btrfs: fix the memory leak caused in lzo_compress_pages()
[BUG] Fstests generic/027 is pretty easy to trigger a slow but steady memory leak if run with "-o compress=lzo" mount option. Normally one single run of generic/027 is enough to eat up at least 4G ram. [CAUSE] In commit d4088803 ("btrfs: subpage: make lzo_compress_pages() compatible") we changed how @page_in is released. But that refactoring makes @page_in only released after all pages being compressed. This leaves error path not releasing @page_in. And by "error path" things like incompressible data will also be treated as an error (-E2BIG). Thus it can cause a memory leak if even nothing wrong happened. [FIX] Add check under @out label to release @page_in when needed, so when we hit any error, the input page is properly released. Reported-by: Josef Bacik <josef@toxicpanda.com> Fixes: d4088803 ("btrfs: subpage: make lzo_compress_pages() compatible") Reviewed-and-tested-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
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