check hash to cylinder groups. If a check hash fails when a cylinder
group is read, no further allocations are attempted in that cylinder
group until it has been fixed by fsck. This avoids a class of
filesystem panics related to corrupted cylinder group maps. The
hash is done using crc32c.
Check hases are added only to UFS2 and not to UFS1 as UFS1 is primarily
used in embedded systems with small memories and low-powered processors
which need as light-weight a filesystem as possible.
Specifics of the changes:
sys/sys/buf.h:
Add BX_FSPRIV to reserve a set of eight b_xflags that may be used
by individual filesystems for their own purpose. Their specific
definitions are found in the header files for each filesystem
that uses them. Also add fields to struct buf as noted below.
sys/kern/vfs_bio.c:
It is only necessary to compute a check hash for a cylinder
group when it is actually read from disk. When calling bread,
you do not know whether the buffer was found in the cache or
read. So a new flag (GB_CKHASH) and a pointer to a function to
perform the hash has been added to breadn_flags to say that the
function should be called to calculate a hash if the data has
been read. The check hash is placed in b_ckhash and the B_CKHASH
flag is set to indicate that a read was done and a check hash
calculated. Though a rather elaborate mechanism, it should
also work for check hashing other metadata in the future. A
kernel internal API change was to change breada into a static
fucntion and add flags and a function pointer to a check-hash
function.
sys/ufs/ffs/fs.h:
Add flags for types of check hashes; stored in a new word in the
superblock. Define corresponding BX_ flags for the different types
of check hashes. Add a check hash word in the cylinder group.
sys/ufs/ffs/ffs_alloc.c:
In ffs_getcg do the dance with breadn_flags to get a check hash and
if one is provided, check it.
sys/ufs/ffs/ffs_vfsops.c:
Copy across the BX_FFSTYPES flags in background writes.
Update the check hash when writing out buffers that need them.
sys/ufs/ffs/ffs_snapshot.c:
Recompute check hash when updating snapshot cylinder groups.
sys/libkern/crc32.c:
lib/libufs/Makefile:
lib/libufs/libufs.h:
lib/libufs/cgroup.c:
Include libkern/crc32.c in libufs and use it to compute check
hashes when updating cylinder groups.
Four utilities are affected:
sbin/newfs/mkfs.c:
Add the check hashes when building the cylinder groups.
sbin/fsck_ffs/fsck.h:
sbin/fsck_ffs/fsutil.c:
Verify and update check hashes when checking and writing cylinder groups.
sbin/fsck_ffs/pass5.c:
Offer to add check hashes to existing filesystems.
Precompute check hashes when rebuilding cylinder group
(although this will be done when it is written in fsutil.c
it is necessary to do it early before comparing with the old
cylinder group)
sbin/dumpfs/dumpfs.c
Print out the new check hash flag(s)
sbin/fsdb/Makefile:
Needs to add libufs now used by pass5.c imported from fsck_ffs.
Reviewed by: kib
Tested by: Peter Holm (pho)
superblocks created in revision 322297 only works on disks
with sector sizes up to 4K. This update allows the recovery
information to be created by newfs and used by fsck on disks
with sector sizes up to 64K. Note that FFS currently limits
filesystem to be mounted from disks with up to 8K sectors.
Expanding this limitation will be the subject of another
commit.
Reported by: Peter Holm
Reviewed with: kib
unable to automatically find alternate superblocks. This checkin
places the information needed to find alternate superblocks to the
end of the area reserved for the boot block.
Filesystems created with a newfs of this vintage or later will
create the recovery information. If you have a filesystem created
prior to this change and wish to have a recovery block created for
your filesystem, you can do so by running fsck in forground mode
(i.e., do not use the -p or -y options). As it starts, fsck will
ask ``SAVE DATA TO FIND ALTERNATE SUPERBLOCKS'' to which you should
answer yes.
Discussed with: kib, imp
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D11589
Renumber cluase 4 to 3, per what everybody else did when BSD granted
them permission to remove clause 3. My insistance on keeping the same
numbering for legal reasons is too pedantic, so give up on that point.
Submitted by: Jan Schaumann <jschauma@stevens.edu>
Pull Request: https://github.com/freebsd/freebsd/pull/96
fsck, the latter does not accept the referred to "-b" flag.
This change was accidently committed directly to 9-STABLE in
r237505.
PR: 82720
Submitted by: David D.W. Downey
MFC after: 1 week
manual page:
There is no need to call arc4random_stir() before using
arc4random() functions family, since they automatically
initialize themselves.
No objection: des
MFC after: 2 weeks
running time for a full fsck. It also reduces the random access time
for large files and speeds the traversal time for directory tree walks.
The key idea is to reserve a small area in each cylinder group
immediately following the inode blocks for the use of metadata,
specifically indirect blocks and directory contents. The new policy
is to preferentially place metadata in the metadata area and
everything else in the blocks that follow the metadata area.
