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UBIFS: make space fixup work in the remount case 

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
pages.

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@linux.intel.com>
Reported-by: Mark Jackson <mpfj-list@mimc.co.uk>
Cc: stable@vger.kernel.org # 3.0+
This commit is contained in:
Artem Bityutskiy 2013-03-14 10:49:23 +02:00
parent f6161aa153
commit 67e753ca41
1 changed files with 6 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
fs/ubifs/super.c
View File

@ -1568,6 +1568,12 @@ 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;
@ -1684,12 +1690,6 @@ 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;
}
mutex_unlock(&c->umount_mutex);
return err;