* Work items for the bdi_writeback threads
*/
struct bdi_work {
- struct list_head list;
- struct rcu_head rcu_head;
+ struct list_head list; /* pending work list */
+ struct rcu_head rcu_head; /* for RCU free/clear of work */
- unsigned long seen;
- atomic_t pending;
+ unsigned long seen; /* threads that have seen this work */
+ atomic_t pending; /* number of threads still to do work */
- struct wb_writeback_args args;
+ struct wb_writeback_args args; /* writeback arguments */
- unsigned long state;
+ unsigned long state; /* flag bits, see WS_* */
};
enum {
}
static inline void bdi_work_init(struct bdi_work *work,
- struct writeback_control *wbc)
+ struct wb_writeback_args *args)
{
INIT_RCU_HEAD(&work->rcu_head);
- work->args.sb = wbc->sb;
- work->args.nr_pages = wbc->nr_to_write;
- work->args.sync_mode = wbc->sync_mode;
- work->args.range_cyclic = wbc->range_cyclic;
- work->args.for_kupdate = 0;
+ work->args = *args;
work->state = WS_USED;
}
BUG_ON(!bdi->wb_cnt);
/*
- * Make sure stores are seen before it appears on the list
+ * list_add_tail_rcu() contains the necessary barriers to
+ * make sure the above stores are seen before the item is
+ * noticed on the list
*/
- smp_mb();
-
spin_lock(&bdi->wb_lock);
list_add_tail_rcu(&work->list, &bdi->work_list);
spin_unlock(&bdi->wb_lock);
}
static void bdi_alloc_queue_work(struct backing_dev_info *bdi,
- struct writeback_control *wbc)
+ struct wb_writeback_args *args)
{
struct bdi_work *work;
*/
work = kmalloc(sizeof(*work), GFP_ATOMIC);
if (work) {
- bdi_work_init(work, wbc);
+ bdi_work_init(work, args);
bdi_queue_work(bdi, work);
} else {
struct bdi_writeback *wb = &bdi->wb;
}
}
-void bdi_start_writeback(struct writeback_control *wbc)
+/**
+ * bdi_sync_writeback - start and wait for writeback
+ * @bdi: the backing device to write from
+ * @sb: write inodes from this super_block
+ *
+ * Description:
+ * This does WB_SYNC_ALL data integrity writeback and waits for the
+ * IO 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_sync_writeback(struct backing_dev_info *bdi,
+ struct super_block *sb)
{
- /*
- * WB_SYNC_NONE is opportunistic writeback. If this allocation fails,
- * bdi_queue_work() will wake up the thread and flush old data. This
- * should ensure some amount of progress in freeing memory.
- */
- if (wbc->sync_mode != WB_SYNC_ALL)
- bdi_alloc_queue_work(wbc->bdi, wbc);
- else {
- struct bdi_work work;
+ struct wb_writeback_args args = {
+ .sb = sb,
+ .sync_mode = WB_SYNC_ALL,
+ .nr_pages = LONG_MAX,
+ .range_cyclic = 0,
+ };
+ struct bdi_work work;
- bdi_work_init(&work, wbc);
- work.state |= WS_ONSTACK;
+ bdi_work_init(&work, &args);
+ work.state |= WS_ONSTACK;
- bdi_queue_work(wbc->bdi, &work);
- bdi_wait_on_work_clear(&work);
- }
+ bdi_queue_work(bdi, &work);
+ bdi_wait_on_work_clear(&work);
+}
+
+/**
+ * bdi_start_writeback - start writeback
+ * @bdi: the backing device to write from
+ * @nr_pages: the number of pages to write
+ *
+ * Description:
+ * This does WB_SYNC_NONE opportunistic writeback. The IO is only
+ * started when this function returns, we make no guarentees on
+ * completion. Caller need not hold sb s_umount semaphore.
+ *
+ */
+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);
}
/*
/*
* Return the next bdi_work struct that hasn't been processed by this
- * wb thread yet
+ * 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).
*/
static struct bdi_work *get_next_work_item(struct backing_dev_info *bdi,
struct bdi_writeback *wb)
rcu_read_lock();
list_for_each_entry_rcu(work, &bdi->work_list, list) {
- if (!test_and_clear_bit(wb->nr, &work->seen))
+ if (!test_bit(wb->nr, &work->seen))
continue;
+ clear_bit(wb->nr, &work->seen);
ret = work;
break;
}
wait_jiffies = msecs_to_jiffies(dirty_writeback_interval * 10);
- set_current_state(TASK_INTERRUPTIBLE);
- schedule_timeout(wait_jiffies);
+ schedule_timeout_interruptible(wait_jiffies);
try_to_freeze();
}
}
/*
- * Schedule writeback for all backing devices. Can only be used for
- * WB_SYNC_NONE writeback, WB_SYNC_ALL should use bdi_start_writeback()
- * and pass in the superblock.