The size of this area can be set when creating a filesystem using
newfs(8) or changed in an existing filesystem using tunefs(8).
Both utilities use the `-k held-for-metadata-blocks' option to
specify the amount of space to be held for metadata blocks in each
cylinder group. By default, newfs(8) sets this area to half of
minfree (typically 4% of the data area).
This work was inspired by a paper presented at Usenix's FAST '13:
www.usenix.org/conference/fast13/ffsck-fast-file-system-checker
Details of this implementation appears in the April 2013 of ;login:
www.usenix.org/publications/login/april-2013-volume-38-number-2.
A copy of the April 2013 ;login: paper can also be downloaded
from: www.mckusick.com/publications/faster_fsck.pdf.
Reviewed by: kib
Tested by: Peter Holm
MFC after: 4 weeks
extended using growfs(8). The problem here is that geom_label checks if
the filesystem size recorded in UFS superblock is equal to the provider
(i.e. device) size. This check cannot be removed due to backward
compatibility. On the other hand, in most cases growfs(8) cannot set
fs_size in the superblock to match the provider size, because, differently
from newfs(8), it cannot recompute cylinder group sizes.
To fix this problem, add another superblock field, fs_providersize, used
only for this purpose. The geom_label(4) will attach if either fs_size
(filesystem created with newfs(8)) or fs_providersize (filesystem expanded
using growfs(8)) matches the device size.
PR: kern/165962
Reviewed by: mckusick
Sponsored by: FreeBSD Foundation
These tools declare global variables without using the static keyword,
even though their use is limited to a single C-file, or without placing
an extern declaration of them in the proper header file.
This avoids a potentially many-hours-long loop of failed writes if newfs
finds a partially-overwritten superblock (or, for that matter, random
garbage which happens to have superblock magic bytes); on one occasion I
found newfs trying to zero 800 million superblocks on a 50 MB disk.
Reviewed by: mckusick
MFC after: 1 week
include sys/time.h instead of time.h. This include is incorrect as
per the manpages for the APIs and the POSIX definitions. This commit
replaces sys/time.h where necessary with time.h.
The commit also includes some minor style(9) header fixup in newfs.
This commit is part of a larger effort by Garrett Cooper started in
//depot/user/gcooper/posix-conformance-work/ -- to make FreeBSD more
POSIX compliant.
Submitted by: Garrett Cooper yanegomi at gmail dot com
Large (60GB) filesystems created using "newfs -U -O 1 -b 65536 -f 8192"
show incorrect results from "df" for free and used space when mounted
immediately after creation. fsck on the new filesystem (before ever
mounting it once) gives a "SUMMARY INFORMATION BAD" error in phase 5.
This error hasn't occurred in any runs of fsck immediately after
"newfs -U -b 65536 -f 8192" (leaving out the "-O 1" option).
Solution:
The default UFS1 superblock is located at offset 8K in the filesystem
partition; the default UFS2 superblock is located at offset 64K in
the filesystem partition. For UFS1 filesystems with a blocksize of
64K, the first alternate superblock resides at 64K which is the the
location used for the default UFS2 superblock. By default, the
system first checks for a valid superblock at the default location
for a UFS2 filoesystem. For a UFS1 filesystem with a blocksize of
64K, there is a valid UFS1 superblock at this location. Thus, even
though it is expected to be a backup superblock, the system will
use it as its default superblock. So, we have to ensure that all the
statistcs on usage are correct in this first alternate superblock
as it is the superblock that will actually be used.
While tracking down this problem, another limitation of UFS1 became
evident. For UFS1, the number of inodes per cylinder group is stored
in an int16_t. Thus the maximum number of inodes per cylinder group
is limited to 2^15 - 1. This limit can easily be exceeded for block
sizes of 32K and above. Thus when building UFS1 filesystems, newfs
must limit the number of inodes per cylinder group to 2^15 - 1.
Reported by: Guy Helmer<ghelmer@palisadesys.com>
Followup by: Bruce Cran <brucec@freebsd.org>
PR: 107692
MFC after: 4 weeks
inodes by cutting back on the number of inodes per cylinder group if
necessary to stay under the limit. For a default (16K block) file
system, this limit begins to take effect for file systems above 32Tb.
This fix is in addition to -r203763 which corrected a problem in the
kernel that treated large inode numbers as negative rather than unsigned.
For a default (16K block) file system, this bug began to show up at a
file system size above about 16Tb.
Reported by: Scott Burns, John Kilburg, Bruce Evans
Followup by: Jeff Roberson
PR: 133980
MFC after: 2 weeks
want to prepare disk images for emulators (though 'makefs' in port
can do something similar).
This relies on:
+ minor changes to pass the consistency checks even when working on a file;
+ an additional option, '-p partition' , to specify the disk partition to
initialize;
+ some changes on the I/O routines to deal with partition offsets.
