xfs: shut down zoned file systems on writeback errors

Zoned writeback allocates space from an open zone and advances the
in-memory allocation state before submitting the bio. The completion
path only records the written blocks and updates the mapping on success.
If the write fails, XFS cannot tell how far the device write pointer
advanced and cannot safely roll the open zone accounting back.

This was observed while investigating xfs/643 and xfs/646 on an external
ZNS realtime device. A writeback error after consuming space from an
open zone left later writers waiting for open-zone or GC progress that
could not happen. xfs/643 exposed this through the GC defragmentation
path, while xfs/646 exposed the same failure mode through the
truncate/EOF-zeroing space wait path.

There is no local recovery path in ioend completion that can restore a
consistent zoned allocation state after the device has rejected the
write. Treat writeback errors for zoned inodes as fatal and force a
file system shutdown from the ioend completion path. The existing
shutdown path wakes zoned allocation waiters and makes future space
waits return -EIO instead of leaving tasks stuck waiting for progress.

Signed-off-by: Yao Sang <sangyao@kylinos.cn>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Carlos Maiolino <cem@kernel.org>

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