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

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/*
* 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/gfp.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 <linux/freezer.h>
#include <linux/list_sort.h>
#include "xfs_sb.h"
#include "xfs_inum.h"
#include "xfs_log.h"
#include "xfs_ag.h"
#include "xfs_mount.h"
#include "xfs_trace.h"
static kmem_zone_t *xfs_buf_zone;
STATIC int xfsbufd(void *);
STATIC void xfs_buf_delwri_queue(xfs_buf_t *, int);
static struct workqueue_struct *xfslogd_workqueue;
struct workqueue_struct *xfsdatad_workqueue;
struct workqueue_struct *xfsconvertd_workqueue;
#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));
static inline int
xfs_buf_is_vmapped(
struct xfs_buf *bp)
{
/*
* Return true if the buffer is vmapped.
*
* The XBF_MAPPED flag is set if the buffer should be mapped, but the
* code is clever enough to know it doesn't have to map a single page,
* so the check has to be both for XBF_MAPPED and bp->b_page_count > 1.
*/
return (bp->b_flags & XBF_MAPPED) && bp->b_page_count > 1;
}
static inline int
xfs_buf_vmap_len(
struct xfs_buf *bp)
{
return (bp->b_page_count * PAGE_SIZE) - bp->b_offset;
}
/*
* 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 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 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);
}
/*
* xfs_buf_lru_add - add a buffer to the LRU.
*
* The LRU takes a new reference to the buffer so that it will only be freed
* once the shrinker takes the buffer off the LRU.
*/
STATIC void
xfs_buf_lru_add(
struct xfs_buf *bp)
{
struct xfs_buftarg *btp = bp->b_target;
spin_lock(&btp->bt_lru_lock);
if (list_empty(&bp->b_lru)) {
atomic_inc(&bp->b_hold);
list_add_tail(&bp->b_lru, &btp->bt_lru);
btp->bt_lru_nr++;
}
spin_unlock(&btp->bt_lru_lock);
}
/*
* xfs_buf_lru_del - remove a buffer from the LRU
*
* The unlocked check is safe here because it only occurs when there are not
* b_lru_ref counts left on the inode under the pag->pag_buf_lock. it is there
* to optimise the shrinker removing the buffer from the LRU and calling
* xfs_buf_free(). i.e. it removes an unneccessary round trip on the
* bt_lru_lock.
*/
STATIC void
xfs_buf_lru_del(
struct xfs_buf *bp)
{
struct xfs_buftarg *btp = bp->b_target;
if (list_empty(&bp->b_lru))
return;
spin_lock(&btp->bt_lru_lock);
if (!list_empty(&bp->b_lru)) {
list_del_init(&bp->b_lru);
btp->bt_lru_nr--;
}
spin_unlock(&btp->bt_lru_lock);
}
/*
* When we mark a buffer stale, we remove the buffer from the LRU and clear the
* b_lru_ref count so that the buffer is freed immediately when the buffer
* reference count falls to zero. If the buffer is already on the LRU, we need
* to remove the reference that LRU holds on the buffer.
*
* This prevents build-up of stale buffers on the LRU.
*/
void
xfs_buf_stale(
struct xfs_buf *bp)
{
bp->b_flags |= XBF_STALE;
atomic_set(&(bp)->b_lru_ref, 0);
if (!list_empty(&bp->b_lru)) {
struct xfs_buftarg *btp = bp->b_target;
spin_lock(&btp->bt_lru_lock);
if (!list_empty(&bp->b_lru)) {
list_del_init(&bp->b_lru);
btp->bt_lru_nr--;
atomic_dec(&bp->b_hold);
}
spin_unlock(&btp->bt_lru_lock);
}
ASSERT(atomic_read(&bp->b_hold) >= 1);
}
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);
atomic_set(&bp->b_lru_ref, 1);
init_completion(&bp->b_iowait);
INIT_LIST_HEAD(&bp->b_lru);
INIT_LIST_HEAD(&bp->b_list);
RB_CLEAR_NODE(&bp->b_rbnode);
sema_init(&bp->b_sema, 0); /* 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);
trace_xfs_buf_init(bp, _RET_IP_);
}
/*
* 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_pages = NULL;
}
}
/*
* 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)
{
trace_xfs_buf_free(bp, _RET_IP_);
ASSERT(list_empty(&bp->b_lru));
if (bp->b_flags & (_XBF_PAGE_CACHE|_XBF_PAGES)) {
uint i;
if (xfs_buf_is_vmapped(bp))
vm_unmap_ram(bp->b_addr - bp->b_offset,
bp->b_page_count);
for (i = 0; i < bp->b_page_count; i++) {
struct page *page = bp->b_pages[i];
if (bp->b_flags & _XBF_PAGE_CACHE)
ASSERT(!PagePrivate(page));
page_cache_release(page);
}
}
