[PATCH 1/4] erofs-utils: compress trailing data for big pcluster properly

[Gao Xiang]

Compress in smaller pcluster size if the trailing data isn't enough for
maximum pcluster size instead of leaving trailing data uncompressed.

Fixes: b71dc92df6f1 ("erofs-utils: mkfs: support multiple block compression")
Signed-off-by: Gao Xiang <xiang at kernel.org>
---
 lib/compress.c   | 11 ++++++++---
 lib/compressor.c |  5 ++++-
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/lib/compress.c b/lib/compress.c
index deef6a2c8ae3..e146416890f0 100644
--- a/lib/compress.c
+++ b/lib/compress.c
@@ -166,9 +166,12 @@ static int vle_compress_one(struct erofs_inode *inode,
 		bool raw;
 
 		if (len <= pclustersize) {
-			if (final)
-				goto nocompression;
-			break;
+			if (final) {
+				if (len <= EROFS_BLKSIZ)
+					goto nocompression;
+			} else {
+				break;
+			}
 		}
 
 		count = len;
@@ -195,6 +198,8 @@ nocompression:
 					EROFS_BLKSIZ - tailused : 0;
 
 			ctx->compressedblks = DIV_ROUND_UP(ret, EROFS_BLKSIZ);
+			DBG_BUGON(ctx->compressedblks * EROFS_BLKSIZ >= count);
+
 			/* zero out garbage trailing data for non-0padding */
 			if (!erofs_sb_has_lz4_0padding())
 				memset(dst + ret, 0,
diff --git a/lib/compressor.c b/lib/compressor.c
index b2434e0e5418..8836e0c785ba 100644
--- a/lib/compressor.c
+++ b/lib/compressor.c
@@ -28,6 +28,7 @@ int erofs_compress_destsize(struct erofs_compress *c,
 			    void *dst,
 			    unsigned int dstsize)
 {
+	unsigned uncompressed_size;
 	int ret;
 
 	DBG_BUGON(!c->alg);
@@ -40,7 +41,9 @@ int erofs_compress_destsize(struct erofs_compress *c,
 		return ret;
 
 	/* check if there is enough gains to compress */
-	if (*srcsize <= dstsize * c->compress_threshold / 100)
+	uncompressed_size = *srcsize;
+	if (roundup(ret, EROFS_BLKSIZ) >= uncompressed_size *
+	    c->compress_threshold / 100)
 		return -EAGAIN;
 	return ret;
 }
-- 
2.20.1