On Wed, 8 Aug 2012 16:45:57 +0200, David Sterba wrote: > On Sun, Aug 05, 2012 at 04:11:47PM +0200, Olivier Bonvalet wrote: >> Aug 5 16:10:12 backup2 kernel: [ 58.674758] parent transid verify failed on 615015833600 wanted 110423 found 110424 1st mirror fails verify_parent_transid(). >> Aug 5 16:10:12 backup2 kernel: [ 58.675090] parent transid verify failed on 615015833600 wanted 110423 found 110424 2nd mirror fails verify_parent_transid(). >> Aug 5 16:10:12 backup2 kernel: [ 58.675523] btrfs read error corrected: ino 1 off 615015833600 (dev /dev/mapper/vg--backupplug-backup sector 1209083504) That's a bug. It is wrong to ignore the previous results from verify_parent_transid() and to call repair_eb_io_failure() which rewrites one mirror and claims to have corrected an error. But it's not a major issue, just a misleading message in the kernel log and a disk write operation which does not repair anything. > This looks strange, the the corrupted block belongs to metadata, I > assume you have the DUP profile, so there is a good copy that can be > used instead, the error message confirms that, but ... > >> Aug 5 16:10:12 backup2 kernel: [ 58.675536] Failed to read block groups: -5 That's correct, because the UPTODATE flag in the extent is not set (verify_parent_transid() clears it when it detects an error). > ... ? -5 means EIO, which is returned when a block cannot be read, so > unless there's a different reason for it, this looks like a missed > oportunity to fix an error and continue. > > The same error messages are present in the logs from 3.4 version. > >> Aug 5 16:10:12 backup2 kernel: [ 58.704720] btrfs: open_ctree failed The summary is that the block was not correctable, both mirrors had the same old transid. The bug is that the call to repair_io_failure() should not have been done because verify_parent_transid() indicated errors. I'll prepare a patch for it. Changing btree_read_extent_buffer_pages() to set ret to -EIO if verify_parent_transid() fails should fix the issue. -- 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
