Mainly focus on files that use BSD 3-Clause license.
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.
Special thanks to Wind River for providing access to "The Duke of
Highlander" tool: an older (2014) run over FreeBSD tree was useful as a
starting point.
When QUEUE_MACRO_DEBUG_TRASH is configured, the queue linkage fields
are trashed upon removal of the item, so be sure to only read them before
removing the item.
No functional change intended.
MFC after: 1 week
Sponsored by: Dell EMC Isilon
Normally wakeups() are performed for completed softupdates work items
in workitem_free() before the underlying memory is free()'d.
complete_jseg() was clearing the "wakeup needed" flag in work items to
defer the wakeup until the end of each loop iteration. However, this
resulted in the item being free'd before it's address was used with
wakeup(). As a result, another part of the kernel could allocate this
memory from malloc() and use it as a wait channel for a different
"event" with a different lock. This triggered an assertion failure
when the lock passed to sleepq_add() did not match the existing lock
associated with the sleep queue. Fix this by removing the code to
defer the wakeup in complete_jseg() allowing the wakeup to occur
slightly earlier in workitem_free() before free() is called.
The main reason I can think of for deferring a wakeup() would be to
avoid waking up a waiter while holding a lock that the waiter would
need. However, no locks are dropped in between the wakeup() in
workitem_free() and the end of the loop in complete_jseg() as far as I
can tell.
In general I think it is not safe to do a wakeup() after free() as one
cannot control how other parts of the kernel that might reuse the
address for a different wait channel will handle spurious wakeups.
Reported by: pho
Reviewed by: kib
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D12494
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)
ino64 expanded nlink_t to 64 bits, but the on-disk format for UFS is still
limited to 16 bits. This is a nop currently but will matter if LINK_MAX is
increased in the future.
Reviewed by: kib
Sponsored by: Chelsio Communications
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
vnode lock.
Caller of softdep_count_dependencies() may own a buffer lock, which
might conflict with the lock order.
Reported and tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 10 days
softdep_count_dependencies().
Buffer's b_dep list is protected by the SU mount lock. Owning the
buffer lock is not enough to guarantee the stability of the list.
Calculation of the UFS mount owning the workitems from the buffer must
be much more careful to not dereference the work item which might be
freed meantime. To get to ump, use the pointers chain which does not
involve workitems at all.
Reported and tested by: pho
Reviewed by: mckusick
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
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
Update the use of the B_CACHE flag (since the May 1999 commit
that made it the correct test here).
Reported by: Andreas Longwitz <longwitz@incore.de>
Reviewed by: kib
Tested by: Peter Holm
MFC after: 1 week
For freshly allocated snapdata, Lock sn_lock in advance, so
si_snapdata readers see the locked snapdata and not race.
For existing snapdata, if the thread was put to sleep waiting for
sn_lock, re-read si_snapdata. This either closes the race or makes
the reliance on LK_DRAIN less important.
Reported and tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
It is possible for ffs_snapblkfree() to race and lock snaplock while
the devvp snapdata is instantiated, but no snapshots exist. In this
case the loop over snapshots in ffs_snapblkfree() is not executed, and
the local variable vp is left initialized to NULL.
Unlock using &sn->sn_lock and not vp->v_vnlock. For the inodes on the
snapshot list, the locks are same.
Reported and tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
in ffs_snapremove().
Apparently ffs_snapremove() may be called with the snap lock recursed,
at least one trace demonstrated this when snapshot vnode was unlinked
while synced. It was inactivated from the syncer thread.
Reported and tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
group. Change all code points that open-coded this functionality
to use the new function. This commit is a refactoring with no
change in functionality.
In the future this change allows more robust checking of cylinder
group reads along the lines discussed in the hardening UFS session
at BSDCan (retry I/O, add checksums, etc). For more detail see the
session notes at https://wiki.freebsd.org/DevSummit/201706/HardeningUFS
Reviewed by: kib
host.
