Teach zpool scrub to scrub only blocks in error log

Added a flag '-e' in zpool scrub to scrub only blocks in error log. A
user can pause, resume and cancel the error scrub by passing additional
command line arguments -p -s just like a regular scrub. This involves
adding a new flag, creating new libzfs interfaces, a new ioctl, and the
actual iteration and read-issuing logic. Error scrubbing is executed in
multiple txg to make sure pool performance is not affected.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Co-authored-by: TulsiJain tulsi.jain@delphix.com
Signed-off-by: George Amanakis <gamanakis@gmail.com>
Closes #8995
Closes #12355

include/sys/dmu.h

@@ -378,6 +378,7 @@ typedef struct dmu_buf {
 #define	DMU_POOL_DDT_STATS		"DDT-statistics"
 #define	DMU_POOL_CREATION_VERSION	"creation_version"
 #define	DMU_POOL_SCAN			"scan"
+#define	DMU_POOL_ERRORSCRUB		"error_scrub"
 #define	DMU_POOL_FREE_BPOBJ		"free_bpobj"
 #define	DMU_POOL_BPTREE_OBJ		"bptree_obj"
 #define	DMU_POOL_EMPTY_BPOBJ		"empty_bpobj"

include/sys/dsl_scan.h

@@ -29,6 +29,7 @@
 
 #include <sys/zfs_context.h>
 #include <sys/zio.h>
+#include <sys/zap.h>
 #include <sys/ddt.h>
 #include <sys/bplist.h>
 
@@ -78,6 +79,21 @@ typedef enum dsl_scan_flags {
 
 #define	DSL_SCAN_FLAGS_MASK (DSF_VISIT_DS_AGAIN)
 
+typedef struct dsl_errorscrub_phys {
+	uint64_t dep_func; /* pool_scan_func_t */
+	uint64_t dep_state; /* dsl_scan_state_t */
+	uint64_t dep_cursor; /* serialized zap cursor for tracing progress */
+	uint64_t dep_start_time; /* error scrub start time, unix timestamp */
+	uint64_t dep_end_time; /* error scrub end time, unix timestamp */
+	uint64_t dep_to_examine; /* total error blocks to be scrubbed */
+	uint64_t dep_examined; /* blocks scrubbed so far */
+	uint64_t dep_errors;	/* error scrub I/O error count */
+	uint64_t dep_paused_flags; /* flag for paused */
+} dsl_errorscrub_phys_t;
+
+#define	ERRORSCRUB_PHYS_NUMINTS (sizeof (dsl_errorscrub_phys_t) \
+	/ sizeof (uint64_t))
+
 /*
  * Every pool will have one dsl_scan_t and this structure will contain
  * in-memory information about the scan and a pointer to the on-disk
@@ -151,11 +167,15 @@ typedef struct dsl_scan {
 	uint64_t scn_avg_zio_size_this_txg;
 	uint64_t scn_zios_this_txg;
 
+	/* zap cursor for tracing error scrub progress */
+	zap_cursor_t errorscrub_cursor;
 	/* members needed for syncing scan status to disk */
 	dsl_scan_phys_t scn_phys;	/* on disk representation of scan */
 	dsl_scan_phys_t scn_phys_cached;
 	avl_tree_t scn_queue;		/* queue of datasets to scan */
 	uint64_t scn_queues_pending;	/* outstanding data to issue */
+	/* members needed for syncing error scrub status to disk */
+	dsl_errorscrub_phys_t errorscrub_phys;
 } dsl_scan_t;
 
 typedef struct dsl_scan_io_queue dsl_scan_io_queue_t;
@@ -171,8 +191,12 @@ int dsl_scan_cancel(struct dsl_pool *);
 int dsl_scan(struct dsl_pool *, pool_scan_func_t);
 void dsl_scan_assess_vdev(struct dsl_pool *dp, vdev_t *vd);
 boolean_t dsl_scan_scrubbing(const struct dsl_pool *dp);
-int dsl_scrub_set_pause_resume(const struct dsl_pool *dp, pool_scrub_cmd_t cmd);
+boolean_t dsl_errorscrubbing(const struct dsl_pool *dp);
+boolean_t dsl_errorscrub_active(dsl_scan_t *scn);
 void dsl_scan_restart_resilver(struct dsl_pool *, uint64_t txg);
+int dsl_scrub_set_pause_resume(const struct dsl_pool *dp,
+    pool_scrub_cmd_t cmd);
+void dsl_errorscrub_sync(struct dsl_pool *, dmu_tx_t *);
 boolean_t dsl_scan_resilvering(struct dsl_pool *dp);
 boolean_t dsl_scan_resilver_scheduled(struct dsl_pool *dp);
 boolean_t dsl_dataset_unstable(struct dsl_dataset *ds);
@@ -184,6 +208,7 @@ void dsl_scan_ds_clone_swapped(struct dsl_dataset *ds1, struct dsl_dataset *ds2,
     struct dmu_tx *tx);
 boolean_t dsl_scan_active(dsl_scan_t *scn);
 boolean_t dsl_scan_is_paused_scrub(const dsl_scan_t *scn);
+boolean_t dsl_errorscrub_is_paused(const dsl_scan_t *scn);
 void dsl_scan_freed(spa_t *spa, const blkptr_t *bp);
 void dsl_scan_io_queue_destroy(dsl_scan_io_queue_t *queue);
 void dsl_scan_io_queue_vdev_xfer(vdev_t *svd, vdev_t *tvd);

include/sys/fs/zfs.h

@@ -1036,6 +1036,7 @@ typedef enum pool_scan_func {
 	POOL_SCAN_NONE,
 	POOL_SCAN_SCRUB,
 	POOL_SCAN_RESILVER,
+	POOL_SCAN_ERRORSCRUB,
 	POOL_SCAN_FUNCS
 } pool_scan_func_t;
 
