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[RFC/PATCH] fsck: default to "git fsck --full"

From
Junio C Hamano <gitster@pobox.com>
Date
Oct 20, 2009, 18:46 UTC
Message-ID
<7v3a5doqcg.fsf_-_@alter.siamese.dyndns.org>
In-Reply-To
<vpq1vkygtx6.fsf@bauges.imag.fr>

Linus and other git developers from the early days trained their fingers to type the command, every once in a while even without thinking, to check the consistency of the repository back when the lower core part of the git was still being developed. Developers who wanted to make sure that git correctly dealt with packfiles could deliberately trigger their creation and checked them after they were created carefully, but loose objects are the ones that are written by various commands from random codepaths. It made some technical sense to have a mode that checked only loose objects from the debugging point of view for that reason.

Even for git developers, there no longer is any reason to type "git fsck" every five minutes these days, worried that some newly created objects might be corrupt due to recent change to git.

The reason we did not make "--full" the default is probably we trust our filesystems a bit too much. At least, we trusted filesystems more than we trusted the lower core part of git that was under development.

Once a packfile is created and we always use it read-only, there didn't seem to be much point in suspecting that the underlying filesystems or disks may corrupt them in such a way that is not caught by the SHA-1 checksum over the entire packfile and per object checksum. That trust in the filesystems might have been a good tradeoff between fsck performance and reliability on platforms git was initially developed on and for, but it may not be true anymore as we run on many more platforms these days.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
Matthieu Moy <Matthieu.Moy@grenoble-inp.fr> writes:
Show 16 quoted lines
> Johannes Schindelin <Johannes.Schindelin@gmx.de> writes:
> ...
>> On Tue, 20 Oct 2009, Alex Riesen wrote:
>> ...
>>> --no-full works
>>
>> It works.  Technically.  For human users, though, --loose-objects-only 
>> (with a shortcut "--loose") would be better.
>
> OTOH, the advantage of "--no-full" is that it's compatible with
> existing Git versions. If I learn Git 1.6.6 with --no-full, and use it
> in a script, then my stript works also with older Gits.
>
> But anyway, I think very few people are actually interested in "git
> --no-full" (or call it whatever you like), so I don't think this is
> very important.

For human users, I think --full vs --no-full is quite a nice suggestion, given that we already have advertised --full and people know the option.

Also people know that splicing "no-" after the double dash is often the way to negate a boolean-looking option.

The actual patch to do this is tiny, but that is just a bonus ;-)
 Documentation/RelNotes-1.6.6.txt |   10 ++++++++++
 Documentation/git-fsck.txt       |    5 +++--
 builtin-fsck.c                   |    2 +-
 3 files changed, 14 insertions(+), 3 deletions(-)
diff --git a/Documentation/RelNotes-1.6.6.txt b/Documentation/RelNotes-1.6.6.txt
index 5f1fecb..1896e05 100644
--- a/Documentation/RelNotes-1.6.6.txt
+++ b/Documentation/RelNotes-1.6.6.txt
@@ -1,6 +1,13 @@
 GIT v1.6.6 Release Notes
 ========================
 
+In this release, "git fsck" defaults to "git fsck --full" and checks
+packfiles.  If you prefer a quicker check only on loose objects (the
+old default), you can say "git fsck --no-full".  This has been
+supported by 1.5.4 and newer versions of git, so it is safe to write
+it in your script if you use slightly older git on some of your
+machines.
+
 In git 1.7.0, which is planned to be the release after 1.6.6, "git
 push" into a branch that is currently checked out will be refused by
 default.
@@ -38,6 +45,9 @@ Updates since v1.6.5
 
 (usability, bells and whistles)
 
+ * "git fsck" by default checks the packfiles (i.e. "--full" is the
+   default); you can turn it off with "git fsck --no-full".
+
  * "git log --decorate" shows the location of HEAD as well.
 
 (developers)
diff --git a/Documentation/git-fsck.txt b/Documentation/git-fsck.txt
index 287c4fc..6fe9484 100644
--- a/Documentation/git-fsck.txt
+++ b/Documentation/git-fsck.txt
@@ -10,7 +10,7 @@ SYNOPSIS
 --------
 [verse]
 'git fsck' [--tags] [--root] [--unreachable] [--cache] [--no-reflogs]
-	 [--full] [--strict] [--verbose] [--lost-found] [<object>*]
+	 [--[no-]full] [--strict] [--verbose] [--lost-found] [<object>*]
 
 DESCRIPTION
 -----------
@@ -52,7 +52,8 @@ index file, all SHA1 references in .git/refs/*, and all reflogs (unless
 	or $GIT_DIR/objects/info/alternates,
 	and in packed git archives found in $GIT_DIR/objects/pack
 	and corresponding pack subdirectories in alternate
-	object pools.
+	object pools.  This is now default; you can turn it off
+	with --no-full.
 
 --strict::
 	Enable more strict checking, namely to catch a file mode
diff --git a/builtin-fsck.c b/builtin-fsck.c
index c58b0e3..2d88e45 100644
--- a/builtin-fsck.c
+++ b/builtin-fsck.c
@@ -19,7 +19,7 @@ static int show_root;
 static int show_tags;
 static int show_unreachable;
 static int include_reflogs = 1;
-static int check_full;
+static int check_full = 1;
 static int check_strict;
 static int keep_cache_objects;
 static unsigned char head_sha1[20];
Previous: Matthieu MoyNext: Nicolas Pitre
Message 13 of 21 in “git fsck not identifying corrupted packs”
  1. Sergio CallegariOct 19, 2009
  2. Johannes SixtOct 19, 2009
  3. Johannes SchindelinOct 19, 2009
  4. Junio C HamanoOct 19, 2009
  5. Wesley J. LandakerOct 19, 2009
  6. Robin RosenbergOct 20, 2009
  7. Wesley J. LandakerOct 20, 2009
  8. Matthieu MoyOct 20, 2009
  9. Junio C HamanoOct 20, 2009
  10. Alex RiesenOct 20, 2009
  11. Johannes SchindelinOct 20, 2009
  12. Matthieu MoyOct 20, 2009
  13. fsck: default to "git fsck --full"Junio C Hamano, Oct 20, 2009
  14. Nicolas PitreOct 20, 2009
  15. Junio C HamanoOct 20, 2009
  16. Nicolas PitreOct 20, 2009
  17. Alex RiesenOct 20, 2009
  18. Sergio CallegariOct 19, 2009
  19. Wesley J. LandakerOct 19, 2009
  20. Matthieu MoyOct 20, 2009
  21. Gabor GombasOct 19, 2009

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