Re: Misterious warning about file system boundaries [It's a bug, not a mystery.]

[Jeff King <peff@peff.net>]

On Thu, Jun 10, 2010 at 07:53:47AM -0700, Junio C Hamano wrote:

> Jeff King <peff@peff.net> writes:
> 
> > Since the early-warning suggestion is generating false positives, and I
> > don't think there is a portable and reliable way around it, dropping it
> > makes sense to me.
> 
> Makes sense.  Let's make it so (I won't have time to do that myself until
> late this evening, though).
> 
> Thanks.

Here it is with a nice commit message (though since it is only in next,
I guess you can just merge the early part and both 52b98a and my revert
will be dropped). It's on top of ld/discovery-limit-to-fs, of course.

Note that it would be possible to do a warning in some instances. We
just can't trust the on-disk index ce_dev information, so if you
actually refreshed two cross-filesystem entries we could detect that.
That is such a minority case that I doubt it is worth caring about,
though.

-- >8 --
Subject: [PATCH] Revert "write-index: check and warn when worktree crosses a filesystem boundary"

This reverts commit 52b98a7d2f12b5d0dd076221d40f8fa93598e11a.

The goal of that commit was to warn users early when their
worktree crossed filesystem boundaries. It worked by
comparing the st_dev stat information in the index, and
warning when we had more than one device.

However, the stat information may come from multiple runs,
and the st_dev field is not necessarily stable. In
particular, st_dev will change on Linux across reboots.
Index entries from the previous reboot will appear to come
from a different device, triggering a false positive.

Since this message is really only an early warning for
people who will be bit by the new
GIT_DISCOVERY_ACROSS_FILESYSTEM behavior, and because they
will get an actual error later on (when we can't find their
cross-filesystem .git directory), we can just scrap the
early warning.

Signed-off-by: Jeff King <peff@peff.net>
---
 read-cache.c |   14 --------------
 1 files changed, 0 insertions(+), 14 deletions(-)

diff --git a/read-cache.c b/read-cache.c
index e381ea5..f1f789b 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -1550,8 +1550,6 @@ int write_index(struct index_state *istate, int newfd)
 	struct cache_entry **cache = istate->cache;
 	int entries = istate->cache_nr;
 	struct stat st;
-	int first_valid_ent = -1;
-	int more_than_one_dev;
 
 	for (i = removed = extended = 0; i < entries; i++) {
 		if (cache[i]->ce_flags & CE_REMOVE)
@@ -1574,7 +1572,6 @@ int write_index(struct index_state *istate, int newfd)
 	if (ce_write(&c, newfd, &hdr, sizeof(hdr)) < 0)
 		return -1;
 
-	more_than_one_dev = 0;
 	for (i = 0; i < entries; i++) {
 		struct cache_entry *ce = cache[i];
 		if (ce->ce_flags & CE_REMOVE)
@@ -1583,19 +1580,8 @@ int write_index(struct index_state *istate, int newfd)
 			ce_smudge_racily_clean_entry(ce);
 		if (ce_write_entry(&c, newfd, ce) < 0)
 			return -1;
-		if (ce_uptodate(ce)) {
-			if (first_valid_ent < 0)
-				first_valid_ent = i;
-			else if (ce->ce_dev != cache[first_valid_ent]->ce_dev)
-				more_than_one_dev = 1;
-		}
 	}
 
-	if (more_than_one_dev &&
-	    !git_env_bool("GIT_DISCOVERY_ACROSS_FILESYSTEM", 0))
-		warning("working tree spans across filesystems but "
-			"GIT_DISCOVERY_ACROSS_FILESYSTEM is not set.");
-
 	/* Write extension data here */
 	if (istate->cache_tree) {
 		struct strbuf sb = STRBUF_INIT;
-- 
1.7.1.516.gd5539.dirty