File: [Development] / xfs-linux / linux-2.4 / Attic / xfs_buf.c (download)
Revision 1.203, Tue Jan 18 22:34:00 2005 UTC (12 years, 9 months ago) by hch
Branch: MAIN
Changes since 1.202: +1 -1
lines
pagebuf_lock_value is also needed for trace builds
implement pagebuf_lock_value for XFS_BLI_TRACE also
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/*
* Copyright (c) 2000-2004 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/
*/
/*
* The xfs_buf.c code 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. xfs_buf.c assembles
* buffers (xfs_buf_t) 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/locks.h>
#include <linux/sysctl.h>
#include <linux/proc_fs.h>
#include <linux/hash.h>
#include "xfs_linux.h"
#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
#ifndef VM_MAP
#define VM_MAP VM_ALLOC
#endif
/*
* File wide globals
*/
STATIC kmem_cache_t *pagebuf_cache;
STATIC kmem_shaker_t pagebuf_shake;
#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_ioapply(xfs_buf_t *);
STATIC int pagebuf_daemon_wakeup(int, unsigned int);
STATIC void pagebuf_delwri_queue(xfs_buf_t *, int);
STATIC void pagebuf_runall_queues(struct list_head[]);
/*
* Pagebuf debugging
*/
#ifdef PAGEBUF_TRACE
void
pagebuf_trace(
xfs_buf_t *pb,
char *id,
void *data,
void *ra)
{
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));
/*
* Mapping of multi-page buffers into contiguous virtual space
*/
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(
xfs_buf_t *pb,
xfs_buftarg_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(xfs_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.
* I/O 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 = XFS_BUF_DADDR_NULL;
atomic_set(&pb->pb_pin_count, 0);
init_waitqueue_head(&pb->pb_waiters);
XFS_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(
xfs_buf_t *pb,
int page_count,
page_buf_flags_t 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 = kmem_alloc(sizeof(struct page *) *
page_count, pb_to_km(flags));
if (pb->pb_pages == NULL)
return -ENOMEM;
}
memset(pb->pb_pages, 0, sizeof(struct page *) * page_count);
}
return 0;
}
/*
* Frees pb_pages if it was malloced.
*/
STATIC void
_pagebuf_free_pages(
xfs_buf_t *bp)
{
if (bp->pb_pages != bp->pb_page_array) {
kmem_free(bp->pb_pages,
bp->pb_page_count * sizeof(struct page *));
}
}
/*
* Releases the specified buffer.
*
* The modification state of any associated pages is left unchanged.
* The buffer most not be on any hash - use pagebuf_rele instead for
* hashed and refcounted buffers
*/
void
pagebuf_free(
xfs_buf_t *bp)
{
PB_TRACE(bp, "free", 0);
ASSERT(list_empty(&bp->pb_hash_list));
if (bp->pb_flags & _PBF_PAGE_CACHE) {
uint i;
if ((bp->pb_flags & PBF_MAPPED) && (bp->pb_page_count > 1))
free_address(bp->pb_addr - bp->pb_offset);
for (i = 0; i < bp->pb_page_count; i++)
page_cache_release(bp->pb_pages[i]);
_pagebuf_free_pages(bp);
} else if (bp->pb_flags & _PBF_KMEM_ALLOC) {
/*
* XXX(hch): bp->pb_count_desired might be incorrect (see
* pagebuf_associate_memory for details), but fortunately
* the Linux version of kmem_free ignores the len argument..
*/
kmem_free(bp->pb_addr, bp->pb_count_desired);
_pagebuf_free_pages(bp);
}
pagebuf_deallocate(bp);
}
/*
* Finds all pages for buffer in question and builds it's page list.
