writeback: Add a 'reason' to wb_writeback_work

This creates a new 'reason' field in a wb_writeback_work
structure, which unambiguously identifies who initiates
writeback activity.  A 'wb_reason' enumeration has been
added to writeback.h, to enumerate the possible reasons.

The 'writeback_work_class' and tracepoint event class and
'writeback_queue_io' tracepoints are updated to include the
symbolic 'reason' in all trace events.

And the 'writeback_inodes_sbXXX' family of routines has had
a wb_stats parameter added to them, so callers can specify
why writeback is being started.

Acked-by: Jan Kara <jack@suse.cz>
Signed-off-by: Curt Wohlgemuth <curtw@google.com>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/fs/quota/quota.c b/fs/quota/quota.c
index 10b6be3ca280..4bae57fc603b 100644
--- a/fs/quota/quota.c
+++ b/fs/quota/quota.c
@@ -286,7 +286,7 @@ static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id,
                 /* caller already holds s_umount */
                 if (sb->s_flags & MS_RDONLY)
                         return -EROFS;
-                writeback_inodes_sb(sb);
+                writeback_inodes_sb(sb, WB_REASON_SYNC);
                 return 0;
         default:
                 return -EINVAL;