f2fs: add a kernel thread to issue discard commands asynchronously

This patch adds a kernel thread to issue discard commands.
It proposes three states, D_PREP, D_SUBMIT, and D_DONE to identify current
bio status.

Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

1 files changed, 12 insertions, 0 deletions

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 90eb2b3..3a57d97 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -133,6 +133,8 @@ enum {
 		(SM_I(sbi)->trim_sections * (sbi)->segs_per_sec)
 #define BATCHED_TRIM_BLOCKS(sbi)	\
 		(BATCHED_TRIM_SEGMENTS(sbi) << (sbi)->log_blocks_per_seg)
+
+#define DISCARD_ISSUE_RATE	8
 #define DEF_CP_INTERVAL			60	/* 60 secs */
 #define DEF_IDLE_INTERVAL		5	/* 5 secs */
 
@@ -181,18 +183,28 @@ struct discard_entry {
 	int len;		/* # of consecutive blocks of the discard */
 };
 
+enum {
+	D_PREP,
+	D_SUBMIT,
+	D_DONE,
+};
+
 struct discard_cmd {
 	struct list_head list;		/* command list */
 	struct completion wait;		/* compleation */
 	block_t lstart;			/* logical start address */
 	block_t len;			/* length */
 	struct bio *bio;		/* bio */
+	int state;			/* state */
 };
 
 struct discard_cmd_control {
+	struct task_struct *f2fs_issue_discard;	/* discard thread */
 	struct list_head discard_entry_list;	/* 4KB discard entry list */
 	int nr_discards;			/* # of discards in the list */
 	struct list_head discard_cmd_list;	/* discard cmd list */
+	wait_queue_head_t discard_wait_queue;	/* waiting queue for wake-up */
+	struct mutex cmd_lock;
 	int max_discards;			/* max. discards to be issued */
 };