[ 3.5.y.z extended stable ] Patch "UBIFS: make space fixup work in the remount case" has been added to staging queue

Luis Henriques luis.henriques at canonical.com
Fri Apr 5 17:22:06 UTC 2013

This is a note to let you know that I have just added a patch titled

    UBIFS: make space fixup work in the remount case

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:


If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see



>From 39467565a02cb91c1f9bb41d65947267a5228035 Mon Sep 17 00:00:00 2001
From: Artem Bityutskiy <artem.bityutskiy at linux.intel.com>
Date: Thu, 14 Mar 2013 10:49:23 +0200
Subject: [PATCH] UBIFS: make space fixup work in the remount case

commit 67e753ca41782913d805ff4a8a2b0f60b26b7915 upstream.

The UBIFS space fixup is a useful feature which allows to fixup the "broken"
flash space at the time of the first mount. The "broken" space is usually the
result of using a "dumb" industrial flasher which is not able to skip empty
NAND pages and just writes all 0xFFs to the empty space, which has grave
side-effects for UBIFS when UBIFS trise to write useful data to those empty

The fix-up feature works roughly like this:
1. mkfs.ubifs sets the fixup flag in UBIFS superblock when creating the image
   (see -F option)
2. when the file-system is mounted for the first time, UBIFS notices the fixup
   flag and re-writes the entire media atomically, which may take really a lot
   of time.
3. UBIFS clears the fixup flag in the superblock.

This works fine when the file system is mounted R/W for the very first time.
But it did not really work in the case when we first mount the file-system R/O,
and then re-mount R/W. The reason was that we started the fixup procedure too
late, which we cannot really do because we have to fixup the space before it
starts being used.

Signed-off-by: Artem Bityutskiy <artem.bityutskiy at linux.intel.com>
Reported-by: Mark Jackson <mpfj-list at mimc.co.uk>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
 fs/ubifs/super.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c
index 5862dd9..202c0e4 100644
--- a/fs/ubifs/super.c
+++ b/fs/ubifs/super.c
@@ -1579,6 +1579,12 @@ static int ubifs_remount_rw(struct ubifs_info *c)
 	c->remounting_rw = 1;
 	c->ro_mount = 0;

+	if (c->space_fixup) {
+		err = ubifs_fixup_free_space(c);
+		if (err)
+			return err;
+	}
 	err = check_free_space(c);
 	if (err)
 		goto out;
@@ -1695,12 +1701,6 @@ static int ubifs_remount_rw(struct ubifs_info *c)
 		err = dbg_check_space_info(c);

-	if (c->space_fixup) {
-		err = ubifs_fixup_free_space(c);
-		if (err)
-			goto out;
-	}
 	return err;


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