File: [Development] / xfs-linux / linux-2.6 / xfs_buf.c (download)
Revision 1.230, Thu Nov 23 05:05:36 2006 UTC (10 years, 11 months ago) by dgc.longdrop.melbourne.sgi.com
Branch: MAIN
Changes since 1.229: +60 -57
lines
Fix a synchronous buftarg flush deadlock when freezing.
At the last stage of a freeze, we flush the buftarg synchronously
over and over again until it succeeds twice without skipping
any buffers.
The delwri list flush skips pinned buffers, but tries to flush
all others. It removes the buffers from the delwri list, then tries
to lock them one at a time as it traverses the list to issue
the I/O. It holds them locked until we issue all of the I/O
and then unlocks them once we've waited for it to complete.
The problem is that during a freeze, the filesystem may
still be doing stuff - like flushing delalloc data buffers -
in the background and hence we can be trying to lock buffers
that were on the delwri list at the same time. Hence we can
get ABBA deadlocks between threads doing allocation and the
buftarg flush (freeze) thread.
Fix it by skipping locked (and pinned) buffers as we traverse the
delwri buffer list.
Merge of xfs-linux-melb:xfs-kern:27535a by kenmcd.
Skip locked buffers when flushing the buftarg delwri buffer list
to prevent deadlocks with allocation when synchronously flushing
the buftarg during a freeze.
|
/*
* Copyright (c) 2000-2006 Silicon Graphics, Inc.
* All Rights Reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms 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. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "xfs.h"
#include <linux/stddef.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/pagemap.h>
#include <linux/init.h>
#include <linux/vmalloc.h>
#include <linux/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 <linux/migrate.h>
#include <linux/backing-dev.h>
#include "xfs_linux.h"
STATIC kmem_zone_t *xfs_buf_zone;
STATIC kmem_shaker_t xfs_buf_shake;
STATIC int xfsbufd(void *);
STATIC int xfsbufd_wakeup(int, gfp_t);
STATIC void xfs_buf_delwri_queue(xfs_buf_t *, int);
STATIC struct workqueue_struct *xfslogd_workqueue;
struct workqueue_struct *xfsdatad_workqueue;
#ifdef XFS_BUF_TRACE
void
xfs_buf_trace(
xfs_buf_t *bp,
char *id,
void *data,
void *ra)
{
ktrace_enter(xfs_buf_trace_buf,
bp, id,
(void *)(unsigned long)bp->b_flags,
(void *)(unsigned long)bp->b_hold.counter,
(void *)(unsigned long)bp->b_sema.count.counter,
(void *)current,
data, ra,
(void *)(unsigned long)((bp->b_file_offset>>32) & 0xffffffff),
(void *)(unsigned long)(bp->b_file_offset & 0xffffffff),
(void *)(unsigned long)bp->b_buffer_length,
NULL, NULL, NULL, NULL, NULL);
}
ktrace_t *xfs_buf_trace_buf;
#define XFS_BUF_TRACE_SIZE 4096
#define XB_TRACE(bp, id, data) \
xfs_buf_trace(bp, id, (void *)data, (void *)__builtin_return_address(0))
#else
#define XB_TRACE(bp, id, data) do { } while (0)
#endif
#ifdef XFS_BUF_LOCK_TRACKING
# define XB_SET_OWNER(bp) ((bp)->b_last_holder = current->pid)
# define XB_CLEAR_OWNER(bp) ((bp)->b_last_holder = -1)
# define XB_GET_OWNER(bp) ((bp)->b_last_holder)
#else
# define XB_SET_OWNER(bp) do { } while (0)
# define XB_CLEAR_OWNER(bp) do { } while (0)
# define XB_GET_OWNER(bp) do { } while (0)
#endif
#define xb_to_gfp(flags) \
((((flags) & XBF_READ_AHEAD) ? __GFP_NORETRY : \
((flags) & XBF_DONT_BLOCK) ? GFP_NOFS : GFP_KERNEL) | __GFP_NOWARN)
#define xb_to_km(flags) \
(((flags) & XBF_DONT_BLOCK) ? KM_NOFS : KM_SLEEP)
#define xfs_buf_allocate(flags) \
kmem_zone_alloc(xfs_buf_zone, xb_to_km(flags))
#define xfs_buf_deallocate(bp) \
kmem_zone_free(xfs_buf_zone, (bp));
/*
* 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)
{
set_page_private(page,
page_private(page) | page_region_mask(offset, length));
if (page_private(page) == ~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(page) & 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_NOWAIT);
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 xfs_buf_t object manipulation
*/
STATIC void
_xfs_buf_initialize(
xfs_buf_t *bp,
xfs_buftarg_t *target,
xfs_off_t range_base,
size_t range_length,
xfs_buf_flags_t flags)
{
/*
* We don't want certain flags to appear in b_flags.
*/
flags &= ~(XBF_LOCK|XBF_MAPPED|XBF_DONT_BLOCK|XBF_READ_AHEAD);
memset(bp, 0, sizeof(xfs_buf_t));
atomic_set(&bp->b_hold, 1);
init_MUTEX_LOCKED(&bp->b_iodonesema);
INIT_LIST_HEAD(&bp->b_list);
INIT_LIST_HEAD(&bp->b_hash_list);
init_MUTEX_LOCKED(&bp->b_sema); /* held, no waiters */
XB_SET_OWNER(bp);
bp->b_target = target;
bp->b_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).
