[PATCH] md: forbid a RAID5 from having both a bitmap and a journal.

[NeilBrown <neilb@suse.com>]

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Having both a bitmap and a journal is pointless.
Attempting to do so can corrupt the bitmap if the journal
replay happens before the bitmap is initialized.
Rather than try to avoid this corruption, simply
refuse to allow arrays with both a bitmap and a journal.
So:
 - if raid5_run sees both are present, fail.
 - if adding a bitmap finds a journal is present, fail
 - if adding a journal finds a bitmap is present, fail.

Cc: stable@vger.kernel.org (4.10+)
Signed-off-by: NeilBrown <neilb@suse.com>
---

This patch should replace 8031c3ddc70ab, which should be reverted.

Thanks,
NeilBrown


 drivers/md/bitmap.c | 6 ++++++
 drivers/md/md.c     | 2 +-
 drivers/md/raid5.c  | 7 +++++++
 3 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
index cae57b5be817..f425905c97fa 100644
--- a/drivers/md/bitmap.c
+++ b/drivers/md/bitmap.c
@@ -1816,6 +1816,12 @@ struct bitmap *bitmap_create(struct mddev *mddev, int slot)
 
 	BUG_ON(file && mddev->bitmap_info.offset);
 
+	if (test_bit(MD_HAS_JOURNAL, &mddev->flags)) {
+		pr_notice("md/raid:%s: array with journal cannot have bitmap\n",
+			  mdname(mddev));
+		return ERR_PTR(-EBUSY);
+	}
+
 	bitmap = kzalloc(sizeof(*bitmap), GFP_KERNEL);
 	if (!bitmap)
 		return ERR_PTR(-ENOMEM);
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 63ecfb063b76..bf06ff017eda 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -6384,7 +6384,7 @@ static int add_new_disk(struct mddev *mddev, mdu_disk_info_t *info)
 					break;
 				}
 			}
-			if (has_journal) {
+			if (has_journal || mddev->bitmap) {
 				export_rdev(rdev);
 				return -EBUSY;
 			}
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 4f40ccd21cbb..e070e5c68801 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -7134,6 +7134,13 @@ static int raid5_run(struct mddev *mddev)
 			min_offset_diff = diff;
 	}
 
+	if ((test_bit(MD_HAS_JOURNAL, &mddev->flags) || journal_dev) &&
+	    (mddev->bitmap_info.offset || mddev->bitmap_info.file)) {
+		pr_notice("md/raid:%s: array cannot have both journal and bitmap\n",
+			  mdname(mddev));
+		return -EINVAL;
+	}
+
 	if (mddev->reshape_position != MaxSector) {
 		/* Check that we can continue the reshape.
 		 * Difficulties arise if the stripe we would write to
-- 
2.14.0.rc0.dirty


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