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=-5.7 required=3.0 tests=AWL,BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,RCVD_IN_DNSWL_HI,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 D717B1FEB3 for ; Fri, 6 Jan 2017 16:23:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S967482AbdAFQXe (ORCPT ); Fri, 6 Jan 2017 11:23:34 -0500 Received: from alum-mailsec-scanner-5.mit.edu ([18.7.68.17]:44603 "EHLO alum-mailsec-scanner-5.mit.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S966898AbdAFQXN (ORCPT ); Fri, 6 Jan 2017 11:23:13 -0500 X-AuditID: 12074411-fbbff700000009b7-02-586fc46a04e1 Received: from outgoing-alum.mit.edu (OUTGOING-ALUM.MIT.EDU [18.7.68.33]) by alum-mailsec-scanner-5.mit.edu (Symantec Messaging Gateway) with SMTP id DC.E6.02487.A64CF685; Fri, 6 Jan 2017 11:23:06 -0500 (EST) Received: from bagpipes.fritz.box (p57906F4E.dip0.t-ipconnect.de [87.144.111.78]) (authenticated bits=0) (User authenticated as mhagger@ALUM.MIT.EDU) by outgoing-alum.mit.edu (8.13.8/8.12.4) with ESMTP id v06GMmWw023262 (version=TLSv1/SSLv3 cipher=AES128-SHA bits=128 verify=NOT); Fri, 6 Jan 2017 11:23:04 -0500 From: Michael Haggerty To: Junio C Hamano Cc: git@vger.kernel.org, Jeff King , David Turner , Jacob Keller , Philip Oakley , Michael Haggerty Subject: [PATCH v4 08/23] lock_ref_sha1_basic(): use raceproof_create_file() Date: Fri, 6 Jan 2017 17:22:28 +0100 Message-Id: X-Mailer: git-send-email 2.9.3 In-Reply-To: References: X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFjrBIsWRmVeSWpSXmKPExsUixO6iqJt1JD/CoPeskkXXlW4mi4beK8wW uxf3M1vcXjGf2WLJw9fMFj9aepgtOqfKOrB7/H3/gclj56y77B7Ll65j9OhqP8Lm8ax3D6PH xUvKHp83yQWwR3HZpKTmZJalFunbJXBldO1YxVjwSqji55oLzA2My/i7GDk4JARMJPbPyexi 5OIQErjMKLHq3wMWCOcEk8SfV1uYuhg5OdgEdCUW9TSD2SICahIT2w6BFTELfGCU+NU5ix0k ISzgI3Hq4F6wIhYBVYkjEyGaeQWiJB5t/MMKYksIyElc2vaFGcTmFLCQaNz1jRHEFhIwl/g0 8TDzBEaeBYwMqxjlEnNKc3VzEzNzilOTdYuTE/PyUot0TfVyM0v0UlNKNzFCAkxwB+OMk3KH GAU4GJV4eCO88iKEWBPLiitzDzFKcjApifKGOeZHCPEl5adUZiQWZ8QXleakFh9ilOBgVhLh tTsElONNSaysSi3Kh0lJc7AoifPyLVH3ExJITyxJzU5NLUgtgsnKcHAoSfD+AWkULEpNT61I y8wpQUgzcXCCDOcBGi54GGR4cUFibnFmOkT+FKOilDjvFpBmAZBERmkeXC8sAbxiFAd6RZhX GKSdB5g84LpfAQ1mAhnsCTa4JBEhJdXAOF+Is2QX076vTd2zztgsOdd3TOjc8scXD73f8fX8 jDOdtaU1TB86/hjHiLLMsIg5dIR3geTrS95FhVWsJlHPXIS/Z6UcUGWaI1W+cfE0szb5zl83 r5lcyq5r0X3BmVW1/PDD+sfJ4mtDXdurV77x2NRxdmZcyZ2W+ZXrntYLTZw0eYfL48NKUkos xRmJhlrMRcWJADtRUo7bAgAA Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Instead of coding the retry loop inline, use raceproof_create_file() to make lock acquisition safe against directory creation/deletion races. Signed-off-by: Michael Haggerty --- refs/files-backend.c | 35 +++++++++-------------------------- 1 file changed, 9 insertions(+), 26 deletions(-) diff --git a/refs/files-backend.c b/refs/files-backend.c index 7d4658a..74de289 100644 --- a/refs/files-backend.c +++ b/refs/files-backend.c @@ -1985,6 +1985,13 @@ static int remove_empty_directories(struct strbuf *path) return remove_dir_recursively(path, REMOVE_DIR_EMPTY_ONLY); } +static int create_reflock(const char *path, void *cb) +{ + struct lock_file *lk = cb; + + return hold_lock_file_for_update(lk, path, LOCK_NO_DEREF) < 0 ? -1 : 0; +} + /* * Locks a ref returning the lock on success and NULL on failure. * On failure errno is set to something meaningful. @@ -2002,7 +2009,6 @@ static struct ref_lock *lock_ref_sha1_basic(struct files_ref_store *refs, int last_errno = 0; int mustexist = (old_sha1 && !is_null_sha1(old_sha1)); int resolve_flags = RESOLVE_REF_NO_RECURSE; - int attempts_remaining = 3; int resolved; assert_main_repository(&refs->base, "lock_ref_sha1_basic"); @@ -2067,35 +2073,12 @@ static struct ref_lock *lock_ref_sha1_basic(struct files_ref_store *refs, lock->ref_name = xstrdup(refname); - retry: - switch (safe_create_leading_directories_const(ref_file.buf)) { - case SCLD_OK: - break; /* success */ - case SCLD_VANISHED: - if (--attempts_remaining > 0) - goto retry; - /* fall through */ - default: + if (raceproof_create_file(ref_file.buf, create_reflock, lock->lk)) { last_errno = errno; - strbuf_addf(err, "unable to create directory for '%s'", - ref_file.buf); + unable_to_lock_message(ref_file.buf, errno, err); goto error_return; } - if (hold_lock_file_for_update(lock->lk, ref_file.buf, LOCK_NO_DEREF) < 0) { - last_errno = errno; - if (errno == ENOENT && --attempts_remaining > 0) - /* - * Maybe somebody just deleted one of the - * directories leading to ref_file. Try - * again: - */ - goto retry; - else { - unable_to_lock_message(ref_file.buf, errno, err); - goto error_return; - } - } if (verify_lock(lock, old_sha1, mustexist, err)) { last_errno = errno; goto error_return; -- 2.9.3