_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",
__func__, gfp_mask);
XFS_STATS_INC(xb_page_retries);
congestion_wait(BLK_RW_ASYNC, 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_flags |= _XBF_PAGE_LOCKED;
} else if (!PagePrivate(page)) {
if (test_page_region(page, offset, nbytes))
page_count++;
}
}
bp->b_pages[i] = page;
offset = 0;
}
if (!(bp->b_flags & _XBF_PAGE_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;
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) {
bp->b_addr = vm_map_ram(bp->b_pages, bp->b_page_count,
-1, 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;
struct xfs_perag *pag;
struct rb_node **rbp;
struct rb_node *parent;
xfs_buf_t *bp;
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));
/* get tree root */
pag = xfs_perag_get(btp->bt_mount,
xfs_daddr_to_agno(btp->bt_mount, ioff));
/* walk tree */
spin_lock(&pag->pag_buf_lock);
rbp = &pag->pag_buf_tree.rb_node;
parent = NULL;
bp = NULL;
while (*rbp) {
parent = *rbp;
bp = rb_entry(parent, struct xfs_buf, b_rbnode);
if (range_base < bp->b_file_offset)
rbp = &(*rbp)->rb_left;
else if (range_base > bp->b_file_offset)
rbp = &(*rbp)->rb_right;
else {
/*
* found a block offset match. If the range doesn't
* match, the only way this is allowed is if the buffer
* in the cache is stale and the transaction that made
* it stale has not yet committed. i.e. we are
* reallocating a busy extent. Skip this buffer and
* continue searching to the right for an exact match.
*/
if (bp->b_buffer_length != range_length) {
ASSERT(bp->b_flags & XBF_STALE);
rbp = &(*rbp)->rb_right;
continue;
}
atomic_inc(&bp->b_hold);
goto found;
}
}
/* No match found */
if (new_bp) {
_xfs_buf_initialize(new_bp, btp, range_base,
range_length, flags);
rb_link_node(&new_bp->b_rbnode, parent, rbp);
rb_insert_color(&new_bp->b_rbnode, &pag->pag_buf_tree);
/* the buffer keeps the perag reference until it is freed */
new_bp->b_pag = pag;
spin_unlock(&pag->pag_buf_lock);
} else {
XFS_STATS_INC(xb_miss_locked);
spin_unlock(&pag->pag_buf_lock);
xfs_perag_put(pag);
}
return new_bp;
found:
spin_unlock(&pag->pag_buf_lock);
xfs_perag_put(pag);
if (xfs_buf_cond_lock(bp)) {
/* failed, so wait for the lock if requested. */
if (!(flags & XBF_TRYLOCK)) {
xfs_buf_lock(bp);
XFS_STATS_INC(xb_get_locked_waited);
} else {
xfs_buf_rele(bp);
XFS_STATS_INC(xb_busy_locked);
return NULL;
}
}
if (bp->b_flags & XBF_STALE) {
ASSERT((bp->b_flags & _XBF_DELWRI_Q) == 0);
bp->b_flags &= XBF_MAPPED;
}
trace_xfs_buf_find(bp, flags, _RET_IP_);
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(
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",
__func__);
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;
trace_xfs_buf_get(bp, flags, _RET_IP_);
return bp;
no_buffer:
if (flags & (XBF_LOCK | XBF_TRYLOCK))
xfs_buf_unlock(bp);
xfs_buf_rele(bp);
return NULL;
}
STATIC int
_xfs_buf_read(
xfs_buf_t *bp,
xfs_buf_flags_t flags)
{
int status;
ASSERT(!(flags & (XBF_DELWRI|XBF_WRITE)));
ASSERT(bp->b_bn != XFS_BUF_DADDR_NULL);
bp->b_flags &= ~(XBF_WRITE | XBF_ASYNC | XBF_DELWRI | \
XBF_READ_AHEAD | _XBF_RUN_QUEUES);
bp->b_flags |= flags & (XBF_READ | XBF_ASYNC | \
XBF_READ_AHEAD | _XBF_RUN_QUEUES);
status = xfs_buf_iorequest(bp);
if (status || XFS_BUF_ISERROR(bp) || (flags & XBF_ASYNC))
return status;
return xfs_buf_iowait(bp);
}
xfs_buf_t *
xfs_buf_read(
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(target, ioff, isize, flags);
if (bp) {
trace_xfs_buf_read(bp, flags, _RET_IP_);
if (!XFS_BUF_ISDONE(bp)) {
XFS_STATS_INC(xb_get_read);
_xfs_buf_read(bp, flags);
} else if (flags & XBF_ASYNC) {
/*
* Read ahead call which is already satisfied,
* drop the buffer
*/
goto no_buffer;
} else {
/* 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)
{
struct backing_dev_info *bdi;
bdi = target->bt_mapping->backing_dev_info;
if (bdi_read_congested(bdi))
return;
xfs_buf_read(target, ioff, isize,
XBF_TRYLOCK|XBF_ASYNC|XBF_READ_AHEAD|XBF_DONT_BLOCK);
}
/*
* Read an uncached buffer from disk. Allocates and returns a locked
* buffer containing the disk contents or nothing.
