f2fs: run discard jobs when put_super

When we umount f2fs, we need to avoid long delay due to discard commands, which
is actually taking tens of seconds, if storage is very slow on UNMAP. So, this
patch introduces timeout-based work on it.

By default, let me give 5 seconds for discard.

Reviewed-by: Chao Yu <[e-mail]>
Signed-off-by: Jaegeuk Kim <[e-mail]>

Documentation/ABI/testing/sysfs-fs-f2fs

···
 		The unit size is one block, now only support configuring in range
 		of [1, 512].
 
+What:          /sys/fs/f2fs/<disk>/umount_discard_timeout
+Date:          January 2019
+Contact:       "Jaegeuk Kim" <[e-mail]>
+Description:
+		Set timeout to issue discard commands during umount.
+		Default: 5 secs
+
 What:		/sys/fs/f2fs/<disk>/max_victim_search
 Date:		January 2014
 Contact:	"Jaegeuk Kim" <[e-mail]>

fs/f2fs/f2fs.h

···
 #define DEF_CP_INTERVAL			60	/* 60 secs */
 #define DEF_IDLE_INTERVAL		5	/* 5 secs */
 #define DEF_DISABLE_INTERVAL		5	/* 5 secs */
+#define DEF_UMOUNT_DISCARD_TIMEOUT	5	/* 5 secs */
 
 struct cp_control {
 	int reason;
···
 	bool sync;			/* submit discard with REQ_SYNC flag */
 	bool ordered;			/* issue discard by lba order */
 	unsigned int granularity;	/* discard granularity */
+	int timeout;			/* discard timeout for put_super */
 };
 
 struct discard_cmd_control {
···
 	DISCARD_TIME,
 	GC_TIME,
 	DISABLE_TIME,
+	UMOUNT_DISCARD_TIMEOUT,
 	MAX_TIME,
 };
 
···
 bool f2fs_is_checkpointed_data(struct f2fs_sb_info *sbi, block_t blkaddr);
 void f2fs_drop_discard_cmd(struct f2fs_sb_info *sbi);
 void f2fs_stop_discard_thread(struct f2fs_sb_info *sbi);
-bool f2fs_wait_discard_bios(struct f2fs_sb_info *sbi);
+bool f2fs_issue_discard_timeout(struct f2fs_sb_info *sbi);
 void f2fs_clear_prefree_segments(struct f2fs_sb_info *sbi,
 					struct cp_control *cpc);
 void f2fs_dirty_to_prefree(struct f2fs_sb_info *sbi);

fs/f2fs/segment.c

···
 
 	dpolicy->max_requests = DEF_MAX_DISCARD_REQUEST;
 	dpolicy->io_aware_gran = MAX_PLIST_NUM;
+	dpolicy->timeout = 0;
 
 	if (discard_type == DPOLICY_BG) {
 		dpolicy->min_interval = DEF_MIN_DISCARD_ISSUE_TIME;
···
 	int i, issued = 0;
 	bool io_interrupted = false;
 
+	if (dpolicy->timeout != 0)
+		f2fs_update_time(sbi, dpolicy->timeout);
+
 	for (i = MAX_PLIST_NUM - 1; i >= 0; i--) {
+		if (dpolicy->timeout != 0 &&
+				f2fs_time_over(sbi, dpolicy->timeout))
+			break;
+
 		if (i + 1 < dpolicy->granularity)
 			break;
 
···
 }
 
 /* This comes from f2fs_put_super */
-bool f2fs_wait_discard_bios(struct f2fs_sb_info *sbi)
+bool f2fs_issue_discard_timeout(struct f2fs_sb_info *sbi)
 {
 	struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
 	struct discard_policy dpolicy;
···
 
 	__init_discard_policy(sbi, &dpolicy, DPOLICY_UMOUNT,
 					dcc->discard_granularity);
+	dpolicy.timeout = UMOUNT_DISCARD_TIMEOUT;
 	__issue_discard_cmd(sbi, &dpolicy);
 	dropped = __drop_discard_cmd(sbi);
 

fs/f2fs/super.c

···
 	}
 
 	/* be sure to wait for any on-going discard commands */
-	dropped = f2fs_wait_discard_bios(sbi);
+	dropped = f2fs_issue_discard_timeout(sbi);
 
 	if ((f2fs_hw_support_discard(sbi) || f2fs_hw_should_discard(sbi)) &&
 					!sbi->discard_blks && !dropped) {
···
 	sbi->interval_time[DISCARD_TIME] = DEF_IDLE_INTERVAL;
 	sbi->interval_time[GC_TIME] = DEF_IDLE_INTERVAL;
 	sbi->interval_time[DISABLE_TIME] = DEF_DISABLE_INTERVAL;
+	sbi->interval_time[UMOUNT_DISCARD_TIMEOUT] =
+				DEF_UMOUNT_DISCARD_TIMEOUT;
 	clear_sbi_flag(sbi, SBI_NEED_FSCK);
 
 	for (i = 0; i < NR_COUNT_TYPE; i++)

fs/f2fs/sysfs.c

···
 F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, discard_idle_interval,
 					interval_time[DISCARD_TIME]);
 F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, gc_idle_interval, interval_time[GC_TIME]);
+F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info,
+		umount_discard_timeout, interval_time[UMOUNT_DISCARD_TIMEOUT]);
 F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, iostat_enable, iostat_enable);
 F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, readdir_ra, readdir_ra);
 F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, gc_pin_file_thresh, gc_pin_file_threshold);
···
 	ATTR_LIST(idle_interval),
 	ATTR_LIST(discard_idle_interval),
 	ATTR_LIST(gc_idle_interval),
+	ATTR_LIST(umount_discard_timeout),
 	ATTR_LIST(iostat_enable),
 	ATTR_LIST(readdir_ra),
 	ATTR_LIST(gc_pin_file_thresh),