/*
* Passed into wb_writeback(), essentially a subset of writeback_control
*/
-struct wb_writeback_args {
+struct wb_writeback_work {
long nr_pages;
struct super_block *sb;
enum writeback_sync_modes sync_mode;
unsigned int for_kupdate:1;
unsigned int range_cyclic:1;
unsigned int for_background:1;
-};
-/*
- * Work items for the bdi_writeback threads
- */
-struct bdi_work {
struct list_head list; /* pending work list */
- struct rcu_head rcu_head; /* for RCU free/clear of work */
-
- unsigned long seen; /* threads that have seen this work */
- atomic_t pending; /* number of threads still to do work */
-
- struct wb_writeback_args args; /* writeback arguments */
-
- unsigned long state; /* flag bits, see WS_* */
+ struct completion *done; /* set if the caller waits */
};
-enum {
- WS_INPROGRESS = 0,
- WS_ONSTACK,
-};
-
-static inline void bdi_work_init(struct bdi_work *work,
- struct wb_writeback_args *args)
-{
- INIT_RCU_HEAD(&work->rcu_head);
- work->args = *args;
- __set_bit(WS_INPROGRESS, &work->state);
-}
-
/**
* writeback_in_progress - determine whether there is writeback in progress
* @bdi: the device's backing_dev_info structure.
return !list_empty(&bdi->work_list);
}
-static void bdi_work_free(struct rcu_head *head)
-{
- struct bdi_work *work = container_of(head, struct bdi_work, rcu_head);
-
- clear_bit(WS_INPROGRESS, &work->state);
- smp_mb__after_clear_bit();
- wake_up_bit(&work->state, WS_INPROGRESS);
-
- if (!test_bit(WS_ONSTACK, &work->state))
- kfree(work);
-}
-
-static void wb_clear_pending(struct bdi_writeback *wb, struct bdi_work *work)
+static void bdi_queue_work(struct backing_dev_info *bdi,
+ struct wb_writeback_work *work)
{
- /*
- * The caller has retrieved the work arguments from this work,
- * drop our reference. If this is the last ref, delete and free it
- */
- if (atomic_dec_and_test(&work->pending)) {
- struct backing_dev_info *bdi = wb->bdi;
-
- spin_lock(&bdi->wb_lock);
- list_del_rcu(&work->list);
- spin_unlock(&bdi->wb_lock);
-
- call_rcu(&work->rcu_head, bdi_work_free);
- }
-}
-
-static void bdi_queue_work(struct backing_dev_info *bdi, struct bdi_work *work)
-{
- work->seen = bdi->wb_mask;
- BUG_ON(!work->seen);
- atomic_set(&work->pending, bdi->wb_cnt);
- BUG_ON(!bdi->wb_cnt);
-
- /*
- * list_add_tail_rcu() contains the necessary barriers to
- * make sure the above stores are seen before the item is
- * noticed on the list
- */
spin_lock(&bdi->wb_lock);
- list_add_tail_rcu(&work->list, &bdi->work_list);
+ list_add_tail(&work->list, &bdi->work_list);
spin_unlock(&bdi->wb_lock);
/*
}
}
-/*
- * Used for on-stack allocated work items. The caller needs to wait until
- * the wb threads have acked the work before it's safe to continue.
- */
-static void bdi_wait_on_work_done(struct bdi_work *work)
+static void
+__bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages,
+ bool range_cyclic, bool for_background)
{
- wait_on_bit(&work->state, WS_INPROGRESS, bdi_sched_wait,
- TASK_UNINTERRUPTIBLE);
-}
-
-static void bdi_alloc_queue_work(struct backing_dev_info *bdi,
- struct wb_writeback_args *args)
-{
- struct bdi_work *work;
+ struct wb_writeback_work *work;
/*
* This is WB_SYNC_NONE writeback, so if allocation fails just
* wakeup the thread for old dirty data writeback
*/
- work = kmalloc(sizeof(*work), GFP_ATOMIC);
- if (work) {
- bdi_work_init(work, args);
- bdi_queue_work(bdi, work);
- } else {
- struct bdi_writeback *wb = &bdi->wb;
-
- if (wb->task)
- wake_up_process(wb->task);
+ work = kzalloc(sizeof(*work), GFP_ATOMIC);
+ if (!work) {
+ if (bdi->wb.task)
+ wake_up_process(bdi->wb.task);
+ return;
}
-}
-/**
- * bdi_queue_work_onstack - start and wait for writeback
- * @sb: write inodes from this super_block
- *
- * Description:
- * This function initiates writeback and waits for the operation to
- * complete. Callers must hold the sb s_umount semaphore for
- * reading, to avoid having the super disappear before we are done.
