/*
* Copyright (c) 2000-2005 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/bio.h>
#include <linux/sysctl.h>
#include <linux/proc_fs.h>
#include <linux/workqueue.h>
#include <linux/percpu.h>
#include <linux/blkdev.h>
#include <linux/hash.h>
#include <linux/kthread.h>
#include "xfs_linux.h"
/*
* File wide globals
*/
STATIC kmem_cache_t *pagebuf_zone;
STATIC kmem_shaker_t pagebuf_shake;
STATIC int xfsbufd_wakeup(int, gfp_t);
STATIC void pagebuf_delwri_queue(xfs_buf_t *, int);
STATIC struct workqueue_struct *xfslogd_workqueue;
struct workqueue_struct *xfsdatad_workqueue;
/*
* 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_NORETRY : \
((flags) & PBF_DONT_BLOCK) ? GFP_NOFS : GFP_KERNEL) | __GFP_NOWARN)
#define pb_to_km(flags) \
(((flags) & PBF_DONT_BLOCK) ? KM_NOFS : KM_SLEEP)
#define pagebuf_allocate(flags) \
kmem_zone_alloc(pagebuf_zone, pb_to_km(flags))
#define pagebuf_deallocate(pb) \
kmem_zone_free(pagebuf_zone, (pb));
/*
* Page Region interfaces.
*
* For pages in filesystems where the blocksize is smaller than the
* pagesize, we use the page->private field (long) to hold a bitmap
* of uptodate regions within the page.
*
* Each such region is "bytes per page / bits per long" bytes long.
*
* NBPPR == number-of-bytes-per-page-region
* BTOPR == bytes-to-page-region (rounded up)
* BTOPRT == bytes-to-page-region-truncated (rounded down)
*/
#if (BITS_PER_LONG == 32)
#define PRSHIFT (PAGE_CACHE_SHIFT - 5) /* (32 == 1<<5) */
#elif (BITS_PER_LONG == 64)
#define PRSHIFT (PAGE_CACHE_SHIFT - 6) /* (64 == 1<<6) */
#else
#error BITS_PER_LONG must be 32 or 64
#endif
#define NBPPR (PAGE_CACHE_SIZE/BITS_PER_LONG)
#define BTOPR(b) (((unsigned int)(b) + (NBPPR - 1)) >> PRSHIFT)
#define BTOPRT(b) (((unsigned int)(b) >> PRSHIFT))
STATIC unsigned long
page_region_mask(
size_t offset,
size_t length)
{
unsigned long mask;
int first, final;
first = BTOPR(offset);
final = BTOPRT(offset + length - 1);
first = min(first, final);
mask = ~0UL;
mask <<= BITS_PER_LONG - (final - first);
mask >>= BITS_PER_LONG - (final);
ASSERT(offset + length <= PAGE_CACHE_SIZE);
ASSERT((final - first) < BITS_PER_LONG && (final - first) >= 0);
return mask;
}
STATIC inline void
set_page_region(
struct page *page,
size_t offset,
size_t length)
{
page->private |= page_region_mask(offset, length);
if (page->private == ~0UL)
SetPageUptodate(page);
}
STATIC inline int
test_page_region(
struct page *page,
size_t offset,
size_t length)
{
unsigned long mask = page_region_mask(offset, length);
return (mask && (page->private & mask) == mask);
}
/*
* 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 DEFINE_SPINLOCK(as_lock);
/*
* 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)) {
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;
size_t size = bp->pb_count_desired;
size_t nbytes, offset;
gfp_t 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;
offset = bp->pb_offset;
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
"XFS: possible memory allocation "
"deadlock in %s (mode:0x%x)\n",
__FUNCTION__, gfp_mask);
XFS_STATS_INC(pb_page_retries);
xfsbufd_wakeup(0, gfp_mask);
blk_congestion_wait(WRITE, HZ/50);
goto retry;
}
XFS_STATS_INC(pb_page_found);
nbytes = min_t(size_t, size, PAGE_CACHE_SIZE - offset);
size -= nbytes;
if (!PageUptodate(page)) {
page_count--;
if (blocksize >= PAGE_CACHE_SIZE) {
if (flags & PBF_READ)
bp->pb_locked = 1;
} else if (!PagePrivate(page)) {
if (test_page_region(page, offset, nbytes))
page_count++;
}
}
bp->pb_pages[i] = page;
offset = 0;
}
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;
}
/*
* 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;
}
/*
* 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)
{
struct backing_dev_info *bdi;
bdi = target->pbr_mapping->backing_dev_info;
if (bdi_read_congested(bdi))
return;
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;
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);
pagebuf_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))
blk_run_address_space(pb->pb_target->pbr_mapping);
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))
blk_run_address_space(pb->pb_target->pbr_mapping);
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.
