erofs: preserve LZMA decoders on resize failure

The pool-resize path frees each stream's old decoder before allocating
its replacement. If an allocation fails after some streams have already
been replaced, the failed stream is put back on the list with state ==
NULL. z_erofs_lzma_max_dictsize is still advanced as if the whole
pool had been resized.

An existing LZMA mount can select the broken stream and pass
NULL to xz_dec_microlzma_reset(). A retry at the same size also
skip another resize attempt. Since the global maximum was advanced,
thus, the invalid state is left unrepaired.

Allocate each replacement before freeing the old decoder, temporarily
retaining one old decoder during allocation. Stop at the first failure
and advance z_erofs_lzma_max_dictsize only after all streams satisfy
the request.

Record each stream's dictionary capacity so retries can skip streams
already enlarged before a partial failure.

Fixes: 622ceaddb764 ("erofs: lzma compression support")
Cc: stable@vger.kernel.org
Signed-off-by: Nikhil Gurudasani <nikhilgurudasani314@gmail.com>
Reviewed-by: Gao Xiang <xiang@kernel.org>
Signed-off-by: Gao Xiang <xiang@kernel.org>

0 files changed, 0 insertions, 0 deletions