*/
struct xfs_buf *
xfs_buf_read_uncached(
struct xfs_mount *mp,
struct xfs_buftarg *target,
xfs_daddr_t daddr,
size_t length,
int flags)
{
xfs_buf_t *bp;
int error;
bp = xfs_buf_get_uncached(target, length, flags);
if (!bp)
return NULL;
/* set up the buffer for a read IO */
xfs_buf_lock(bp);
XFS_BUF_SET_ADDR(bp, daddr);
XFS_BUF_READ(bp);
XFS_BUF_BUSY(bp);
xfsbdstrat(mp, bp);
error = xfs_buf_iowait(bp);
if (error || bp->b_error) {
xfs_buf_relse(bp);
return NULL;
}
return bp;
}
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 ((!is_vmalloc_addr(addr))) {
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;
unsigned long pageaddr;
unsigned long offset;
size_t buflen;
int page_count;
pageaddr = (unsigned long)mem & PAGE_CACHE_MASK;
offset = (unsigned long)mem - pageaddr;
buflen = PAGE_CACHE_ALIGN(len + offset);
page_count = buflen >> PAGE_CACHE_SHIFT;
/* 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, XBF_DONT_BLOCK);
if (rval)
return rval;
bp->b_offset = offset;
for (i = 0; i < bp->b_page_count; i++) {
bp->b_pages[i] = mem_to_page((void *)pageaddr);
pageaddr += PAGE_CACHE_SIZE;
}
bp->b_count_desired = len;
bp->b_buffer_length = buflen;
bp->b_flags |= XBF_MAPPED;
bp->b_flags &= ~_XBF_PAGE_LOCKED;
return 0;
}
xfs_buf_t *
xfs_buf_get_uncached(
struct xfs_buftarg *target,
size_t len,
int flags)
{
unsigned long page_count = PAGE_ALIGN(len) >> PAGE_SHIFT;
int error, i;
xfs_buf_t *bp;
bp = xfs_buf_allocate(0);
if (unlikely(bp == NULL))
goto fail;
_xfs_buf_initialize(bp, target, 0, len, 0);
error = _xfs_buf_get_pages(bp, page_count, 0);
if (error)
goto fail_free_buf;
for (i = 0; i < page_count; i++) {
bp->b_pages[i] = alloc_page(xb_to_gfp(flags));
if (!bp->b_pages[i])
goto fail_free_mem;
}
bp->b_flags |= _XBF_PAGES;
error = _xfs_buf_map_pages(bp, XBF_MAPPED);
if (unlikely(error)) {
printk(KERN_WARNING "%s: failed to map pages\n",
__func__);
goto fail_free_mem;
}
xfs_buf_unlock(bp);
trace_xfs_buf_get_uncached(bp, _RET_IP_);
return bp;
fail_free_mem:
while (--i >= 0)
__free_page(bp->b_pages[i]);
_xfs_buf_free_pages(bp);
fail_free_buf:
xfs_buf_deallocate(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)
{
trace_xfs_buf_hold(bp, _RET_IP_);
atomic_inc(&bp->b_hold);
}
/*
* 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)
{
struct xfs_perag *pag = bp->b_pag;
trace_xfs_buf_rele(bp, _RET_IP_);
if (!pag) {
ASSERT(list_empty(&bp->b_lru));
ASSERT(RB_EMPTY_NODE(&bp->b_rbnode));
if (atomic_dec_and_test(&bp->b_hold))
xfs_buf_free(bp);
return;
}
ASSERT(!RB_EMPTY_NODE(&bp->b_rbnode));
ASSERT(atomic_read(&bp->b_hold) > 0);
if (atomic_dec_and_lock(&bp->b_hold, &pag->pag_buf_lock)) {
if (!(bp->b_flags & XBF_STALE) &&
atomic_read(&bp->b_lru_ref)) {
xfs_buf_lru_add(bp);
spin_unlock(&pag->pag_buf_lock);
} else {
xfs_buf_lru_del(bp);
ASSERT(!(bp->b_flags & (XBF_DELWRI|_XBF_DELWRI_Q)));
rb_erase(&bp->b_rbnode, &pag->pag_buf_tree);
spin_unlock(&pag->pag_buf_lock);
xfs_perag_put(pag);
xfs_buf_free(bp);
}
}
}
/*
* 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.
