On Sun, 10 Jan 2016 08:07:50 AM cheater00 . wrote: > Would like to point out that this can cause data loss. If I'm writing > to disk and the disk becomes unexpectedly read only - that data will > be lost, because who in their right mind makes their code expect this > and builds a contingency (e.g. caching, backpressure, etc)... There are lots of situations when a filesystem can become read-only, it's a fairly standard response to disk errors. You should be able to handle that if your application deals with important data. I was under the impression that this bug didn't make the disk read-only (IE you can delete/truncate files to free space) but instead incorrectly told the application that there was no space. ENOSPACE is very common and all apps have to deal with it. > There's no loss of data on the disk because the data doesn't make it > to disk in the first place. But it's exactly the same as if the data > had been written to disk, and then lost. No it's not. If you write data and a fsync() or fdatasync() call succeeds then it's on disk, otherwise not. All apps which depend on data being written to disk (EG database servers and mail servers) use fsync() and fdatasync(). On Sun, 10 Jan 2016 02:59:46 PM cheater00 . wrote: > Not really - at power loss the whole system is unreachable and can not > accept incoming jobs/RPCs. When btrfs bugs out, it can still do that, > and will not be able to say "oops i messed up" because it's not the > kind of error that you'd be expected to handle as a programmer. So say > an email server will not accept incoming emails at power loss, whereas > if btrfs bugs out it will accept emails but will put them in a black > hole. So it's more urgent than "hey this is like power loss and we > can't really do much about power loss so let's ignore this issue for > now" Please test this with the common mail server software, EG Postfix, Exim, Procmail, Maildrop, Dovecot, etc. The BTRFS bug as described won't cause data loss with any of them. -- My Main Blog http://etbe.coker.com.au/ My Documents Blog http://doc.coker.com.au/ -- 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
