btrfs: zoned: write out partially allocated region
cow_file_range() works in an all-or-nothing way: if it fails to allocate an extent for a part of the given region, it gives up all the region including the successfully allocated parts. On cow_file_range(), run_delalloc_zoned() writes data for the region only when it successfully allocate all the region. This all-or-nothing allocation and write-out are problematic when available space in all the block groups are get tight with the active zone restriction. btrfs_reserve_extent() try hard to utilize the left space in the active block groups and gives up finally and fails with -ENOSPC. However, if we send IOs for the successfully allocated region, we can finish a zone and can continue on the rest of the allocation on a newly allocated block group. This patch implements the partial write-out for run_delalloc_zoned(). With this patch applied, cow_file_range() returns -EAGAIN to tell the caller to do something to progress the further allocation, and tells the successfully allocated region with done_offset. Furthermore, the zoned extent allocator returns -EAGAIN to tell cow_file_range() going back to the caller side. Actually, we still need to wait for an IO to complete to continue the allocation. The next patch implements that part. CC: stable@vger.kernel.org # 5.16+ Fixes: afba2bc0 ("btrfs: zoned: implement active zone tracking") Signed-off-by:Naohiro Aota <naohiro.aota@wdc.com> Signed-off-by:
David Sterba <dsterba@suse.com>
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b6a98021