*
* If we come across a stale, pinned, locked buffer, we know that we are
* being asked to lock a buffer that has been reallocated. Because it is
* pinned, we know that the log has not been pushed to disk and hence it
* will still be locked. Rather than continuing to have trylock attempts
* fail until someone else pushes the log, push it ourselves before
* returning. This means that the xfsaild will not get stuck trying
* to push on stale inode buffers.
*/
int
xfs_buf_cond_lock(
xfs_buf_t *bp)
{
int locked;
locked = down_trylock(&bp->b_sema) == 0;
if (locked)
XB_SET_OWNER(bp);
else if (atomic_read(&bp->b_pin_count) && (bp->b_flags & XBF_STALE))
xfs_log_force(bp->b_target->bt_mount, 0);
trace_xfs_buf_cond_lock(bp, _RET_IP_);
return locked ? 0 : -EBUSY;
}
int
xfs_buf_lock_value(
xfs_buf_t *bp)
{
return bp->b_sema.count;
}
/*
* 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.
*
* If we come across a stale, pinned, locked buffer, we know that we
* are being asked to lock a buffer that has been reallocated. Because
* it is pinned, we know that the log has not been pushed to disk and
* hence it will still be locked. Rather than sleeping until someone
* else pushes the log, push it ourselves before trying to get the lock.
*/
void
xfs_buf_lock(
xfs_buf_t *bp)
{
trace_xfs_buf_lock(bp, _RET_IP_);
if (atomic_read(&bp->b_pin_count) && (bp->b_flags & XBF_STALE))
xfs_log_force(bp->b_target->bt_mount, 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);
trace_xfs_buf_lock_done(bp, _RET_IP_);
}
/*
* 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);
trace_xfs_buf_unlock(bp, _RET_IP_);
}
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(
struct work_struct *work)
{
xfs_buf_t *bp =
container_of(work, xfs_buf_t, b_iodone_work);
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)
{
trace_xfs_buf_iodone(bp, _RET_IP_);
bp->b_flags &= ~(XBF_READ | XBF_WRITE | XBF_READ_AHEAD);
if (bp->b_error == 0)
bp->b_flags |= XBF_DONE;
if ((bp->b_iodone) || (bp->b_flags & XBF_ASYNC)) {
if (schedule) {
INIT_WORK(&bp->b_iodone_work, xfs_buf_iodone_work);
queue_work(xfslogd_workqueue, &bp->b_iodone_work);
} else {
xfs_buf_iodone_work(&bp->b_iodone_work);
}
} else {
complete(&bp->b_iowait);
}
}
void
xfs_buf_ioerror(
xfs_buf_t *bp,
int error)
{
ASSERT(error >= 0 && error <= 0xffff);
bp->b_error = (unsigned short)error;
trace_xfs_buf_ioerror(bp, error, _RET_IP_);
}
int
xfs_bwrite(
struct xfs_mount *mp,
struct xfs_buf *bp)
{
int error;
bp->b_flags |= XBF_WRITE;
bp->b_flags &= ~(XBF_ASYNC | XBF_READ);
xfs_buf_delwri_dequeue(bp);
xfs_bdstrat_cb(bp);
error = xfs_buf_iowait(bp);
if (error)
xfs_force_shutdown(mp, SHUTDOWN_META_IO_ERROR);
xfs_buf_relse(bp);
return error;
}
void
xfs_bdwrite(
void *mp,
struct xfs_buf *bp)
{
trace_xfs_buf_bdwrite(bp, _RET_IP_);
bp->b_flags &= ~XBF_READ;
bp->b_flags |= (XBF_DELWRI | XBF_ASYNC);
xfs_buf_delwri_queue(bp, 1);
}
/*
* Called when we want to stop a buffer from getting written or read.