*/
STATIC int
_pagebuf_lookup_pages(
xfs_buf_t *bp,
uint flags)
{
struct address_space *mapping = bp->pb_target->pbr_mapping;
size_t blocksize = bp->pb_target->pbr_bsize;
int gfp_mask = pb_to_gfp(flags);
unsigned short page_count, i;
pgoff_t first;
loff_t end;
int error;
end = bp->pb_file_offset + bp->pb_buffer_length;
page_count = page_buf_btoc(end) - page_buf_btoct(bp->pb_file_offset);
error = _pagebuf_get_pages(bp, page_count, flags);
if (unlikely(error))
return error;
bp->pb_flags |= _PBF_PAGE_CACHE;
first = bp->pb_file_offset >> PAGE_CACHE_SHIFT;
for (i = 0; i < bp->pb_page_count; i++) {
struct page *page;
uint retries = 0;
retry:
page = find_or_create_page(mapping, first + i, gfp_mask);
if (unlikely(page == NULL)) {
if (flags & PBF_READ_AHEAD) {
bp->pb_page_count = i;
for (i = 0; i < bp->pb_page_count; i++)
unlock_page(bp->pb_pages[i]);
return -ENOMEM;
}
/*
* This could deadlock.
*
* But until all the XFS lowlevel code is revamped to
* handle buffer allocation failures we can't do much.
*/
if (!(++retries % 100))
printk(KERN_ERR
"possible deadlock in %s (mode:0x%x)\n",
__FUNCTION__, gfp_mask);
XFS_STATS_INC(pb_page_retries);
pagebuf_daemon_wakeup(0, gfp_mask);
set_current_state(TASK_UNINTERRUPTIBLE);
schedule_timeout(10);
goto retry;
}
XFS_STATS_INC(pb_page_found);
/* if we need to do I/O on a page record the fact */
if (!Page_Uptodate(page)) {
page_count--;
if (blocksize == PAGE_CACHE_SIZE && (flags & PBF_READ))
bp->pb_locked = 1;
}
bp->pb_pages[i] = page;
}
if (!bp->pb_locked) {
for (i = 0; i < bp->pb_page_count; i++)
unlock_page(bp->pb_pages[i]);
}
if (page_count) {
/* if we have any uptodate pages, mark that in the buffer */
bp->pb_flags &= ~PBF_NONE;
/* if some pages aren't uptodate, mark that in the buffer */
if (page_count != bp->pb_page_count)
bp->pb_flags |= PBF_PARTIAL;
}
PB_TRACE(bp, "lookup_pages", (long)page_count);
return error;
}
/*
* Map buffer into kernel address-space if nessecary.
*/
STATIC int
_pagebuf_map_pages(
xfs_buf_t *bp,
uint flags)
{
/* A single page buffer is always mappable */
if (bp->pb_page_count == 1) {
bp->pb_addr = page_address(bp->pb_pages[0]) + bp->pb_offset;
bp->pb_flags |= PBF_MAPPED;
} else if (flags & PBF_MAPPED) {
if (as_list_len > 64)
purge_addresses();
bp->pb_addr = vmap(bp->pb_pages, bp->pb_page_count,
VM_MAP, PAGE_KERNEL);
if (unlikely(bp->pb_addr == NULL))
return -ENOMEM;
bp->pb_addr += bp->pb_offset;
bp->pb_flags |= PBF_MAPPED;
}
return 0;
}
/*
* 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);
run_task_queue(&tq_disk);
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.
*/
xfs_buf_t *
_pagebuf_find(
xfs_buftarg_t *btp, /* block device target */
loff_t ioff, /* starting offset of range */
size_t isize, /* length of range */
page_buf_flags_t flags, /* PBF_TRYLOCK */
xfs_buf_t *new_pb)/* newly allocated buffer */
{
loff_t range_base;
size_t range_length;
xfs_bufhash_t *hash;
xfs_buf_t *pb, *n;
range_base = (ioff << BBSHIFT);
range_length = (isize << BBSHIFT);
/* Check for IOs smaller than the sector size / not sector aligned */
ASSERT(!(range_length < (1 << btp->pbr_sshift)));
ASSERT(!(range_base & (loff_t)btp->pbr_smask));
hash = &btp->bt_hash[hash_long((unsigned long)ioff, btp->bt_hashshift)];
spin_lock(&hash->bh_lock);
list_for_each_entry_safe(pb, n, &hash->bh_list, pb_hash_list) {
ASSERT(btp == pb->pb_target);
if (pb->pb_file_offset == range_base &&
pb->pb_buffer_length == range_length) {
/*
* If we look at something, bring it to the
* front of the list for next time.