- */
-static void bdi_queue_work_onstack(struct wb_writeback_args *args)
-{
- struct bdi_work work;
-
- bdi_work_init(&work, args);
- __set_bit(WS_ONSTACK, &work.state);
+ work->sync_mode = WB_SYNC_NONE;
+ work->nr_pages = nr_pages;
+ work->range_cyclic = range_cyclic;
+ work->for_background = for_background;
- bdi_queue_work(args->sb->s_bdi, &work);
- bdi_wait_on_work_done(&work);
+ bdi_queue_work(bdi, work);
}
/**
*/
void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages)
{
- struct wb_writeback_args args = {
- .sync_mode = WB_SYNC_NONE,
- .nr_pages = nr_pages,
- .range_cyclic = 1,
- };
-
- bdi_alloc_queue_work(bdi, &args);
+ __bdi_start_writeback(bdi, nr_pages, true, false);
}
/**
*/
void bdi_start_background_writeback(struct backing_dev_info *bdi)
{
- struct wb_writeback_args args = {
- .sync_mode = WB_SYNC_NONE,
- .nr_pages = LONG_MAX,
- .for_background = 1,
- .range_cyclic = 1,
- };
- bdi_alloc_queue_work(bdi, &args);
+ __bdi_start_writeback(bdi, LONG_MAX, true, true);
}
/*
/*
* Write a portion of b_io inodes which belong to @sb.
- * If @wbc->sb != NULL, then find and write all such
+ *
+ * If @only_this_sb is true, then find and write all such
* inodes. Otherwise write only ones which go sequentially
* in reverse order.
+ *
* Return 1, if the caller writeback routine should be
* interrupted. Otherwise return 0.
*/
-static int writeback_sb_inodes(struct super_block *sb,
- struct bdi_writeback *wb,
- struct writeback_control *wbc)
+static int writeback_sb_inodes(struct super_block *sb, struct bdi_writeback *wb,
+ struct writeback_control *wbc, bool only_this_sb)
{
while (!list_empty(&wb->b_io)) {
long pages_skipped;
struct inode *inode = list_entry(wb->b_io.prev,
struct inode, i_list);
- if (wbc->sb && sb != inode->i_sb) {
- /* super block given and doesn't
- match, skip this inode */
- redirty_tail(inode);
- continue;
- }
- if (sb != inode->i_sb)
- /* finish with this superblock */
+
+ if (inode->i_sb != sb) {
+ if (only_this_sb) {
+ /*
+ * We only want to write back data for this
+ * superblock, move all inodes not belonging
+ * to it back onto the dirty list.
+ */
+ redirty_tail(inode);
+ continue;
+ }
+
+ /*
+ * The inode belongs to a different superblock.
+ * Bounce back to the caller to unpin this and
+ * pin the next superblock.
+ */
return 0;
+ }
+
if (inode->i_state & (I_NEW | I_WILL_FREE)) {
requeue_io(inode);
continue;
return 1;
}
-static void writeback_inodes_wb(struct bdi_writeback *wb,
- struct writeback_control *wbc)
+void writeback_inodes_wb(struct bdi_writeback *wb,
+ struct writeback_control *wbc)
{
int ret = 0;
struct inode, i_list);
struct super_block *sb = inode->i_sb;
- if (wbc->sb) {
- /*
- * We are requested to write out inodes for a specific
- * superblock. This means we already have s_umount
- * taken by the caller which also waits for us to
- * complete the writeout.
