Root vnodes looekd up all the time, e.g. when crossing a mount point.
Currently used routines always perform a costly lookup which can be
trivially avoided.
Reviewed by: jeff (previous version), kib
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D21646
When a VFS option passed to nmount is present but NULL the kernel will
place an empty option in its internal list. This will have a NULL
pointer and a length of 0. When we come to read one of these the kernel
will try to load from the last address of virtual memory. This is
normally invalid so will fault resulting in a kernel panic.
Fix this by checking if the length is valid before dereferencing.
MFC after: 3 days
Sponsored by: DARPA, AFRL
The two options are
* nocover/cover: Prevent/allow mounting over an existing root mountpoint.
E.g., "mount -t ufs -o nocover /dev/sd1a /usr/local" will fail if /usr/local
is already a mountpoint.
* emptydir/noemptydir: Prevent/allow mounting on a non-empty directory.
E.g., "mount -t ufs -o emptydir /dev/sd1a /usr" will fail.
Neither of these options is intended to be a default, for historical and
compatibility reasons.
Reviewed by: allanjude, kib
Differential Revision: https://reviews.freebsd.org/D21458
There are 3 counters modified all the time in this structure - one for
keeping the structure alive, one for preventing unmount and one for
tracking active writers. Exact values of these counters are very rarely
needed, which makes them a prime candidate for conversion to a per-cpu
scheme, resulting in much better performance.
Sample benchmark performing fstatfs (modifying 2 out of 3 counters) on
a 104-way 2 socket Skylake system:
before: 852393 ops/s
after: 76682077 ops/s
Reviewed by: kib, jeff
Tested by: pho
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D21637
New primitive is introduced to denote sections can operate locklessly
on aspects of struct mount, but which can also be disabled if necessary.
This provides an opportunity to start scaling common case modifications
while providing stable state of the struct when facing unmount, write
suspendion or other events.
mnt_ref is the first counter to start being managed in this manner with
the intent to make it per-cpu.
Reviewed by: kib, jeff
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D21425
After all the changes, its dynamic scope is same as for MNTK_UNMOUNT,
but to allow the syncer vnode to be re-installed on unmount failure.
But the case of syncer was already handled by using the VV_FORCEINSMQ
flag for quite some time.
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
fs-specific part of vfs_statfs routines only fill in small portion of the
structure. Previous code was always copying everything at a higher layer to
acoomodate it and this patch does the same.
'df' (no arguments) worked fine because the caller uses mnt_stat itself as the
target buffer, making all the copying a no-op for its own case.
'df /' and similar use a different consumer which passes its own buffer and
this is where you can run into trouble.
Reported by: cy
Fixes: r351193
Sponsored by: The FreeBSD Foundation
The struct is already populated on each mount (and remount). Fields are either
constant or not used by filesystem in the first place.
Some infrequently used functions use it to avoid having to allocate a new buffer
and are left alone.
The current code results in an avoidable copying single-threaded and significant
cache line bouncing multithreaded
While here deduplicate initial filling of the struct.
Reviewed by: kib
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D21317
Similar to r348026, exhaustive search for uses of CTRn() and cross reference
ktr.h includes. Where it was obvious that an OS compat header of some kind
included ktr.h indirectly, .c files were left alone. Some of these files
clearly got ktr.h via header pollution in some scenarios, or tinderbox would
not be passing prior to this revision, but go ahead and explicitly include it
in files using it anyway.
Like r348026, these CUs did not show up in tinderbox as missing the include.
Reported by: peterj (arm64/mp_machdep.c)
X-MFC-With: r347984
Sponsored by: Dell EMC Isilon
be called before VFS_ROOT() is called. Move the call for VFS_STATFS()
so that it is done after VFS_MOUNT(), but before VFS_ROOT().
This change actually improves the robustness of the mount system
call because it returns an error rather than failing silently
when VFS_STATFS() returns failure.
Reported by: Rebecca Cran <rebecca@bluestop.org>
Sponsored by: Netflix
check-hash fails. Panic'ing is not an appropriate response. So, check
for an error return from VFS_ROOT() and when an error is reported,
unwind and return the error.
Reported by: Gary Jennejohn (gj)
Sponsored by: Netflix
Use bypass to catch any NFS VOP dispatch and route it through the
wrapper which does sigdeferstop() and then dispatches original
VOP. NFS does not need a bypass below it, which is not supported.
The vop offset in the vop_vector is added since otherwise it is
impossible to get vop_op_t from the internal table, and I did not
wanted to create the layered fs only to wrap NFS VOPs.
VFS_OP()s wrap is straightforward.
Requested and reviewed by: mjg (previous version)
Tested by: pho
Sponsored by: The FreeBSD Foundation
Differential revision: https://reviews.freebsd.org/D17658
by doing most of the work in a new function prison_add_vfs in kern_jail.c
Now a jail-enabled filesystem need only mark itself with VFCF_JAIL, and
the rest is taken care of. This includes adding a jail parameter like
allow.mount.foofs, and a sysctl like security.jail.mount_foofs_allowed.
Both of these used to be a static list of known filesystems, with
predefined permission bits.
Reviewed by: kib
Differential Revision: D14681
If the operation is not an update, if neither r/w nor r/o mode is
explicitly requested, if the error code hints at the possibility of the
media being read-only, and if the fallback is allowed, then we can try
to automatically downgrade to the readonly mode.
