From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS31976 209.132.180.0/23 X-Spam-Status: No, score=-3.0 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,RCVD_IN_DNSWL_HI,T_RP_MATCHES_RCVD shortcircuit=no autolearn=ham autolearn_force=no version=3.4.0 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by dcvr.yhbt.net (Postfix) with ESMTP id 1368F1F404 for ; Sat, 13 Jan 2018 16:18:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755159AbeAMQSe (ORCPT ); Sat, 13 Jan 2018 11:18:34 -0500 Received: from eir.is.scarlet.be ([193.74.71.27]:19522 "EHLO eir.is.scarlet.be" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755143AbeAMQSd (ORCPT ); Sat, 13 Jan 2018 11:18:33 -0500 X-Greylist: delayed 366 seconds by postgrey-1.27 at vger.kernel.org; Sat, 13 Jan 2018 11:18:33 EST DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=scarlet.be; s=scarlet; t=1515859926; bh=/O8PCweOgxAQKGdAMk+KQnrkQcusgkoNdK+oFWMJbiU=; h=From:To:Cc:Subject:Date:Message-Id; b=FUvzwygzfTzWJYlpJ1/nzrm8o9oNZ2h5+QmikeoKtq6M4ojmYxdQPPyuC6IS7C4Q/ Fi3FELrwxyQ6W92y93NY9ki4rqQ6OqArxxxIPvd7ppt/lCAGh/oE8x97gKJ1XT5QU/ EPpgVc4r/KjAh8+HcgLLSP2AD0kkY46UP+LyGtng= Received: from localhost.localdomain (ip-213-49-134-254.dsl.scarlet.be [213.49.134.254]) by eir.is.scarlet.be (8.14.9/8.14.9) with ESMTP id w0DGC5Tg018524 (version=TLSv1/SSLv3 cipher=AES256-SHA bits=256 verify=NOT); Sat, 13 Jan 2018 17:12:06 +0100 X-Scarlet: d=1515859926 c=213.49.134.254 From: Kim Gybels To: git@vger.kernel.org Cc: Junio C Hamano , Johannes Schindelin , Michael Haggerty , Kim Gybels Subject: [PATCH] packed_ref_cache: don't use mmap() for small files Date: Sat, 13 Jan 2018 17:11:49 +0100 Message-Id: <20180113161149.9564-1-kgybels@infogroep.be> X-Mailer: git-send-email 2.15.1.windows.2 X-DCC-scarlet.be-Metrics: eir 20002; Body=5 Fuz1=5 Fuz2=5 X-Virus-Scanned: clamav-milter 0.98.1-exp at eir X-Virus-Status: Clean Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Take a hint from commit ea68b0ce9f8ce8da3e360aed3cbd6720159ffbee and use read() instead of mmap() for small packed-refs files. This also fixes the problem[1] where xmmap() returns NULL for zero length[2], for which munmap() later fails. Alternatively, we could simply check for NULL before munmap(), or introduce an xmunmap() that could be used together with xmmap(). [1] https://github.com/git-for-windows/git/issues/1410 [2] Logic introduced in commit 9130ac1e1966adb9922e64f645730d0d45383495 Signed-off-by: Kim Gybels --- refs/packed-backend.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) diff --git a/refs/packed-backend.c b/refs/packed-backend.c index dab8a85d9a..7177e5bc2f 100644 --- a/refs/packed-backend.c +++ b/refs/packed-backend.c @@ -455,6 +455,8 @@ static void verify_buffer_safe(struct snapshot *snapshot) last_line, eof - last_line); } +#define SMALL_FILE_SIZE (32*1024) + /* * Depending on `mmap_strategy`, either mmap or read the contents of * the `packed-refs` file into the snapshot. Return 1 if the file @@ -489,21 +491,21 @@ static int load_contents(struct snapshot *snapshot) die_errno("couldn't stat %s", snapshot->refs->path); size = xsize_t(st.st_size); - switch (mmap_strategy) { - case MMAP_NONE: + if (!size) { + snapshot->buf = NULL; + snapshot->eof = NULL; + snapshot->mmapped = 0; + } else if (size <= SMALL_FILE_SIZE || mmap_strategy == MMAP_NONE) { snapshot->buf = xmalloc(size); bytes_read = read_in_full(fd, snapshot->buf, size); if (bytes_read < 0 || bytes_read != size) die_errno("couldn't read %s", snapshot->refs->path); snapshot->eof = snapshot->buf + size; snapshot->mmapped = 0; - break; - case MMAP_TEMPORARY: - case MMAP_OK: + } else { snapshot->buf = xmmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0); snapshot->eof = snapshot->buf + size; snapshot->mmapped = 1; - break; } close(fd); -- 2.15.1.windows.2