*/
bp->b_buffer_length = bp->b_count_desired = range_length;
bp->b_flags = flags;
bp->b_bn = XFS_BUF_DADDR_NULL;
atomic_set(&bp->b_pin_count, 0);
init_waitqueue_head(&bp->b_waiters);
XFS_STATS_INC(xb_create);
XB_TRACE(bp, "initialize", target);
}
/*
* Allocate a page array capable of holding a specified number
* of pages, and point the page buf at it.
*/
STATIC int
_xfs_buf_get_pages(
xfs_buf_t *bp,
int page_count,
xfs_buf_flags_t flags)
{
/* Make sure that we have a page list */
if (bp->b_pages == NULL) {
bp->b_offset = xfs_buf_poff(bp->b_file_offset);
bp->b_page_count = page_count;
if (page_count <= XB_PAGES) {
bp->b_pages = bp->b_page_array;
} else {
bp->b_pages = kmem_alloc(sizeof(struct page *) *
page_count, xb_to_km(flags));
if (bp->b_pages == NULL)
return -ENOMEM;
}
memset(bp->b_pages, 0, sizeof(struct page *) * page_count);
}
return 0;
}
/*
* Frees b_pages if it was allocated.
*/
STATIC void
_xfs_buf_free_pages(
xfs_buf_t *bp)
{
if (bp->b_pages != bp->b_page_array) {
kmem_free(bp->b_pages,
bp->b_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 xfs_buf_rele instead for
* hashed and refcounted buffers
*/
void
xfs_buf_free(
xfs_buf_t *bp)
{
XB_TRACE(bp, "free", 0);
ASSERT(list_empty(&bp->b_hash_list));
if (bp->b_flags & _XBF_PAGE_CACHE) {
uint i;
if ((bp->b_flags & XBF_MAPPED) && (bp->b_page_count > 1))
free_address(bp->b_addr - bp->b_offset);
for (i = 0; i < bp->b_page_count; i++) {
struct page *page = bp->b_pages[i];
ASSERT(!PagePrivate(page));
page_cache_release(page);
}
_xfs_buf_free_pages(bp);
} else if (bp->b_flags & _XBF_KMEM_ALLOC) {
/*
* XXX(hch): bp->b_count_desired might be incorrect (see
* xfs_buf_associate_memory for details), but fortunately
* the Linux version of kmem_free ignores the len argument..
*/
kmem_free(bp->b_addr, bp->b_count_desired);
_xfs_buf_free_pages(bp);
}
xfs_buf_deallocate(bp);
}
/*
* Finds all pages for buffer in question and builds it's page list.
*/
STATIC int
_xfs_buf_lookup_pages(
xfs_buf_t *bp,
uint flags)
{
struct address_space *mapping = bp->b_target->bt_mapping;
size_t blocksize = bp->b_target->bt_bsize;
size_t size = bp->b_count_desired;
size_t nbytes, offset;
gfp_t gfp_mask = xb_to_gfp(flags);
unsigned short page_count, i;
pgoff_t first;
xfs_off_t end;
int error;
end = bp->b_file_offset + bp->b_buffer_length;
page_count = xfs_buf_btoc(end) - xfs_buf_btoct(bp->b_file_offset);
error = _xfs_buf_get_pages(bp, page_count, flags);
if (unlikely(error))
return error;
bp->b_flags |= _XBF_PAGE_CACHE;
offset = bp->b_offset;
first = bp->b_file_offset >> PAGE_CACHE_SHIFT;
for (i = 0; i < bp->b_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 & XBF_READ_AHEAD) {
bp->b_page_count = i;
for (i = 0; i < bp->b_page_count; i++)
unlock_page(bp->b_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(xb_page_retries);
xfsbufd_wakeup(0, gfp_mask);
congestion_wait(WRITE, HZ/50);
goto retry;
}
XFS_STATS_INC(xb_page_found);
nbytes = min_t(size_t, size, PAGE_CACHE_SIZE - offset);
size -= nbytes;
ASSERT(!PagePrivate(page));
if (!PageUptodate(page)) {
page_count--;
if (blocksize >= PAGE_CACHE_SIZE) {
if (flags & XBF_READ)
bp->b_locked = 1;
} else if (!PagePrivate(page)) {
if (test_page_region(page, offset, nbytes))
page_count++;
}
}
bp->b_pages[i] = page;
offset = 0;
}
if (!bp->b_locked) {
for (i = 0; i < bp->b_page_count; i++)
unlock_page(bp->b_pages[i]);
}
if (page_count == bp->b_page_count)
bp->b_flags |= XBF_DONE;
XB_TRACE(bp, "lookup_pages", (long)page_count);
return error;
}
/*
* Map buffer into kernel address-space if nessecary.
*/
STATIC int
_xfs_buf_map_pages(
xfs_buf_t *bp,
uint flags)
{
/* A single page buffer is always mappable */
if (bp->b_page_count == 1) {
bp->b_addr = page_address(bp->b_pages[0]) + bp->b_offset;
bp->b_flags |= XBF_MAPPED;
} else if (flags & XBF_MAPPED) {
if (as_list_len > 64)
purge_addresses();
bp->b_addr = vmap(bp->b_pages, bp->b_page_count,
VM_MAP, PAGE_KERNEL);
if (unlikely(bp->b_addr == NULL))
return -ENOMEM;
bp->b_addr += bp->b_offset;
bp->b_flags |= XBF_MAPPED;
}
return 0;
}
/*
* Finding and Reading Buffers
*/
/*
* Look 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 *
_xfs_buf_find(
xfs_buftarg_t *btp, /* block device target */
xfs_off_t ioff, /* starting offset of range */
size_t isize, /* length of range */
xfs_buf_flags_t flags,
xfs_buf_t *new_bp)
{
xfs_off_t range_base;
size_t range_length;
xfs_bufhash_t *hash;
xfs_buf_t *bp, *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->bt_sshift)));
ASSERT(!(range_base & (xfs_off_t)btp->bt_smask));
hash = &btp->bt_hash[hash_long((unsigned long)ioff, btp->bt_hashshift)];
spin_lock(&hash->bh_lock);
list_for_each_entry_safe(bp, n, &hash->bh_list, b_hash_list) {
ASSERT(btp == bp->b_target);
if (bp->b_file_offset == range_base &&
bp->b_buffer_length == range_length) {
/*
* If we look at something, bring it to the
* front of the list for next time.