* We attach the EIO error, muck with its flags, and call xfs_buf_ioend
* so that the proper iodone callbacks get called.
*/
STATIC int
xfs_bioerror(
xfs_buf_t *bp)
{
#ifdef XFSERRORDEBUG
ASSERT(XFS_BUF_ISREAD(bp) || bp->b_iodone);
#endif
/*
* No need to wait until the buffer is unpinned, we aren't flushing it.
*/
XFS_BUF_ERROR(bp, EIO);
/*
* We're calling xfs_buf_ioend, so delete XBF_DONE flag.
*/
XFS_BUF_UNREAD(bp);
XFS_BUF_UNDELAYWRITE(bp);
XFS_BUF_UNDONE(bp);
XFS_BUF_STALE(bp);
xfs_buf_ioend(bp, 0);
return EIO;
}
/*
* Same as xfs_bioerror, except that we are releasing the buffer
* here ourselves, and avoiding the xfs_buf_ioend call.
* This is meant for userdata errors; metadata bufs come with
* iodone functions attached, so that we can track down errors.
*/
STATIC int
xfs_bioerror_relse(
struct xfs_buf *bp)
{
int64_t fl = XFS_BUF_BFLAGS(bp);
/*
* No need to wait until the buffer is unpinned.
* We aren't flushing it.
*
* chunkhold expects B_DONE to be set, whether
* we actually finish the I/O or not. We don't want to
* change that interface.
*/
XFS_BUF_UNREAD(bp);
XFS_BUF_UNDELAYWRITE(bp);
XFS_BUF_DONE(bp);
XFS_BUF_STALE(bp);
XFS_BUF_CLR_IODONE_FUNC(bp);
if (!(fl & XBF_ASYNC)) {
/*
* Mark b_error and B_ERROR _both_.
* Lot's of chunkcache code assumes that.
* There's no reason to mark error for
* ASYNC buffers.
*/
XFS_BUF_ERROR(bp, EIO);
XFS_BUF_FINISH_IOWAIT(bp);
} else {
xfs_buf_relse(bp);
}
return EIO;
}
/*
* All xfs metadata buffers except log state machine buffers
* get this attached as their b_bdstrat callback function.
* This is so that we can catch a buffer
* after prematurely unpinning it to forcibly shutdown the filesystem.
*/
int
xfs_bdstrat_cb(
struct xfs_buf *bp)
{
if (XFS_FORCED_SHUTDOWN(bp->b_target->bt_mount)) {
trace_xfs_bdstrat_shut(bp, _RET_IP_);
/*
* Metadata write that didn't get logged but
* written delayed anyway. These aren't associated
* with a transaction, and can be ignored.
*/
if (!bp->b_iodone && !XFS_BUF_ISREAD(bp))
return xfs_bioerror_relse(bp);
else
return xfs_bioerror(bp);
}
xfs_buf_iorequest(bp);
return 0;
}
/*
* Wrapper around bdstrat so that we can stop data from going to disk in case
* we are shutting down the filesystem. Typically user data goes thru this
* path; one of the exceptions is the superblock.
