From: Patrick Steinhardt <ps@pks.im>
To: git@vger.kernel.org
Cc: "Jeff King" <peff@peff.net>,
"Johannes Schindelin" <Johannes.Schindelin@gmx.de>,
"Ævar Arnfjörð Bjarmason" <avarab@gmail.com>,
"Junio C Hamano" <gitster@pobox.com>, "Eric Wong" <e@80x24.org>,
"Neeraj K. Singh" <neerajsi@microsoft.com>
Subject: [PATCH v2 2/3] wrapper: provide function to sync directories
Date: Wed, 10 Nov 2021 12:40:59 +0100 [thread overview]
Message-ID: <3ac9d4d7abd224a4c0991f1036f2d95eedb9ceac.1636544377.git.ps@pks.im> (raw)
In-Reply-To: <cover.1636544377.git.ps@pks.im>
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In ec983eb5d2 (core.fsyncobjectfiles: batched disk flushes, 2021-10-04),
we have introduced batched syncing of object files. This mode works by
only requesting a writeback of the page cache backing the file on
written files, followed by a single hardware-flush via a temporary file
created in the directory we want to flush. Given modern journaling file
systems, this pattern is expected to be durable.
While it's possible to reuse the `git_fsync()` helper to synchronize the
page cache only, there is no helper which would allow for doing a
hardware flush of a directory by creating a temporary file. Other
callers which want to follow the same pattern would thus have to repeat
this logic.
Extract a new helper `git_fsync_dir()` from the object files code which
neatly encapsulates this logic such that it can be reused.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
---
bulk-checkin.c | 13 +++----------
git-compat-util.h | 7 +++++++
wrapper.c | 21 +++++++++++++++++++++
3 files changed, 31 insertions(+), 10 deletions(-)
diff --git a/bulk-checkin.c b/bulk-checkin.c
index 4deee1af46..e6ebdd1db5 100644
--- a/bulk-checkin.c
+++ b/bulk-checkin.c
@@ -98,16 +98,9 @@ static void do_batch_fsync(void)
* hardware.
*/
- if (needs_batch_fsync) {
- struct strbuf temp_path = STRBUF_INIT;
- struct tempfile *temp;
-
- strbuf_addf(&temp_path, "%s/bulk_fsync_XXXXXX", get_object_directory());
- temp = xmks_tempfile(temp_path.buf);
- fsync_or_die(get_tempfile_fd(temp), get_tempfile_path(temp));
- delete_tempfile(&temp);
- strbuf_release(&temp_path);
- }
+ if (needs_batch_fsync &&
+ git_fsync_dir(get_object_directory()) < 0)
+ die_errno("fsyncing object directory");
if (bulk_fsync_objdir)
tmp_objdir_migrate(bulk_fsync_objdir);
diff --git a/git-compat-util.h b/git-compat-util.h
index 97f97178e7..f890bd07fd 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -1221,6 +1221,13 @@ enum fsync_action {
int git_fsync(int fd, enum fsync_action action);
+/*
+ * Issue a full hardware flush against a temporary file in the given directory
+ * to ensure that all files inside that directory are durable before any renames
+ * occur.
+ */
+int git_fsync_dir(const char *path);
+
/*
* Preserves errno, prints a message, but gives no warning for ENOENT.
* Returns 0 on success, which includes trying to unlink an object that does
diff --git a/wrapper.c b/wrapper.c
index e20df4f3a6..6c6cc8b74f 100644
--- a/wrapper.c
+++ b/wrapper.c
@@ -3,6 +3,7 @@
*/
#include "cache.h"
#include "config.h"
+#include "tempfile.h"
static int memory_limit_check(size_t size, int gentle)
{
@@ -601,6 +602,26 @@ int git_fsync(int fd, enum fsync_action action)
return 0;
}
+int git_fsync_dir(const char *path)
+{
+ struct strbuf temp_path = STRBUF_INIT;
+ struct tempfile *temp;
+
+ strbuf_addf(&temp_path, "%s/bulk_fsync_XXXXXX", path);
+
+ temp = mks_tempfile(temp_path.buf);
+ if (!temp)
+ return -1;
+
+ if (git_fsync(get_tempfile_fd(temp), FSYNC_HARDWARE_FLUSH) < 0)
+ return -1;
+
+ delete_tempfile(&temp);
+ strbuf_release(&temp_path);
+
+ return 0;
+}
+
static int warn_if_unremovable(const char *op, const char *file, int rc)
{
int err;
--
2.33.1
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next prev parent reply other threads:[~2021-11-10 11:41 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-04 12:38 [PATCH] refs: sync loose refs to disk before committing them Patrick Steinhardt
2021-11-04 13:14 ` Ævar Arnfjörð Bjarmason
2021-11-04 14:51 ` Patrick Steinhardt
2021-11-04 21:24 ` Junio C Hamano
2021-11-04 22:36 ` Neeraj Singh
2021-11-05 1:40 ` Junio C Hamano
2021-11-05 6:36 ` Jeff King
2021-11-05 8:35 ` Ævar Arnfjörð Bjarmason
2021-11-05 9:04 ` Jeff King
2021-11-05 7:07 ` Jeff King
2021-11-05 7:17 ` Jeff King
2021-11-05 9:12 ` Johannes Schindelin
2021-11-05 9:22 ` Patrick Steinhardt
2021-11-05 9:34 ` Jeff King
2021-11-09 11:25 ` Patrick Steinhardt
2021-11-10 8:36 ` Jeff King
2021-11-10 9:16 ` Patrick Steinhardt
2021-11-10 11:40 ` [PATCH v2 0/3] " Patrick Steinhardt
2021-11-10 11:40 ` [PATCH v2 1/3] wrapper: handle EINTR in `git_fsync()` Patrick Steinhardt
2021-11-10 14:33 ` Johannes Schindelin
2021-11-10 14:39 ` Ævar Arnfjörð Bjarmason
2021-11-10 11:40 ` Patrick Steinhardt [this message]
2021-11-10 14:40 ` [PATCH v2 2/3] wrapper: provide function to sync directories Ævar Arnfjörð Bjarmason
2021-11-10 11:41 ` [PATCH v2 3/3] refs: add configuration to enable flushing of refs Patrick Steinhardt
2021-11-10 14:49 ` Ævar Arnfjörð Bjarmason
2021-11-10 19:15 ` Neeraj Singh
2021-11-10 20:23 ` Ævar Arnfjörð Bjarmason
2021-11-11 0:03 ` Neeraj Singh
2021-11-11 12:14 ` Patrick Steinhardt
2021-11-11 12:06 ` Patrick Steinhardt
2021-11-11 0:18 ` Neeraj Singh
2021-11-10 14:44 ` [PATCH v2 0/3] refs: sync loose refs to disk before committing them Johannes Schindelin
2021-11-10 20:45 ` Jeff King
2021-11-11 11:47 ` Patrick Steinhardt
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