From: Timo Sirainen <timo.sirainen@open-xchange.com>
Date: Fri, 27 Mar 2020 16:26:23 +0000 (+0200)
Subject: lib-index: Check if maximum cache file size has reached only after locking
X-Git-Tag: 2.3.11.2~408
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e2bde6ef36e89307648a948dccf91226ac8a2d5d;p=thirdparty%2Fdovecot%2Fcore.git

lib-index: Check if maximum cache file size has reached only after locking

This avoids race conditions.
---

diff --git a/src/lib-index/mail-cache-transaction.c b/src/lib-index/mail-cache-transaction.c
index 8e8224cbc3..0fe5540583 100644
--- a/src/lib-index/mail-cache-transaction.c
+++ b/src/lib-index/mail-cache-transaction.c
@@ -199,17 +199,6 @@ static int mail_cache_transaction_lock(struct mail_cache_transaction_ctx *ctx)
 		cache->index->optimization_set.cache.max_size;
 	int ret;
 
-	(void)mail_cache_open_and_verify(cache);
-	if (!ctx->tried_compression && ctx->cache_data != NULL &&
-	    cache->last_stat_size + ctx->cache_data->used >= cache_max_size) {
-		/* Looks like cache file is becoming too large. Try to compress
-		   it to free up some space. */
-		if (!MAIL_CACHE_IS_UNUSABLE(cache) &&
-		    (cache->hdr->continued_record_count > 0 ||
-		     cache->hdr->deleted_record_count > 0))
-			(void)mail_cache_transaction_compress(ctx);
-	}
-
 	if ((ret = mail_cache_lock(cache)) <= 0) {
 		if (ret < 0)
 			return -1;
@@ -224,6 +213,18 @@ static int mail_cache_transaction_lock(struct mail_cache_transaction_ctx *ctx)
 	}
 	i_assert(!MAIL_CACHE_IS_UNUSABLE(cache));
 
+	if (!ctx->tried_compression && ctx->cache_data != NULL &&
+	    cache->last_stat_size + ctx->cache_data->used >= cache_max_size) {
+		/* Looks like cache file is becoming too large. Try to compress
+		   it to free up some space. */
+		if (cache->hdr->continued_record_count > 0 ||
+		    cache->hdr->deleted_record_count > 0) {
+			(void)mail_cache_unlock(cache);
+			(void)mail_cache_transaction_compress(ctx);
+			return mail_cache_transaction_lock(ctx);
+		}
+	}
+
 	if (ctx->cache_file_seq == 0)
 		ctx->cache_file_seq = cache->hdr->file_seq;
 	else if (ctx->cache_file_seq != cache->hdr->file_seq) {