*/
atomic_inc(&bp->b_hold);
list_move(&bp->b_hash_list, &hash->bh_list);
goto found;
}
}
/* No match found */
if (new_bp) {
_xfs_buf_initialize(new_bp, btp, range_base,
range_length, flags);
new_bp->b_hash = hash;
list_add(&new_bp->b_hash_list, &hash->bh_list);
} else {
XFS_STATS_INC(xb_miss_locked);
}
spin_unlock(&hash->bh_lock);
return new_bp;
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(&bp->b_sema)) {
if (!(flags & XBF_TRYLOCK)) {
/* wait for buffer ownership */
XB_TRACE(bp, "get_lock", 0);
xfs_buf_lock(bp);
XFS_STATS_INC(xb_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 buffer at least overlaps our
* buffer and is locked, therefore our buffer
* either does not exist, or is this buffer.
*/
xfs_buf_rele(bp);
XFS_STATS_INC(xb_busy_locked);
return NULL;
}
} else {
/* trylock worked */
XB_SET_OWNER(bp);
}
if (bp->b_flags & XBF_STALE) {
ASSERT((bp->b_flags & _XBF_DELWRI_Q) == 0);
bp->b_flags &= XBF_MAPPED;
}
XB_TRACE(bp, "got_lock", 0);
XFS_STATS_INC(xb_get_locked);
return bp;
}
/*
* 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(
xfs_buftarg_t *target,/* target for buffer */
xfs_off_t ioff, /* starting offset of range */
size_t isize, /* length of range */
xfs_buf_flags_t flags)
{
xfs_buf_t *bp, *new_bp;
int error = 0, i;
new_bp = xfs_buf_allocate(flags);
if (unlikely(!new_bp))
return NULL;
bp = _xfs_buf_find(target, ioff, isize, flags, new_bp);
if (bp == new_bp) {
error = _xfs_buf_lookup_pages(bp, flags);
if (error)
goto no_buffer;
} else {
xfs_buf_deallocate(new_bp);
if (unlikely(bp == NULL))
return NULL;
}
for (i = 0; i < bp->b_page_count; i++)
mark_page_accessed(bp->b_pages[i]);
if (!(bp->b_flags & XBF_MAPPED)) {
error = _xfs_buf_map_pages(bp, flags);
if (unlikely(error)) {
printk(KERN_WARNING "%s: failed to map pages\n",
__FUNCTION__);
goto no_buffer;
}
}
XFS_STATS_INC(xb_get);
/*
* Always fill in the block number now, the mapped cases can do
* their own overlay of this later.
*/
bp->b_bn = ioff;
bp->b_count_desired = bp->b_buffer_length;
XB_TRACE(bp, "get", (unsigned long)flags);
return bp;
no_buffer:
if (flags & (XBF_LOCK | XBF_TRYLOCK))
xfs_buf_unlock(bp);
xfs_buf_rele(bp);
return NULL;
}
xfs_buf_t *
xfs_buf_read_flags(
xfs_buftarg_t *target,
xfs_off_t ioff,
size_t isize,
xfs_buf_flags_t flags)
{
xfs_buf_t *bp;
flags |= XBF_READ;
bp = xfs_buf_get_flags(target, ioff, isize, flags);
if (bp) {
if (!XFS_BUF_ISDONE(bp)) {
XB_TRACE(bp, "read", (unsigned long)flags);
XFS_STATS_INC(xb_get_read);
xfs_buf_iostart(bp, flags);
} else if (flags & XBF_ASYNC) {
XB_TRACE(bp, "read_async", (unsigned long)flags);
/*
* Read ahead call which is already satisfied,
* drop the buffer
*/
goto no_buffer;
} else {
XB_TRACE(bp, "read_done", (unsigned long)flags);
/* We do not want read in the flags */
bp->b_flags &= ~XBF_READ;
}
}
return bp;
no_buffer:
if (flags & (XBF_LOCK | XBF_TRYLOCK))
xfs_buf_unlock(bp);
xfs_buf_rele(bp);
return NULL;
}
/*
* If we are not low on memory then do the readahead in a deadlock
* safe manner.