*/
atomic_inc(&pb->pb_hold);
list_move(&pb->pb_hash_list, &hash->bh_list);
goto found;
}
}
/* No match found */
if (new_pb) {
_pagebuf_initialize(new_pb, btp, range_base,
range_length, flags);
new_pb->pb_hash = hash;
list_add(&new_pb->pb_hash_list, &hash->bh_list);
} else {
XFS_STATS_INC(pb_miss_locked);
}
spin_unlock(&hash->bh_lock);
return new_pb;
found:
spin_unlock(&hash->bh_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.
*/
if (down_trylock(&pb->pb_sema)) {
if (!(flags & PBF_TRYLOCK)) {
/* wait for buffer ownership */
PB_TRACE(pb, "get_lock", 0);
pagebuf_lock(pb);
XFS_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);
XFS_STATS_INC(pb_busy_locked);
return (NULL);
}
} else {
/* trylock worked */
PB_SET_OWNER(pb);
}
if (pb->pb_flags & PBF_STALE)
pb->pb_flags &= PBF_MAPPED;
PB_TRACE(pb, "got_lock", 0);
XFS_STATS_INC(pb_get_locked);
return (pb);
}
/*
* xfs_buf_get_flags assembles a buffer covering the specified range.
*
* Storage in memory for all portions of the buffer will be allocated,
* although backing storage may not be.
*/
xfs_buf_t *
xfs_buf_get_flags( /* allocate a buffer */
xfs_buftarg_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 */
{
xfs_buf_t *pb, *new_pb;
int error = 0, i;
new_pb = pagebuf_allocate(flags);
if (unlikely(!new_pb))
return NULL;
pb = _pagebuf_find(target, ioff, isize, flags, new_pb);
if (pb == new_pb) {
error = _pagebuf_lookup_pages(pb, flags);
if (error)
goto no_buffer;
} else {
pagebuf_deallocate(new_pb);
if (unlikely(pb == NULL))
return NULL;
}
for (i = 0; i < pb->pb_page_count; i++)
mark_page_accessed(pb->pb_pages[i]);
if (!(pb->pb_flags & PBF_MAPPED)) {
error = _pagebuf_map_pages(pb, flags);
if (unlikely(error)) {
printk(KERN_WARNING "%s: failed to map pages\n",
__FUNCTION__);
goto no_buffer;
}
}
XFS_STATS_INC(pb_get);
/*
* 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;
PB_TRACE(pb, "get", (unsigned long)flags);
return pb;
no_buffer:
if (flags & (PBF_LOCK | PBF_TRYLOCK))
pagebuf_unlock(pb);
pagebuf_rele(pb);
return NULL;
}
xfs_buf_t *
xfs_buf_read_flags(
xfs_buftarg_t *target,
loff_t ioff,
size_t isize,
page_buf_flags_t flags)
{
xfs_buf_t *pb;
flags |= PBF_READ;
pb = xfs_buf_get_flags(target, ioff, isize, flags);
if (pb) {
if (PBF_NOT_DONE(pb)) {
PB_TRACE(pb, "read", (unsigned long)flags);
XFS_STATS_INC(pb_get_read);
pagebuf_iostart(pb, flags);
} else if (flags & PBF_ASYNC) {
PB_TRACE(pb, "read_async", (unsigned long)flags);
/*
* Read ahead call which is already satisfied,
* drop the buffer
*/
goto no_buffer;
} else {
PB_TRACE(pb, "read_done", (unsigned long)flags);
/* We do not want read in the flags */
pb->pb_flags &= ~PBF_READ;
}
}
return pb;
no_buffer:
if (flags & (PBF_LOCK | PBF_TRYLOCK))
pagebuf_unlock(pb);
pagebuf_rele(pb);
return NULL;
}
/*
* Create a skeletal pagebuf (no pages associated with it).