+ * Schedule writeback for all backing devices. This does WB_SYNC_NONE
+ * writeback, for integrity writeback see bdi_sync_writeback().
*/
-static void bdi_writeback_all(struct writeback_control *wbc)
+static void bdi_writeback_all(struct super_block *sb, long nr_pages)
{
+ struct wb_writeback_args args = {
+ .sb = sb,
+ .nr_pages = nr_pages,
+ .sync_mode = WB_SYNC_NONE,
+ };
struct backing_dev_info *bdi;
- WARN_ON(wbc->sync_mode == WB_SYNC_ALL);
-
rcu_read_lock();
list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) {
if (!bdi_has_dirty_io(bdi))
continue;
- bdi_alloc_queue_work(bdi, wbc);
+ bdi_alloc_queue_work(bdi, &args);
}
rcu_read_unlock();
*/
void wakeup_flusher_threads(long nr_pages)
{
- struct writeback_control wbc = {
- .sync_mode = WB_SYNC_NONE,
- .older_than_this = NULL,
- .range_cyclic = 1,
- };
-
if (nr_pages == 0)
nr_pages = global_page_state(NR_FILE_DIRTY) +
global_page_state(NR_UNSTABLE_NFS);
- wbc.nr_to_write = nr_pages;
- bdi_writeback_all(&wbc);
+ bdi_writeback_all(NULL, nr_pages);
}
static noinline void block_dump___mark_inode_dirty(struct inode *inode)
* on the writer throttling path, and we get decent balancing between many
* throttled threads: we don't want them all piling up on inode_sync_wait.
*/
-static void wait_sb_inodes(struct writeback_control *wbc)
+static void wait_sb_inodes(struct super_block *sb)
{
struct inode *inode, *old_inode = NULL;
* We need to be protected against the filesystem going from
* r/o to r/w or vice versa.
*/
- WARN_ON(!rwsem_is_locked(&wbc->sb->s_umount));
+ WARN_ON(!rwsem_is_locked(&sb->s_umount));
spin_lock(&inode_lock);
* In which case, the inode may not be on the dirty list, but
* we still have to wait for that writeout.
*/
- list_for_each_entry(inode, &wbc->sb->s_inodes, i_sb_list) {
+ list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
struct address_space *mapping;
if (inode->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE|I_NEW))
* for IO completion of submitted IO. The number of pages submitted is
* returned.
*/
-long writeback_inodes_sb(struct super_block *sb)
+void writeback_inodes_sb(struct super_block *sb)
{
- struct writeback_control wbc = {
- .sb = sb,
- .sync_mode = WB_SYNC_NONE,
- .range_start = 0,
- .range_end = LLONG_MAX,
- };
unsigned long nr_dirty = global_page_state(NR_FILE_DIRTY);
unsigned long nr_unstable = global_page_state(NR_UNSTABLE_NFS);
long nr_to_write;
nr_to_write = nr_dirty + nr_unstable +
(inodes_stat.nr_inodes - inodes_stat.nr_unused);
- wbc.nr_to_write = nr_to_write;
- bdi_writeback_all(&wbc);
- return nr_to_write - wbc.nr_to_write;
+ bdi_writeback_all(sb, nr_to_write);
}
EXPORT_SYMBOL(writeback_inodes_sb);
* This function writes and waits on any dirty inode belonging to this
* super_block. The number of pages synced is returned.
*/
-long sync_inodes_sb(struct super_block *sb)
+void sync_inodes_sb(struct super_block *sb)
{
- struct writeback_control wbc = {
- .sb = sb,
- .bdi = sb->s_bdi,
- .sync_mode = WB_SYNC_ALL,
- .range_start = 0,
- .range_end = LLONG_MAX,
- };
- long nr_to_write = LONG_MAX; /* doesn't actually matter */
-
- wbc.nr_to_write = nr_to_write;
- bdi_start_writeback(&wbc);
- wait_sb_inodes(&wbc);
- return nr_to_write - wbc.nr_to_write;
+ bdi_sync_writeback(sb->s_bdi, sb);
+ wait_sb_inodes(sb);
}
EXPORT_SYMBOL(sync_inodes_sb);
projects / firefly-linux-kernel-4.4.55.git / blobdiff