File: [Development] / xfs-linux / linux-2.6 / xfs_buf.c (download)
Revision 1.138, Thu Jan 29 19:05:20 2004 UTC (13 years, 8 months ago) by hch
Branch: MAIN
Changes since 1.137: +21 -32
lines
Stop using sleep_on
Switch pagebuf_daemon from sleep_on to schedule_timeout
|
/*
* 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/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/bio.h>
#include <linux/sysctl.h>
#include <linux/proc_fs.h>
#include <linux/workqueue.h>
#include <linux/suspend.h>
#include <linux/percpu.h>
#include <support/ktrace.h>
#include <support/debug.h>
#include "kmem.h"
#include "xfs_types.h"
#include "xfs_cred.h"
#include "xfs_lrw.h"
#include "xfs_buf.h"
#define BBSHIFT 9
#define BN_ALIGN_MASK ((1 << (PAGE_CACHE_SHIFT - BBSHIFT)) - 1)
#ifndef GFP_READAHEAD
#define GFP_READAHEAD (__GFP_NOWARN|__GFP_NORETRY)
#endif
/*
* File wide globals
*/
STATIC kmem_cache_t *pagebuf_cache;
STATIC void pagebuf_daemon_wakeup(void);
STATIC void pagebuf_delwri_queue(page_buf_t *, int);
STATIC struct workqueue_struct *pagebuf_logio_workqueue;
STATIC struct workqueue_struct *pagebuf_dataio_workqueue;
/*
* 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 pbstats {
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_PER_CPU(struct pbstats, pbstats);
/* We don't disable preempt, not too worried about poking the
* wrong cpu's stat for now */
#define PB_STATS_INC(count) (__get_cpu_var(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;
#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 pb_to_km(flags) \
(((flags) & PBF_DONT_BLOCK) ? KM_NOFS : KM_SLEEP)
#define pagebuf_allocate(flags) \
kmem_zone_alloc(pagebuf_cache, pb_to_km(flags))
#define pagebuf_deallocate(pb) \
kmem_zone_free(pagebuf_cache, (pb));
/*
* Pagebuf hashing
*/
#define NBITS 8
#define NHASH (1<<NBITS)
typedef struct {
struct list_head pb_hash;
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);
}
}
}
/*
* 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)
{
page_buf_flags_t pb_flags = pb->pb_flags;
pb_hash_t *hash;
PB_TRACE(pb, "free_object", 0);
pb->pb_flags |= PBF_FREED;
if (pb->pb_flags & _PBF_LOCKABLE) {
hash = pb_hash(pb);
spin_lock(&hash->pb_hash_lock);
if (!list_empty(&pb->pb_hash_list))
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]) &&
(pb->pb_flags & _PBF_MEM_SLAB)) {
kfree(pb->pb_addr);
} else {
_pagebuf_freepages(pb);
}
if (pb->pb_pages != pb->pb_page_array)
kfree(pb->pb_pages);
pb->pb_pages = NULL;
}
pb->pb_flags &= ~(_PBF_MEM_ALLOCATED|_PBF_MEM_SLAB);
}
}
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, nbytes;
unsigned int blocksize, sectorshift;
size_t size, offset;
/* 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;
sectorshift = pb->pb_target->pbr_sshift;
size = pb->pb_count_desired;
offset = pb->pb_offset;
/* 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(pb_page_retries);
pagebuf_daemon_wakeup();
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);
}
nbytes = PAGE_CACHE_SIZE - offset;
if (nbytes > size)
nbytes = size;
size -= nbytes;
if (!PageUptodate(page)) {
if (blocksize == PAGE_CACHE_SIZE) {
if (flags & PBF_READ)
pb->pb_locked = 1;
good_pages--;
} else if (!PagePrivate(page)) {
unsigned long i, range;
/*
* In this case page->private holds a bitmap
* of uptodate sectors within the page
*/
ASSERT(blocksize < PAGE_CACHE_SIZE);
range = (offset + nbytes) >> sectorshift;
for (i = offset >> sectorshift; i < range; i++)
if (!test_bit(i, &page->private))
break;
if (i != range)
good_pages--;
} else {
good_pages--;
}
}
offset = 0;
}
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_MAP, 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;
