[PATCH 04/11] writeback: separate the flushing state/task from the bdi

From: Jens Axboe
Date: Mon May 18 2009 - 08:25:09 EST

Add a struct bdi_writeback for tracking and handling dirty IO. This
is in preparation for adding > 1 flusher task per bdi.

Signed-off-by: Jens Axboe <jens.axboe@xxxxxxxxxx>
---
fs/fs-writeback.c | 140 +++++++++++++++++-----------
include/linux/backing-dev.h | 42 +++++----
mm/backing-dev.c | 218 ++++++++++++++++++++++++++++--------------
3 files changed, 256 insertions(+), 144 deletions(-)

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 8a25d14..50e21e8 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -46,9 +46,11 @@ int nr_pdflush_threads;
* unless they implement their own. Which is somewhat inefficient, as this
* may prevent concurrent writeback against multiple devices.
*/
-static int writeback_acquire(struct backing_dev_info *bdi)
+static int writeback_acquire(struct bdi_writeback *wb)
{
- return !test_and_set_bit(BDI_pdflush, &bdi->state);
+ struct backing_dev_info *bdi = wb->bdi;
+
+ return !test_and_set_bit(wb->nr, &bdi->wb_active);
}

/**
@@ -59,19 +61,38 @@ static int writeback_acquire(struct backing_dev_info *bdi)
*/
int writeback_in_progress(struct backing_dev_info *bdi)
{
- return test_bit(BDI_pdflush, &bdi->state);
+ return bdi->wb_active != 0;
}

/**
* writeback_release - relinquish exclusive writeback access against a device.
* @bdi: the device's backing_dev_info structure
*/
-static void writeback_release(struct backing_dev_info *bdi)
+static void writeback_release(struct bdi_writeback *wb)
{
- WARN_ON_ONCE(!writeback_in_progress(bdi));
- bdi->wb_arg.nr_pages = 0;
- bdi->wb_arg.sb = NULL;
- clear_bit(BDI_pdflush, &bdi->state);
+ struct backing_dev_info *bdi = wb->bdi;
+
+ wb->nr_pages = 0;
+ wb->sb = NULL;
+ clear_bit(wb->nr, &bdi->wb_active);
+}
+
+static void wb_start_writeback(struct bdi_writeback *wb, struct super_block *sb,
+ long nr_pages)
+{
+ if (!wb_has_dirty_io(wb))
+ return;
+
+ if (writeback_acquire(wb)) {
+ wb->nr_pages = nr_pages;
+ wb->sb = sb;
+
+ /*
+ * make above store seen before the task is woken
+ */
+ smp_mb();
+ wake_up(&wb->wait);
+ }
}

int bdi_start_writeback(struct backing_dev_info *bdi, struct super_block *sb,
@@ -81,21 +102,12 @@ int bdi_start_writeback(struct backing_dev_info *bdi, struct super_block *sb,
* This only happens the first time someone kicks this bdi, so put
* it out-of-line.
*/
- if (unlikely(!bdi->task)) {
+ if (unlikely(!bdi->wb.task)) {
bdi_add_default_flusher_task(bdi);
return 1;
}

- if (writeback_acquire(bdi)) {
- bdi->wb_arg.nr_pages = nr_pages;
- bdi->wb_arg.sb = sb;
- /*
- * make above store seen before the task is woken
- */
- smp_mb();
- wake_up(&bdi->wait);
- }
-
+ wb_start_writeback(&bdi->wb, sb, nr_pages);
return 0;
}

@@ -123,12 +135,12 @@ int bdi_start_writeback(struct backing_dev_info *bdi, struct super_block *sb,
* older_than_this takes precedence over nr_to_write. So we'll only write back
* all dirty pages if they are all attached to "old" mappings.
*/
-static void bdi_kupdated(struct backing_dev_info *bdi)
+static void wb_kupdated(struct bdi_writeback *wb)
{
unsigned long oldest_jif;
long nr_to_write;
struct writeback_control wbc = {
- .bdi = bdi,
+ .bdi = wb->bdi,
.sync_mode = WB_SYNC_NONE,
.older_than_this = &oldest_jif,
.nr_to_write = 0,
@@ -155,15 +167,19 @@ static void bdi_kupdated(struct backing_dev_info *bdi)
}
}

