| Message ID | 1540554201-11305-1-git-send-email-nborisov@suse.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | Misc cleanups in balance code | expand |
On Fri, Oct 26, 2018 at 02:43:16PM +0300, Nikolay Borisov wrote: > While investigating the balance hang I came across various inconsistencies in > the source. This series aims to fix those. > > The first patch is (I believe) a fix to a longstanding bug that could cause > balance to fail due to ENOSPC. The code no properly ensures that there is > at least 1g of unallocated space on every device being balance. > > Patch 2 makes btrfs_can_relocate a bit more obvious and removes leftovers from > previous cleanup > > Patches 3/4/5 remove some redundant code from various functions. > > This series has survived multiple xfstest runs. > > Nikolay Borisov (5): > btrfs: Ensure at least 1g is free for balance > btrfs: Refactor btrfs_can_relocate > btrfs: Remove superfluous check form btrfs_remove_chunk > btrfs: Sink find_lock_delalloc_range's 'max_bytes' argument > btrfs: Replace BUG_ON with ASSERT in find_lock_delalloc_range Patches 2-5 on the way to misc-next, thanks. The first one can have user visible consequences, so I'd rather first find out why the 1MB was there and if it's really a bug and what exactly will change when it's 1G.
On 16.11.18 г. 17:18 ч., David Sterba wrote: > On Fri, Oct 26, 2018 at 02:43:16PM +0300, Nikolay Borisov wrote: >> While investigating the balance hang I came across various inconsistencies in >> the source. This series aims to fix those. >> >> The first patch is (I believe) a fix to a longstanding bug that could cause >> balance to fail due to ENOSPC. The code no properly ensures that there is >> at least 1g of unallocated space on every device being balance. >> >> Patch 2 makes btrfs_can_relocate a bit more obvious and removes leftovers from >> previous cleanup >> >> Patches 3/4/5 remove some redundant code from various functions. >> >> This series has survived multiple xfstest runs. >> >> Nikolay Borisov (5): >> btrfs: Ensure at least 1g is free for balance >> btrfs: Refactor btrfs_can_relocate >> btrfs: Remove superfluous check form btrfs_remove_chunk >> btrfs: Sink find_lock_delalloc_range's 'max_bytes' argument >> btrfs: Replace BUG_ON with ASSERT in find_lock_delalloc_range > > Patches 2-5 on the way to misc-next, thanks. The first one can have user > visible consequences, so I'd rather first find out why the 1MB was there > and if it's really a bug and what exactly will change when it's 1G. I'm fine with that, one thing I don't agree with, though, is the conclusion that patch 1 has user visible consequence. As a matter of fact it does not. If btrfs_shrink_device fails with ENOSPC we just break, i/e we don't try to free balance space for any of the other devices, but this doesn't stop from balance actually continuing. As it stands today I think "step one" in __btrfs_balance is more or less null-op, i.e cycles are wasted since all we do is shrink every device by 1mb, ensuring one more mb is already free. I think this is very insufficient for a balance operation and when it succeeds during normal operation it's due to the device already having enough unallocated space before the balance. Anyway, I will speak with Chris to try and find out why the code uses 1mb >