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* [PATCH] enable core.fsyncObjectFiles by default
@ 2018-01-17 18:48 Christoph Hellwig
  2018-01-17 19:04 ` Junio C Hamano
  2018-01-17 20:55 ` Jeff King
  0 siblings, 2 replies; 60+ messages in thread
From: Christoph Hellwig @ 2018-01-17 18:48 UTC (permalink / raw)
  To: git; +Cc: linux-fsdevel

fsync is required for data integrity as there is no gurantee that
data makes it to disk at any specified time without it.  Even for
ext3 with data=ordered mode the file system will only commit all
data at some point in time that is not guaranteed.

I've lost data on development machines with various times countless
times due to the lack of this option, and now lost trees on a
git server with ext4 as well yesterday.  It's time to make git
safe by default.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 Documentation/config.txt | 6 ++----
 environment.c            | 2 +-
 2 files changed, 3 insertions(+), 5 deletions(-)

diff --git a/Documentation/config.txt b/Documentation/config.txt
index 0e25b2c92..9a1cec5c8 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -866,10 +866,8 @@ core.whitespace::
 core.fsyncObjectFiles::
 	This boolean will enable 'fsync()' when writing object files.
 +
-This is a total waste of time and effort on a filesystem that orders
-data writes properly, but can be useful for filesystems that do not use
-journalling (traditional UNIX filesystems) or that only journal metadata
-and not file contents (OS X's HFS+, or Linux ext3 with "data=writeback").
+This option is enabled by default and ensures actual data integrity
+by calling fsync after writing object files.
 
 core.preloadIndex::
 	Enable parallel index preload for operations like 'git diff'
diff --git a/environment.c b/environment.c
index 63ac38a46..c74375b5e 100644
--- a/environment.c
+++ b/environment.c
@@ -36,7 +36,7 @@ const char *git_hooks_path;
 int zlib_compression_level = Z_BEST_SPEED;
 int core_compression_level;
 int pack_compression_level = Z_DEFAULT_COMPRESSION;
-int fsync_object_files;
+int fsync_object_files = 1;
 size_t packed_git_window_size = DEFAULT_PACKED_GIT_WINDOW_SIZE;
 size_t packed_git_limit = DEFAULT_PACKED_GIT_LIMIT;
 size_t delta_base_cache_limit = 96 * 1024 * 1024;
-- 
2.14.2


^ permalink raw reply	[flat|nested] 60+ messages in thread
* [PATCH] Enable core.fsyncObjectFiles by default
@ 2015-06-23 21:57 Stefan Beller
  2015-06-23 22:21 ` Junio C Hamano
                   ` (2 more replies)
  0 siblings, 3 replies; 60+ messages in thread
From: Stefan Beller @ 2015-06-23 21:57 UTC (permalink / raw)
  To: git; +Cc: gitster, peff, torvalds, Stefan Beller

Linus Torvalds started a discussion[1] if we want to play rather safe
than use defaults which make sense only for the most power users of Git:

> So git is "safe" in the sense that you won't really lose any data,
> but you may well be inconvenienced.  The "fsync each object" config
> option is there in case you don't want that inconvenience, but it
> should be noted that it can make for a hell of a performance impact.

> Of course, it might well be the case that the actual default
> might be worth turning around. Most git users probably don't
> care about that kind of "apply two hundred patches from Andrew
> Morton" kind of workload, although "rebase a big patch-series"
> does end up doing basically the same thing, and might be more
> common.

This patch enables fsync_object_files by default.

[1] https://plus.google.com/u/1/+JonathanCorbet/posts/JBxiKPe3VXa

Signed-off-by: Stefan Beller <sbeller@google.com>
---
 Documentation/config.txt | 8 ++++----
 environment.c            | 2 +-
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/Documentation/config.txt b/Documentation/config.txt
index 43bb53c..dce2640 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -693,10 +693,10 @@ core.whitespace::
 core.fsyncObjectFiles::
 	This boolean will enable 'fsync()' when writing object files.
 +
-This is a total waste of time and effort on a filesystem that orders
-data writes properly, but can be useful for filesystems that do not use
-journalling (traditional UNIX filesystems) or that only journal metadata
-and not file contents (OS X's HFS+, or Linux ext3 with "data=writeback").
+This ensures objects are written to disk instead of relying on the
+operating systems cache and eventual write. Disabling this option will
+yield performance with a trade off in safety for repository corruption
+during power loss.
 