-static void bdi_pdflush(struct backing_dev_info *bdi)
+static void generic_sync_wb_inodes(struct bdi_writeback *wb,
+ struct super_block *sb,
+ struct writeback_control *wbc);
+
+static void wb_writeback(struct bdi_writeback *wb)
{
struct writeback_control wbc = {
- .bdi = bdi,
+ .bdi = wb->bdi,
.sync_mode = WB_SYNC_NONE,
.older_than_this = NULL,
.range_cyclic = 1,
};
- long nr_pages = bdi->wb_arg.nr_pages;
+ long nr_pages = wb->nr_pages;

for (;;) {
unsigned long background_thresh, dirty_thresh;
@@ -177,7 +193,7 @@ static void bdi_pdflush(struct backing_dev_info *bdi)
wbc.encountered_congestion = 0;
wbc.nr_to_write = MAX_WRITEBACK_PAGES;
wbc.pages_skipped = 0;
- generic_sync_bdi_inodes(bdi->wb_arg.sb, &wbc);
+ generic_sync_wb_inodes(wb, wb->sb, &wbc);
nr_pages -= MAX_WRITEBACK_PAGES - wbc.nr_to_write;
/*
* If we ran out of stuff to write, bail unless more_io got set
@@ -194,13 +210,13 @@ static void bdi_pdflush(struct backing_dev_info *bdi)
* Handle writeback of dirty data for the device backed by this bdi. Also
* wakes up periodically and does kupdated style flushing.
*/
-int bdi_writeback_task(struct backing_dev_info *bdi)
+int bdi_writeback_task(struct bdi_writeback *wb)
{
while (!kthread_should_stop()) {
unsigned long wait_jiffies;
DEFINE_WAIT(wait);

- prepare_to_wait(&bdi->wait, &wait, TASK_INTERRUPTIBLE);
+ prepare_to_wait(&wb->wait, &wait, TASK_INTERRUPTIBLE);
wait_jiffies = msecs_to_jiffies(dirty_writeback_interval * 10);
schedule_timeout(wait_jiffies);
try_to_freeze();
@@ -219,13 +235,13 @@ int bdi_writeback_task(struct backing_dev_info *bdi)
* pdflush style writeout.
*
*/
- if (writeback_acquire(bdi))
- bdi_kupdated(bdi);
+ if (writeback_acquire(wb))
+ wb_kupdated(wb);
else
- bdi_pdflush(bdi);
+ wb_writeback(wb);

- writeback_release(bdi);
- finish_wait(&bdi->wait, &wait);
+ writeback_release(wb);
+ finish_wait(&wb->wait, &wait);
}

return 0;
@@ -248,6 +264,14 @@ restart:
rcu_read_unlock();
}

+/*
+ * We have only a single wb per bdi, so just return that.
+ */
+static inline struct bdi_writeback *inode_get_wb(struct inode *inode)
+{
+ return &inode_to_bdi(inode)->wb;
+}
+
/**
* __mark_inode_dirty - internal function
* @inode: inode to mark
@@ -346,9 +370,10 @@ void __mark_inode_dirty(struct inode *inode, int flags)
* reposition it (that would break b_dirty time-ordering).
*/
if (!was_dirty) {
+ struct bdi_writeback *wb = inode_get_wb(inode);
+
inode->dirtied_when = jiffies;
- list_move(&inode->i_list,
- &inode_to_bdi(inode)->b_dirty);
+ list_move(&inode->i_list, &wb->b_dirty);
}
}
out:
@@ -375,16 +400,16 @@ static int write_inode(struct inode *inode, int sync)
*/
static void redirty_tail(struct inode *inode)
{
- struct backing_dev_info *bdi = inode_to_bdi(inode);
+ struct bdi_writeback *wb = inode_get_wb(inode);

- if (!list_empty(&bdi->b_dirty)) {
+ if (!list_empty(&wb->b_dirty)) {
struct inode *tail;

- tail = list_entry(bdi->b_dirty.next, struct inode, i_list);
+ tail = list_entry(wb->b_dirty.next, struct inode, i_list);
if (time_before(inode->dirtied_when, tail->dirtied_when))
inode->dirtied_when = jiffies;
}
- list_move(&inode->i_list, &bdi->b_dirty);
+ list_move(&inode->i_list, &wb->b_dirty);
}