*/
void
xfs_buf_readahead(
xfs_buftarg_t *target,
xfs_off_t ioff,
size_t isize,
xfs_buf_flags_t flags)
{
struct backing_dev_info *bdi;
bdi = target->bt_mapping->backing_dev_info;
if (bdi_read_congested(bdi))
return;
flags |= (XBF_TRYLOCK|XBF_ASYNC|XBF_READ_AHEAD);
xfs_buf_read_flags(target, ioff, isize, flags);
}
xfs_buf_t *
xfs_buf_get_empty(
size_t len,
xfs_buftarg_t *target)
{
xfs_buf_t *bp;
bp = xfs_buf_allocate(0);
if (bp)
_xfs_buf_initialize(bp, target, 0, len, 0);
return bp;
}
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
xfs_buf_associate_memory(
xfs_buf_t *bp,
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 (bp->b_pages)
_xfs_buf_free_pages(bp);
bp->b_pages = NULL;
bp->b_addr = mem;
rval = _xfs_buf_get_pages(bp, page_count, 0);
if (rval)
return rval;
bp->b_offset = offset;
ptr = (size_t) mem & PAGE_CACHE_MASK;
end = PAGE_CACHE_ALIGN((size_t) mem + len);
end_cur = end;
/* set up first page */
bp->b_pages[0] = mem_to_page(mem);
ptr += PAGE_CACHE_SIZE;
bp->b_page_count = ++i;
while (ptr < end) {
bp->b_pages[i] = mem_to_page((void *)ptr);
bp->b_page_count = ++i;
ptr += PAGE_CACHE_SIZE;
}
bp->b_locked = 0;
bp->b_count_desired = bp->b_buffer_length = len;
bp->b_flags |= XBF_MAPPED;
return 0;
}
xfs_buf_t *
xfs_buf_get_noaddr(
size_t len,
xfs_buftarg_t *target)
{
size_t malloc_len = len;
xfs_buf_t *bp;
void *data;
int error;
bp = xfs_buf_allocate(0);
if (unlikely(bp == NULL))
goto fail;
_xfs_buf_initialize(bp, target, 0, len, 0);
try_again:
data = kmem_alloc(malloc_len, KM_SLEEP | KM_MAYFAIL | KM_LARGE);
if (unlikely(data == NULL))
goto fail_free_buf;
/* check whether alignment matches.. */
if ((__psunsigned_t)data !=
((__psunsigned_t)data & ~target->bt_smask)) {
/* .. else double the size and try again */
kmem_free(data, malloc_len);
malloc_len <<= 1;
goto try_again;
}
error = xfs_buf_associate_memory(bp, data, len);
if (error)
goto fail_free_mem;
bp->b_flags |= _XBF_KMEM_ALLOC;
xfs_buf_unlock(bp);
XB_TRACE(bp, "no_daddr", data);
return bp;
fail_free_mem:
kmem_free(data, malloc_len);
fail_free_buf:
xfs_buf_free(bp);
fail:
return NULL;
}
/*
* 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
xfs_buf_hold(
xfs_buf_t *bp)
{
atomic_inc(&bp->b_hold);
XB_TRACE(bp, "hold", 0);
}
/*
* Releases a hold on the specified buffer. If the
* the hold count is 1, calls xfs_buf_free.
*/
void
xfs_buf_rele(
xfs_buf_t *bp)
{
xfs_bufhash_t *hash = bp->b_hash;
XB_TRACE(bp, "rele", bp->b_relse);
if (unlikely(!hash)) {
ASSERT(!bp->b_relse);
if (atomic_dec_and_test(&bp->b_hold))
xfs_buf_free(bp);
return;
}
if (atomic_dec_and_lock(&bp->b_hold, &hash->bh_lock)) {
if (bp->b_relse) {
atomic_inc(&bp->b_hold);
spin_unlock(&hash->bh_lock);
(*(bp->b_relse)) (bp);
} else if (bp->b_flags & XBF_FS_MANAGED) {
spin_unlock(&hash->bh_lock);
} else {
ASSERT(!(bp->b_flags & (XBF_DELWRI|_XBF_DELWRI_Q)));
list_del_init(&bp->b_hash_list);
spin_unlock(&hash->bh_lock);
xfs_buf_free(bp);
}
} else {
/*
* Catch reference count leaks
*/
ASSERT(atomic_read(&bp->b_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.
*/
/*
* 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 buffer objects, not for
* synchronizing independent access to the underlying pages.
*/
int
xfs_buf_cond_lock(
xfs_buf_t *bp)
{
int locked;
locked = down_trylock(&bp->b_sema) == 0;
if (locked) {
XB_SET_OWNER(bp);
}
XB_TRACE(bp, "cond_lock", (long)locked);
return locked ? 0 : -EBUSY;
}
#if defined(DEBUG) || defined(XFS_BLI_TRACE)
int
xfs_buf_lock_value(
xfs_buf_t *bp)
{
return atomic_read(&bp->b_sema.count);
}
#endif
/*
* Locks a buffer object.
* Note that this in no way locks the underlying pages, so it is only
* useful for synchronizing concurrent use of buffer objects, not for
* synchronizing independent access to the underlying pages.
*/
void
xfs_buf_lock(
xfs_buf_t *bp)
{
XB_TRACE(bp, "lock", 0);
if (atomic_read(&bp->b_io_remaining))
blk_run_address_space(bp->b_target->bt_mapping);
down(&bp->b_sema);
XB_SET_OWNER(bp);
XB_TRACE(bp, "locked", 0);
}
/*
* Releases the lock on the buffer object.
* 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
xfs_buf_unlock(
xfs_buf_t *bp)
{
if ((bp->b_flags & (XBF_DELWRI|_XBF_DELWRI_Q)) == XBF_DELWRI) {
atomic_inc(&bp->b_hold);
bp->b_flags |= XBF_ASYNC;
xfs_buf_delwri_queue(bp, 0);
}
XB_CLEAR_OWNER(bp);
up(&bp->b_sema);
XB_TRACE(bp, "unlock", 0);
}
/*
* Pinning Buffer Storage in Memory
* Ensure that no attempt to force a buffer to disk will succeed.
