File: [Development] / xfs-linux / linux-2.4 / Attic / xfs_buf.c (download)
Revision 1.207, Wed Aug 24 15:12:31 2005 UTC (12 years, 2 months ago) by dgc.longdrop.melbourne.sgi.com
Branch: MAIN
Changes since 1.206: +39 -17
lines
Fix racy access to pb_flags.
pagebuf_rele() modified pb_flags after the pagebuf had been unlocked
if the buffer was delwri. At high load, this could result in a race
when the superblock was being synced that would result the flags
being incorrect and the iodone functions being executed incorrectly.
This then leads to iclog callback failures or AIL list corruptions
resulting in filesystem shutdowns.
Merge of xfs-linux-melb:xfs-kern:23616a by kenmcd.
Move delwri buffer processing to before the buffer is unlocked
so flags are modified while the buffer is still locked.
Also use a flag to keep track of whether we are already in
the delwri queue.
|
/*
* 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 & ~__GFP_HIGH);
if (likely(aentry != NULL)) {
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) {
ASSERT((pb->pb_flags & _PBF_DELWRI_Q) == 0);
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_FS_MANAGED) {
do_free = 0;
}
if (do_free) {
ASSERT((pb->pb_flags & (PBF_DELWRI|_PBF_DELWRI_Q)) == 0);
list_del_init(&pb->pb_hash_list);
spin_unlock(&hash->bh_lock);
xfs_buf_free(pb);
} else {
spin_unlock(&hash->bh_lock);
}
} else {
/*
* Catch reference count leaks
*/
ASSERT(atomic_read(&pb->pb_hold) >= 0);
}
}
/*
* 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).
*
* If the buffer is marked delwri but is not queued, do so before we
* unlock the buffer as we need to set flags correctly. We also need to
* take a reference for the delwri queue because the unlocker is going to
* drop their's and they don't know we just queued it.
*/
void
pagebuf_unlock( /* unlock buffer */
xfs_buf_t *pb) /* buffer to unlock */
{
if ((pb->pb_flags & (PBF_DELWRI|_PBF_DELWRI_Q)) == PBF_DELWRI) {
atomic_inc(&pb->pb_hold);
pb->pb_flags |= PBF_ASYNC;
pagebuf_delwri_queue(pb, 0);
}
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);
/*
* Catch superblock reference count leaks
* immediately
*/
BUG_ON(bp->pb_bn == 0);
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));
}
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_NOFS;
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|PBF_ASYNC)) ==
(PBF_DELWRI|PBF_ASYNC));
spin_lock(&pbd_delwrite_lock);
/* If already in the queue, dequeue and place at tail */
if (!list_empty(&pb->pb_list)) {
ASSERT(pb->pb_flags & _PBF_DELWRI_Q);
if (unlock)
atomic_dec(&pb->pb_hold);
list_del(&pb->pb_list);
}
pb->pb_flags |= _PBF_DELWRI_Q;
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)) {
ASSERT(pb->pb_flags & _PBF_DELWRI_Q);
list_del_init(&pb->pb_list);
dequeued = 1;
}
pb->pb_flags &= ~(PBF_DELWRI|_PBF_DELWRI_Q);
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|_PBF_DELWRI_Q);
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|_PBF_DELWRI_Q));
PB_TRACE(pb, "walkq2", (long)pagebuf_ispin(pb));
if (pagebuf_ispin(pb)) {
pincount++;
continue;
}
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) {
pagebuf_lock(pb);
pb->pb_flags &= ~(PBF_DELWRI|_PBF_DELWRI_Q);
pb->pb_flags |= PBF_WRITE;
if (wait)
pb->pb_flags &= ~PBF_ASYNC;
else
list_del_init(&pb->pb_list);
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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