*/
xfs_buf_t *
pagebuf_lookup(
xfs_buftarg_t *target,
loff_t ioff,
size_t isize,
page_buf_flags_t flags)
{
xfs_buf_t *pb;
flags |= _PBF_PRIVATE_BH;
pb = pagebuf_allocate(flags);
if (pb) {
_pagebuf_initialize(pb, target, ioff, isize, flags);
}
return pb;
}
/*
* If we are not low on memory then do the readahead in a deadlock
* safe manner.
*/
void
pagebuf_readahead(
xfs_buftarg_t *target,
loff_t ioff,
size_t isize,
page_buf_flags_t flags)
{
flags |= (PBF_TRYLOCK|PBF_ASYNC|PBF_READ_AHEAD);
xfs_buf_read_flags(target, ioff, isize, flags);
}
xfs_buf_t *
pagebuf_get_empty(
size_t len,
xfs_buftarg_t *target)
{
xfs_buf_t *pb;
pb = pagebuf_allocate(0);
if (pb)
_pagebuf_initialize(pb, target, 0, len, 0);
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(
xfs_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)
_pagebuf_free_pages(pb);
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;
}
xfs_buf_t *
pagebuf_get_no_daddr(
size_t len,
xfs_buftarg_t *target)
{
size_t malloc_len = len;
xfs_buf_t *bp;
void *data;
int error;
bp = pagebuf_allocate(0);
if (unlikely(bp == NULL))
goto fail;
_pagebuf_initialize(bp, target, 0, len, PBF_FORCEIO);
try_again:
data = kmem_alloc(malloc_len, KM_SLEEP | KM_MAYFAIL);
if (unlikely(data == NULL))
goto fail_free_buf;
/* check whether alignment matches.. */
if ((__psunsigned_t)data !=
((__psunsigned_t)data & ~target->pbr_smask)) {
/* .. else double the size and try again */
kmem_free(data, malloc_len);
malloc_len <<= 1;
goto try_again;
}
error = pagebuf_associate_memory(bp, data, len);
if (error)
goto fail_free_mem;
bp->pb_flags |= _PBF_KMEM_ALLOC;
pagebuf_unlock(bp);
PB_TRACE(bp, "no_daddr", data);
return bp;
fail_free_mem:
kmem_free(data, malloc_len);
fail_free_buf:
pagebuf_free(bp);
fail:
return NULL;
}
/*
* 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(
xfs_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(
xfs_buf_t *pb)
{
xfs_bufhash_t *hash = pb->pb_hash;
PB_TRACE(pb, "rele", pb->pb_relse);
/*
* pagebuf_lookup buffers are not hashed, not delayed write,
* and don't have their own release routines. Special case.
