sched: add bit_wait_io for 3.18 ext4 backport

Excerpted from commit 743162013: "sched: Remove proliferation of
wait_on_bit() action functions"

Signed-off-by: Theodore Ts'o <tytso@mit.edu>

1 files changed, 9 insertions, 0 deletions

diff --git a/kernel/wait.c b/kernel/wait.c
index 6698e0c04..bca170ef3 100644
--- a/kernel/wait.c
+++ b/kernel/wait.c
@@ -287,3 +287,12 @@ wait_queue_head_t *bit_waitqueue(void *word, int bit)
 	return &zone->wait_table[hash_long(val, zone->wait_table_bits)];
 }
 EXPORT_SYMBOL(bit_waitqueue);
+
+__sched int bit_wait_io(void *word)
+{
+	if (signal_pending_state(current->state, current))
+		return 1;
+	io_schedule();
+	return 0;
+}
+EXPORT_SYMBOL(bit_wait_io);