*/
void
xfsbdstrat(
struct xfs_mount *mp,
struct xfs_buf *bp)
{
if (XFS_FORCED_SHUTDOWN(mp)) {
trace_xfs_bdstrat_shut(bp, _RET_IP_);
xfs_bioerror_relse(bp);
return;
}
xfs_buf_iorequest(bp);
}
STATIC void
_xfs_buf_ioend(
xfs_buf_t *bp,
int schedule)
{
if (atomic_dec_and_test(&bp->b_io_remaining) == 1) {
bp->b_flags &= ~_XBF_PAGE_LOCKED;
xfs_buf_ioend(bp, schedule);
}
}
STATIC void
xfs_buf_bio_end_io(
struct bio *bio,
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;
xfs_buf_ioerror(bp, -error);
if (!error && xfs_buf_is_vmapped(bp) && (bp->b_flags & XBF_READ))
invalidate_kernel_vmap_range(bp->b_addr, xfs_buf_vmap_len(bp));
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 (bp->b_flags & _XBF_PAGE_LOCKED)
unlock_page(page);
} while (bvec >= bio->bi_io_vec);
_xfs_buf_ioend(bp, 1);
bio_put(bio);
}
STATIC void
_xfs_buf_ioapply(
xfs_buf_t *bp)
{
int 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;
total_nr_pages = bp->b_page_count;
map_i = 0;
if (bp->b_flags & XBF_ORDERED) {
ASSERT(!(bp->b_flags & XBF_READ));
rw = WRITE_FLUSH_FUA;
} else if (bp->b_flags & XBF_LOG_BUFFER) {
ASSERT(!(bp->b_flags & XBF_READ_AHEAD));
bp->b_flags &= ~_XBF_RUN_QUEUES;
rw = (bp->b_flags & XBF_WRITE) ? WRITE_SYNC : READ_SYNC;
} 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_META : READ_META;
} 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|_XBF_PAGE_LOCKED)) ==
(XBF_READ|_XBF_PAGE_LOCKED)) &&
(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;
}
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)) {
if (xfs_buf_is_vmapped(bp)) {
flush_kernel_vmap_range(bp->b_addr,
xfs_buf_vmap_len(bp));
}
submit_bio(rw, bio);
if (size)
goto next_chunk;
} else {
/*
* if we get here, no pages were added to the bio. However,
* we can't just error out here - if the pages are locked then
* we have to unlock them otherwise we can hang on a later
* access to the page.
*/
xfs_buf_ioerror(bp, EIO);
if (bp->b_flags & _XBF_PAGE_LOCKED) {
int i;
for (i = 0; i < bp->b_page_count; i++)
unlock_page(bp->b_pages[i]);
}
bio_put(bio);
}
}
int
xfs_buf_iorequest(
xfs_buf_t *bp)
{
trace_xfs_buf_iorequest(bp, _RET_IP_);
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)
{
trace_xfs_buf_iowait(bp, _RET_IP_);
if (atomic_read(&bp->b_io_remaining))
blk_run_address_space(bp->b_target->bt_mapping);
wait_for_completion(&bp->b_iowait);
trace_xfs_buf_iowait_done(bp, _RET_IP_);
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 */
void *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. These buffers will have an elevated hold count, so wait on those
* while freeing all the buffers only held by the LRU.
*/
void
xfs_wait_buftarg(
struct xfs_buftarg *btp)
{
struct xfs_buf *bp;
restart:
spin_lock(&btp->bt_lru_lock);
while (!list_empty(&btp->bt_lru)) {
bp = list_first_entry(&btp->bt_lru, struct xfs_buf, b_lru);
if (atomic_read(&bp->b_hold) > 1) {
spin_unlock(&btp->bt_lru_lock);
delay(100);
goto restart;
}
/*
* clear the LRU reference count so the bufer doesn't get
* ignored in xfs_buf_rele().
*/
atomic_set(&bp->b_lru_ref, 0);
spin_unlock(&btp->bt_lru_lock);
xfs_buf_rele(bp);
spin_lock(&btp->bt_lru_lock);
}
spin_unlock(&btp->bt_lru_lock);
}
int
xfs_buftarg_shrink(
struct shrinker *shrink,
int nr_to_scan,
gfp_t mask)
{
struct xfs_buftarg *btp = container_of(shrink,
struct xfs_buftarg, bt_shrinker);
struct xfs_buf *bp;
LIST_HEAD(dispose);
if (!nr_to_scan)
return btp->bt_lru_nr;
spin_lock(&btp->bt_lru_lock);
while (!list_empty(&btp->bt_lru)) {
if (nr_to_scan-- <= 0)
break;
bp = list_first_entry(&btp->bt_lru, struct xfs_buf, b_lru);
/*
* Decrement the b_lru_ref count unless the value is already
* zero. If the value is already zero, we need to reclaim the
* buffer, otherwise it gets another trip through the LRU.
*/
if (!atomic_add_unless(&bp->b_lru_ref, -1, 0)) {
list_move_tail(&bp->b_lru, &btp->bt_lru);
continue;
}
/*
* remove the buffer from the LRU now to avoid needing another
* lock round trip inside xfs_buf_rele().