*/
if (unlikely(!hash)) {
ASSERT(!pb->pb_relse);
if (atomic_dec_and_test(&pb->pb_hold))
xfs_buf_free(pb);
return;
}
if (atomic_dec_and_lock(&pb->pb_hold, &hash->bh_lock)) {
int do_free = 1;
if (pb->pb_relse) {
atomic_inc(&pb->pb_hold);
spin_unlock(&hash->bh_lock);
(*(pb->pb_relse)) (pb);
spin_lock(&hash->bh_lock);
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) {
list_del_init(&pb->pb_hash_list);
spin_unlock(&hash->bh_lock);
xfs_buf_free(pb);
} else {
spin_unlock(&hash->bh_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) */
xfs_buf_t *pb)
{
int locked;
locked = down_trylock(&pb->pb_sema) == 0;
if (locked) {
PB_SET_OWNER(pb);
}
PB_TRACE(pb, "cond_lock", (long)locked);
return(locked ? 0 : -EBUSY);
}
#if defined(DEBUG) || defined(XFS_BLI_TRACE)
/*
* pagebuf_lock_value
*
* Return lock value for a pagebuf
*/
int
pagebuf_lock_value(
xfs_buf_t *pb)
{
return(atomic_read(&pb->pb_sema.count));
}
#endif
/*
* 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(
xfs_buf_t *pb)
{
PB_TRACE(pb, "lock", 0);
if (atomic_read(&pb->pb_io_remaining))
run_task_queue(&tq_disk);
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 */
xfs_buf_t *pb) /* buffer to unlock */
{
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(
xfs_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(
xfs_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(
xfs_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(
xfs_buf_t *pb)
{
DECLARE_WAITQUEUE (wait, current);
if (atomic_read(&pb->pb_pin_count) == 0)
return;
add_wait_queue(&pb->pb_waiters, &wait);
for (;;) {
set_current_state(TASK_UNINTERRUPTIBLE);
if (atomic_read(&pb->pb_pin_count) == 0)
break;
if (atomic_read(&pb->pb_io_remaining))
run_task_queue(&tq_disk);
schedule();
}
remove_wait_queue(&pb->pb_waiters, &wait);
set_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)
{
xfs_buf_t *bp = (xfs_buf_t *)v;
if (bp->pb_iodone)
(*(bp->pb_iodone))(bp);
else if (bp->pb_flags & PBF_ASYNC)
xfs_buf_relse(bp);
}
void
pagebuf_iodone(
xfs_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 */
xfs_buf_t *pb, /* buffer to mark */
int error) /* error to store (0 if none) */
{
ASSERT(error >= 0 && error <= 0xffff);
pb->pb_error = (unsigned short)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 */
xfs_buf_t *pb, /* buffer to start */
page_buf_flags_t flags) /* PBF_LOCK, PBF_ASYNC, PBF_READ, */
/* PBF_WRITE, PBF_DELWRI, */
/* 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);
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_READ_AHEAD | _PBF_RUN_QUEUES);
BUG_ON(pb->pb_bn == XFS_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(
xfs_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_PAGE_CACHE);
}
STATIC void
_pagebuf_iodone(
xfs_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;
xfs_buf_t *pb = (xfs_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);
}
/*
* Handling of buftargs.
*/
/*
* Wait for any bufs with callbacks that have been submitted but
* have not yet returned... walk the hash list for the target.
*/
void
xfs_wait_buftarg(
xfs_buftarg_t *btp)
{
xfs_buf_t *bp, *n;
xfs_bufhash_t *hash;
uint i;
for (i = 0; i < (1 << btp->bt_hashshift); i++) {
hash = &btp->bt_hash[i];
again:
spin_lock(&hash->bh_lock);
list_for_each_entry_safe(bp, n, &hash->bh_list, pb_hash_list) {
ASSERT(btp == bp->pb_target);
if (!(bp->pb_flags & PBF_FS_MANAGED)) {
spin_unlock(&hash->bh_lock);
delay(100);
goto again;
}
}
spin_unlock(&hash->bh_lock);
}
}
/*
* Allocate buffer hash table for a given target.
* For devices containing metadata (i.e. not the log/realtime devices)
* we need to allocate a much larger hash table.
