Add display of checksums to zdb -R

The function zdb_read_block (zdb -R) was always intended to have a :c 
flag which would read the DVA and length supplied by the user, and 
display the checksum. Since we don't know which checksum goes with 
the data, we should calculate and display them all.

For each checksum in the table, read in the data at the supplied 
DVA:length, calculate the checksum, and display it. Update the man 
page and create a zfs test for the new feature.

Reviewed-by: Brian Behlendorf <[email protected]>
Reviewed-by: Kjeld Schouten <[email protected]>
Signed-off-by: Paul Zuchowski <[email protected]>
Closes #9607 

1 files changed, 58 insertions, 2 deletions

diff --git a/cmd/zdb/zdb.c b/cmd/zdb/zdb.c
index 81c9eaf8c..2d35bd0f9 100644
--- a/cmd/zdb/zdb.c
+++ b/cmd/zdb/zdb.c
@@ -26,6 +26,7 @@
  * Copyright 2016 Nexenta Systems, Inc.
  * Copyright (c) 2017, 2018 Lawrence Livermore National Security, LLC.
  * Copyright (c) 2015, 2017, Intel Corporation.
+ * Copyright (c) 2019 Datto Inc.
  */
 
 #include <stdio.h>
@@ -6340,7 +6341,7 @@ name:
  *	size           - Amount of data to read, in hex, in bytes
  *	flags          - A string of characters specifying options
  *		 b: Decode a blkptr at given offset within block
- *		*c: Calculate and display checksums
+ *		 c: Calculate and display checksums
  *		 d: Decompress data before dumping
  *		 e: Byteswap data before dumping
  *		 g: Display data as a gang block header
@@ -6348,7 +6349,6 @@ name:
  *		 p: Do I/O to physical offset
  *		 r: Dump raw data to stdout
  *
- *              * = not yet implemented
  */
 static void
 zdb_read_block(char *thing, spa_t *spa)
@@ -6566,6 +6566,62 @@ zdb_read_block(char *thing, spa_t *spa)
 	else
 		zdb_dump_block(thing, buf, size, flags);
 
+	/*
+	 * If :c was specified, iterate through the checksum table to
+	 * calculate and display each checksum for our specified
+	 * DVA and length.
+	 */
+	if ((flags & ZDB_FLAG_CHECKSUM) && !(flags & ZDB_FLAG_RAW) &&
+	    !(flags & ZDB_FLAG_GBH)) {
+		zio_t *czio, *cio;
+		(void) printf("\n");
+		for (enum zio_checksum ck = ZIO_CHECKSUM_LABEL;
+		    ck < ZIO_CHECKSUM_FUNCTIONS; ck++) {
+
+			if ((zio_checksum_table[ck].ci_flags &
+			    ZCHECKSUM_FLAG_EMBEDDED) ||
+			    ck == ZIO_CHECKSUM_NOPARITY) {
+				continue;
+			}
+			BP_SET_CHECKSUM(bp, ck);
+			spa_config_enter(spa, SCL_STATE, FTAG, RW_READER);
+			czio = zio_root(spa, NULL, NULL, ZIO_FLAG_CANFAIL);
+			czio->io_bp = bp;
+
+			if (vd == vd->vdev_top) {
+				cio = zio_read(czio, spa, bp, pabd, psize,
+				    NULL, NULL,
+				    ZIO_PRIORITY_SYNC_READ,
+				    ZIO_FLAG_CANFAIL | ZIO_FLAG_RAW |
+				    ZIO_FLAG_DONT_RETRY, NULL);
+				zio_nowait(cio);
+			} else {
+				zio_nowait(zio_vdev_child_io(czio, bp, vd,
+				    offset, pabd, psize, ZIO_TYPE_READ,
+				    ZIO_PRIORITY_SYNC_READ,
+				    ZIO_FLAG_DONT_CACHE |
+				    ZIO_FLAG_DONT_PROPAGATE |
+				    ZIO_FLAG_DONT_RETRY |
+				    ZIO_FLAG_CANFAIL | ZIO_FLAG_RAW |
+				    ZIO_FLAG_SPECULATIVE |
+				    ZIO_FLAG_OPTIONAL, NULL, NULL));
+			}
+			error = zio_wait(czio);
+			if (error == 0 || error == ECKSUM) {
+				zio_checksum_compute(czio, ck, pabd, lsize);
+				printf("%12s\tcksum=%llx:%llx:%llx:%llx\n",
+				    zio_checksum_table[ck].ci_name,
+				    (u_longlong_t)bp->blk_cksum.zc_word[0],
+				    (u_longlong_t)bp->blk_cksum.zc_word[1],
+				    (u_longlong_t)bp->blk_cksum.zc_word[2],
+				    (u_longlong_t)bp->blk_cksum.zc_word[3]);
+			} else {
+				printf("error %d reading block\n", error);
+			}
+			spa_config_exit(spa, SCL_STATE, FTAG);
+		}
+	}
+
 	if (borrowed)
 		abd_return_buf_copy(pabd, buf, size);