From dbae70d452a0858d62915166d93650c98fe6639c Mon Sep 17 00:00:00 2001
From: Mikulas Patocka <mpatocka@redhat.com>
Date: Wed, 12 May 2021 08:28:43 -0400
Subject: [PATCH] dm integrity: revert to not using discard filler when
 recalulating

Revert the commit 7a5b96b4784454ba258e83dc7469ddbacd3aaac3 ("dm integrity:
use discard support when recalculating").

There's a bug that when we write some data beyond the current recalculate
boundary, the checksum will be rewritten with the discard filler later.
And the data will no longer have integrity protection. There's no easy
fix for this case.

Also, another problematic case is if dm-integrity is used to detect
bitrot (random device errors, bit flips, etc); dm-integrity should
detect that even for unused sectors. With commit 7a5b96b4784 it can
happen that such change is undetected (because discard filler is not a
valid checksum).

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Acked-by: Milan Broz <gmazyland@gmail.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
---
 drivers/md/dm-integrity.c | 57 +++++++++++++++++----------------------
 1 file changed, 24 insertions(+), 33 deletions(-)

diff --git a/drivers/md/dm-integrity.c b/drivers/md/dm-integrity.c
index 781942aeddd1..6d00e619a141 100644
--- a/drivers/md/dm-integrity.c
+++ b/drivers/md/dm-integrity.c
@@ -2689,30 +2689,26 @@ static void integrity_recalc(struct work_struct *w)
 	if (unlikely(dm_integrity_failed(ic)))
 		goto err;
 
-	if (!ic->discard) {
-		io_req.bi_op = REQ_OP_READ;
-		io_req.bi_op_flags = 0;
-		io_req.mem.type = DM_IO_VMA;
-		io_req.mem.ptr.addr = ic->recalc_buffer;
-		io_req.notify.fn = NULL;
-		io_req.client = ic->io;
-		io_loc.bdev = ic->dev->bdev;
-		io_loc.sector = get_data_sector(ic, area, offset);
-		io_loc.count = n_sectors;
+	io_req.bi_op = REQ_OP_READ;
+	io_req.bi_op_flags = 0;
+	io_req.mem.type = DM_IO_VMA;
+	io_req.mem.ptr.addr = ic->recalc_buffer;
+	io_req.notify.fn = NULL;
+	io_req.client = ic->io;
+	io_loc.bdev = ic->dev->bdev;
+	io_loc.sector = get_data_sector(ic, area, offset);
+	io_loc.count = n_sectors;
 
-		r = dm_io(&io_req, 1, &io_loc, NULL);
-		if (unlikely(r)) {
-			dm_integrity_io_error(ic, "reading data", r);
-			goto err;
-		}
+	r = dm_io(&io_req, 1, &io_loc, NULL);
+	if (unlikely(r)) {
+		dm_integrity_io_error(ic, "reading data", r);
+		goto err;
+	}
 
-		t = ic->recalc_tags;
-		for (i = 0; i < n_sectors; i += ic->sectors_per_block) {
-			integrity_sector_checksum(ic, logical_sector + i, ic->recalc_buffer + (i << SECTOR_SHIFT), t);
-			t += ic->tag_size;
-		}
-	} else {
-		t = ic->recalc_tags + (n_sectors >> ic->sb->log2_sectors_per_block) * ic->tag_size;
+	t = ic->recalc_tags;
+	for (i = 0; i < n_sectors; i += ic->sectors_per_block) {
+		integrity_sector_checksum(ic, logical_sector + i, ic->recalc_buffer + (i << SECTOR_SHIFT), t);
+		t += ic->tag_size;
 	}
 
 	metadata_block = get_metadata_sector_and_offset(ic, area, offset, &metadata_offset);
@@ -4368,13 +4364,11 @@ static int dm_integrity_ctr(struct dm_target *ti, unsigned argc, char **argv)
 			goto bad;
 		}
 		INIT_WORK(&ic->recalc_work, integrity_recalc);
-		if (!ic->discard) {
-			ic->recalc_buffer = vmalloc(RECALC_SECTORS << SECTOR_SHIFT);
-			if (!ic->recalc_buffer) {
-				ti->error = "Cannot allocate buffer for recalculating";
-				r = -ENOMEM;
-				goto bad;
-			}
+		ic->recalc_buffer = vmalloc(RECALC_SECTORS << SECTOR_SHIFT);
+		if (!ic->recalc_buffer) {
+			ti->error = "Cannot allocate buffer for recalculating";
+			r = -ENOMEM;
+			goto bad;
 		}
 		ic->recalc_tags = kvmalloc_array(RECALC_SECTORS >> ic->sb->log2_sectors_per_block,
 						 ic->tag_size, GFP_KERNEL);
@@ -4383,9 +4377,6 @@ static int dm_integrity_ctr(struct dm_target *ti, unsigned argc, char **argv)
 			r = -ENOMEM;
 			goto bad;
 		}
-		if (ic->discard)
-			memset(ic->recalc_tags, DISCARD_FILLER,
-			       (RECALC_SECTORS >> ic->sb->log2_sectors_per_block) * ic->tag_size);
 	} else {
 		if (ic->sb->flags & cpu_to_le32(SB_FLAG_RECALCULATING)) {
 			ti->error = "Recalculate can only be specified with internal_hash";
@@ -4579,7 +4570,7 @@ static void dm_integrity_dtr(struct dm_target *ti)
 
 static struct target_type integrity_target = {
 	.name			= "integrity",
-	.version		= {1, 9, 0},
+	.version		= {1, 10, 0},
 	.module			= THIS_MODULE,
 	.features		= DM_TARGET_SINGLETON | DM_TARGET_INTEGRITY,
 	.ctr			= dm_integrity_ctr,
-- 
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