*/
STATIC void
pagebuf_iodone_work(
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) {
INIT_WORK(&pb->pb_iodone_work, pagebuf_iodone_work, pb);
queue_work(dataio ? xfsdatad_workqueue :
xfslogd_workqueue, &pb->pb_iodone_work);
} else {
pagebuf_iodone_work(pb);
}
} else {
up(&pb->pb_iodonesema);
}
}
/*
* pagebuf_ioerror
*
* pagebuf_ioerror sets the error code for a buffer.
*/
void
pagebuf_ioerror( /* mark/clear buffer error flag */
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 routine for pagebuf_iorequest
*/
STATIC __inline__ int
_pagebuf_iolocked(
xfs_buf_t *pb)
{
ASSERT(pb->pb_flags & (PBF_READ|PBF_WRITE));
if (pb->pb_flags & PBF_READ)
return pb->pb_locked;
return 0;
}
STATIC __inline__ void
_pagebuf_iodone(
xfs_buf_t *pb,
int schedule)
{
if (atomic_dec_and_test(&pb->pb_io_remaining) == 1) {
pb->pb_locked = 0;
pagebuf_iodone(pb, (pb->pb_flags & PBF_FS_DATAIOD), schedule);
}
}
STATIC int
bio_end_io_pagebuf(
struct bio *bio,
unsigned int bytes_done,
int error)
{
xfs_buf_t *pb = (xfs_buf_t *)bio->bi_private;
unsigned int blocksize = pb->pb_target->pbr_bsize;
struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
if (bio->bi_size)
return 1;
if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
pb->pb_error = EIO;
do {
struct page *page = bvec->bv_page;
if (unlikely(pb->pb_error)) {
if (pb->pb_flags & PBF_READ)
ClearPageUptodate(page);
SetPageError(page);
} else if (blocksize == PAGE_CACHE_SIZE) {
SetPageUptodate(page);
} else if (!PagePrivate(page) &&
(pb->pb_flags & _PBF_PAGE_CACHE)) {
set_page_region(page, bvec->bv_offset, bvec->bv_len);
}
if (--bvec >= bio->bi_io_vec)
prefetchw(&bvec->bv_page->flags);
if (_pagebuf_iolocked(pb)) {
unlock_page(page);
}
} while (bvec >= bio->bi_io_vec);
_pagebuf_iodone(pb, 1);
bio_put(bio);
return 0;
}
STATIC void
_pagebuf_ioapply(
xfs_buf_t *pb)
{
int i, rw, map_i, total_nr_pages, nr_pages;
struct bio *bio;
int offset = pb->pb_offset;
int size = pb->pb_count_desired;
sector_t sector = pb->pb_bn;
unsigned int blocksize = pb->pb_target->pbr_bsize;
int locking = _pagebuf_iolocked(pb);
total_nr_pages = pb->pb_page_count;
map_i = 0;
if (pb->pb_flags & _PBF_RUN_QUEUES) {
pb->pb_flags &= ~_PBF_RUN_QUEUES;
rw = (pb->pb_flags & PBF_READ) ? READ_SYNC : WRITE_SYNC;
} else {
rw = (pb->pb_flags & PBF_READ) ? READ : WRITE;
}
/* Special code path for reading a sub page size pagebuf in --
* we populate up the whole page, and hence the other metadata
* in the same page. This optimization is only valid when the
* filesystem block size and the page size are equal.