The latter was a bit tricky to implement, see the details in newfs.h:
in newfs, I/O is done through libufs which assumes that the file
descriptor refers to the whole partition. Introducing support for
the offset in libufs would require a non-backward compatible change
in the library, to be dealt with a version bump or with symbol
versioning.
I felt both approaches to be overkill for this specific application,
especially because there might be other changes to libufs that might
become necessary in the near future.
So I used the following trick:
- read access is always done by calling bread() directly, so we just add
the offset in the (few) places that call bread();
- write access is done through bwrite() and sbwrite(), which in turn
calls bwrite(). To avoid rewriting sbwrite(), we supply our own version
of bwrite() here, which takes precedence over the version in libufs.
MFC after: 4 weeks
Implement -E option which will erase the filesystem sectors before
making the new filesystem. Reserved space in front of the superblock
(bootcode) is not erased.
NB: Erasing can take as long time as writing every sector sequentially.
This is relevant for all flash based disks which use wearlevelling.
affect the largest file size that is allowed by the file system.
On the other hand, when creating a snapshot, the snapshot file will
appear as it is as big as the file system itself. Hence we will not
be able to create a file system on large file systems with small
block sizes.
Add a warning about this, and gives some hints to correct the issue.
Reviewed by: mckusick
MFC After: 1 week
the new filesystem. This is intended for memory and vnode filesystems
that will never be fsck'ed or dumped.
Obtained from: St. Bernard Software RAPID
MFC after: 2 weeks
has only been partly initialized via newfs(8) so that it applies to both
UFS1 and UFS2.
Submitted by: "Xin LI" delphij at frontfree dot net
MFC: maybe?
permits users of newfs to set the multilabel flag on UFS1 and UFS2
file systems from inception without using tunefs.
Obtained from: TrustedBSD Project
Sponsored by: DARPA, McAfee Research
of newfs, to signify the newfs operation has not yet completed. Re-
write the superblock with the correct magic number once all of the
cylinder groups have been created to show the operation has finished.
Sponsored by: St. Bernard Software
a new filesystem. Dump and fsck will create snapshots in this
directory rather than in the root for two reasons:
1) For terabyte-sized filesystems, the snapshot may require many
minutes to build. Although the filesystem will not be suspended
during most of the snapshot build, the snapshot file itself is
locked during the entire snapshot build period. Thus, if it is
accessed during the period that it is being built, the process
trying to access it will block holding its containing directory
locked. If the snapshot is in the root, the root will lock and
the system will come to a halt until the snapshot finishes. By
putting the snapshot in a subdirectory, it is out of the likely
path of any process traversing through the root and hence much
less likely to cause a lock race to the root.
2) The dump program is usually run by a non-root user running with
operator group privilege. Such a user is typically not permitted
to create files in the root of a filesystem. By having a directory
in group operator with group write access available, such a user
will be able to create a snapshot there. Having the dump program
create its snapshot in a subdirectory below the root will benefit
from point (1) as well.
Sponsored by: DARPA & NAI Labs.
The old way of just returning could result in a file system
extremely likely to panic the kernel. The warning printed
wouldn't help much since tools invoking newfs(8), e.g., mdmfs(8),
couldn't detect the error.
PR: bin/55078
MFC after: 1 week
with UFS1, the UFS1 superblocks were not deleted. This allowed any
RELENG_4 (or other non-UFS2-aware) fsck to think it knew how to "fix"
the file system, resulting in severe data scrambling.
This patch is a more advanced version than the one originally submitted.
Lukas improved it based on feedback from Kirk, and testing by me. It
blanks all UFS1 superblocks (if any) during a UFS2 newfs, thereby causing
fsck's that are not UFS2 aware to generate the "SEARCH FOR ALTERNATE
SUPER-BLOCK FAILED" message, and exit without damaging the fs.
PR: bin/51619
Submitted by: Lukas Ertl <l.ertl@univie.ac.at>
Reviewed by: kirk
Approved by: re (scottl)
changed to use libufs in revision 1.71. Without this, any write
failures in newfs were silently ignored.
Note that this will display a meaningless errno string in the case
of a short write as opposed to a write error, since bwrite()'s
return value does not allow the caller to determine if errno is
valid.
Reported by: Lukas Ertl <l.ertl@univie.ac.at>
Reviewed by: jmallett
Approved by: re (bmah)
values for the initial inode generation numbers in newfs and for
newly allocated inode generation numbers in the kernel.
Submitted by: Theo de Raadt <deraadt@cvs.openbsd.org>
Sponsored by: DARPA & NAI Labs.
version of such. Differences in filesystems generated were found to be
from 1) sbwrite with the "all" parameter 2) removal of writecache. The
sbwrite call was made to perform as the original version, and otherwise
this was checked against a version of newfs with the write cache removed.