Problems start appearing when there are several threads all doing
operations on a UFS volume and the SU workqueue needs a cleanup. It is
possible that each thread calling softdep_request_cleanup() owns the
lock for some dirty vnode (e.g. all of them are executing mkdir(2),
mknod(2), creat(2) etc) and all vnodes which must be flushed are locked
by corresponding thread. Then, we get all the threads simultaneously
entering softdep_request_cleanup().
There are two problems:
- Several threads execute MNT_VNODE_FOREACH_ALL() loops in parallel. Due
to the locking, they quickly start executing 'in phase' with the speed
of the slowest thread.
- Since each thread already owns the lock for a dirty vnode, other threads
non-blocking attempt to lock the vnode owned by other thread fail,
and loops executing without making the progress.
Retry logic does not allow the situation to recover. The result is
a livelock.
Fix these problems by making the following changes:
- Allow only one thread to enter MNT_VNODE_FOREACH_ALL() loop per mp.
A new flag FLUSH_RC_ACTIVE guards the loop.
- If there were failed locking attempts during the loop, abort retry
even if there are still work items on the mp work list. An
assumption is that the items will be cleaned when other thread
either fsyncs its vnode, or unlock and allow yet another thread to
make the progress.
It is possible now that some calls would get undeserved ENOSPC from
ffs_alloc(), because the cleanup is not aggressive enough. But I do
not see how can we reliably clean up workitems if calling
softdep_request_cleanup() while still owning the vnode lock. I thought
about scheme where ffs_alloc() returns ERESTART and saves the retry
counter somewhere in struct thread, to return to the top level, unlock
the vnode and retry. But IMO the very rare (and unproven) spurious
ENOSPC is not worth the complications.
Reported and tested by: pho
Style and comments by: mckusick
Reviewed by: mckusick
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
the last step of ffs_unmount().
It is possible that the mount point is recorded for cleanup in AST
context while softdep flush is executed during unmount. The workitems
are flushed by other means for the unmount, but the stray reference to
struct mount blocks destruction of mount. Check for the situation and
manually call vfs_rel() before returning from ffs_unmount().
Reported and tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
makefs(1) has a number of signedness warnings (when built with higher
WARNS), most of which can be addressed by careful application of casts
in makefs itself.
There is one case where a signedness warning arises from the blksize
macro, so must be addressed in the macro itself.
Reviewed by: kib, mckusick
MFC after: 1 month
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D10589
Rather than the global NAME_MAX constant. This change is required to
support systems with a NAME_MAX/MAXNAMLEN that differs from UFS_MAXNAMLEN.
This was missed in r313475 due to the alternative spelling ("NAME_MAX") of
MAXNAMLEN. This change is also similar in spirit to r313780.
Reported by: ngie@
Sponsored by: Dell EMC Isilon
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
Thread might create a condition for delayed SU cleanup, which creates
a reference to the mount point in td_su, but exit without returning
through userret(), e.g. when terminating due to single-threading or
process exit. In this case, td_su reference is not dropped and mount
point cannot be freed.
Handle the situation by clearing td_su also in the thread destructor
and in exit1(). softdep_ast_cleanup() has to receive the thread as
argument, since e.g. thread destructor is executed in different
context.
Reported and tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
As suggested in r167010, use the structure type and macros to access and
modify UFS2 extended attributes. Add assertions that pointers are
aligned in places where we now access the data through a structure
pointer, instead of character-by-character.
PR: 216127
Reported by: dewayne at heuristicsystems.com.au
Reviewed by: kib@
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D9225
The swap pager enqueues laundered pages near the head of the inactive queue
to avoid another trip through LRU before reclamation. This change adds
support for this behaviour to the vnode pager and makes use of it in UFS and
ext2fs. Some ioflag handling is consolidated into a common subroutine so
that this support can be easily extended to other filesystems which make use
of the buffer cache. No changes are needed for ZFS since its putpages
routine always undirties the pages before returning, and the laundry
thread requeues the pages appropriately in this case.
Reviewed by: alc, kib
Differential Revision: https://reviews.freebsd.org/D8589
Currently mount update keeps vfs_busy(9) reference on the mount point
during MNT_UPDATE VFS_MOUNT() vfsops call. This already provides the
exclusion, but is problematic for filesystems which need to perform
namei(9) during VFS_MOUNT(MNT_UPDATE) operations, e.g. to refresh
mnt_from path, because namei(9) must not be called while the
vfs_busy(9) reference is owned.
