On Fri, Apr 9, 2010 at 12:20 PM, Darrick J. Wong <djwong@xxxxxxxxxx> wrote: > On Mon, Apr 05, 2010 at 03:02:20PM -0700, Darrick J. Wong wrote: >> Hi all, >> >> I wrote a program called e4frag that deliberately tries to fragment an ext4 >> filesystem via EXT4_IOC_MOVE_EXT so that I could run e4defrag through its >> paces. While running e4frag and e4defrag concurrently on a kernel source tree, >> I discovered ongoing file corruption. It appears that if e4frag and e4defrag >> hit the same file at same time, the file ends up with a 4K data block from >> somewhere else. "Somewhere else" seems to be a small chunk of binary gibberish >> followed by contents from other files(!) Obviously this isn't a good thing to > > It seems that if you mount the filesystem with -o sync this problem goes away. > > --D That implies to me that there is a missing block flush prior to a lock being released. That should not be too hard to find by code inspection. As conceptually interested as I am in ext4_ioc_move_ext, I have not really gone through the code with any detail. Maybe I'll contribute by doing that. Greg -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