}
/*
* 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;
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 | \
_PBF_MEM_SLAB;
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) {
PB_TRACE(pb, "get_read_async", (unsigned long)flags);
/*
* 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 {
PB_TRACE(pb, "get_read_done", (unsigned long)flags);
/* We do not want read in the flags */
pb->pb_flags &= ~PBF_READ;
}
} else {
PB_TRACE(pb, "get_write", (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;
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)
{
struct backing_dev_info *bdi;
bdi = target->pbr_mapping->backing_dev_info;
if (bdi_read_congested(bdi))
return;
if (bdi_write_congested(bdi))
return;
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;
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 (unlikely(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 | _PBF_MEM_SLAB);
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_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_TRACE(pb, "rele", pb->pb_relse);
if (atomic_dec_and_test(&pb->pb_hold)) {
int do_free = 1;
if (pb->pb_relse) {
atomic_inc(&pb->pb_hold);
(*(pb->pb_relse)) (pb);
do_free = 0;
}
if (pb->pb_flags & PBF_DELWRI) {
pb->pb_flags |= PBF_ASYNC;
atomic_inc(&pb->pb_hold);
pagebuf_delwri_queue(pb, 0);
do_free = 0;
} else if (pb->pb_flags & PBF_FS_MANAGED) {
do_free = 0;
}
if (do_free) {
pagebuf_free(pb);
}
}
}
/*
* 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_work(
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) {
INIT_WORK(&pb->pb_iodone_work, pagebuf_iodone_work, pb);
queue_work(dataio ? pagebuf_dataio_workqueue :
pagebuf_logio_workqueue, &pb->pb_iodone_work);
} else {
pagebuf_iodone_work(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 routine for pagebuf_iorequest
*/
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 __inline__ void
_pagebuf_iodone(
page_buf_t *pb,
int schedule)
{
if (atomic_dec_and_test(&pb->pb_io_remaining) == 1) {
pb->pb_locked = 0;
pagebuf_iodone(pb, (pb->pb_flags & PBF_FS_DATAIOD), schedule);
}
}
STATIC int
bio_end_io_pagebuf(
struct bio *bio,
unsigned int bytes_done,
int error)
{
page_buf_t *pb = (page_buf_t *)bio->bi_private;
unsigned int i, blocksize = pb->pb_target->pbr_bsize;
unsigned int sectorshift = pb->pb_target->pbr_sshift;
struct bio_vec *bvec = bio->bi_io_vec;
if (bio->bi_size)
return 1;
if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
pb->pb_error = EIO;
for (i = 0; i < bio->bi_vcnt; i++, bvec++) {
struct page *page = bvec->bv_page;
if (pb->pb_error) {
SetPageError(page);
} else if (blocksize == PAGE_CACHE_SIZE) {
SetPageUptodate(page);
} else if (!PagePrivate(page)) {
unsigned int j, range;
ASSERT(blocksize < PAGE_CACHE_SIZE);
range = (bvec->bv_offset + bvec->bv_len) >> sectorshift;
for (j = bvec->bv_offset >> sectorshift; j < range; j++)
set_bit(j, &page->private);
if (page->private == (unsigned long)(PAGE_CACHE_SIZE-1))
SetPageUptodate(page);
}
if (_pagebuf_iolocked(pb)) {
unlock_page(page);
}
}
_pagebuf_iodone(pb, 1);
bio_put(bio);
return 0;
}
void
_pagebuf_ioapply(
page_buf_t *pb)
{
int i, map_i, total_nr_pages, nr_pages;
struct bio *bio;
int offset = pb->pb_offset;
int size = pb->pb_count_desired;
sector_t sector = pb->pb_bn;
unsigned int blocksize = pb->pb_target->pbr_bsize;
int locking = _pagebuf_iolocked(pb);
total_nr_pages = pb->pb_page_count;
map_i = 0;
/* Special code path for reading a sub page size pagebuf in --
* we populate up the whole page, and hence the other metadata
* in the same page. This optimization is only valid when the
* filesystem block size and the page size are equal.