Check for MNT_UPDATE flag before setting MNTK_UNMOUNT, and for
MNTK_UNMOUNT before entering innards of vfs_domount_update(), failing
syscalls with EBUSY if conflict is detected. Keep vfs_busy(9)
reference around VFS_MOUNT(MNT_UPDATE) calls still to not change VFS
KPI.
In the update path in ffs_mount(), drop vfs_busy() reference around
namei(), which is now safe due to unmount never executing in parallel
with VFS_MOUNT(MNT_UPDATE), and which avoids the deadlock.
Reported and tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
data structure sizes when mounting and reloading UFS/FFS
filesystems by using a u_long rather than an int for the size.
Reported by: Mariusz Zaborski <oshogbo@>
MFC after: 1 week
which also use buffer cache.
Most important addition to the code is the handling of filesystems
where the block size is less than the machine page size, which might
require reading several buffers to validate single page.
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
See the comments for more detailed description of the algorithm.
The pager is used unconditionally when the block size of the
underlying device is larger than the machine page size, since local
vnode pager cannot handle the configuration [1]. Otherwise, the
vfs.ffs.use_buf_pager sysctl allows to switch to the local pager.
Measurements demonstrated no regression in the ever-important
buildworld benchmark, and small (~5%) throughput improvements in the
special microbenchmark configuration for dbench over swap-backed
md(4).
Code can be generalized and reused for other filesystems which use
buffer cache.
Reported by: Anton Yuzhaninov <citrin@citrin.ru> [1]
Tested by: pho
Benchmarked by: mjg, pho
Reviewed by: alc, markj, mckusick (previous version)
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
Differential revision: https://reviews.freebsd.org/D8198
Reclaimed vnode type is VBAD, so succesful comparision like
devvp->v_type != VREG does not imply that the devvp references
snapshot, it might be due to a reclaimed vnode. Explicitely check the
vnode type.
In the the most important case of ffs_blkfree(), the devfs vnode is
locked and its type is stable. In other cases, if the vnode is
reclaimed right after the check, hopefully the buffer methods return
right error codes.
Reviewed by: mckusick
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
Remove redunand i_dev and i_fs pointers, which are available as
ip->i_ump->um_dev and ip->i_ump->um_fs, and reorder members by size to
reduce padding. To compensate added derefences, the most often i_ump
access to differentiate between UFS1 and UFS2 dinode layout is
removed, by addition of the new i_flag IN_UFS2. Overall, this
actually reduces the amount of memory dereferences.
On 64bit machine, original struct inode size is 176, reduced to 152
bytes with the change.
Tested by: pho (previous version)
Reviewed by: mckusick
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
mounts in almost all cases instead of in most cases. Don't override
DOINGASYNC() by any condition except IO_SYNC.
Fix previous sprinking of DOINGASYNC() checks. Don't override IO_SYNC
by DOINGASYNC(). In ffs_write() and ffs_extwrite(), there were
intentional overrides that just broke O_SYNC of data. In
ffs_truncate(), there are 5 calls to ffs_update(), 4 with
apparently-unintentional overrides and 1 without; this had no effect
due to the main async mount hack descibed below.
Fix 1 place in ffs_truncate() where the caller's IO_ASYNC was overridden
for the soft updates case too (to do a delayed write instead of a sync
write). This is supposed to be the only change that affects anything
except async mounts.
In ffs_update(), remove the 19 year old efficiency hack of ignoring
the waitfor flag for async mounts, so that fsync() almost works for
async mounts. All callers are supposed to be fixed to not ask for a
sync update unless they are for fsync() or [I]O_SYNC operations.
fsync() now almost works for async mounts. It used to sync the data
but not the most important metdata (the inode). It still doesn't sync
associated directories.
This gave 10-20% fewer writes for my makeworld benchmark with async
mounted tmp and obj directories from an already small number.
