Clear ref_blkno output when block is already dirty - #315
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scoutfs_block_dirty_ref() only sets *ref_blkno on the path that allocates a new cow block. The early return paths leave it untouched, so a caller that reads it back gets whatever value was on the stack. This is harmless with the current callers. dirty_alloc_blocks() bails out before calling here when the blocks are already dirty, so the early return on an already-dirty block is never reached, and the error paths return a negative value that callers check before using ref_blkno. Signed-off-by: Auke Kok <auke.kok@versity.com>
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block_dirty_ref() skipped setting *ref_blkno when the block was already dirty, leaving the caller with a stale value passed by reference.
dirty_alloc_blocks() calls it twice but when the referenced block is already dirty, it will receive the uninitialized stack value back, and then adding it freed list with list_block_add() later.
Set it to 0 on the already-dirty fast path so callers do not try to free a random block.