@@ -1099,6 +1100,20 @@ typedef struct pool_scan_stat {
 	uint64_t	pss_pass_scrub_spent_paused;
 	uint64_t	pss_pass_issued; /* issued bytes per scan pass */
 	uint64_t	pss_issued;	/* total bytes checked by scanner */
+
+	/* error scrub values stored on disk */
+	uint64_t	pss_error_scrub_func;	/* pool_scan_func_t */
+	uint64_t	pss_error_scrub_state;	/* dsl_scan_state_t */
+	uint64_t	pss_error_scrub_start;	/* error scrub start time */
+	uint64_t	pss_error_scrub_end;	/* error scrub end time */
+	uint64_t	pss_error_scrub_examined; /* error blocks issued I/O */
+	/* error blocks to be issued I/O */
+	uint64_t	pss_error_scrub_to_be_examined;
+
+	/* error scrub values not stored on disk */
+	/* error scrub pause time in milliseconds */
+	uint64_t	pss_pass_error_scrub_pause;
+
 } pool_scan_stat_t;
 
 typedef struct pool_removal_stat {
@@ -1120,6 +1135,7 @@ typedef enum dsl_scan_state {
 	DSS_SCANNING,
 	DSS_FINISHED,
 	DSS_CANCELED,
+	DSS_ERRORSCRUBBING,
 	DSS_NUM_STATES
 } dsl_scan_state_t;
 
@@ -1360,7 +1376,7 @@ typedef enum {
  */
 typedef enum zfs_ioc {
 	/*
-	 * Core features - 81/128 numbers reserved.
+	 * Core features - 88/128 numbers reserved.
 	 */
 #ifdef __FreeBSD__
 	ZFS_IOC_FIRST =	0,
@@ -1455,6 +1471,7 @@ typedef enum zfs_ioc {
 	ZFS_IOC_WAIT_FS,			/* 0x5a54 */
 	ZFS_IOC_VDEV_GET_PROPS,			/* 0x5a55 */
 	ZFS_IOC_VDEV_SET_PROPS,			/* 0x5a56 */
+	ZFS_IOC_POOL_SCRUB,			/* 0x5a57 */
 
 	/*
 	 * Per-platform (Optional) - 8/128 numbers reserved.

include/sys/spa.h

@@ -1155,6 +1155,7 @@ extern void zfs_post_state_change(spa_t *spa, vdev_t *vd, uint64_t laststate);
 extern void zfs_post_autoreplace(spa_t *spa, vdev_t *vd);
 extern uint64_t spa_approx_errlog_size(spa_t *spa);
 extern int spa_get_errlog(spa_t *spa, void *uaddr, uint64_t *count);
+extern uint64_t spa_get_last_errlog_size(spa_t *spa);
 extern void spa_errlog_rotate(spa_t *spa);
 extern void spa_errlog_drain(spa_t *spa);
 extern void spa_errlog_sync(spa_t *spa, uint64_t txg);
@@ -1165,6 +1166,13 @@ extern void spa_swap_errlog(spa_t *spa, uint64_t new_head_ds,
 extern void sync_error_list(spa_t *spa, avl_tree_t *t, uint64_t *obj,
     dmu_tx_t *tx);
 extern void spa_upgrade_errlog(spa_t *spa, dmu_tx_t *tx);
+extern int find_top_affected_fs(spa_t *spa, uint64_t head_ds,
+    zbookmark_err_phys_t *zep, uint64_t *top_affected_fs);
+extern int find_birth_txg(struct dsl_dataset *ds, zbookmark_err_phys_t *zep,
+    uint64_t *birth_txg);
+extern void zep_to_zb(uint64_t dataset, zbookmark_err_phys_t *zep,
+    zbookmark_phys_t *zb);
+extern void name_to_errphys(char *buf, zbookmark_err_phys_t *zep);
 
 /* vdev cache */
 extern void vdev_cache_stat_init(void);

include/sys/spa_impl.h

@@ -295,6 +295,10 @@ struct spa {
 	uint64_t	spa_scan_pass_exam;	/* examined bytes per pass */
 	uint64_t	spa_scan_pass_issued;	/* issued bytes per pass */
 
+	/* error scrub pause time in milliseconds */
+	uint64_t	spa_scan_pass_errorscrub_pause;
+	/* total error scrub paused time in milliseconds */
+	uint64_t	spa_scan_pass_errorscrub_spent_paused;
 	/*
 	 * We are in the middle of a resilver, and another resilver
 	 * is needed once this one completes. This is set iff any

include/sys/sysevent/eventdefs.h

@@ -123,6 +123,11 @@ extern "C" {
 #define	ESC_ZFS_TRIM_CANCEL		"trim_cancel"
 #define	ESC_ZFS_TRIM_RESUME		"trim_resume"
 #define	ESC_ZFS_TRIM_SUSPEND		"trim_suspend"
+#define	ESC_ZFS_ERRORSCRUB_START	"errorscrub_start"
+#define	ESC_ZFS_ERRORSCRUB_FINISH	"errorscrub_finish"
+#define	ESC_ZFS_ERRORSCRUB_ABORT	"errorscrub_abort"
+#define	ESC_ZFS_ERRORSCRUB_RESUME	"errorscrub_resume"
+#define	ESC_ZFS_ERRORSCRUB_PAUSED	"errorscrub_paused"
 
 /*
  * datalink subclass definitions.