Message ID | 20200102112746.145045-4-wqu@suse.com (mailing list archive) |
---|---|
State | New, archived |
Headers | show |
Series | Introduce per-profile available space array to avoid over-confident can_overcommit() | expand |
On 1/2/20 6:27 AM, Qu Wenruo wrote: > For the following disk layout, can_overcommit() can cause false > confidence in available space: > > devid 1 unallocated: 1T > devid 2 unallocated: 10T > metadata type: RAID1 > > As can_overcommit() simply uses unallocated space with factor to > calculate the allocatable metadata chunk size. > > can_overcommit() believes we still have 5.5T for metadata chunks, while > the truth is, we only have 1T available for metadata chunks. > This can lead to ENOSPC at run_delalloc_range() and cause transaction > abort. > > Since factor based calculation can't distinguish RAID1/RAID10 and DUP at > all, we need proper chunk-allocator level awareness to do such estimation. > > Thankfully, we have per-profile available space already calculated, just > use that facility to avoid such false confidence. > > Reported-by: Marc Lehmann <schmorp@schmorp.de> > Signed-off-by: Qu Wenruo <wqu@suse.com> I don't expect this will change much as you mess with the other code, so you can go ahead and add Reviewed-by: Josef Bacik <josef@toxicpanda.com> To this one, thanks, Josef
diff --git a/fs/btrfs/space-info.c b/fs/btrfs/space-info.c index f09aa6ee9113..c26aba9e7124 100644 --- a/fs/btrfs/space-info.c +++ b/fs/btrfs/space-info.c @@ -164,10 +164,10 @@ static int can_overcommit(struct btrfs_fs_info *fs_info, enum btrfs_reserve_flush_enum flush, bool system_chunk) { + enum btrfs_raid_types index; u64 profile; u64 avail; u64 used; - int factor; /* Don't overcommit when in mixed mode. */ if (space_info->flags & BTRFS_BLOCK_GROUP_DATA) @@ -179,16 +179,15 @@ static int can_overcommit(struct btrfs_fs_info *fs_info, profile = btrfs_metadata_alloc_profile(fs_info); used = btrfs_space_info_used(space_info, true); - avail = atomic64_read(&fs_info->free_chunk_space); /* - * If we have dup, raid1 or raid10 then only half of the free - * space is actually usable. For raid56, the space info used - * doesn't include the parity drive, so we don't have to - * change the math + * Grab avail space from per-profile array which should be as accurate + * as chunk allocator. */ - factor = btrfs_bg_type_to_factor(profile); - avail = div_u64(avail, factor); + index = btrfs_bg_flags_to_raid_index(profile); + spin_lock(&fs_info->fs_devices->per_profile_lock); + avail = fs_info->fs_devices->per_profile_avail[index]; + spin_unlock(&fs_info->fs_devices->per_profile_lock); /* * If we aren't flushing all things, let us overcommit up to
For the following disk layout, can_overcommit() can cause false confidence in available space: devid 1 unallocated: 1T devid 2 unallocated: 10T metadata type: RAID1 As can_overcommit() simply uses unallocated space with factor to calculate the allocatable metadata chunk size. can_overcommit() believes we still have 5.5T for metadata chunks, while the truth is, we only have 1T available for metadata chunks. This can lead to ENOSPC at run_delalloc_range() and cause transaction abort. Since factor based calculation can't distinguish RAID1/RAID10 and DUP at all, we need proper chunk-allocator level awareness to do such estimation. Thankfully, we have per-profile available space already calculated, just use that facility to avoid such false confidence. Reported-by: Marc Lehmann <schmorp@schmorp.de> Signed-off-by: Qu Wenruo <wqu@suse.com> --- fs/btrfs/space-info.c | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-)