- */
- if (sb != wbc->sb) {
- redirty_tail(inode);
- continue;
- }
-
- WARN_ON(!rwsem_is_locked(&sb->s_umount));
-
- ret = writeback_sb_inodes(sb, wb, wbc);
- } else {
- if (!pin_sb_for_writeback(sb)) {
- requeue_io(inode);
- continue;
- }
- ret = writeback_sb_inodes(sb, wb, wbc);
- drop_super(sb);
+ if (!pin_sb_for_writeback(sb)) {
+ requeue_io(inode);
+ continue;
}
+ ret = writeback_sb_inodes(sb, wb, wbc, false);
+ drop_super(sb);
if (ret)
break;
/* Leave any unwritten inodes on b_io */
}
-void writeback_inodes_wbc(struct writeback_control *wbc)
+static void __writeback_inodes_sb(struct super_block *sb,
+ struct bdi_writeback *wb, struct writeback_control *wbc)
{
- struct backing_dev_info *bdi = wbc->bdi;
+ WARN_ON(!rwsem_is_locked(&sb->s_umount));
- writeback_inodes_wb(&bdi->wb, wbc);
+ wbc->wb_start = jiffies; /* livelock avoidance */
+ spin_lock(&inode_lock);
+ if (!wbc->for_kupdate || list_empty(&wb->b_io))
+ queue_io(wb, wbc->older_than_this);
+ writeback_sb_inodes(sb, wb, wbc, true);
+ spin_unlock(&inode_lock);
}
/*
* all dirty pages if they are all attached to "old" mappings.
*/
static long wb_writeback(struct bdi_writeback *wb,
- struct wb_writeback_args *args)
+ struct wb_writeback_work *work)
{
struct writeback_control wbc = {
- .bdi = wb->bdi,
- .sb = args->sb,
- .sync_mode = args->sync_mode,
+ .sync_mode = work->sync_mode,
.older_than_this = NULL,
- .for_kupdate = args->for_kupdate,
- .for_background = args->for_background,
- .range_cyclic = args->range_cyclic,
+ .for_kupdate = work->for_kupdate,
+ .for_background = work->for_background,
+ .range_cyclic = work->range_cyclic,
};
unsigned long oldest_jif;
long wrote = 0;
/*
* Stop writeback when nr_pages has been consumed
*/
- if (args->nr_pages <= 0)
+ if (work->nr_pages <= 0)
break;
/*
* For background writeout, stop when we are below the
* background dirty threshold
*/
- if (args->for_background && !over_bground_thresh())
+ if (work->for_background && !over_bground_thresh())
break;
wbc.more_io = 0;
wbc.nr_to_write = MAX_WRITEBACK_PAGES;
wbc.pages_skipped = 0;
- writeback_inodes_wb(wb, &wbc);
- args->nr_pages -= MAX_WRITEBACK_PAGES - wbc.nr_to_write;
+ if (work->sb)
+ __writeback_inodes_sb(work->sb, wb, &wbc);
+ else
+ writeback_inodes_wb(wb, &wbc);
+ work->nr_pages -= MAX_WRITEBACK_PAGES - wbc.nr_to_write;
wrote += MAX_WRITEBACK_PAGES - wbc.nr_to_write;
/*
}
/*
- * Return the next bdi_work struct that hasn't been processed by this
- * wb thread yet. ->seen is initially set for each thread that exists
- * for this device, when a thread first notices a piece of work it
- * clears its bit. Depending on writeback type, the thread will notify
- * completion on either receiving the work (WB_SYNC_NONE) or after
- * it is done (WB_SYNC_ALL).
+ * Return the next wb_writeback_work struct that hasn't been processed yet.