*/
if ((pb->pb_buffer_length < PAGE_CACHE_SIZE) &&
(pb->pb_flags & PBF_READ) && locking &&
(blocksize == PAGE_CACHE_SIZE)) {
bio = bio_alloc(GFP_NOIO, 1);
bio->bi_bdev = pb->pb_target->pbr_bdev;
bio->bi_sector = sector - (offset >> BBSHIFT);
bio->bi_end_io = bio_end_io_pagebuf;
bio->bi_private = pb;
bio_add_page(bio, pb->pb_pages[0], PAGE_CACHE_SIZE, 0);
size = 0;
atomic_inc(&pb->pb_io_remaining);
goto submit_io;
}
/* Lock down the pages which we need to for the request */
if (locking && (pb->pb_flags & PBF_WRITE) && (pb->pb_locked == 0)) {
for (i = 0; size; i++) {
int nbytes = PAGE_CACHE_SIZE - offset;
struct page *page = pb->pb_pages[i];
if (nbytes > size)
nbytes = size;
lock_page(page);
size -= nbytes;
offset = 0;
}
offset = pb->pb_offset;
size = pb->pb_count_desired;
}
next_chunk:
atomic_inc(&pb->pb_io_remaining);
nr_pages = BIO_MAX_SECTORS >> (PAGE_SHIFT - BBSHIFT);
if (nr_pages > total_nr_pages)
nr_pages = total_nr_pages;
bio = bio_alloc(GFP_NOIO, nr_pages);
bio->bi_bdev = pb->pb_target->pbr_bdev;
bio->bi_sector = sector;
bio->bi_end_io = bio_end_io_pagebuf;
bio->bi_private = pb;
for (; size && nr_pages; nr_pages--, map_i++) {
int nbytes = PAGE_CACHE_SIZE - offset;
if (nbytes > size)
nbytes = size;
if (bio_add_page(bio, pb->pb_pages[map_i],
nbytes, offset) < nbytes)
break;
offset = 0;
sector += nbytes >> BBSHIFT;
size -= nbytes;
total_nr_pages--;
}
submit_io:
if (likely(bio->bi_size)) {
submit_bio(rw, bio);
if (size)
goto next_chunk;
} else {
bio_put(bio);
pagebuf_ioerror(pb, EIO);
}
}
/*
* 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);
_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))
blk_run_address_space(pb->pb_target->pbr_mapping);
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;
}
}
/*
* 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));
}
STATIC int
xfs_setsize_buftarg_flags(
xfs_buftarg_t *btp,
unsigned int blocksize,
unsigned int sectorsize,
int verbose)
{
btp->pbr_bsize = blocksize;
btp->pbr_sshift = ffs(sectorsize) - 1;
btp->pbr_smask = sectorsize - 1;
if (set_blocksize(btp->pbr_bdev, sectorsize)) {
printk(KERN_WARNING
"XFS: Cannot set_blocksize to %u on device %s\n",
sectorsize, XFS_BUFTARG_NAME(btp));
return EINVAL;
}
if (verbose &&
(PAGE_CACHE_SIZE / BITS_PER_LONG) > sectorsize) {
printk(KERN_WARNING
"XFS: %u byte sectors in use on device %s. "
"This is suboptimal; %u or greater is ideal.\n",
sectorsize, XFS_BUFTARG_NAME(btp),
(unsigned int)PAGE_CACHE_SIZE / BITS_PER_LONG);
}
return 0;
}
/*
* When allocating the initial buffer target we have not yet
* read in the superblock, so don't know what sized sectors
* are being used is at this early stage. Play safe.
*/
STATIC int
xfs_setsize_buftarg_early(
xfs_buftarg_t *btp,
struct block_device *bdev)
{
return xfs_setsize_buftarg_flags(btp,
PAGE_CACHE_SIZE, bdev_hardsect_size(bdev), 0);
}
int
xfs_setsize_buftarg(
xfs_buftarg_t *btp,
unsigned int blocksize,
unsigned int sectorsize)
{
return xfs_setsize_buftarg_flags(btp, blocksize, sectorsize, 1);
}
STATIC int
xfs_mapping_buftarg(
xfs_buftarg_t *btp,
struct block_device *bdev)
{
struct backing_dev_info *bdi;
struct inode *inode;
struct address_space *mapping;
static struct address_space_operations mapping_aops = {
.sync_page = block_sync_page,
};
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_bdev = bdev;
inode->i_rdev = bdev->bd_dev;
bdi = blk_get_backing_dev_info(bdev);
if (!bdi)
bdi = &default_backing_dev_info;
mapping = &inode->i_data;
mapping->a_ops = &mapping_aops;
mapping->backing_dev_info = bdi;
mapping_set_gfp_mask(mapping, GFP_NOFS);
btp->pbr_mapping = mapping;
return 0;
}
xfs_buftarg_t *
xfs_alloc_buftarg(
struct block_device *bdev,
int external)
{
xfs_buftarg_t *btp;