 core.preloadIndex::
 	Enable parallel index preload for operations like 'git diff'
diff --git a/environment.c b/environment.c
index 61c685b..b406f5e 100644
--- a/environment.c
+++ b/environment.c
@@ -35,7 +35,7 @@ const char *git_attributes_file;
 int zlib_compression_level = Z_BEST_SPEED;
 int core_compression_level;
 int core_compression_seen;
-int fsync_object_files;
+int fsync_object_files = 1;
 size_t packed_git_window_size = DEFAULT_PACKED_GIT_WINDOW_SIZE;
 size_t packed_git_limit = DEFAULT_PACKED_GIT_LIMIT;
 size_t delta_base_cache_limit = 96 * 1024 * 1024;
-- 
2.4.1.345.gab207b6.dirty

^ permalink raw reply	[flat|nested] 60+ messages in thread

end of thread, back to index

Thread overview: 60+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-01-17 18:48 [PATCH] enable core.fsyncObjectFiles by default Christoph Hellwig
2018-01-17 19:04 ` Junio C Hamano
2018-01-17 19:35   ` Christoph Hellwig
2018-01-17 20:05     ` Andreas Schwab
2018-01-17 19:37   ` Matthew Wilcox
2018-01-17 19:42     ` Christoph Hellwig
2018-01-17 21:44   ` Ævar Arnfjörð Bjarmason
2018-01-17 22:07     ` Linus Torvalds
2018-01-17 22:25       ` Linus Torvalds
2018-01-17 23:16       ` Ævar Arnfjörð Bjarmason
2018-01-17 23:42         ` Linus Torvalds
2018-01-17 23:52       ` Theodore Ts'o
2018-01-17 23:57         ` Linus Torvalds
2018-01-18 16:27           ` Christoph Hellwig
2018-01-19 19:08             ` Junio C Hamano
2018-01-20 22:14               ` Theodore Ts'o
2018-01-20 22:27                 ` Junio C Hamano
2018-01-22 15:09                   ` Ævar Arnfjörð Bjarmason
2018-01-22 18:09                     ` Theodore Ts'o
2018-01-23  0:47                       ` Jeff King
2018-01-23  5:45                         ` Theodore Ts'o
2018-01-23 16:17                           ` Jeff King
2018-01-23  0:25                     ` Jeff King
2018-01-21 21:32             ` Chris Mason
2020-09-17 11:06         ` Ævar Arnfjörð Bjarmason
2020-09-17 11:28           ` [RFC PATCH 0/2] should core.fsyncObjectFiles fsync the dir entry + docs Ævar Arnfjörð Bjarmason
2020-09-17 11:28           ` [RFC PATCH 1/2] sha1-file: fsync() loose dir entry when core.fsyncObjectFiles Ævar Arnfjörð Bjarmason
2020-09-17 13:16             ` Jeff King
2020-09-17 15:09               ` Christoph Hellwig
2020-09-17 14:09             ` Christoph Hellwig
2020-09-17 14:55               ` Jeff King
2020-09-17 14:56                 ` Christoph Hellwig
2020-09-17 15:37                   ` Junio C Hamano
2020-09-17 17:12                     ` Jeff King
2020-09-17 20:37                       ` Taylor Blau
2020-09-22 10:42               ` Ævar Arnfjörð Bjarmason
2020-09-17 20:21             ` Johannes Sixt
2020-09-22  8:24               ` Ævar Arnfjörð Bjarmason
2020-11-19 11:38                 ` Johannes Schindelin
2020-09-17 11:28           ` [RFC PATCH 2/2] core.fsyncObjectFiles: make the docs less flippant Ævar Arnfjörð Bjarmason
2020-09-17 14:12             ` Christoph Hellwig
2020-09-17 15:43             ` Junio C Hamano
2020-09-17 20:15               ` Johannes Sixt
2020-10-08  8:13               ` Johannes Schindelin
2020-10-08 15:57                 ` Ævar Arnfjörð Bjarmason
2020-10-08 18:53                   ` Junio C Hamano
2020-10-09 10:44                   ` Johannes Schindelin
2020-09-17 19:21             ` Marc Branchaud
2020-09-17 14:14           ` [PATCH] enable core.fsyncObjectFiles by default Christoph Hellwig
2020-09-17 15:30           ` Junio C Hamano
2018-01-17 20:55 ` Jeff King
2018-01-17 21:10   ` Christoph Hellwig
  -- strict thread matches above, loose matches on Subject: below --
2015-06-23 21:57 [PATCH] Enable " Stefan Beller
2015-06-23 22:21 ` Junio C Hamano
2015-06-23 23:29   ` Theodore Ts'o
2015-06-24  5:32     ` Junio C Hamano
2015-06-24 14:30       ` Theodore Ts'o
2015-06-24  1:07 ` Duy Nguyen
2015-06-24  3:37 ` Jeff King
2015-06-24  5:20   ` Junio C Hamano

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