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;
}
pb->pb_flags &= ~PBF_DELWRI;
pb->pb_flags |= PBF_WRITE;
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);
pagebuf_iostrategy(pb);
}
if (as_list_len > 0)
purge_addresses();
if (count)
blk_run_queues();
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;
int flush_cnt = 0;
pagebuf_runall_queues(pagebuf_dataiodone_tq);
pagebuf_runall_queues(pagebuf_logiodone_tq);
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, "walkq2", (long)pagebuf_ispin(pb));
if (pagebuf_ispin(pb)) {
pincount++;
continue;
}
pb->pb_flags &= ~PBF_DELWRI;
pb->pb_flags |= PBF_WRITE;
list_move(&pb->pb_list, &tmp);
}
/* ok found all the items that can be worked on
* drop the lock and process the private list */
spin_unlock(&pbd_delwrite_lock);
list_for_each_safe(curr, next, &tmp) {
pb = list_entry(curr, page_buf_t, pb_list);
if (flags & PBDF_WAIT)
pb->pb_flags &= ~PBF_ASYNC;
else
list_del_init(curr);
pagebuf_lock(pb);
pagebuf_iostrategy(pb);
if (++flush_cnt > 32) {
blk_run_queues();
flush_cnt = 0;
}
}
blk_run_queues();
/* must run list the second time even if PBDF_WAIT isn't
* to reset all the pb_list pointers
*/
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);
}
if (pinptr)
*pinptr = pincount;
}
STATIC int
pagebuf_daemon_start(void)
{
int cpu, pcpu;
kernel_thread(pagebuf_daemon, NULL, CLONE_FS|CLONE_FILES|CLONE_VM);
for (cpu = 0; cpu < min(smp_num_cpus, MAX_IO_DAEMONS); cpu++) {
pcpu = CPU_TO_DAEMON(cpu_logical_map(cpu));
if (kernel_thread(pagebuf_logiodone_daemon,
(void *)(long) cpu,
CLONE_FS|CLONE_FILES|CLONE_VM) < 0) {
printk("pagebuf_logiodone daemon failed to start\n");
} else {
while (!pb_logio_daemons[pcpu])
yield();
}
}
for (cpu = 0; cpu < min(smp_num_cpus, MAX_IO_DAEMONS); cpu++) {
pcpu = CPU_TO_DAEMON(cpu_logical_map(cpu));
if (kernel_thread(pagebuf_dataiodone_daemon,
(void *)(long) cpu,
CLONE_FS|CLONE_FILES|CLONE_VM) < 0) {
printk("pagebuf_dataiodone daemon failed to start\n");
} else {
while (!pb_dataio_daemons[pcpu])
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 < min(smp_num_cpus, MAX_IO_DAEMONS); pcpu++) {
cpu = CPU_TO_DAEMON(cpu_logical_map(pcpu));
pb_logio_daemons[cpu] = 0;
wake_up(&pagebuf_logiodone_wait[cpu]);
wait_event_interruptible(pagebuf_logiodone_wait[cpu],
pb_logio_daemons[cpu] == -1);
pb_dataio_daemons[cpu] = 0;
wake_up(&pagebuf_dataiodone_wait[cpu]);
wait_event_interruptible(pagebuf_dataiodone_wait[cpu],
pb_dataio_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_dointvec_minmax(ctl, write, filp, buffer, lenp);
if (!ret && write && *valp) {
printk("XFS Clearing pbstats\n");
memset(&pbstats, 0, sizeof(pbstats));
pb_params.stats_clear.val = 0;
}
return ret;
}
STATIC struct ctl_table_header *pagebuf_table_header;
STATIC ctl_table pagebuf_table[] = {
{PB_FLUSH_INT, "flush_int", &pb_params.flush_interval.val,
sizeof(int), 0644, NULL, &proc_dointvec_minmax,
&sysctl_intvec, NULL,
&pb_params.flush_interval.min, &pb_params.flush_interval.max},
{PB_FLUSH_AGE, "flush_age", &pb_params.age_buffer.val,
sizeof(int), 0644, NULL, &proc_dointvec_minmax,
&sysctl_intvec, NULL,
&pb_params.age_buffer.min, &pb_params.age_buffer.max},
{PB_STATS_CLEAR, "stats_clear", &pb_params.stats_clear.val,
sizeof(int), 0644, NULL, &pb_stats_clear_handler,
&sysctl_intvec, NULL,
&pb_params.stats_clear.min, &pb_params.stats_clear.max},
#ifdef PAGEBUF_TRACE
{PB_DEBUG, "debug", &pb_params.debug.val,
sizeof(int), 0644, NULL, &proc_dointvec_minmax,
&sysctl_intvec, NULL,
&pb_params.debug.min, &pb_params.debug.max},
#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 i;
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);
for (i = 0; i < NHASH; i++) {
spin_lock_init(&pbhash[i].pb_hash_lock);
INIT_LIST_HEAD(&pbhash[i].pb_hash);
}
#ifdef PAGEBUF_TRACE
pagebuf_trace_buf = ktrace_alloc(PAGEBUF_TRACE_SIZE, KM_SLEEP);
#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);
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);
#ifdef DEBUG
EXPORT_SYMBOL(pbd_delwrite_queue);
#endif
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