*/
STATIC void
xfs_alloc_bufhash(
xfs_buftarg_t *btp,
int external)
{
unsigned int i;
btp->bt_hashshift = external ? 3 : 8; /* 8 or 256 buckets */
btp->bt_hashmask = (1 << btp->bt_hashshift) - 1;
btp->bt_hash = kmem_zalloc((1 << btp->bt_hashshift) *
sizeof(xfs_bufhash_t), KM_SLEEP);
for (i = 0; i < (1 << btp->bt_hashshift); i++) {
spin_lock_init(&btp->bt_hash[i].bh_lock);
INIT_LIST_HEAD(&btp->bt_hash[i].bh_list);
}
}
STATIC void
xfs_free_bufhash(
xfs_buftarg_t *btp)
{
kmem_free(btp->bt_hash,
(1 << btp->bt_hashshift) * sizeof(xfs_bufhash_t));
btp->bt_hash = NULL;
}
void
xfs_free_buftarg(
xfs_buftarg_t *btp,
int external)
{
xfs_flush_buftarg(btp, 1);
if (external)
xfs_blkdev_put(btp->pbr_bdev);
xfs_free_bufhash(btp);
iput(btp->pbr_mapping->host);
kmem_free(btp, sizeof(*btp));
}
void
xfs_incore_relse(
xfs_buftarg_t *btp,
int delwri_only,
int wait)
{
destroy_buffers(btp->pbr_kdev);
truncate_inode_pages(btp->pbr_mapping, 0LL);
}
int
xfs_setsize_buftarg(
xfs_buftarg_t *btp,
unsigned int blocksize,
unsigned int sectorsize)
{
btp->pbr_bsize = blocksize;
btp->pbr_sshift = ffs(sectorsize) - 1;
btp->pbr_smask = sectorsize - 1;
if (set_blocksize(btp->pbr_kdev, sectorsize)) {
printk(KERN_WARNING
"XFS: Cannot set_blocksize to %u on device 0x%x\n",
sectorsize, kdev_t_to_nr(btp->pbr_kdev));
return EINVAL;
}
return 0;
}
STATIC int
xfs_mapping_buftarg(
xfs_buftarg_t *btp,
struct block_device *bdev)
{
kdev_t kdev;
struct inode *inode;
struct address_space *mapping;
static struct address_space_operations mapping_aops = {
.sync_page = block_sync_page,
};
kdev = to_kdev_t(bdev->bd_dev);
inode = new_inode(bdev->bd_inode->i_sb);
if (!inode) {
printk(KERN_WARNING
"XFS: Cannot allocate mapping inode for device %s\n",
XFS_BUFTARG_NAME(btp));
return ENOMEM;
}
inode->i_mode = S_IFBLK;
inode->i_dev = kdev;
inode->i_rdev = kdev;
inode->i_bdev = bdev;
mapping = &inode->i_data;
mapping->a_ops = &mapping_aops;
mapping->gfp_mask = GFP_KERNEL;
btp->pbr_mapping = mapping;
return 0;
}
xfs_buftarg_t *
xfs_alloc_buftarg(
struct block_device *bdev,
int external)
{
xfs_buftarg_t *btp;
kdev_t kdev;
btp = kmem_zalloc(sizeof(*btp), KM_SLEEP);
kdev = to_kdev_t(bdev->bd_dev);
btp->pbr_dev = bdev->bd_dev;
btp->pbr_kdev = kdev;
btp->pbr_bdev = bdev;
switch (MAJOR(btp->pbr_dev)) {
case MD_MAJOR:
case EVMS_MAJOR:
btp->pbr_flags = PBR_ALIGNED_ONLY;
break;
case LOOP_MAJOR:
case LVM_BLK_MAJOR:
btp->pbr_flags = PBR_SECTOR_ONLY;
break;
}
if (xfs_setsize_buftarg(btp, PAGE_CACHE_SIZE, get_hardsect_size(kdev)))
goto error;
if (xfs_mapping_buftarg(btp, bdev))
goto error;
xfs_alloc_bufhash(btp, external);
return btp;
error:
kmem_free(btp, sizeof(*btp));
return NULL;
}
/*
* 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 */
xfs_buftarg_t *pbr, /* device parameters (bsz, ssz, dev) */
xfs_buf_t *pb, /* pagebuf holding it, can be NULL */
xfs_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(
xfs_buf_t *pb,
loff_t offset,
struct page *page,
size_t pg_offset,
size_t pg_length,
int last)
{
xfs_daddr_t bn = pb->pb_bn;
xfs_buftarg_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 -- the core I/O request routine.
