block processor: simplify backlog accounting

Simply count the number of blocks we hand out (malloc'ed or recycled)
and decrease the counter when we put blocks back for recycling.

The sync() part becomes a little more complicated, because we can get
stuck with a backlog of 1 or 2 because we have a fragment or current
block buffer in use. We also need to accout for this when creating the
processor, because we need to be able to request at least 2 blocks
without stalling.

Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>

1 files changed, 4 insertions, 2 deletions

diff --git a/lib/sqfs/block_processor/frontend.c b/lib/sqfs/block_processor/frontend.c
index ccf54c0..a4a38e9 100644
--- a/lib/sqfs/block_processor/frontend.c
+++ b/lib/sqfs/block_processor/frontend.c
@@ -28,6 +28,8 @@ static int get_new_block(sqfs_block_processor_t *proc, sqfs_block_t **out)
 
 	memset(blk, 0, sizeof(*blk));
 	*out = blk;
+
+	proc->backlog += 1;
 	return 0;
 }
 
@@ -56,11 +58,11 @@ int enqueue_block(sqfs_block_processor_t *proc, sqfs_block_t *blk)
 		if (status == 0)
 			status = SQFS_ERROR_ALLOC;
 
-		free(blk);
+		blk->next = proc->free_list;
+		proc->free_list = blk;
 		return status;
 	}
 
-	proc->backlog += 1;
 	return 0;
 }