From b11e3e4a2804779a1444c4f4ab2f564e960f8474 Mon Sep 17 00:00:00 2001
From: Simon Rettberg
Date: Tue, 7 Nov 2017 16:39:58 +0100
Subject: [SERVER] Properly clamp to 4k borders in updateCachemap()

Refs #3231
---
 src/server/image.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

(limited to 'src/server')

diff --git a/src/server/image.c b/src/server/image.c
index f0db0a8..d5dd208 100644
--- a/src/server/image.c
+++ b/src/server/image.c
@@ -110,8 +110,15 @@ void image_updateCachemap(dnbd3_image_t *image, uint64_t start, uint64_t end, co
 	assert( image != NULL );
 	// This should always be block borders due to how the protocol works, but better be safe
 	// than accidentally mark blocks as cached when they really aren't entirely cached.
-	end &= ~(uint64_t)(DNBD3_BLOCK_SIZE - 1);
-	start = (uint64_t)(start + DNBD3_BLOCK_SIZE - 1) & ~(uint64_t)(DNBD3_BLOCK_SIZE - 1);
+	if ( set ) {
+		// If we set as cached, move "inwards" in case we're not at 4k border
+		end &= ~(uint64_t)(DNBD3_BLOCK_SIZE - 1);
+		start = (uint64_t)(start + DNBD3_BLOCK_SIZE - 1) & ~(uint64_t)(DNBD3_BLOCK_SIZE - 1);
+	} else {
+		// If marking as NOT cached, move "outwards" in case we're not at 4k border
+		start &= ~(uint64_t)(DNBD3_BLOCK_SIZE - 1);
+		end = (uint64_t)(end + DNBD3_BLOCK_SIZE - 1) & ~(uint64_t)(DNBD3_BLOCK_SIZE - 1);
+	}
 	bool dirty = false;
 	uint64_t pos = start;
 	spin_lock( &image->lock );
-- 
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