On Tue, Nov 20, 2018 at 08:04:58AM +1100, Dave Chinner wrote: > From: Dave Chinner <dchinner@xxxxxxxxxx> > > Just tried to punch a 40T sparse file when enospc was triggered due > to extent size hints consuming more space than expected. It failed > with: > > # sudo xfs_io -c "fpunch 0 40t" /mnt/fast/xfs-arekm.img > fallocate: No space left on device > # > > because the writeback error of ENOSPC was being reported. We're > going to free that space, so we don't care if there was a ENOSPC > writeback error. So ignore ENOSPC errors and punch anyway. > > Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx> > --- > fs/xfs/xfs_bmap_util.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c > index 167ff4297e5c..cc7a0d47c529 100644 > --- a/fs/xfs/xfs_bmap_util.c > +++ b/fs/xfs/xfs_bmap_util.c > @@ -1060,8 +1060,13 @@ xfs_flush_unmap_range( > start = round_down(offset, rounding); > end = round_up(offset + len, rounding) - 1; > > + /* > + * We're going to trash the data in this range, so if writeback reports > + * an enospc error, don't let it stop us from /freeing the space/ in the > + * range to alleviate the ENOSPC condition. > + */ > error = filemap_write_and_wait_range(inode->i_mapping, start, end); > - if (error) > + if (error && error != -ENOSPC) I think there's a bug here -- COLLAPSE_RANGE and INSERT_RANGE call xfs_prepare_shift to writeback and invalidate the pagecache from a selected offset to EOF, and _prepare_shift calls _flush_unmap_range. So if we have a dirty 100 block file and we ask xfs to collapse 3 blocks at block 17, it'll _prepare_shift blocks 20-99 before shifting them down by 3 blocks. If we instead asked to insert 3 blocks at block 17, it'll _prepare_shift blocks 17-99 before shifting them up by 3 blocks. Unlike the punch/reflink cases, the _prepare_shift ranges aren't doomed, so the user might want to know if the write fails. --D > return error; > truncate_pagecache_range(inode, start, end); > return 0; > -- > 2.19.1 >