*/
int
pagebuf_iorequest( /* start real I/O */
xfs_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);
if (xfs_io_bypass && (pb->pb_flags & PBF_DIRECTIO)) {
request_queue_t *q;
io_private_t *iop;
int error = 0;
q = blk_get_queue(pb->pb_target->pbr_dev);
if (q && q->queuedata &&
XIO_MAGIC == (*(unsigned int *)q->queuedata)) {
iop = (io_private_t *)q->queuedata;
if (iop->map_io_request) {
int index;
int locking = _pagebuf_iolocked(pb);
if (pb->pb_flags & PBF_WRITE)
if (locking && !pb->pb_locked) {
for (index = 0; index < pb->pb_page_count; index++)
lock_page(pb->pb_pages[index]);
pb->pb_locked = 1;
}
error = iop->map_io_request((void *)pb);
if (error)
pagebuf_ioerror(pb, error);
pb->pb_flags &= ~PBF_DIRECTIO;
_pagebuf_iodone(pb, 0);
pagebuf_rele(pb);
return 0;
}
}
}
_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(
xfs_buf_t *pb)
{
PB_TRACE(pb, "iowait", 0);
if (atomic_read(&pb->pb_io_remaining))
run_task_queue(&tq_disk);
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;
}
caddr_t
pagebuf_offset(
xfs_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(
xfs_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 xfs_buf_t.
*/
STATIC void
_pagebuf_ioapply( /* apply function to pages */
xfs_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_flags & PBF_DIRECTIO) &&
(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)
run_task_queue(&tq_disk);
}
}
/*
* Delayed write buffer list handling
*/
STATIC LIST_HEAD(pbd_delwrite_queue);
STATIC spinlock_t pbd_delwrite_lock = SPIN_LOCK_UNLOCKED;
STATIC void
pagebuf_delwri_queue(
xfs_buf_t *pb,
int unlock)
{
PB_TRACE(pb, "delwri_q", (long)unlock);
ASSERT(pb->pb_flags & PBF_DELWRI);
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_queuetime = jiffies;
spin_unlock(&pbd_delwrite_lock);
if (unlock)
pagebuf_unlock(pb);
}
void
pagebuf_delwri_dequeue(
xfs_buf_t *pb)
{
int dequeued = 0;
spin_lock(&pbd_delwrite_lock);
if ((pb->pb_flags & PBF_DELWRI) && !list_empty(&pb->pb_list)) {
list_del_init(&pb->pb_list);
dequeued = 1;
}
pb->pb_flags &= ~PBF_DELWRI;
spin_unlock(&pbd_delwrite_lock);
if (dequeued)
pagebuf_rele(pb);
PB_TRACE(pb, "delwri_dq", (long)dequeued);
}
/*
* 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 */
sigmask_lock();
sigfillset(¤t->blocked);
__recalc_sigpending(current);
sigmask_unlock();
/* 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 */
STATIC DECLARE_COMPLETION(pagebuf_daemon_done);
STATIC struct task_struct *pagebuf_daemon_task;
STATIC int pagebuf_daemon_active;
STATIC int force_flush;
STATIC int
pagebuf_daemon_wakeup(
int priority,
unsigned int mask)
{
force_flush = 1;
barrier();
wake_up_process(pagebuf_daemon_task);
return 0;
}
STATIC int
pagebuf_daemon(
void *data)
{
struct list_head tmp;
unsigned long age;
xfs_buf_t *pb, *n;
int count;
/* Set up the thread */
daemonize();
/* Mark it active */
pagebuf_daemon_task = current;
pagebuf_daemon_active = 1;
barrier();
/* Avoid signals */
sigmask_lock();
sigfillset(¤t->blocked);
__recalc_sigpending(current);
sigmask_unlock();
strcpy(current->comm, "xfsbufd");
current->flags |= PF_MEMALLOC;
INIT_LIST_HEAD(&tmp);
do {
set_current_state(TASK_INTERRUPTIBLE);
schedule_timeout((xfs_buf_timer_centisecs * HZ) / 100);
count = 0;
age = (xfs_buf_age_centisecs * HZ) / 100;
spin_lock(&pbd_delwrite_lock);
list_for_each_entry_safe(pb, n, &pbd_delwrite_queue, pb_list) {
PB_TRACE(pb, "walkq1", (long)pagebuf_ispin(pb));
ASSERT(pb->pb_flags & PBF_DELWRI);
if (!pagebuf_ispin(pb) && !pagebuf_cond_lock(pb)) {
if (!force_flush &&
time_before(jiffies,
pb->pb_queuetime + age)) {
pagebuf_unlock(pb);
break;
}
pb->pb_flags &= ~PBF_DELWRI;
pb->pb_flags |= PBF_WRITE;
list_move(&pb->pb_list, &tmp);
count++;
}
}
spin_unlock(&pbd_delwrite_lock);
while (!list_empty(&tmp)) {
pb = list_entry(tmp.next, xfs_buf_t, pb_list);
list_del_init(&pb->pb_list);
pagebuf_iostrategy(pb);
}
if (as_list_len > 0)
purge_addresses();
if (count)
run_task_queue(&tq_disk);
force_flush = 0;
} while (pagebuf_daemon_active);
complete_and_exit(&pagebuf_daemon_done, 0);
}
/*
* Go through all incore buffers, and release buffers if they belong to
* the given device. This is used in filesystem error handling to
* preserve the consistency of its metadata.
