Page MenuHomeFreeBSD
Differential D50196

makefs: Ensure that FFS superblocks are reproducible
ClosedPublic
Actions

Authored by markj on Tue, May 6, 3:53 PM.
Tags
None
Referenced Files
Unknown Object (File)
Tue, May 27, 6:00 AM
Unknown Object (File)
Mon, May 26, 4:32 PM
Unknown Object (File)
Fri, May 23, 9:40 PM
Unknown Object (File)
Thu, May 22, 8:20 PM
Unknown Object (File)
Sun, May 11, 8:40 AM
Unknown Object (File)
Sun, May 11, 7:45 AM
Unknown Object (File)
Sat, May 10, 7:46 AM
Unknown Object (File)
Sat, May 10, 7:43 AM
View All 9 Files
Subscribers
imp

Details

Reviewers
emaste
mckusick
Commits
rG764ccf410c3c: makefs: Ensure that FFS superblocks are reproducible
Summary

The superblock structure has space reserved for a pointer to an
in-memory structure that gets created at mount time. makefs populates
it since that simplifies code elsewhere. However, the pointer value
ends up in the output file, which breaks reproducibility.

Zero the field instead, as its on-disk value is ignored.

Sponsored by: Klara, Inc.
Sponsored by: The FreeBSD Foundation

Diff Detail

Repository
rG FreeBSD src repository
Lint
Lint Skipped
Unit
Tests Skipped
Build Status
Buildable 63946
Build 60830: arc lint + arc unit

Event Timeline

markj created this revision.Tue, May 6, 3:53 PM
Herald added a subscriber: imp. · View Herald TranscriptTue, May 6, 3:53 PM
markj requested review of this revision.Tue, May 6, 3:53 PM
Harbormaster completed remote builds in B63946: Diff 154952.Tue, May 6, 3:53 PM
emaste accepted this revision.Tue, May 6, 4:44 PM

Fine with me (even if it does seem a little strange to zero fs_si, copy, and then restore it).
Out of curiosity what do we do in kernel ffs?

This revision is now accepted and ready to land.Tue, May 6, 4:44 PM
markj added a comment.Tue, May 6, 4:48 PM
In D50196#1144990, @emaste wrote:

Fine with me (even if it does seem a little strange to zero fs_si, copy, and then restore it).

At first I tried not populating it at all, but that introduces a bunch of complexity elsewhere.

Out of curiosity what do we do in kernel ffs?

The on-disk value seems to be ignored. ffs_sbget() allocates the summary info structure and glues it into the returned superblock structure, overwriting whatever happened to be on disk.

Closed by commit rG764ccf410c3c: makefs: Ensure that FFS superblocks are reproducible (authored by markj). · Explain WhyThu, May 8, 4:04 PM
This revision was automatically updated to reflect the committed changes.
markj added a commit: rG764ccf410c3c: makefs: Ensure that FFS superblocks are reproducible.
mckusick added a comment.Thu, May 8, 7:58 PM

This has been fixed in newfs for some time. Along with numerous other changes like checkhash validations, superblock integrity checks, and other fixes and improvements. In my opinion makefs/ffs should just use use newfs/mkfs.c rather than (poorly) trying to parody it.

Revision Contents
Changeset List

PathSize
usr.sbin/
makefs/
ffs/
12 lines

Diff 154952

View Options

usr.sbin/makefs/ffs/mkfs.c

Loading...