Messages in this thread |  | | Date | Wed, 14 Feb 2007 16:08:49 -0500 | Subject | Re: Fix(es) for ext2 fsync bug | From | sfaibish <> |
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Val,
Maybe it is not only our (FS people) problem. We probably need to bring the kernel people judge as ext2 and ext3 are the base Linux FS. I add the kernel list for opinion.
/Sorin
On Wed, 14 Feb 2007 14:54:54 -0500, Valerie Henson <val_henson@linux.intel.com> wrote:
> Just some quick notes on possible ways to fix the ext2 fsync bug that > eXplode found. Whether or not anyone will bother to implement it is > another matter. > > Background: The eXplode file system checker found a bug in ext2 fsync > behavior. Do the following: truncate file A, create file B which > reallocates one of A's old indirect blocks, fsync file B. If you then > crash before file A's metadata is all written out, fsck will complete > the truncate for file A... thereby deleting file B's data. So fsync > file B doesn't guarantee data is on disk after a crash. Details: > > http://www.stanford.edu/~engler/explode-osdi06.pdf > > Two possible solutions I can think of: > > * Rearrange order of duplicate block checking and fixing file size in > fsck. Not sure how hard this is. (Ted?) > > * Keep a set of "still allocated on disk" block bitmaps that gets > flushed whenever a sync happens. Don't allocate these blocks. > Journaling file systems already have to do this. > > -VAL > - > To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" > in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > >
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