*/
void
xfs_buf_pin(
xfs_buf_t *bp)
{
atomic_inc(&bp->b_pin_count);
XB_TRACE(bp, "pin", (long)bp->b_pin_count.counter);
}
void
xfs_buf_unpin(
xfs_buf_t *bp)
{
if (atomic_dec_and_test(&bp->b_pin_count))
wake_up_all(&bp->b_waiters);
XB_TRACE(bp, "unpin", (long)bp->b_pin_count.counter);
}
int
xfs_buf_ispin(
xfs_buf_t *bp)
{
return atomic_read(&bp->b_pin_count);
}
STATIC void
xfs_buf_wait_unpin(
xfs_buf_t *bp)
{
DECLARE_WAITQUEUE (wait, current);
if (atomic_read(&bp->b_pin_count) == 0)
return;
add_wait_queue(&bp->b_waiters, &wait);
for (;;) {
set_current_state(TASK_UNINTERRUPTIBLE);
if (atomic_read(&bp->b_pin_count) == 0)
break;
if (atomic_read(&bp->b_io_remaining))
blk_run_address_space(bp->b_target->bt_mapping);
schedule();
}
remove_wait_queue(&bp->b_waiters, &wait);
set_current_state(TASK_RUNNING);
}
/*
* Buffer Utility Routines
*/
STATIC void
xfs_buf_iodone_work(
void *v)
{
xfs_buf_t *bp = (xfs_buf_t *)v;
if (bp->b_iodone)
(*(bp->b_iodone))(bp);
else if (bp->b_flags & XBF_ASYNC)
xfs_buf_relse(bp);
}
void
xfs_buf_ioend(
xfs_buf_t *bp,
int schedule)
{
bp->b_flags &= ~(XBF_READ | XBF_WRITE);
if (bp->b_error == 0)
bp->b_flags |= XBF_DONE;
XB_TRACE(bp, "iodone", bp->b_iodone);
if ((bp->b_iodone) || (bp->b_flags & XBF_ASYNC)) {
if (schedule) {
INIT_WORK(&bp->b_iodone_work, xfs_buf_iodone_work, bp);
queue_work(xfslogd_workqueue, &bp->b_iodone_work);
} else {
xfs_buf_iodone_work(bp);
}
} else {
up(&bp->b_iodonesema);
}
}
void
xfs_buf_ioerror(
xfs_buf_t *bp,
int error)
{
ASSERT(error >= 0 && error <= 0xffff);
bp->b_error = (unsigned short)error;
XB_TRACE(bp, "ioerror", (unsigned long)error);
}
/*
* Initiate I/O on a buffer, based on the flags supplied.
* The b_iodone routine in the buffer supplied will only be called
* when all of the subsidiary I/O requests, if any, have been completed.
*/
int
xfs_buf_iostart(
xfs_buf_t *bp,
xfs_buf_flags_t flags)
{
int status = 0;
XB_TRACE(bp, "iostart", (unsigned long)flags);
if (flags & XBF_DELWRI) {
bp->b_flags &= ~(XBF_READ | XBF_WRITE | XBF_ASYNC);
bp->b_flags |= flags & (XBF_DELWRI | XBF_ASYNC);
xfs_buf_delwri_queue(bp, 1);
return status;
}
bp->b_flags &= ~(XBF_READ | XBF_WRITE | XBF_ASYNC | XBF_DELWRI | \
XBF_READ_AHEAD | _XBF_RUN_QUEUES);
bp->b_flags |= flags & (XBF_READ | XBF_WRITE | XBF_ASYNC | \
XBF_READ_AHEAD | _XBF_RUN_QUEUES);
BUG_ON(bp->b_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 & XBF_WRITE) ?
xfs_buf_iostrategy(bp) : xfs_buf_iorequest(bp);
/* 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 & XBF_ASYNC))
status = xfs_buf_iowait(bp);
return status;
}
STATIC __inline__ int
_xfs_buf_iolocked(
xfs_buf_t *bp)
{
ASSERT(bp->b_flags & (XBF_READ | XBF_WRITE));
if (bp->b_flags & XBF_READ)
return bp->b_locked;
return 0;
}
STATIC __inline__ void
_xfs_buf_ioend(
xfs_buf_t *bp,
int schedule)
{
if (atomic_dec_and_test(&bp->b_io_remaining) == 1) {
bp->b_locked = 0;
xfs_buf_ioend(bp, schedule);
}
}
STATIC int
xfs_buf_bio_end_io(
struct bio *bio,
unsigned int bytes_done,
int error)
{
xfs_buf_t *bp = (xfs_buf_t *)bio->bi_private;
unsigned int blocksize = bp->b_target->bt_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))
bp->b_error = EIO;
do {
struct page *page = bvec->bv_page;
ASSERT(!PagePrivate(page));
if (unlikely(bp->b_error)) {
if (bp->b_flags & XBF_READ)
ClearPageUptodate(page);
} else if (blocksize >= PAGE_CACHE_SIZE) {
SetPageUptodate(page);
} else if (!PagePrivate(page) &&
(bp->b_flags & _XBF_PAGE_CACHE)) {
set_page_region(page, bvec->bv_offset, bvec->bv_len);
}
if (--bvec >= bio->bi_io_vec)
prefetchw(&bvec->bv_page->flags);
if (_xfs_buf_iolocked(bp)) {
unlock_page(page);
}
} while (bvec >= bio->bi_io_vec);
_xfs_buf_ioend(bp, 1);
bio_put(bio);
return 0;
}
STATIC void
_xfs_buf_ioapply(
xfs_buf_t *bp)
{
int i, rw, map_i, total_nr_pages, nr_pages;
struct bio *bio;
int offset = bp->b_offset;
int size = bp->b_count_desired;
sector_t sector = bp->b_bn;
unsigned int blocksize = bp->b_target->bt_bsize;
int locking = _xfs_buf_iolocked(bp);
total_nr_pages = bp->b_page_count;
map_i = 0;
if (bp->b_flags & XBF_ORDERED) {
ASSERT(!(bp->b_flags & XBF_READ));
rw = WRITE_BARRIER;
} else if (bp->b_flags & _XBF_RUN_QUEUES) {
ASSERT(!(bp->b_flags & XBF_READ_AHEAD));
bp->b_flags &= ~_XBF_RUN_QUEUES;
rw = (bp->b_flags & XBF_WRITE) ? WRITE_SYNC : READ_SYNC;
} else {
rw = (bp->b_flags & XBF_WRITE) ? WRITE :
(bp->b_flags & XBF_READ_AHEAD) ? READA : READ;
}
/* Special code path for reading a sub page size buffer 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 is not smaller than the page size.
