Patch "ubi: Make volume resize power cut aware" has been added to the 4.7-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    ubi: Make volume resize power cut aware

to the 4.7-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     ubi-make-volume-resize-power-cut-aware.patch
and it can be found in the queue-4.7 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 4946784bd3924b1374f05eebff2fd68660bae866 Mon Sep 17 00:00:00 2001
From: Richard Weinberger <richard@nod.at>
Date: Thu, 23 Jun 2016 19:30:38 +0200
Subject: ubi: Make volume resize power cut aware

From: Richard Weinberger <richard@nod.at>

commit 4946784bd3924b1374f05eebff2fd68660bae866 upstream.

When the volume resize operation shrinks a volume,
LEBs will be unmapped. Since unmapping will not erase these
LEBs immediately we have to wait for that operation to finish.
Otherwise in case of a power cut right after writing the new
volume table the UBI attach process can find more LEBs than the
volume table knows. This will render the UBI image unattachable.

Fix this issue by waiting for erase to complete and write the new
volume table afterward.

Reported-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Reviewed-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/mtd/ubi/vmt.c |   25 ++++++++++++++++++-------
 1 file changed, 18 insertions(+), 7 deletions(-)

--- a/drivers/mtd/ubi/vmt.c
+++ b/drivers/mtd/ubi/vmt.c
@@ -488,13 +488,6 @@ int ubi_resize_volume(struct ubi_volume_
 		spin_unlock(&ubi->volumes_lock);
 	}
 
-	/* Change volume table record */
-	vtbl_rec = ubi->vtbl[vol_id];
-	vtbl_rec.reserved_pebs = cpu_to_be32(reserved_pebs);
-	err = ubi_change_vtbl_record(ubi, vol_id, &vtbl_rec);
-	if (err)
-		goto out_acc;
-
 	if (pebs < 0) {
 		for (i = 0; i < -pebs; i++) {
 			err = ubi_eba_unmap_leb(ubi, vol, reserved_pebs + i);
@@ -512,6 +505,24 @@ int ubi_resize_volume(struct ubi_volume_
 		spin_unlock(&ubi->volumes_lock);
 	}
 
+	/*
+	 * When we shrink a volume we have to flush all pending (erase) work.
+	 * Otherwise it can happen that upon next attach UBI finds a LEB with
+	 * lnum > highest_lnum and refuses to attach.
+	 */
+	if (pebs < 0) {
+		err = ubi_wl_flush(ubi, vol_id, UBI_ALL);
+		if (err)
+			goto out_acc;
+	}
+
+	/* Change volume table record */
+	vtbl_rec = ubi->vtbl[vol_id];
+	vtbl_rec.reserved_pebs = cpu_to_be32(reserved_pebs);
+	err = ubi_change_vtbl_record(ubi, vol_id, &vtbl_rec);
+	if (err)
+		goto out_acc;
+
 	vol->reserved_pebs = reserved_pebs;
 	if (vol->vol_type == UBI_DYNAMIC_VOLUME) {
 		vol->used_ebs = reserved_pebs;


Patches currently in stable-queue which might be from richard@nod.at are

queue-4.7/um-fix-possible-deadlock-in-sig_handler_common.patch
queue-4.7/ubi-fix-race-condition-between-ubi-device-creation-and-udev.patch
queue-4.7/ubi-fix-early-logging.patch
queue-4.7/ubi-make-volume-resize-power-cut-aware.patch