/*
@@ -392,7 +417,9 @@ static void redirty_tail(struct inode *inode)
*/
static void requeue_io(struct inode *inode)
{
- list_move(&inode->i_list, &inode_to_bdi(inode)->b_more_io);
+ struct bdi_writeback *wb = inode_get_wb(inode);
+
+ list_move(&inode->i_list, &wb->b_more_io);
}

static void inode_sync_complete(struct inode *inode)
@@ -439,11 +466,10 @@ static void move_expired_inodes(struct list_head *delaying_queue,
/*
* Queue all expired dirty inodes for io, eldest first.
*/
-static void queue_io(struct backing_dev_info *bdi,
- unsigned long *older_than_this)
+static void queue_io(struct bdi_writeback *wb, unsigned long *older_than_this)
{
- list_splice_init(&bdi->b_more_io, bdi->b_io.prev);
- move_expired_inodes(&bdi->b_dirty, &bdi->b_io, older_than_this);
+ list_splice_init(&wb->b_more_io, wb->b_io.prev);
+ move_expired_inodes(&wb->b_dirty, &wb->b_io, older_than_this);
}

/*
@@ -604,20 +630,20 @@ __writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
return __sync_single_inode(inode, wbc);
}

-void generic_sync_bdi_inodes(struct super_block *sb,
- struct writeback_control *wbc)
+static void generic_sync_wb_inodes(struct bdi_writeback *wb,
+ struct super_block *sb,
+ struct writeback_control *wbc)
{
const int is_blkdev_sb = sb_is_blkdev_sb(sb);
- struct backing_dev_info *bdi = wbc->bdi;
const unsigned long start = jiffies; /* livelock avoidance */

spin_lock(&inode_lock);

- if (!wbc->for_kupdate || list_empty(&bdi->b_io))
- queue_io(bdi, wbc->older_than_this);
+ if (!wbc->for_kupdate || list_empty(&wb->b_io))
+ queue_io(wb, wbc->older_than_this);

- while (!list_empty(&bdi->b_io)) {
- struct inode *inode = list_entry(bdi->b_io.prev,
+ while (!list_empty(&wb->b_io)) {
+ struct inode *inode = list_entry(wb->b_io.prev,
struct inode, i_list);
long pages_skipped;

@@ -629,7 +655,7 @@ void generic_sync_bdi_inodes(struct super_block *sb,
continue;
}

- if (!bdi_cap_writeback_dirty(bdi)) {
+ if (!bdi_cap_writeback_dirty(wb->bdi)) {
redirty_tail(inode);
if (is_blkdev_sb) {
/*
@@ -651,7 +677,7 @@ void generic_sync_bdi_inodes(struct super_block *sb,
continue;
}

- if (wbc->nonblocking && bdi_write_congested(bdi)) {
+ if (wbc->nonblocking && bdi_write_congested(wb->bdi)) {
wbc->encountered_congestion = 1;
if (!is_blkdev_sb)
break; /* Skip a congested fs */
@@ -685,7 +711,7 @@ void generic_sync_bdi_inodes(struct super_block *sb,
wbc->more_io = 1;
break;
}
- if (!list_empty(&bdi->b_more_io))
+ if (!list_empty(&wb->b_more_io))
wbc->more_io = 1;
}

@@ -693,6 +719,14 @@ void generic_sync_bdi_inodes(struct super_block *sb,
/* Leave any unwritten inodes on b_io */
}

+void generic_sync_bdi_inodes(struct super_block *sb,
+ struct writeback_control *wbc)
+{
+ struct backing_dev_info *bdi = wbc->bdi;
+
+ generic_sync_wb_inodes(&bdi->wb, sb, wbc);
+}
+
/*
* Write out a superblock's list of dirty inodes. A wait will be performed
* upon no inodes, all inodes or the final one, depending upon sync_mode.
diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index a848eea..a0c70f1 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -23,8 +23,8 @@ struct dentry;
* Bits in backing_dev_info.state
*/
enum bdi_state {
- BDI_pdflush, /* A pdflush thread is working this device */
BDI_pending, /* On its way to being activated */
+ BDI_wb_alloc, /* Default embedded wb allocated */
BDI_async_congested, /* The async (write) queue is getting full */
BDI_sync_congested, /* The sync queue is getting full */
BDI_unused, /* Available bits start here */
@@ -40,15 +40,23 @@ enum bdi_stat_item {

#define BDI_STAT_BATCH (8*(1+ilog2(nr_cpu_ids)))