*/
list_move(&bp->b_lru, &dispose);
btp->bt_lru_nr--;
}
spin_unlock(&btp->bt_lru_lock);
while (!list_empty(&dispose)) {
bp = list_first_entry(&dispose, struct xfs_buf, b_lru);
list_del_init(&bp->b_lru);
xfs_buf_rele(bp);
}
return btp->bt_lru_nr;
}
void
xfs_free_buftarg(
struct xfs_mount *mp,
struct xfs_buftarg *btp)
{
unregister_shrinker(&btp->bt_shrinker);
xfs_flush_buftarg(btp, 1);
if (mp->m_flags & XFS_MOUNT_BARRIER)
xfs_blkdev_issue_flush(btp);
iput(btp->bt_mapping->host);
kthread_stop(btp->bt_task);
kmem_free(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_logical_block_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_ino = get_next_ino();
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,
const char *fsname)
{
INIT_LIST_HEAD(&btp->bt_delwrite_queue);
spin_lock_init(&btp->bt_delwrite_lock);
btp->bt_flags = 0;
btp->bt_task = kthread_run(xfsbufd, btp, "xfsbufd/%s", fsname);
if (IS_ERR(btp->bt_task))
return PTR_ERR(btp->bt_task);
return 0;
}
xfs_buftarg_t *
xfs_alloc_buftarg(
struct xfs_mount *mp,
struct block_device *bdev,
int external,
const char *fsname)
{
xfs_buftarg_t *btp;
btp = kmem_zalloc(sizeof(*btp), KM_SLEEP);
btp->bt_mount = mp;
btp->bt_dev = bdev->bd_dev;
btp->bt_bdev = bdev;
INIT_LIST_HEAD(&btp->bt_lru);
spin_lock_init(&btp->bt_lru_lock);
if (xfs_setsize_buftarg_early(btp, bdev))
goto error;
if (xfs_mapping_buftarg(btp, bdev))
goto error;
if (xfs_alloc_delwrite_queue(btp, fsname))
goto error;
btp->bt_shrinker.shrink = xfs_buftarg_shrink;
btp->bt_shrinker.seeks = DEFAULT_SEEKS;
register_shrinker(&btp->bt_shrinker);
return btp;
error:
kmem_free(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;
trace_xfs_buf_delwri_queue(bp, _RET_IP_);
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);
}
if (list_empty(dwq)) {
/* start xfsbufd as it is about to have something to do */
wake_up_process(bp->b_target->bt_task);
}
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);
trace_xfs_buf_delwri_dequeue(bp, _RET_IP_);
}
/*
* If a delwri buffer needs to be pushed before it has aged out, then promote
* it to the head of the delwri queue so that it will be flushed on the next
* xfsbufd run. We do this by resetting the queuetime of the buffer to be older
* than the age currently needed to flush the buffer. Hence the next time the
* xfsbufd sees it is guaranteed to be considered old enough to flush.
*/
void
xfs_buf_delwri_promote(
struct xfs_buf *bp)
{
struct xfs_buftarg *btp = bp->b_target;
long age = xfs_buf_age_centisecs * msecs_to_jiffies(10) + 1;
ASSERT(bp->b_flags & XBF_DELWRI);
ASSERT(bp->b_flags & _XBF_DELWRI_Q);
/*
* Check the buffer age before locking the delayed write queue as we
* don't need to promote buffers that are already past the flush age.
*/
if (bp->b_queuetime < jiffies - age)
return;
bp->b_queuetime = jiffies - age;
spin_lock(&btp->bt_delwrite_lock);
list_move(&bp->b_list, &btp->bt_delwrite_queue);
spin_unlock(&btp->bt_delwrite_lock);
}
STATIC void
xfs_buf_runall_queues(
struct workqueue_struct *queue)
{
flush_workqueue(queue);
}
/*
* 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)
{
xfs_buf_t *bp, *n;
struct list_head *dwq = &target->bt_delwrite_queue;
spinlock_t *dwlk = &target->bt_delwrite_lock;
int skipped = 0;
int force;
force = test_and_clear_bit(XBT_FORCE_FLUSH, &target->bt_flags);
INIT_LIST_HEAD(list);
spin_lock(dwlk);
list_for_each_entry_safe(bp, n, dwq, b_list) {
ASSERT(bp->b_flags & XBF_DELWRI);
if (!XFS_BUF_ISPINNED(bp) && !xfs_buf_cond_lock(bp)) {
if (!force &&
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);
trace_xfs_buf_delwri_split(bp, _RET_IP_);