*/
if ((bp->b_buffer_length < PAGE_CACHE_SIZE) &&
(bp->b_flags & XBF_READ) && locking &&
(blocksize >= PAGE_CACHE_SIZE)) {
bio = bio_alloc(GFP_NOIO, 1);
bio->bi_bdev = bp->b_target->bt_bdev;
bio->bi_sector = sector - (offset >> BBSHIFT);
bio->bi_end_io = xfs_buf_bio_end_io;
bio->bi_private = bp;
bio_add_page(bio, bp->b_pages[0], PAGE_CACHE_SIZE, 0);
size = 0;
atomic_inc(&bp->b_io_remaining);
goto submit_io;
}
/* Lock down the pages which we need to for the request */
if (locking && (bp->b_flags & XBF_WRITE) && (bp->b_locked == 0)) {
for (i = 0; size; i++) {
int nbytes = PAGE_CACHE_SIZE - offset;
struct page *page = bp->b_pages[i];
if (nbytes > size)
nbytes = size;
lock_page(page);
size -= nbytes;
offset = 0;
}
offset = bp->b_offset;
size = bp->b_count_desired;
}
next_chunk:
atomic_inc(&bp->b_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 = bp->b_target->bt_bdev;
bio->bi_sector = sector;
bio->bi_end_io = xfs_buf_bio_end_io;
bio->bi_private = bp;
for (; size && nr_pages; nr_pages--, map_i++) {
int rbytes, nbytes = PAGE_CACHE_SIZE - offset;
if (nbytes > size)
nbytes = size;
rbytes = bio_add_page(bio, bp->b_pages[map_i], nbytes, offset);
if (rbytes < 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);
xfs_buf_ioerror(bp, EIO);
}
}
int
xfs_buf_iorequest(
xfs_buf_t *bp)
{
XB_TRACE(bp, "iorequest", 0);
if (bp->b_flags & XBF_DELWRI) {
xfs_buf_delwri_queue(bp, 1);
return 0;
}
if (bp->b_flags & XBF_WRITE) {
xfs_buf_wait_unpin(bp);
}
xfs_buf_hold(bp);
/* 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 xfs_buf_ioend too early.
*/
atomic_set(&bp->b_io_remaining, 1);
_xfs_buf_ioapply(bp);
_xfs_buf_ioend(bp, 0);
xfs_buf_rele(bp);
return 0;
}
/*
* Waits for I/O to complete on the buffer supplied.
* It returns immediately if no I/O is pending.
* It returns the I/O error code, if any, or 0 if there was no error.
*/
int
xfs_buf_iowait(
xfs_buf_t *bp)
{
XB_TRACE(bp, "iowait", 0);
if (atomic_read(&bp->b_io_remaining))
blk_run_address_space(bp->b_target->bt_mapping);
down(&bp->b_iodonesema);
XB_TRACE(bp, "iowaited", (long)bp->b_error);
return bp->b_error;
}
xfs_caddr_t
xfs_buf_offset(
xfs_buf_t *bp,
size_t offset)
{
struct page *page;
if (bp->b_flags & XBF_MAPPED)
return XFS_BUF_PTR(bp) + offset;
offset += bp->b_offset;
page = bp->b_pages[offset >> PAGE_CACHE_SHIFT];
return (xfs_caddr_t)page_address(page) + (offset & (PAGE_CACHE_SIZE-1));
}
/*
* Move data into or out of a buffer.