-struct bdi_writeback_arg {
- unsigned long nr_pages;
- struct super_block *sb;
+struct bdi_writeback {
+ struct backing_dev_info *bdi; /* our parent bdi */
+ unsigned int nr;
+
+ struct task_struct *task; /* writeback task */
+ wait_queue_head_t wait;
+ struct list_head b_dirty; /* dirty inodes */
+ struct list_head b_io; /* parked for writeback */
+ struct list_head b_more_io; /* parked for more writeback */
+
+ unsigned long nr_pages;
+ struct super_block *sb;
};

struct backing_dev_info {
- struct list_head bdi_list;
struct rcu_head rcu_head;
-
+ struct list_head bdi_list;
unsigned long ra_pages; /* max readahead in PAGE_CACHE_SIZE units */
unsigned long state; /* Always use atomic bitops on this */
unsigned int capabilities; /* Device capabilities */
@@ -65,14 +73,11 @@ struct backing_dev_info {
unsigned int min_ratio;
unsigned int max_ratio, max_prop_frac;

- struct device *dev;
+ struct bdi_writeback wb; /* default writeback info for this bdi */
+ unsigned long wb_active; /* bitmap of active tasks */
+ unsigned long wb_mask; /* number of registered tasks */

- struct task_struct *task; /* writeback task */
- wait_queue_head_t wait;
- struct bdi_writeback_arg wb_arg; /* protected by BDI_pdflush */
- struct list_head b_dirty; /* dirty inodes */
- struct list_head b_io; /* parked for writeback */
- struct list_head b_more_io; /* parked for more writeback */
+ struct device *dev;

#ifdef CONFIG_DEBUG_FS
struct dentry *debug_dir;
@@ -89,18 +94,19 @@ int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev);
void bdi_unregister(struct backing_dev_info *bdi);
int bdi_start_writeback(struct backing_dev_info *bdi, struct super_block *sb,
long nr_pages);
-int bdi_writeback_task(struct backing_dev_info *bdi);
+int bdi_writeback_task(struct bdi_writeback *wb);
void bdi_writeback_all(struct super_block *sb, long nr_pages);
void bdi_add_default_flusher_task(struct backing_dev_info *bdi);
+int bdi_has_dirty_io(struct backing_dev_info *bdi);

extern spinlock_t bdi_lock;
extern struct list_head bdi_list;

-static inline int bdi_has_dirty_io(struct backing_dev_info *bdi)
+static inline int wb_has_dirty_io(struct bdi_writeback *wb)
{
- return !list_empty(&bdi->b_dirty) ||
- !list_empty(&bdi->b_io) ||
- !list_empty(&bdi->b_more_io);
+ return !list_empty(&wb->b_dirty) ||
+ !list_empty(&wb->b_io) ||
+ !list_empty(&wb->b_more_io);
}

static inline void __add_bdi_stat(struct backing_dev_info *bdi,
diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index c759449..677a8c6 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -199,17 +199,59 @@ static int __init default_bdi_init(void)
}
subsys_initcall(default_bdi_init);

+static void bdi_wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi)
+{
+ memset(wb, 0, sizeof(*wb));
+
+ wb->bdi = bdi;
+ init_waitqueue_head(&wb->wait);
+ INIT_LIST_HEAD(&wb->b_dirty);
+ INIT_LIST_HEAD(&wb->b_io);
+ INIT_LIST_HEAD(&wb->b_more_io);
+}
+
+static void bdi_flush_io(struct backing_dev_info *bdi)
+{
+ struct writeback_control wbc = {
+ .bdi = bdi,
+ .sync_mode = WB_SYNC_NONE,
+ .older_than_this = NULL,
+ .range_cyclic = 1,
+ .nr_to_write = 1024,
+ };
+
+ generic_sync_bdi_inodes(NULL, &wbc);
+}
+
+static int wb_assign_nr(struct backing_dev_info *bdi, struct bdi_writeback *wb)
+{
+ set_bit(0, &bdi->wb_mask);
+ wb->nr = 0;
+ return 0;
+}
+
+static void bdi_put_wb(struct backing_dev_info *bdi, struct bdi_writeback *wb)
+{
+ clear_bit(wb->nr, &bdi->wb_mask);
+ clear_bit(BDI_wb_alloc, &bdi->state);
+}
+
+static struct bdi_writeback *bdi_new_wb(struct backing_dev_info *bdi)
+{
+ struct bdi_writeback *wb;
+
+ set_bit(BDI_wb_alloc, &bdi->state);
+ wb = &bdi->wb;
+ wb_assign_nr(bdi, wb);
+ return wb;
+}
+
static int bdi_start_fn(void *ptr)
{
- struct backing_dev_info *bdi = ptr;
+ struct bdi_writeback *wb = ptr;
+ struct backing_dev_info *bdi = wb->bdi;
struct task_struct *tsk = current;
-
- /*
- * Add us to the active bdi_list
- */
- spin_lock_bh(&bdi_lock);
- list_add_rcu(&bdi->bdi_list, &bdi_list);
- spin_unlock_bh(&bdi_lock);
+ int ret;

