[PATCH 100/102] UBIFS: make space fixup work in the remount case

From: Luis Henriques
Date: Mon Apr 08 2013 - 05:54:50 EST -stable review patch. If anyone has any objections, please let me know.


From: Artem Bityutskiy <artem.bityutskiy@xxxxxxxxxxxxxxx>

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@xxxxxxxxxxxxxxx>
Reported-by: Mark Jackson <mpfj-list@xxxxxxxxxx>
Signed-off-by: Luis Henriques <luis.henriques@xxxxxxxxxxxxx>
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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