*/
void
xfs_buf_iomove(
xfs_buf_t *bp, /* buffer to process */
size_t boff, /* starting buffer offset */
size_t bsize, /* length to copy */
caddr_t data, /* data address */
xfs_buf_rw_t mode) /* read/write/zero flag */
{
size_t bend, cpoff, csize;
struct page *page;
bend = boff + bsize;
while (boff < bend) {
page = bp->b_pages[xfs_buf_btoct(boff + bp->b_offset)];
cpoff = xfs_buf_poff(boff + bp->b_offset);
csize = min_t(size_t,
PAGE_CACHE_SIZE-cpoff, bp->b_count_desired-boff);
ASSERT(((csize + cpoff) <= PAGE_CACHE_SIZE));
switch (mode) {
case XBRW_ZERO:
memset(page_address(page) + cpoff, 0, csize);
break;
case XBRW_READ:
memcpy(data, page_address(page) + cpoff, csize);
break;
case XBRW_WRITE:
memcpy(page_address(page) + cpoff, data, csize);
}
boff += csize;
data += csize;
}
}
/*
* Handling of buffer targets (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, b_hash_list) {
ASSERT(btp == bp->b_target);
if (!(bp->b_flags & XBF_FS_MANAGED)) {
spin_unlock(&hash->bh_lock);
/*
* Catch superblock reference count leaks
* immediately
*/
BUG_ON(bp->b_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 | KM_LARGE);
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;
}
/*
* buftarg list for delwrite queue processing
*/
STATIC LIST_HEAD(xfs_buftarg_list);
STATIC DEFINE_SPINLOCK(xfs_buftarg_lock);
STATIC void
xfs_register_buftarg(
xfs_buftarg_t *btp)
{
spin_lock(&xfs_buftarg_lock);
list_add(&btp->bt_list, &xfs_buftarg_list);
spin_unlock(&xfs_buftarg_lock);
}
STATIC void
xfs_unregister_buftarg(
xfs_buftarg_t *btp)
{
spin_lock(&xfs_buftarg_lock);
list_del(&btp->bt_list);
spin_unlock(&xfs_buftarg_lock);
}
void
xfs_free_buftarg(
xfs_buftarg_t *btp,
int external)
{
xfs_flush_buftarg(btp, 1);
if (external)
xfs_blkdev_put(btp->bt_bdev);
xfs_free_bufhash(btp);
iput(btp->bt_mapping->host);
/* Unregister the buftarg first so that we don't get a
* wakeup finding a non-existent task
*/
xfs_unregister_buftarg(btp);
kthread_stop(btp->bt_task);
kmem_free(btp, sizeof(*btp));
}
STATIC int
xfs_setsize_buftarg_flags(
xfs_buftarg_t *btp,
unsigned int blocksize,
unsigned int sectorsize,
int verbose)
{
btp->bt_bsize = blocksize;
btp->bt_sshift = ffs(sectorsize) - 1;
btp->bt_smask = sectorsize - 1;
if (set_blocksize(btp->bt_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 const struct address_space_operations mapping_aops = {
.sync_page = block_sync_page,
.migratepage = fail_migrate_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->bt_mapping = mapping;
return 0;
}
STATIC int
xfs_alloc_delwrite_queue(
xfs_buftarg_t *btp)
{
int error = 0;
INIT_LIST_HEAD(&btp->bt_list);
INIT_LIST_HEAD(&btp->bt_delwrite_queue);
spinlock_init(&btp->bt_delwrite_lock, "delwri_lock");
btp->bt_flags = 0;
btp->bt_task = kthread_run(xfsbufd, btp, "xfsbufd");
if (IS_ERR(btp->bt_task)) {
error = PTR_ERR(btp->bt_task);
goto out_error;
}
xfs_register_buftarg(btp);
out_error:
return error;
}
xfs_buftarg_t *
xfs_alloc_buftarg(
struct block_device *bdev,
int external)
{
xfs_buftarg_t *btp;
btp = kmem_zalloc(sizeof(*btp), KM_SLEEP);
btp->bt_dev = bdev->bd_dev;
btp->bt_bdev = bdev;
if (xfs_setsize_buftarg_early(btp, bdev))
goto error;
if (xfs_mapping_buftarg(btp, bdev))
goto error;
if (xfs_alloc_delwrite_queue(btp))
goto error;
xfs_alloc_bufhash(btp, external);
return btp;
error:
kmem_free(btp, sizeof(*btp));
return NULL;
}
/*
* Delayed write buffer handling
*/
STATIC void
xfs_buf_delwri_queue(
xfs_buf_t *bp,
int unlock)
{
struct list_head *dwq = &bp->b_target->bt_delwrite_queue;
spinlock_t *dwlk = &bp->b_target->bt_delwrite_lock;
XB_TRACE(bp, "delwri_q", (long)unlock);
ASSERT((bp->b_flags&(XBF_DELWRI|XBF_ASYNC)) == (XBF_DELWRI|XBF_ASYNC));
spin_lock(dwlk);
/* If already in the queue, dequeue and place at tail */
if (!list_empty(&bp->b_list)) {
ASSERT(bp->b_flags & _XBF_DELWRI_Q);
if (unlock)
atomic_dec(&bp->b_hold);
list_del(&bp->b_list);
}
bp->b_flags |= _XBF_DELWRI_Q;
list_add_tail(&bp->b_list, dwq);
bp->b_queuetime = jiffies;
spin_unlock(dwlk);
if (unlock)
xfs_buf_unlock(bp);
}
void
xfs_buf_delwri_dequeue(
xfs_buf_t *bp)
{
spinlock_t *dwlk = &bp->b_target->bt_delwrite_lock;
int dequeued = 0;
spin_lock(dwlk);
if ((bp->b_flags & XBF_DELWRI) && !list_empty(&bp->b_list)) {
ASSERT(bp->b_flags & _XBF_DELWRI_Q);
list_del_init(&bp->b_list);
dequeued = 1;
}
bp->b_flags &= ~(XBF_DELWRI|_XBF_DELWRI_Q);
spin_unlock(dwlk);
if (dequeued)
xfs_buf_rele(bp);
XB_TRACE(bp, "delwri_dq", (long)dequeued);
}
STATIC void
xfs_buf_runall_queues(
struct workqueue_struct *queue)
{
flush_workqueue(queue);
}
STATIC int
xfsbufd_wakeup(
int priority,
gfp_t mask)
{
xfs_buftarg_t *btp;
spin_lock(&xfs_buftarg_lock);
list_for_each_entry(btp, &xfs_buftarg_list, bt_list) {
if (test_bit(XBT_FORCE_SLEEP, &btp->bt_flags))
continue;
set_bit(XBT_FORCE_FLUSH, &btp->bt_flags);
wake_up_process(btp->bt_task);
}
spin_unlock(&xfs_buftarg_lock);
return 0;
}
/*
* Move as many buffers as specified to the supplied list
* idicating if we skipped any buffers to prevent deadlocks.