tsk->flags |= PF_FLUSHER | PF_SWAPWRITE;
set_freezable();
@@ -225,77 +267,81 @@ static int bdi_start_fn(void *ptr)
clear_bit(BDI_pending, &bdi->state);
wake_up_bit(&bdi->state, BDI_pending);

- return bdi_writeback_task(bdi);
+ ret = bdi_writeback_task(wb);
+
+ bdi_put_wb(bdi, wb);
+ return ret;
+}
+
+int bdi_has_dirty_io(struct backing_dev_info *bdi)
+{
+ return wb_has_dirty_io(&bdi->wb);
}

static int bdi_forker_task(void *ptr)
{
- struct backing_dev_info *bdi, *me = ptr;
+ struct bdi_writeback *me = ptr;

for (;;) {
+ struct backing_dev_info *bdi;
+ struct bdi_writeback *wb;
DEFINE_WAIT(wait);

/*
* Should never trigger on the default bdi
*/
- WARN_ON(bdi_has_dirty_io(me));
+ if (wb_has_dirty_io(me)) {
+ bdi_flush_io(me->bdi);
+ WARN_ON(1);
+ }

prepare_to_wait(&me->wait, &wait, TASK_INTERRUPTIBLE);
+
smp_mb();
if (list_empty(&bdi_pending_list))
schedule();
- else {
+
+ finish_wait(&me->wait, &wait);
repeat:
- bdi = NULL;
+ bdi = NULL;
+ spin_lock_bh(&bdi_lock);
+ if (!list_empty(&bdi_pending_list)) {
+ bdi = list_entry(bdi_pending_list.next,
+ struct backing_dev_info, bdi_list);
+ list_del_init(&bdi->bdi_list);
+ }
+ spin_unlock_bh(&bdi_lock);

- spin_lock_bh(&bdi_lock);
- if (!list_empty(&bdi_pending_list)) {
- bdi = list_entry(bdi_pending_list.next,
- struct backing_dev_info,
- bdi_list);
- list_del_init(&bdi->bdi_list);
- }
- spin_unlock_bh(&bdi_lock);
+ if (!bdi)
+ continue;

- /*
- * If no bdi or bdi already got setup, continue
- */
- if (!bdi || bdi->task)
- continue;
+ wb = bdi_new_wb(bdi);
+ if (!wb)
+ goto readd_flush;

- bdi->task = kthread_run(bdi_start_fn, bdi, "bdi-%s",
+ wb->task = kthread_run(bdi_start_fn, wb, "bdi-%s",
dev_name(bdi->dev));
+ /*
+ * If task creation fails, then readd the bdi to
+ * the pending list and force writeout of the bdi
+ * from this forker thread. That will free some memory
+ * and we can try again.
+ */
+ if (!wb->task) {
+ bdi_put_wb(bdi, wb);
+readd_flush:
/*
- * If task creation fails, then readd the bdi to
- * the pending list and force writeout of the bdi
- * from this forker thread. That will free some memory
- * and we can try again.
+ * Add this 'bdi' to the back, so we get
+ * a chance to flush other bdi's to free
+ * memory.
*/
- if (!bdi->task) {
- struct writeback_control wbc = {
- .bdi = bdi,
- .sync_mode = WB_SYNC_NONE,
- .older_than_this = NULL,
- .range_cyclic = 1,
- };
-
- /*
- * Add this 'bdi' to the back, so we get
- * a chance to flush other bdi's to free
- * memory.
- */
- spin_lock_bh(&bdi_lock);
- list_add_tail(&bdi->bdi_list,
- &bdi_pending_list);
- spin_unlock_bh(&bdi_lock);
-
- wbc.nr_to_write = 1024;
- generic_sync_bdi_inodes(NULL, &wbc);
- goto repeat;
- }
- }
+ spin_lock_bh(&bdi_lock);
+ list_add_tail(&bdi->bdi_list, &bdi_pending_list);
+ spin_unlock_bh(&bdi_lock);

