Report pool suspended due to MMP

When the pool is suspended, record whether it was due to an I/O error or
due to MMP writes failing to succeed within the required time.

Change spa_suspended from uint8_t to zio_suspend_reason_t to store the
reason.

When userspace queries pool status via spa_tryimport(), report the
reason the pool was suspended in a new key,
ZPOOL_CONFIG_SUSPENDED_REASON.

In libzfs, when interpreting the returned config nvlist, report
suspension due to MMP with a new pool status enum value,
ZPOOL_STATUS_IO_FAILURE_MMP.

In status_callback(), which generates and emits the message when 'zpool
status' is executed, add a case to print an appropriate message for the
new pool status enum value.

Reviewed-by: George Melikov <[email protected]>
Reviewed-by: Giuseppe Di Natale <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Reviewed-by: Tony Hutter <[email protected]>
Signed-off-by: Olaf Faaland <[email protected]>
Closes #7296 

4 files changed, 10 insertions, 2 deletions

diff --git a/include/libzfs.h b/include/libzfs.h
index 5288ff7f8..00f22cfb1 100644
--- a/include/libzfs.h
+++ b/include/libzfs.h
@@ -333,6 +333,7 @@ typedef enum {
 	ZPOOL_STATUS_HOSTID_REQUIRED,	/* multihost=on and hostid=0 */
 	ZPOOL_STATUS_IO_FAILURE_WAIT,	/* failed I/O, failmode 'wait' */
 	ZPOOL_STATUS_IO_FAILURE_CONTINUE, /* failed I/O, failmode 'continue' */
+	ZPOOL_STATUS_IO_FAILURE_MMP,	/* failed MMP, failmode not 'panic' */
 	ZPOOL_STATUS_BAD_LOG,		/* cannot read log chain(s) */
 	ZPOOL_STATUS_ERRATA,		/* informational errata available */
 
diff --git a/include/sys/fs/zfs.h b/include/sys/fs/zfs.h
index 88f590276..e40c427f6 100644
--- a/include/sys/fs/zfs.h
+++ b/include/sys/fs/zfs.h
@@ -681,6 +681,7 @@ typedef struct zpool_rewind_policy {
 #define	ZPOOL_CONFIG_RESILVER_TXG	"resilver_txg"
 #define	ZPOOL_CONFIG_COMMENT		"comment"
 #define	ZPOOL_CONFIG_SUSPENDED		"suspended"	/* not stored on disk */
+#define	ZPOOL_CONFIG_SUSPENDED_REASON	"suspended_reason"	/* not stored */
 #define	ZPOOL_CONFIG_TIMESTAMP		"timestamp"	/* not stored on disk */
 #define	ZPOOL_CONFIG_BOOTFS		"bootfs"	/* not stored on disk */
 #define	ZPOOL_CONFIG_MISSING_DEVICES	"missing_vdevs"	/* not stored on disk */
diff --git a/include/sys/spa_impl.h b/include/sys/spa_impl.h
index 66fcafd9c..af1d6aef0 100644
--- a/include/sys/spa_impl.h
+++ b/include/sys/spa_impl.h
@@ -236,7 +236,7 @@ struct spa {
 	zio_t		*spa_suspend_zio_root;	/* root of all suspended I/O */
 	kmutex_t	spa_suspend_lock;	/* protects suspend_zio_root */
 	kcondvar_t	spa_suspend_cv;		/* notification of resume */
-	uint8_t		spa_suspended;		/* pool is suspended */
+	zio_suspend_reason_t	spa_suspended;	/* pool is suspended */
 	uint8_t		spa_claiming;		/* pool is doing zil_claim() */
 	boolean_t	spa_debug;		/* debug enabled? */
 	boolean_t	spa_is_root;		/* pool is root */
diff --git a/include/sys/zio.h b/include/sys/zio.h
index 8d5f99d46..9d3adb7f5 100644
--- a/include/sys/zio.h
+++ b/include/sys/zio.h
@@ -167,6 +167,12 @@ enum zio_encrypt {
 #define	ZIO_FAILURE_MODE_CONTINUE	1
 #define	ZIO_FAILURE_MODE_PANIC		2
 
+typedef enum zio_suspend_reason {
+	ZIO_SUSPEND_NONE = 0,
+	ZIO_SUSPEND_IOERR,
+	ZIO_SUSPEND_MMP,
+} zio_suspend_reason_t;
+
 enum zio_flag {
 	/*
 	 * Flags inherited by gang, ddt, and vdev children,
@@ -610,7 +616,7 @@ extern enum zio_checksum zio_checksum_dedup_select(spa_t *spa,
 extern enum zio_compress zio_compress_select(spa_t *spa,
     enum zio_compress child, enum zio_compress parent);
 
-extern void zio_suspend(spa_t *spa, zio_t *zio);
+extern void zio_suspend(spa_t *spa, zio_t *zio, zio_suspend_reason_t);
 extern int zio_resume(spa_t *spa);
 extern void zio_resume_wait(spa_t *spa);