Re: [PATCH 2/5] coredump: Fix handling of partial writes in dump_emit()

[Rob Landley]

On 4/27/20 10:35 PM, Linus Torvalds wrote:
> On Mon, Apr 27, 2020 at 8:28 PM Jann Horn <jannh@xxxxxxxxxx> wrote:
>>
>> After a partial write, we have to update the input buffer pointer.
> 
> Interesting. It seems this partial write case never triggers (except
> for actually killing the core-dump).
> 
> Or did you find a case where it actually matters?
> 
> Your fix is obviously correct, but it also makes me go "that function
> clearly never actually worked for partial writes, maybe we shouldn't
> even bother?"

Writes to a local filesystem should never be short unless disk full/error.

Once upon a time this was yet another thing that NFS could break that no other
filesystem would break, but I dunno about now? (I think the page cache collates
it and defers the flush until the error can't be reported back anyway?)

Rob