- finish_wait(&me->wait, &wait);
+ bdi_flush_io(bdi);
+ goto repeat;
+ }
}

return 0;
@@ -318,11 +364,21 @@ static void bdi_add_to_pending(struct rcu_head *head)
list_add_tail(&bdi->bdi_list, &bdi_pending_list);
spin_unlock(&bdi_lock);

- wake_up(&default_backing_dev_info.wait);
+ wake_up(&default_backing_dev_info.wb.wait);
}

+/*
+ * Add a new flusher task that gets created for any bdi
+ * that has dirty data pending writeout
+ */
void bdi_add_default_flusher_task(struct backing_dev_info *bdi)
{
+ if (!bdi_cap_writeback_dirty(bdi))
+ return;
+
+ /*
+ * Someone already marked this pending for task creation
+ */
if (test_and_set_bit(BDI_pending, &bdi->state))
return;

@@ -363,9 +419,18 @@ int bdi_register(struct backing_dev_info *bdi, struct device *parent,
* on-demand when they need it.
*/
if (bdi_cap_flush_forker(bdi)) {
- bdi->task = kthread_run(bdi_forker_task, bdi, "bdi-%s",
+ struct bdi_writeback *wb;
+
+ wb = bdi_new_wb(bdi);
+ if (!wb) {
+ ret = -ENOMEM;
+ goto exit;
+ }
+
+ wb->task = kthread_run(bdi_forker_task, wb, "bdi-%s",
dev_name(dev));
- if (!bdi->task) {
+ if (!wb->task) {
+ bdi_put_wb(bdi, wb);
ret = -ENOMEM;
goto exit;
}
@@ -395,34 +460,44 @@ static int sched_wait(void *word)
return 0;
}

+/*
+ * Remove bdi from global list and shutdown any threads we have running
+ */
static void bdi_wb_shutdown(struct backing_dev_info *bdi)
{
+ if (!bdi_cap_writeback_dirty(bdi))
+ return;
+
/*
* If setup is pending, wait for that to complete first
+ * Make sure nobody finds us on the bdi_list anymore
*/
wait_on_bit(&bdi->state, BDI_pending, sched_wait, TASK_UNINTERRUPTIBLE);

+ /*
+ * Make sure nobody finds us on the bdi_list anymore
+ */
spin_lock_bh(&bdi_lock);
list_del_rcu(&bdi->bdi_list);
spin_unlock_bh(&bdi_lock);

/*
- * In case the bdi is freed right after unregister, we need to
- * make sure any RCU sections have exited
+ * Now make sure that anybody who is currently looking at us from
+ * the bdi_list iteration have exited.
*/
synchronize_rcu();
+
+ /*
+ * Finally, kill the kernel thread
+ */
+ kthread_stop(bdi->wb.task);
}

void bdi_unregister(struct backing_dev_info *bdi)
{
if (bdi->dev) {
- if (!bdi_cap_flush_forker(bdi)) {
+ if (!bdi_cap_flush_forker(bdi))
bdi_wb_shutdown(bdi);
- if (bdi->task) {
- kthread_stop(bdi->task);
- bdi->task = NULL;
- }
- }
bdi_debug_unregister(bdi);
device_unregister(bdi->dev);
bdi->dev = NULL;
@@ -440,11 +515,10 @@ int bdi_init(struct backing_dev_info *bdi)
bdi->min_ratio = 0;
bdi->max_ratio = 100;
bdi->max_prop_frac = PROP_FRAC_BASE;
- init_waitqueue_head(&bdi->wait);
INIT_LIST_HEAD(&bdi->bdi_list);
- INIT_LIST_HEAD(&bdi->b_io);
- INIT_LIST_HEAD(&bdi->b_dirty);
- INIT_LIST_HEAD(&bdi->b_more_io);
+ bdi->wb_mask = bdi->wb_active = 0;
+
+ bdi_wb_init(&bdi->wb, bdi);

for (i = 0; i < NR_BDI_STAT_ITEMS; i++) {
err = percpu_counter_init(&bdi->bdi_stat[i], 0);
@@ -469,9 +543,7 @@ void bdi_destroy(struct backing_dev_info *bdi)
{
int i;

- WARN_ON(!list_empty(&bdi->b_dirty));
- WARN_ON(!list_empty(&bdi->b_io));
- WARN_ON(!list_empty(&bdi->b_more_io));
+ WARN_ON(bdi_has_dirty_io(bdi));

bdi_unregister(bdi);

--
1.6.3.rc0.1.gf800

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