Style fixes:
- in ffs_balloc.c, remove rotted quadruplicated comments about the
simplest part of the DOING*() decisions and rearrange the nearly-
quadruplicated code to be more nearly so.
- in ufs_vnops.c, use a consistent style with less negative logic and
no manual "optimization" of || to | in DOING*() expressions.
Reviewed by: kib (previous version)
The buffer lock is retried on failed LK_SLEEPFAIL attempt, and error
from the failed attempt is irrelevant. But since there is path after
retry which does not clear error, it is possible to return spurious
error from the function.
The issue resulted in a spurious failure of softdep_sync_buf(),
causing further spurious failure of ffs_sync().
In collaboration with: pho
Reviewed by: mckusick
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
going to re-read inodes.
Secondary write initiators, e.g. ufs_inactive(), might need to start a
write while owning the vnode lock. Since the suspended state
established by /dev/ufssuspend prevents them from entering
vn_start_secondary_write(), we get deadlock otherwise.
Note that it is arguably not very useful to re-read inodes after
/dev/ufssuspend suspension, because the suspension does not block
readers, and other threads might read existing files in parallel with
suspension owner (for now, only growfs(8)) operations. This
effectively means that suspension owner cannot safely modify existing
inodes, and then there is no sense in re-reading. But keep the code
enabled for now.
Reported and tested by: pho
Reviewed by: mckusick
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
with softupdates panics the kernel. The problem that has been pointed
out is that when there is a transient write error on certain metadata
blocks, specifically directory blocks (PAGEDEP), inode blocks
(INODEDEP), indirect pointer blocks (INDIRDEPS), and cylinder group
(BMSAFEMAP, but only when journaling is enabled), we get a panic
in one of the routines called by softdep_disk_io_initiation that
the I/O is "already started" when we retry the write.
These dependency types potentially need to do roll-backs when called
by softdep_disk_io_initiation before doing a write and then a
roll-forward when called by softdep_disk_write_complete after the
I/O completes. The panic happens when there is a transient error.
At the top of softdep_disk_write_complete we check to see if the
write had an error and if an error occurred we just return. This
return is correct most of the time because the main role of the routines
called by softdep_disk_write_complete is to process the now-completed
dependencies so that the next I/O steps can happen.
But for the four types listed above, they do not get to do their
rollback operations. This causes the panic when softdep_disk_io_initiation
gets called on the second attempt to do the write and the roll-back
routines find that the roll-backs have already been done. As an
aside I note that there is also the problem that the buffer will
have been unlocked and thus made visible to the filesystem and to
user applications with the roll-backs in place.
The way to resolve the problem is to add a flag to the routines called
by softdep_disk_write_complete for the four dependency types noted
that indicates whether the write was successful (WRITESUCCEEDED).
If the write does not succeed, they do just the roll-backs and then
return. If the write was successful they also do their usual
processing of the now-completed dependencies.
The fix was tested by selectively injecting write errors for buffers
holding dependencies of each of the four types noted above and then
verifying that the kernel no longer paniced and that following the
successful retry of the write that the filesystem could be unmounted
and successfully checked cleanly.
PR: 211013
Reviewed by: kib
allocation unwinding.
Dandling buffers are released on UFS_BALLOC() failure to ensure that
later attempt to allocate blocks in close range do not find the blocks
with invalid content, since possible partial block allocations are
unwound. As such, it is not enough to just release the buffers, the
pages must also invalidated and removed from the vnode vm_object
queue. Otherwise the pages might be found later and used to
reconstruct indirect buffers when doing allocations at offset close to
the failure point, and their stale content compromise the filesystem
integrity.
Note that just marking the buffer as B_INVAL is not enough, B_NOCACHE
is required. To be sure, clear the B_CACHE flag as well. This
complements the r174973, which started releasing buffers.
Reported and tested by: pho
Reviewed by: mckusick
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
that recorded allocated blocks numbers match the physical block
numbers of dandling buffers which are released.
When finally freeing the blocks during unwind, assert that dandling
buffers where not re-allocated. They shouldn't, because the vnode lock
is owned exclusive.
Reviewed by: mckusick
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