btp = kmem_zalloc(sizeof(*btp), KM_SLEEP);
btp->pbr_dev = bdev->bd_dev;
btp->pbr_bdev = bdev;
if (xfs_setsize_buftarg_early(btp, bdev))
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;
}
/*
* Pagebuf delayed write buffer handling
*/
STATIC LIST_HEAD(pbd_delwrite_queue);
STATIC DEFINE_SPINLOCK(pbd_delwrite_lock);
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);
}
STATIC void
pagebuf_runall_queues(
struct workqueue_struct *queue)
{
flush_workqueue(queue);
}
/* Defines for pagebuf daemon */
STATIC struct task_struct *xfsbufd_task;
STATIC int xfsbufd_force_flush;
STATIC int xfsbufd_force_sleep;
STATIC int
xfsbufd_wakeup(
int priority,
gfp_t mask)
{
if (xfsbufd_force_sleep)
return 0;
xfsbufd_force_flush = 1;
barrier();
wake_up_process(xfsbufd_task);
return 0;
}
STATIC int
xfsbufd(
void *data)
{
struct list_head tmp;
unsigned long age;
xfs_buftarg_t *target;
xfs_buf_t *pb, *n;
current->flags |= PF_MEMALLOC;
INIT_LIST_HEAD(&tmp);
do {
if (unlikely(freezing(current))) {
xfsbufd_force_sleep = 1;
refrigerator();
} else {
xfsbufd_force_sleep = 0;
}
schedule_timeout_interruptible
(xfs_buf_timer_centisecs * msecs_to_jiffies(10));
age = xfs_buf_age_centisecs * msecs_to_jiffies(10);
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 (!xfsbufd_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);
}
}
spin_unlock(&pbd_delwrite_lock);
while (!list_empty(&tmp)) {
pb = list_entry(tmp.next, xfs_buf_t, pb_list);
target = pb->pb_target;
list_del_init(&pb->pb_list);
pagebuf_iostrategy(pb);
blk_run_address_space(target->pbr_mapping);
}
if (as_list_len > 0)
purge_addresses();
xfsbufd_force_flush = 0;
} while (!kthread_should_stop());
return 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;
pagebuf_runall_queues(xfsdatad_workqueue);
pagebuf_runall_queues(xfslogd_workqueue);
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);
}
/*
* 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);
}
if (wait)
blk_run_address_space(target->pbr_mapping);
return pincount;
}
STATIC int
xfs_buf_daemons_start(void)
{
int error = -ENOMEM;
xfslogd_workqueue = create_workqueue("xfslogd");
if (!xfslogd_workqueue)
goto out;
xfsdatad_workqueue = create_workqueue("xfsdatad");
if (!xfsdatad_workqueue)
goto out_destroy_xfslogd_workqueue;
xfsbufd_task = kthread_run(xfsbufd, NULL, "xfsbufd");
if (IS_ERR(xfsbufd_task)) {
error = PTR_ERR(xfsbufd_task);
goto out_destroy_xfsdatad_workqueue;
}
return 0;
out_destroy_xfsdatad_workqueue:
destroy_workqueue(xfsdatad_workqueue);
out_destroy_xfslogd_workqueue:
destroy_workqueue(xfslogd_workqueue);
out:
return error;
}
/*
* Note: do not mark as __exit, it is called from pagebuf_terminate.
*/
STATIC void
xfs_buf_daemons_stop(void)
{
kthread_stop(xfsbufd_task);
destroy_workqueue(xfslogd_workqueue);
destroy_workqueue(xfsdatad_workqueue);
}
/*
* Initialization and Termination
*/
int __init
pagebuf_init(void)
{
int error = -ENOMEM;
pagebuf_zone = kmem_zone_init(sizeof(xfs_buf_t), "xfs_buf");
if (!pagebuf_zone)
goto out;
#ifdef PAGEBUF_TRACE
pagebuf_trace_buf = ktrace_alloc(PAGEBUF_TRACE_SIZE, KM_SLEEP);
#endif
error = xfs_buf_daemons_start();
if (error)
goto out_free_buf_zone;
pagebuf_shake = kmem_shake_register(xfsbufd_wakeup);
if (!pagebuf_shake) {
error = -ENOMEM;
goto out_stop_daemons;
}
return 0;
out_stop_daemons:
xfs_buf_daemons_stop();
out_free_buf_zone:
#ifdef PAGEBUF_TRACE
ktrace_free(pagebuf_trace_buf);
#endif
kmem_zone_destroy(pagebuf_zone);
out:
return error;
}
/*
* pagebuf_terminate.
*
* Note: do not mark as __exit, this is also called from the __init code.
*/
void
pagebuf_terminate(void)
{
xfs_buf_daemons_stop();
#ifdef PAGEBUF_TRACE
ktrace_free(pagebuf_trace_buf);
#endif
kmem_zone_destroy(pagebuf_zone);
kmem_shake_deregister(pagebuf_shake);
}
