On Thu, Dec 17, 2020 at 03:11:46PM +0000, Filipe Manana wrote: > On Thu, Dec 17, 2020 at 3:03 PM David Sterba <[email protected]> wrote: > > > > On Mon, Dec 14, 2020 at 09:56:40AM +0000, [email protected] wrote: > > > From: Filipe Manana <[email protected]> > > > > > > For a very long time there's been a race between clone/dedupe and memory > > > mapped writes as well as between fallocate and memory mapped writes. For > > > both cases the consequence of the race is that it can makes us deadlock > > > when we are low on available metadata space, since clone/dedupe/fallocate > > > start a transaction while holding file ranges locked, and allocating the > > > metadata can result in the async reclaim task to flush the inodes being > > > used by clone/dedupe/fallocate, if a memory mapped write happened before > > > we locked the file ranges. > > > > > > For the dedupe case, Josef's recent fix [1] ("btrfs: fix race between > > > dedupe > > > and mmap") happens to fix this deadlock problem as well. The first patch > > > in this patchset fixes the issue for both clone and dedupe, as it's > > > centered > > > on the shared extent locking function, and it is independent of Josef's > > > fix > > > (works both with and without that fix). > > > > Thanks, I was wondering how all the patches are related. > > > > > > [1] > > > https://lore.kernel.org/linux-btrfs/afdc2109f83fff1a925d7a66a6a047d4400721d4.1607724668.git.jo...@toxicpanda.com/ > > > > > > Filipe Manana (2): > > > btrfs: fix race between cloning and memory mapped writes leading to > > > deadlock > > > btrfs: fix race between fallocate and memory mapped writes leading to > > > deadlock > > > > Added to misc-next, thanks. > > Something I haven't mentioned afterwards, as I have been waiting for > vger to deliver me the mails for another patchset from Josef (have > been having 2 to 4 days delays) is that that patchset from Josef: > > https://lore.kernel.org/linux-btrfs/[email protected]/ > > replaces this patchset and the following RFC patch: > > https://lore.kernel.org/linux-btrfs/afdc2109f83fff1a925d7a66a6a047d4400721d4.1607724668.git.jo...@toxicpanda.com/ > > We agreed on Slack that a more generic solution was better, even > because the RFC patch above from Josef ended up being racy and didn't > fully fix the problem. > It doesn't help either that the cover letter for the above patchset > from Josef did not mention this, nor was it discussed in the thread > for the RFC patch. > > So please drop this one and replace it with Josef's patchset. I had > just given the review on github: > https://github.com/btrfs/linux/issues/163
I see, thanks. Patches removed from misc-next.