*/
int
xfs_flush_buftarg(
xfs_buftarg_t *target,
int wait)
{
struct list_head tmp;
xfs_buf_t *pb, *n;
int pincount = 0;
int flush_cnt = 0;
pagebuf_runall_queues(pagebuf_dataiodone_tq);
pagebuf_runall_queues(pagebuf_logiodone_tq);
INIT_LIST_HEAD(&tmp);
spin_lock(&pbd_delwrite_lock);
list_for_each_entry_safe(pb, n, &pbd_delwrite_queue, pb_list) {
if (pb->pb_target != target)
continue;
ASSERT(pb->pb_flags & PBF_DELWRI);
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);
}
spin_unlock(&pbd_delwrite_lock);
/*
* Dropped the delayed write list lock, now walk the temporary list
*/
list_for_each_entry_safe(pb, n, &tmp, pb_list) {
if (wait)
pb->pb_flags &= ~PBF_ASYNC;
else
list_del_init(&pb->pb_list);
pagebuf_lock(pb);
pagebuf_iostrategy(pb);
if (++flush_cnt > 32) {
run_task_queue(&tq_disk);
flush_cnt = 0;
}
}
run_task_queue(&tq_disk);
/*
* Remaining list items must be flushed before returning
*/
while (!list_empty(&tmp)) {
pb = list_entry(tmp.next, xfs_buf_t, pb_list);
list_del_init(&pb->pb_list);
xfs_iowait(pb);
xfs_buf_relse(pb);
}
return 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;
pagebuf_daemon_active = 0;
barrier();
wait_for_completion(&pagebuf_daemon_done);
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);
}
}
/*
* Initialization and Termination
*/
int __init
pagebuf_init(void)
{
pagebuf_cache = kmem_cache_create("xfs_buf_t", sizeof(xfs_buf_t), 0,
SLAB_HWCACHE_ALIGN, NULL, NULL);
if (pagebuf_cache == NULL) {
printk("XFS: couldn't init xfs_buf_t cache\n");
return -ENOMEM;
}
if (_pagebuf_prealloc_bh(NR_RESERVED_BH) < NR_RESERVED_BH) {
printk("XFS: couldn't allocate %d reserved buffers\n",
NR_RESERVED_BH);
kmem_zone_destroy(pagebuf_cache);
return -ENOMEM;
}
init_waitqueue_head(&pb_resv_bh_wait);
#ifdef PAGEBUF_TRACE
pagebuf_trace_buf = ktrace_alloc(PAGEBUF_TRACE_SIZE, KM_SLEEP);
#endif
pagebuf_daemon_start();
pagebuf_shake = kmem_shake_register(pagebuf_daemon_wakeup);
if (pagebuf_shake == NULL) {
pagebuf_terminate();
return -ENOMEM;
}
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_zone_destroy(pagebuf_cache);
kmem_shake_deregister(pagebuf_shake);
}
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