On 2019/12/21 上午1:07, Marc Lehmann wrote: >> Just while I was writing this mail, on 5.4.5, the _newly created_ btrfs >> filesystem I restored to went into readonly mode with ENOSPC. Another >> hardware problem? > > btrfs check gave me a possible hint: > > Checking filesystem on /dev/mapper/xmnt-cold15 > UUID: 6e035cfe-5b47-406a-998f-b8ee6567abbc > [1/7] checking root items > [2/7] checking extents > [3/7] checking free space tree > cache and super generation don't match, space cache will be invalidated That's common, and not a problem at all. Btrfs will rebuild the free space tree. > [4/7] checking fs roots > [no other errors] > > But mounting with clear_cache,space_cache=v2 didn't help, df still shows 0 > bytes free, "btrfs f us" still shows 3tb unallocated. I'll play around with > it more... Df reports 0 available is a bug and caused pinned down. It's btrfs_statfs() can't co-operate with latest over-commit behavior. This happens when there are some metadata operation queued. It's completely a runtime false alert, had nothing incorrect on-disk. I had a fix submitted for it. https://patchwork.kernel.org/patch/11293419/ Thanks, Qu >
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