Qu Wenruo posted on Mon, 06 Oct 2014 10:29:53 +0800 as excerpted: > 2 problems here. > > [1] csum mismatch As already mentioned by Ducan and Brendan, the csum > does not match. > > What makes thing much worse, since small file's extent is inlined, the > data is stored in metadata tree blocks, > and the file system is almost empty so the inline extent lies in the > *root* leaf of fs_tree. > These two unfortunate facts makes the whole fs_tree corrupted(only one > leaf, and its cusm dismatch), > which cause btrfs-progs segfault. So I nailed it. =:^) > The good news is that, the bug in btrfs-progs is already fixed by Wang's > patch: > https://patchwork.kernel.org/patch/4254631/ > So at least, btrfs-progs will not segfault anymore. > > [2] two occurences? > So you definitely changed something you should not touch... maybe > another tree root? 1) Single device btrfs, therefore... 2) DUP metadata by default. 3) Small file, therefore... 4) Inlined in (DUP) metadata, therefore... 5) Two occurrences, each a copy of the (metadata-inlined) file in its own instance of the (duped) metadata block. I nailed it again. =:^) But the connection between the mentioned tree root patch and this particular bug had escaped me, so that's useful new information to me too, resolving the problem that I spotted but had no clue whether it was even fixable. Thanks. =:^) -- Duncan - List replies preferred. No HTML msgs. "Every nonfree program has a lord, a master -- and if you use the program, he is your master." Richard Stallman -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
