[PATCH] Don't include devicenumber into INODE_CHANGED test [WAS: Re: running git-update-cache --refresh on different machines on a NFS share always ends up in a lot of io/cpu/time waste]

[Thomas Glanzmann <sithglan@stud.uni-erlangen.de>]

Hello,

> Sorry, I meant "rename", not "link", and yes, it should be NFS-safe. It's 
> how all the mailers do things too, afaik.

okay. I will doublecheck that and come back.

> As to your update-cache problem, it seems to be just due to NFS stat
> caching. You generally should _not_ work on two machines at the same time,
> but it probably does the right thing in the end.

I added some debugging output (see attached patch) and saw that the
reason for the invalid thing is that the inode has changed:

...
name: pull.h 0x00000010
name: read-cache.c 0x00000010
...

#define INODE_CHANGED   0x0010

Same problem tla had. It looked at the device number. And of course the
device number for NFS shares isn't the same on all machines. So I
attached a little patch which fixes the issue for me (and others).

> In general, I would suggest using separate GIT repositories over sharing
> them over NFS. As far as I'm concerned, I think NFS should work in the
> sense that you can work from different clients at _different_times_, and
> I'm certainly not going to guarantee that two different clients that work
> at the same time against the same repository will get sane results.

It is more like that I don't remember on which machine I worked last and
working accidently on my next free window in screen (and I have a lot of
windows). And getting 370 Mbyte over NFS hits my nerves. ;-)

> For example, if you do a "git-checkout-cache -f -a" at the same time, I 
> won't guarantee that things won't race on the working files. Don't do it.

I will not do that. And I will add locking for such operations in my frontend
anyway.

	Thomas

CRAP CRAP CRAP: This is just the patch which showed me the debugging
output:

diff --git a/update-cache.c b/update-cache.c
--- a/update-cache.c
+++ b/update-cache.c
@@ -174,6 +174,8 @@ static struct cache_entry *refresh_entry
 	if (!changed)
 		return ce;
 
+	fprintf(stderr, "name: %s 0x%08x\n", ce->name, changed);
+
 	/*
 	 * If the mode or type has changed, there's no point in trying
 	 * to refresh the entry - it's not going to match

Here is the real patch:

[PATCH] Don't include devicenumber into INODE_CHANGED test

This fixes the problem that git-update-cache --refresh rebuilds the
cache stat information everytime it is started on a different host while
working in the same NFS shared repository.

Signed-off-by: Thomas Glanzmann <sithglan@stud.uni-erlangen.de>

diff --git a/read-cache.c b/read-cache.c
--- a/read-cache.c
+++ b/read-cache.c
@@ -65,8 +65,7 @@ int ce_match_stat(struct cache_entry *ce
 	if (ce->ce_uid != htonl(st->st_uid) ||
 	    ce->ce_gid != htonl(st->st_gid))
 		changed |= OWNER_CHANGED;
-	if (ce->ce_dev != htonl(st->st_dev) ||
-	    ce->ce_ino != htonl(st->st_ino))
+	if (ce->ce_ino != htonl(st->st_ino))
 		changed |= INODE_CHANGED;
 	if (ce->ce_size != htonl(st->st_size))
 		changed |= DATA_CHANGED;