[dm-devel] [PATCH] dm-integrity: revert the discard patch

[Mikulas Patocka]

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, so we revert the whole patch.

Signed-off-by: Mikulas Patocka <mpatocka at redhat.com>

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
@@ -2689,30 +2689,26 @@ next_chunk:
 	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 @@ try_smaller_buffer:
 			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 @@ try_smaller_buffer:
 			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_t
 
 static struct target_type integrity_target = {
 	.name			= "integrity",
-	.version		= {1, 9, 0},
+	.version		= {1, 8, 0},
 	.module			= THIS_MODULE,
 	.features		= DM_TARGET_SINGLETON | DM_TARGET_INTEGRITY,
 	.ctr			= dm_integrity_ctr,