On Wed, Nov 23, 2011 at 06:28:05AM +0800, Andrew Morton wrote: > On Wed, 16 Nov 2011 19:44:21 +0800 > Wu Fengguang <fengguang.wu@xxxxxxxxx> wrote: > > > Due to the (very low) possibility of data loss by partial writes, IMHO > > it would safer to test this patch in linux-next until next merge window, > > Any such bugs will not be discovered in linux-next testing. Yup, I'm afraid. > The only way to find these things in a reasonable period of time is to > go in and find them. For example, intensive fsx-linux testing with > concurrent heavy memory pressure on various filesystems with various > block sizes. And of course concurrent signalling. If you're talking > about O_DIRECT then iirc I hacked support for that into fsx-linux. I > think. How are we going to measure the success/failure? Check if it eventually resulted in filesystem corruption or whatever? When received SIGKILL, fsx-linux itself will just die. > Anyway, what _are_ the scenarios in which we think data can be lost? It's the vision that there may be partial writes on SIGKILL. Before patch, the write will either succeed as a whole or not started at all, depending on the timing of write/SIGKILL. This is kind of atomic operation. However now the write can be half done. If the application really cares about atomic behavior, it can do create-and-rename. However there are always the possibility of broken applications. Maybe this is not that big problem as SIGKILL is considered be to destructive already. Thanks, Fengguang -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
