superblock has a check-hash error, an error message noting the
superblock check-hash failure is printed and the mount fails. The
administrator then runs fsck to repair the filesystem and when
successful, the filesystem can once again be mounted.
This approach fails if the filesystem in question is a root filesystem
from which you are trying to boot. Here, the loader fails when trying
to access the filesystem to get the kernel to boot. So it is necessary
to allow the loader to ignore the superblock check-hash error and make
a best effort to read the kernel. The filesystem may be suffiently
corrupted that the read attempt fails, but there is no harm in trying
since the loader makes no attempt to write to the filesystem.
Once the kernel is loaded and starts to run, it attempts to mount its
root filesystem. Once again, failure means that it breaks to its prompt
to ask where to get its root filesystem. Unless you have an alternate
root filesystem, you are stuck.
Since the root filesystem is initially mounted read-only, it is
safe to make an attempt to mount the root filesystem with the failed
superblock check-hash. Thus, when asked to mount a root filesystem
with a failed superblock check-hash, the kernel prints a warning
message that the root filesystem superblock check-hash needs repair,
but notes that it is ignoring the error and proceeding. It does
mark the filesystem as needing an fsck which prevents it from being
enabled for writing until fsck has been run on it. The net effect
is that the reboot fails to single user, but at least at that point
the administrator has the tools at hand to fix the problem.
Reported by: Rick Macklem (rmacklem@)
Discussed with: Warner Losh (imp@)
Sponsored by: Netflix
to fix the memory leak that I introduced in r328426. Instead of
trying to clear up the possible memory leak in all the clients, I
ensure that it gets cleaned up in the source (e.g., ffs_sbget ensures
that memory is always freed if it returns an error).
The original change in r328426 was a bit sparse in its description.
So I am expanding on its description here (thanks cem@ and rgrimes@
for your encouragement for my longer commit messages).
In preparation for adding check hashing to superblocks, r328426 is
a refactoring of the code to get the reading/writing of the superblock
into one place. Unlike the cylinder group reading/writing which
ends up in two places (ffs_getcg/ffs_geom_strategy in the kernel
and cgget/cgput in libufs), I have the core superblock functions
just in the kernel (ffs_sbfetch/ffs_sbput in ffs_subr.c which is
already imported into utilities like fsck_ffs as well as libufs to
implement sbget/sbput). The ffs_sbfetch and ffs_sbput functions
take a function pointer to do the actual I/O for which there are
four variants:
ffs_use_bread / ffs_use_bwrite for the in-kernel filesystem
g_use_g_read_data / g_use_g_write_data for kernel geom clients
ufs_use_sa_read for the standalone code (stand/libsa/ufs.c
but not stand/libsa/ufsread.c which is size constrained)
use_pread / use_pwrite for libufs
Uses of these interfaces are in the UFS filesystem, geoms journal &
label, libsa changes, and libufs. They also permeate out into the
filesystem utilities fsck_ffs, newfs, growfs, clri, dump, quotacheck,
fsirand, fstyp, and quot. Some of these utilities should probably be
converted to directly use libufs (like dumpfs was for example), but
there does not seem to be much win in doing so.
Tested by: Peter Holm (pho@)
ffs_sbget() may return a superblock buffer even if it fails, so the
caller must be prepared to free it in this case. Moreover, when tasting
alternate superblock locations in a loop, ffs_sbget()'s readfunc
callback must free the previously allocated buffer.
Reported and tested by: pho
Reviewed by: kib (previous version)
Differential Revision: https://reviews.freebsd.org/D14390
Specifically reading is done if ffs_sbget() and writing is done
in ffs_sbput(). These functions are exported to libufs via the
sbget() and sbput() functions which then used in the various
filesystem utilities. This work is in preparation for adding
subperblock check hashes.
No functional change intended.
Reviewed by: kib
Mainly focus on files that use BSD 2-Clause license, however the tool I
was using mis-identified many licenses so this was mostly a manual - error
prone - task.
The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.
brings in support for an optional intent log which eliminates the need
for background fsck on unclean shutdown.
Sponsored by: iXsystems, Yahoo!, and Juniper.
With help from: McKusick and Peter Holm
for the sorts of errors we run into[1]. This also gives us room to put in a
vaguely appropriate casts to silence warnings since our compiler doesn't like
when we compare ssize_t to size_t[2]. Add a cast in sblock.c[3] to silence
a warning because of signed vs. size_t hell (again). Clean up nearby
excessive parenthemutilation[4].
Reviewed by: bde [2] [3]
Suggested by: bde, many [1]
Submitted by: bde [4]
An aside about [4], bde notes that we do not check for a negative value for
the fs bsize. I'm nto going to do that in every situation we use it, one must
expect a reasonable program to pass down reasonable values. Some foot shooting
protection I will tolerate, some I will not. Also he suggests some possible
conditional improvements there, which I may take to heart.
PS: For me at least, this is now WARNS=5 clean...
get it from the fs structure. Really libufs should have interfaces to generate
both what we export, and what we import, based on eachother, and this should
be full of redundant code to make sure everything is right... But really, we
don't even deal with checksums, so plenty of room to improve.
the old 8-bit fs_old_flags to the new location the first time that the
filesystem is mounted by a new kernel. One of the unused flags in
fs_old_flags is used to indicate that the flags have been moved.
Leave the fs_old_flags word intact so that it will work properly if
used on an old kernel.
Change the fs_sblockloc superblock location field to be in units
of bytes instead of in units of filesystem fragments. The old units
did not work properly when the fragment size exceeeded the superblock
size (8192). Update old fs_sblockloc values at the same time that
the flags are moved.
Suggested by: BOUWSMA Barry <freebsd-misuser@netscum.dyndns.dk>
Sponsored by: DARPA & NAI Labs.
the build. It is here to compartmentalise functionality currently duplicated
in many notable programs in the base system. It currently handles block
reads and writes, as well as reading and writing of the filesystem superblock,
and the reading/lookup of inode data. It supports both UFS and UFS2. I
will be maintaining it, and porting programs to use it, however for now, it
is simply being built as part of world.