*/
STATIC int
xfs_buf_delwri_split(
xfs_buftarg_t *target,
struct list_head *list,
unsigned long age,
int flags)
{
xfs_buf_t *bp, *n;
struct list_head *dwq = &target->bt_delwrite_queue;
spinlock_t *dwlk = &target->bt_delwrite_lock;
int skipped = 0;
INIT_LIST_HEAD(list);
spin_lock(dwlk);
list_for_each_entry_safe(bp, n, dwq, b_list) {
XB_TRACE(bp, "walkq1", (long)xfs_buf_ispin(bp));
ASSERT(bp->b_flags & XBF_DELWRI);
if (!xfs_buf_ispin(bp) && !xfs_buf_cond_lock(bp)) {
if (!(flags & XBT_FORCE_FLUSH) &&
time_before(jiffies, bp->b_queuetime + age)) {
xfs_buf_unlock(bp);
break;
}
bp->b_flags &= ~(XBF_DELWRI|_XBF_DELWRI_Q|
_XBF_RUN_QUEUES);
bp->b_flags |= XBF_WRITE;
list_move_tail(&bp->b_list, list);
} else
skipped++;
}
spin_unlock(dwlk);
return skipped;
}
STATIC int
xfsbufd(
void *data)
{
struct list_head tmp;
xfs_buftarg_t *target = (xfs_buftarg_t *)data;
int count;
xfs_buf_t *bp;
current->flags |= PF_MEMALLOC;
do {
if (unlikely(freezing(current))) {
set_bit(XBT_FORCE_SLEEP, &target->bt_flags);
refrigerator();
} else {
clear_bit(XBT_FORCE_SLEEP, &target->bt_flags);
}
schedule_timeout_interruptible(
xfs_buf_timer_centisecs * msecs_to_jiffies(10));
xfs_buf_delwri_split(target, &tmp,
xfs_buf_age_centisecs * msecs_to_jiffies(10),
test_bit(XBT_FORCE_FLUSH, &target->bt_flags)
? XBT_FORCE_FLUSH : 0);
count = 0;
while (!list_empty(&tmp)) {
bp = list_entry(tmp.next, xfs_buf_t, b_list);
ASSERT(target == bp->b_target);
list_del_init(&bp->b_list);
xfs_buf_iostrategy(bp);
count++;
}
if (as_list_len > 0)
purge_addresses();
if (count)
blk_run_address_space(target->bt_mapping);
clear_bit(XBT_FORCE_FLUSH, &target->bt_flags);
} 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 *bp, *n;
int pincount = 0;
xfs_buf_runall_queues(xfsdatad_workqueue);
xfs_buf_runall_queues(xfslogd_workqueue);
pincount = xfs_buf_delwri_split(target, &tmp, 0, XBT_FORCE_FLUSH);
/*
* Dropped the delayed write list lock, now walk the temporary list
*/
list_for_each_entry_safe(bp, n, &tmp, b_list) {
ASSERT(target == bp->b_target);
if (wait)
bp->b_flags &= ~XBF_ASYNC;
else
list_del_init(&bp->b_list);
xfs_buf_iostrategy(bp);
}
if (wait)
blk_run_address_space(target->bt_mapping);
/*
* Remaining list items must be flushed before returning
*/
while (!list_empty(&tmp)) {
bp = list_entry(tmp.next, xfs_buf_t, b_list);
list_del_init(&bp->b_list);
xfs_iowait(bp);
xfs_buf_relse(bp);
}
return pincount;
}
int __init
xfs_buf_init(void)
{
#ifdef XFS_BUF_TRACE
xfs_buf_trace_buf = ktrace_alloc(XFS_BUF_TRACE_SIZE, KM_SLEEP);
#endif
xfs_buf_zone = kmem_zone_init_flags(sizeof(xfs_buf_t), "xfs_buf",
KM_ZONE_HWALIGN, NULL);
if (!xfs_buf_zone)
goto out_free_trace_buf;
xfslogd_workqueue = create_workqueue("xfslogd");
if (!xfslogd_workqueue)
goto out_free_buf_zone;
xfsdatad_workqueue = create_workqueue("xfsdatad");
if (!xfsdatad_workqueue)
goto out_destroy_xfslogd_workqueue;
xfs_buf_shake = kmem_shake_register(xfsbufd_wakeup);
if (!xfs_buf_shake)
goto out_destroy_xfsdatad_workqueue;
return 0;
out_destroy_xfsdatad_workqueue:
destroy_workqueue(xfsdatad_workqueue);
out_destroy_xfslogd_workqueue:
destroy_workqueue(xfslogd_workqueue);
out_free_buf_zone:
kmem_zone_destroy(xfs_buf_zone);
out_free_trace_buf:
#ifdef XFS_BUF_TRACE
ktrace_free(xfs_buf_trace_buf);
#endif
return -ENOMEM;
}
void
xfs_buf_terminate(void)
{
kmem_shake_deregister(xfs_buf_shake);
destroy_workqueue(xfsdatad_workqueue);
destroy_workqueue(xfslogd_workqueue);
kmem_zone_destroy(xfs_buf_zone);
#ifdef XFS_BUF_TRACE
ktrace_free(xfs_buf_trace_buf);
#endif
}
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