*/
-static struct bdi_work *get_next_work_item(struct backing_dev_info *bdi,
- struct bdi_writeback *wb)
+static struct wb_writeback_work *
+get_next_work_item(struct backing_dev_info *bdi, struct bdi_writeback *wb)
{
- struct bdi_work *work, *ret = NULL;
-
- rcu_read_lock();
+ struct wb_writeback_work *work = NULL;
- list_for_each_entry_rcu(work, &bdi->work_list, list) {
- if (!test_bit(wb->nr, &work->seen))
- continue;
- clear_bit(wb->nr, &work->seen);
-
- ret = work;
- break;
+ spin_lock(&bdi->wb_lock);
+ if (!list_empty(&bdi->work_list)) {
+ work = list_entry(bdi->work_list.next,
+ struct wb_writeback_work, list);
+ list_del_init(&work->list);
}
-
- rcu_read_unlock();
- return ret;
+ spin_unlock(&bdi->wb_lock);
+ return work;
}
static long wb_check_old_data_flush(struct bdi_writeback *wb)
(inodes_stat.nr_inodes - inodes_stat.nr_unused);
if (nr_pages) {
- struct wb_writeback_args args = {
+ struct wb_writeback_work work = {
.nr_pages = nr_pages,
.sync_mode = WB_SYNC_NONE,
.for_kupdate = 1,
.range_cyclic = 1,
};
- return wb_writeback(wb, &args);
+ return wb_writeback(wb, &work);
}
return 0;
long wb_do_writeback(struct bdi_writeback *wb, int force_wait)
{
struct backing_dev_info *bdi = wb->bdi;
- struct bdi_work *work;
+ struct wb_writeback_work *work;
long wrote = 0;
while ((work = get_next_work_item(bdi, wb)) != NULL) {
- struct wb_writeback_args args = work->args;
-
/*
* Override sync mode, in case we must wait for completion
+ * because this thread is exiting now.
*/
if (force_wait)
- work->args.sync_mode = args.sync_mode = WB_SYNC_ALL;
-
- /*
- * If this isn't a data integrity operation, just notify
- * that we have seen this work and we are now starting it.
- */
- if (!test_bit(WS_ONSTACK, &work->state))
- wb_clear_pending(wb, work);
+ work->sync_mode = WB_SYNC_ALL;
- wrote += wb_writeback(wb, &args);
+ wrote += wb_writeback(wb, work);
/*
- * This is a data integrity writeback, so only do the
- * notification when we have completed the work.
+ * Notify the caller of completion if this is a synchronous
+ * work item, otherwise just free it.
*/
- if (test_bit(WS_ONSTACK, &work->state))
- wb_clear_pending(wb, work);
+ if (work->done)
+ complete(work->done);
+ else
+ kfree(work);
}
/*
void wakeup_flusher_threads(long nr_pages)
{
struct backing_dev_info *bdi;
- struct wb_writeback_args args = {
- .sync_mode = WB_SYNC_NONE,
- };
- if (nr_pages) {
- args.nr_pages = nr_pages;
- } else {
- args.nr_pages = global_page_state(NR_FILE_DIRTY) +
+ if (!nr_pages) {
+ nr_pages = global_page_state(NR_FILE_DIRTY) +
global_page_state(NR_UNSTABLE_NFS);
}
list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) {
if (!bdi_has_dirty_io(bdi))
continue;
- bdi_alloc_queue_work(bdi, &args);
+ __bdi_start_writeback(bdi, nr_pages, false, false);
}
rcu_read_unlock();
}
{
unsigned long nr_dirty = global_page_state(NR_FILE_DIRTY);
unsigned long nr_unstable = global_page_state(NR_UNSTABLE_NFS);
- struct wb_writeback_args args = {
+ DECLARE_COMPLETION_ONSTACK(done);
+ struct wb_writeback_work work = {
.sb = sb,
.sync_mode = WB_SYNC_NONE,
+ .done = &done,
};
WARN_ON(!rwsem_is_locked(&sb->s_umount));
- args.nr_pages = nr_dirty + nr_unstable +
+ work.nr_pages = nr_dirty + nr_unstable +
(inodes_stat.nr_inodes - inodes_stat.nr_unused);
- bdi_queue_work_onstack(&args);
+ bdi_queue_work(sb->s_bdi, &work);
+ wait_for_completion(&done);
}
EXPORT_SYMBOL(writeback_inodes_sb);
*/
void sync_inodes_sb(struct super_block *sb)
{
- struct wb_writeback_args args = {
+ DECLARE_COMPLETION_ONSTACK(done);
+ struct wb_writeback_work work = {
.sb = sb,
.sync_mode = WB_SYNC_ALL,
.nr_pages = LONG_MAX,
.range_cyclic = 0,
+ .done = &done,
};
WARN_ON(!rwsem_is_locked(&sb->s_umount));
- bdi_queue_work_onstack(&args);
+ bdi_queue_work(sb->s_bdi, &work);
+ wait_for_completion(&done);
+
wait_sb_inodes(sb);
}
EXPORT_SYMBOL(sync_inodes_sb);
git://bbs.cooldavid.org / net-next-2.6.git / commitdiff