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linux-sg2042/fs/xfs/linux-2.6/xfs_buf.c

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/*
* 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 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 <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"
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_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 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++)
page_cache_release(bp->b_pages[i]);
_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);
blk_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;
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);
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;
if (unlikely(bp->b_error)) {
if (bp->b_flags & XBF_READ)
ClearPageUptodate(page);
SetPageError(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_RUN_QUEUES) {
bp->b_flags &= ~_XBF_RUN_QUEUES;
rw = (bp->b_flags & XBF_READ) ? READ_SYNC : WRITE_SYNC;
} else {
rw = (bp->b_flags & XBF_READ) ? READ : WRITE;
}
if (bp->b_flags & XBF_ORDERED) {
ASSERT(!(bp->b_flags & XBF_READ));
rw = WRITE_BARRIER;
}
/* 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);
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 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;
}
STATIC int
xfsbufd(
void *data)
{
struct list_head tmp;
unsigned long age;
xfs_buftarg_t *target = (xfs_buftarg_t *)data;
xfs_buf_t *bp, *n;
struct list_head *dwq = &target->bt_delwrite_queue;
spinlock_t *dwlk = &target->bt_delwrite_lock;
current->flags |= PF_MEMALLOC;
INIT_LIST_HEAD(&tmp);
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));
age = xfs_buf_age_centisecs * msecs_to_jiffies(10);
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 (!test_bit(XBT_FORCE_FLUSH,
&target->bt_flags) &&
time_before(jiffies,
bp->b_queuetime + age)) {
xfs_buf_unlock(bp);
break;
}
bp->b_flags &= ~(XBF_DELWRI|_XBF_DELWRI_Q);
bp->b_flags |= XBF_WRITE;
list_move(&bp->b_list, &tmp);
}
}
spin_unlock(dwlk);
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);
blk_run_address_space(target->bt_mapping);
}
if (as_list_len > 0)
purge_addresses();
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;
struct list_head *dwq = &target->bt_delwrite_queue;
spinlock_t *dwlk = &target->bt_delwrite_lock;
xfs_buf_runall_queues(xfsdatad_workqueue);
xfs_buf_runall_queues(xfslogd_workqueue);
INIT_LIST_HEAD(&tmp);
spin_lock(dwlk);
list_for_each_entry_safe(bp, n, dwq, b_list) {
ASSERT(bp->b_target == target);
ASSERT(bp->b_flags & (XBF_DELWRI | _XBF_DELWRI_Q));
XB_TRACE(bp, "walkq2", (long)xfs_buf_ispin(bp));
if (xfs_buf_ispin(bp)) {
pincount++;
continue;
}
list_move(&bp->b_list, &tmp);
}
spin_unlock(dwlk);
/*
* Dropped the delayed write list lock, now walk the temporary list
*/
list_for_each_entry_safe(bp, n, &tmp, b_list) {
xfs_buf_lock(bp);
bp->b_flags &= ~(XBF_DELWRI|_XBF_DELWRI_Q);
bp->b_flags |= XBF_WRITE;
if (wait)
bp->b_flags &= ~XBF_ASYNC;
else
list_del_init(&bp->b_list);
xfs_buf_iostrategy(bp);
}
/*
* 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);
}
if (wait)
blk_run_address_space(target->bt_mapping);
return pincount;
}
int __init
xfs_buf_init(void)
{
int error = -ENOMEM;
#ifdef XFS_BUF_TRACE
xfs_buf_trace_buf = ktrace_alloc(XFS_BUF_TRACE_SIZE, KM_SLEEP);
#endif
xfs_buf_zone = kmem_zone_init(sizeof(xfs_buf_t), "xfs_buf");
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 error;
}
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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