} else
skipped++;
}
spin_unlock(dwlk);
return skipped;
}
/*
* Compare function is more complex than it needs to be because
* the return value is only 32 bits and we are doing comparisons
* on 64 bit values
*/
static int
xfs_buf_cmp(
void *priv,
struct list_head *a,
struct list_head *b)
{
struct xfs_buf *ap = container_of(a, struct xfs_buf, b_list);
struct xfs_buf *bp = container_of(b, struct xfs_buf, b_list);
xfs_daddr_t diff;
diff = ap->b_bn - bp->b_bn;
if (diff < 0)
return -1;
if (diff > 0)
return 1;
return 0;
}
void
xfs_buf_delwri_sort(
xfs_buftarg_t *target,
struct list_head *list)
{
list_sort(NULL, list, xfs_buf_cmp);
}
STATIC int
xfsbufd(
void *data)
{
xfs_buftarg_t *target = (xfs_buftarg_t *)data;
current->flags |= PF_MEMALLOC;
set_freezable();
do {
long age = xfs_buf_age_centisecs * msecs_to_jiffies(10);
long tout = xfs_buf_timer_centisecs * msecs_to_jiffies(10);
int count = 0;
struct list_head tmp;
if (unlikely(freezing(current))) {
set_bit(XBT_FORCE_SLEEP, &target->bt_flags);
refrigerator();
} else {
clear_bit(XBT_FORCE_SLEEP, &target->bt_flags);
}
/* sleep for a long time if there is nothing to do. */
if (list_empty(&target->bt_delwrite_queue))
tout = MAX_SCHEDULE_TIMEOUT;
schedule_timeout_interruptible(tout);
xfs_buf_delwri_split(target, &tmp, age);
list_sort(NULL, &tmp, xfs_buf_cmp);
while (!list_empty(&tmp)) {
struct xfs_buf *bp;
bp = list_first_entry(&tmp, struct xfs_buf, b_list);
list_del_init(&bp->b_list);
xfs_bdstrat_cb(bp);
count++;
}
if (count)
blk_run_address_space(target->bt_mapping);
} 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)
{
xfs_buf_t *bp;
int pincount = 0;
LIST_HEAD(tmp_list);
LIST_HEAD(wait_list);
xfs_buf_runall_queues(xfsconvertd_workqueue);
xfs_buf_runall_queues(xfsdatad_workqueue);
xfs_buf_runall_queues(xfslogd_workqueue);
set_bit(XBT_FORCE_FLUSH, &target->bt_flags);
pincount = xfs_buf_delwri_split(target, &tmp_list, 0);
/*
* Dropped the delayed write list lock, now walk the temporary list.
* All I/O is issued async and then if we need to wait for completion
* we do that after issuing all the IO.
*/
list_sort(NULL, &tmp_list, xfs_buf_cmp);
while (!list_empty(&tmp_list)) {
bp = list_first_entry(&tmp_list, struct xfs_buf, b_list);
ASSERT(target == bp->b_target);
list_del_init(&bp->b_list);
if (wait) {
bp->b_flags &= ~XBF_ASYNC;
list_add(&bp->b_list, &wait_list);
}
xfs_bdstrat_cb(bp);
}
if (wait) {
/* Expedite and wait for IO to complete. */
blk_run_address_space(target->bt_mapping);
while (!list_empty(&wait_list)) {
bp = list_first_entry(&wait_list, struct xfs_buf, b_list);
list_del_init(&bp->b_list);
xfs_buf_iowait(bp);
xfs_buf_relse(bp);
}
}
return pincount;
}
int __init
xfs_buf_init(void)
{
xfs_buf_zone = kmem_zone_init_flags(sizeof(xfs_buf_t), "xfs_buf",
KM_ZONE_HWALIGN, NULL);
if (!xfs_buf_zone)
goto out;
xfslogd_workqueue = alloc_workqueue("xfslogd",
WQ_MEM_RECLAIM | WQ_HIGHPRI, 1);
if (!xfslogd_workqueue)
goto out_free_buf_zone;
xfsdatad_workqueue = create_workqueue("xfsdatad");
if (!xfsdatad_workqueue)
goto out_destroy_xfslogd_workqueue;
xfsconvertd_workqueue = create_workqueue("xfsconvertd");
if (!xfsconvertd_workqueue)
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:
return -ENOMEM;
}
void
xfs_buf_terminate(void)
{
destroy_workqueue(xfsconvertd_workqueue);
destroy_workqueue(xfsdatad_workqueue);
destroy_workqueue(xfslogd_workqueue);
kmem_zone_destroy(xfs_buf_zone);
}
#ifdef CONFIG_KDB_MODULES
struct list_head *
xfs_get_buftarg_list(void)
{
return &xfs_buftarg_list;
}
#endif
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