*/
if ((pb->pb_buffer_length < PAGE_CACHE_SIZE) &&
(pb->pb_flags & PBF_READ) && locking &&
(blocksize == PAGE_CACHE_SIZE)) {
bio = bio_alloc(GFP_NOIO, 1);
bio->bi_bdev = pb->pb_target->pbr_bdev;
bio->bi_sector = sector - (offset >> BBSHIFT);
bio->bi_end_io = bio_end_io_pagebuf;
bio->bi_private = pb;
bio_add_page(bio, pb->pb_pages[0], PAGE_CACHE_SIZE, 0);
size = 0;
atomic_inc(&pb->pb_io_remaining);
goto submit_io;
}
/* Lock down the pages which we need to for the request */
if (locking && (pb->pb_flags & PBF_WRITE) && (pb->pb_locked == 0)) {
for (i = 0; size; i++) {
int nbytes = PAGE_CACHE_SIZE - offset;
struct page *page = pb->pb_pages[i];
if (nbytes > size)
nbytes = size;
lock_page(page);
size -= nbytes;
offset = 0;
}
offset = pb->pb_offset;
size = pb->pb_count_desired;
}
next_chunk:
atomic_inc(&pb->pb_io_remaining);
nr_pages = BIO_MAX_SECTORS >> (PAGE_SHIFT - BBSHIFT);
if (nr_pages > total_nr_pages)
nr_pages = total_nr_pages;
bio = bio_alloc(GFP_NOIO, nr_pages);
bio->bi_bdev = pb->pb_target->pbr_bdev;
bio->bi_sector = sector;
bio->bi_end_io = bio_end_io_pagebuf;
bio->bi_private = pb;
for (; size && nr_pages; nr_pages--, map_i++) {
int nbytes = PAGE_CACHE_SIZE - offset;
if (nbytes > size)
nbytes = size;
if (bio_add_page(bio, pb->pb_pages[map_i],
nbytes, offset) < nbytes)
break;
offset = 0;
sector += nbytes >> BBSHIFT;
size -= nbytes;
total_nr_pages--;
}
submit_io:
if (likely(bio->bi_size)) {
submit_bio((pb->pb_flags & PBF_READ) ? READ : WRITE, bio);
if (size)
goto next_chunk;
} else {
bio_put(bio);
pagebuf_ioerror(pb, EIO);
}
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_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();
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 delayed write buffer handling
*/
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);
}
STATIC void
pagebuf_runall_queues(
struct workqueue_struct *queue)
{
flush_workqueue(queue);
}
/* Defines for pagebuf daemon */
STATIC DECLARE_COMPLETION(pagebuf_daemon_done);
STATIC struct task_struct *pagebuf_daemon_task;
STATIC int pagebuf_daemon_active;
STATIC int force_flush;
STATIC void
pagebuf_daemon_wakeup(void)
{
force_flush = 1;
barrier();
wake_up_process(pagebuf_daemon_task);
}
STATIC int
pagebuf_daemon(
void *data)
{
int count;
page_buf_t *pb;
struct list_head *curr, *next, tmp;
/* Set up the thread */
daemonize("pagebufd");
current->flags |= PF_MEMALLOC;
pagebuf_daemon_task = current;
pagebuf_daemon_active = 1;
barrier();
INIT_LIST_HEAD(&tmp);
do {
/* swsusp */
if (current->flags & PF_FREEZE)
refrigerator(PF_IOTHREAD);
set_current_state(TASK_INTERRUPTIBLE);
schedule_timeout(pb_params.flush_interval.val);
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 (pagebuf_daemon_active);
complete_and_exit(&pagebuf_daemon_done, 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_dataio_workqueue);
pagebuf_runall_queues(pagebuf_logio_workqueue);
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();
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 rval;
pagebuf_logio_workqueue = create_workqueue("xfslogd");
if (!pagebuf_logio_workqueue)
return -ENOMEM;
pagebuf_dataio_workqueue = create_workqueue("xfsdatad");
if (!pagebuf_dataio_workqueue) {
destroy_workqueue(pagebuf_logio_workqueue);
return -ENOMEM;
}
rval = kernel_thread(pagebuf_daemon, NULL, CLONE_FS|CLONE_FILES);
if (rval < 0) {
destroy_workqueue(pagebuf_logio_workqueue);
destroy_workqueue(pagebuf_dataio_workqueue);
}
return rval;
}
/*
* pagebuf_daemon_stop
*
* Note: do not mark as __exit, it is called from pagebuf_terminate.
*/
STATIC void
pagebuf_daemon_stop(void)
{
pagebuf_daemon_active = 0;
barrier();
wait_for_completion(&pagebuf_daemon_done);
destroy_workqueue(pagebuf_logio_workqueue);
destroy_workqueue(pagebuf_dataio_workqueue);
}
/*
* Pagebuf sysctl interface
*/
STATIC int
pb_stats_clear_handler(
ctl_table *ctl,
int write,
struct file *filp,
void *buffer,
size_t *lenp)
{
int c, ret;
int *valp = ctl->data;
ret = proc_dointvec_minmax(ctl, write, filp, buffer, lenp);
if (!ret && write && *valp) {
printk("XFS Clearing pbstats\n");
for (c = 0; c < NR_CPUS; c++) {
if (!cpu_possible(c)) continue;
memset(&per_cpu(pbstats, c), 0,
sizeof(struct 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 c, i, len, val;
len = 0;
len += sprintf(buffer + len, "pagebuf");
for (i = 0; i < sizeof(struct pbstats) / sizeof(u_int32_t); i++) {
val = 0;
for (c = 0 ; c < NR_CPUS; c++) {
if (!cpu_possible(c)) continue;
val += *(((u_int32_t*)&per_cpu(pbstats, c) + i));
}
len += sprintf(buffer + len, " %u", val);
}
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 */
/*
* 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;
}
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();
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();
#ifdef PAGEBUF_TRACE
ktrace_free(pagebuf_trace_buf);
#endif
kmem_cache_destroy(pagebuf_cache);
unregister_sysctl_table(pagebuf_table_header);
#ifdef CONFIG_PROC_FS
remove_proc_entry("fs/pagebuf/stat", NULL);
remove_proc_entry("fs/pagebuf", NULL);
#endif
}
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