[PATCH] dm-integrity - add the "reset_recalculate" flag

[Mikulas Patocka <mpatocka@xxxxxxxxxx>]

This patch adds a new flag "reset_recalculate" that will restart
recalculating from the beginning of the device. It can be used if we want
to change the hash function. Example:

#!/bin/sh
dmsetup remove_all
rmmod brd
set -e
modprobe brd rd_size=1048576
dmsetup create in --table '0 2000000 integrity /dev/ram0 0 16 J 2 internal_hash:sha256 recalculate'
sleep 10
dmsetup status
dmsetup remove in
dmsetup create in --table '0 2000000 integrity /dev/ram0 0 16 J 2 internal_hash:sha3-256 reset_recalculate'

Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>

Index: linux-2.6/drivers/md/dm-integrity.c
===================================================================
--- linux-2.6.orig/drivers/md/dm-integrity.c
+++ linux-2.6/drivers/md/dm-integrity.c
@@ -262,6 +262,7 @@ struct dm_integrity_c {
 	bool journal_uptodate;
 	bool just_formatted;
 	bool recalculate_flag;
+	bool reset_recalculate_flag;
 	bool discard;
 	bool fix_padding;
 	bool fix_hmac;
@@ -3134,7 +3135,8 @@ static void dm_integrity_resume(struct d
 		rw_journal_sectors(ic, REQ_OP_READ, 0, 0,
 				   ic->n_bitmap_blocks * (BITMAP_BLOCK_SIZE >> SECTOR_SHIFT), NULL);
 		if (ic->mode == 'B') {
-			if (ic->sb->log2_blocks_per_bitmap_bit == ic->log2_blocks_per_bitmap_bit) {
+			if (ic->sb->log2_blocks_per_bitmap_bit == ic->log2_blocks_per_bitmap_bit &&
+			    !ic->reset_recalculate_flag) {
 				block_bitmap_copy(ic, ic->recalc_bitmap, ic->journal);
 				block_bitmap_copy(ic, ic->may_write_bitmap, ic->journal);
 				if (!block_bitmap_op(ic, ic->journal, 0, ic->provided_data_sectors,
@@ -3156,7 +3158,8 @@ static void dm_integrity_resume(struct d
 			}
 		} else {
 			if (!(ic->sb->log2_blocks_per_bitmap_bit == ic->log2_blocks_per_bitmap_bit &&
-			      block_bitmap_op(ic, ic->journal, 0, ic->provided_data_sectors, BITMAP_OP_TEST_ALL_CLEAR))) {
+			      block_bitmap_op(ic, ic->journal, 0, ic->provided_data_sectors, BITMAP_OP_TEST_ALL_CLEAR)) ||
+			    ic->reset_recalculate_flag) {
 				ic->sb->flags |= cpu_to_le32(SB_FLAG_RECALCULATING);
 				ic->sb->recalc_sector = cpu_to_le64(0);
 			}
@@ -3169,6 +3172,10 @@ static void dm_integrity_resume(struct d
 			dm_integrity_io_error(ic, "writing superblock", r);
 	} else {
 		replay_journal(ic);
+		if (ic->reset_recalculate_flag) {
+			ic->sb->flags |= cpu_to_le32(SB_FLAG_RECALCULATING);
+			ic->sb->recalc_sector = cpu_to_le64(0);
+		}
 		if (ic->mode == 'B') {
 			ic->sb->flags |= cpu_to_le32(SB_FLAG_DIRTY_BITMAP);
 			ic->sb->log2_blocks_per_bitmap_bit = ic->log2_blocks_per_bitmap_bit;
@@ -3242,6 +3249,7 @@ static void dm_integrity_status(struct d
 		arg_count += !!ic->meta_dev;
 		arg_count += ic->sectors_per_block != 1;
 		arg_count += !!(ic->sb->flags & cpu_to_le32(SB_FLAG_RECALCULATING));
+		arg_count += ic->reset_recalculate_flag;
 		arg_count += ic->discard;
 		arg_count += ic->mode == 'J';
 		arg_count += ic->mode == 'J';
@@ -3261,6 +3269,8 @@ static void dm_integrity_status(struct d
 			DMEMIT(" block_size:%u", ic->sectors_per_block << SECTOR_SHIFT);
 		if (ic->sb->flags & cpu_to_le32(SB_FLAG_RECALCULATING))
 			DMEMIT(" recalculate");
+		if (ic->reset_recalculate_flag)
+			DMEMIT(" reset_recalculate");
 		if (ic->discard)
 			DMEMIT(" allow_discards");
 		DMEMIT(" journal_sectors:%u", ic->initial_sectors - SB_SECTORS);
@@ -4058,6 +4068,9 @@ static int dm_integrity_ctr(struct dm_ta
 				goto bad;
 		} else if (!strcmp(opt_string, "recalculate")) {
 			ic->recalculate_flag = true;
+		} else if (!strcmp(opt_string, "reset_recalculate")) {
+			ic->recalculate_flag = true;
+			ic->reset_recalculate_flag = true;
 		} else if (!strcmp(opt_string, "allow_discards")) {
 			ic->discard = true;
 		} else if (!strcmp(opt_string, "fix_padding")) {

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