This is especially useful for auto-mounting of removable media that
sometimes can happen to be write-protected.
The fallback to r/o is not enabled by default. It can be requested on a
per-mount basis with a new mount option, 'autoro'. Or it can be
globally allowed by setting vfs.default_autoro.
Reviewed by: cem, kib
MFC after: 3 weeks
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D13361
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.
The manipulations done by mountcheckdirs() are not that useful during
the unmount, they can bring about unexpected security consequences.
Thic change effectively reverts the change in r73241.
The change also allows to simplify the handling of rootvnode global
variable.
Discussed with: mckusick, mjg, kib
Reviewed by: trasz
MFC after: 1 month
Differential Revision: https://reviews.freebsd.org/D12366
If vrele() changes the hold count to zero, it needs to acquire the
vnode lock.
Sponsored by: The FreeBSD Foundation
Discussed with: avg
X-MFC with: r323578
As long as mnt_ref is not zero there can be a consumer that might try
to access mnt_vnodecovered. For this reason the covered vnode must not
be freed until mnt_ref goes to zero.
So, move the release of the covered vnode to vfs_mount_destroy.
Reviewed by: kib
MFC after: 3 weeks
Differential Revision: https://reviews.freebsd.org/D12329
A long long time ago the register keyword told the compiler to store
the corresponding variable in a CPU register, but it is not relevant
for any compiler used in the FreeBSD world today.
ANSIfy related prototypes while here.
Reviewed by: cem, jhb
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D10193
Right now size of the structure is 472 bytes on amd64, which is
already large and stack allocations are indesirable. With the ino64
work, MNAMELEN is increased to 1024, which will make it impossible to have
struct statfs on the stack.
Extracted from: ino64 work by gleb
Discussed with: mckusick
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
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
Other uses of cache_purgevfs() do rely on the cache purge for correct
operations, when paths are invalidated without unmount.
Reported and tested by: jkim
Discussed with: mjg
Sponsored by: The FreeBSD Foundation
Previously free vnodes would always by directly returned to the global
LRU list. With this change up to mnt_free_list_batch vnodes are collected
first.
syncer runs always return the batch regardless of its size.
While vnodes on per-mnt lists are not counted as free, they can be
returned in case of vnode shortage.
Reviewed by: kib
Tested by: pho
any open vnodes before proceeding. Make autounmound(8) use this flag.
Without it, even an unsuccessfull unmount causes filesystem flush,
which interferes with normal operation.
Reviewed by: kib@
Approved by: re (gjb@)
MFC after: 1 month
Differential Revision: https://reviews.freebsd.org/D7047
we set MNTK_UNMOUNT flag on the mp. Otherwise parallel unmount which
wins race with us could dereference the covered vnode, and we are
left with the locked freed memory.
Reported and tested by: pho
Sponsored by: The FreeBSD Foundation
Approved by: re (gjb)
MFC after: 1 week
This is a bit hackish, but the flag is currently set only for ZFS
snapshots mounted under .zfs. mountcheckdirs() can change cdir/rdir
references to a covered vnode. But for the said snapshots the covered
vnode is really ephemeral and it must never be accessed (except
for a few specific cases).
To do: consider removing mountcheckdirs() entirely
MFC after: 5 days
export_args on mount update, bzero() is consistent with
vfs_oexport_conv().
Make the code structure more explicit by using switch.
Return EINVAL if export option layout (deduced from size) is unknown.
Based on the submission by: bde
Sponsored by: The FreeBSD Foundation
reason this didn't result in an unclean shutdown is that devfs ignores
MNT_FORCE flag.
Reviewed by: kib@
MFC after: 1 month
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D3467
asserts are made. Remove them, since we might dereference freed
memory. Leaked locks are asserted by the syscall return code anyway.
Reported and tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Nothing stops a parallel unmount to suceed before the given call to
dounmount() checks and locks the covered vnode. Prevent dounmount()
from acting on the freed (although type-stable) memory by changing the
interface to require the mount point to be referenced. dounmount()
consumes the reference on return, regardless of the sucessfull or
erronous result.
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
unmount, which causes error from nmount(2) call when performing
MNT_DELEXPORT over the directory which ceased to be a mount point.
The race is legitimate and innocent, but results in the chatty mountd.
Silence it by providing an distinguished error code for the situation,
and ignoring the error in mountd loop.
Based on the patch by: Andreas Longwitz <longwitz@incore.de>
Prodded and tested by: bdrewery
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
Since VFS does not/cannot stop writes, sync might run indefinitely, or
be a wrong thing to do at all. E. g. NFS ignores VFS_SYNC() for
forced unmounts, since non-responding server does not allow sync to
finish. On the other hand, filesystems can and do stop writes using
fs-specific facilities, and should already fully flush caches in
VFS_UNMOUNT() due to the race.
Adjust msdosfs tp sync in unmount for forced call, to accomodate the
new behaviour. Note that it is still racy, since writes are not
stopped.
Discussed with: avg, bjk, mckusick
Reported and tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 3 weeks
UNIX systems, eg. MacOS X and Solaris. It uses Sun-compatible map format,
has proper kernel support, and LDAP integration.
There are still a few outstanding problems; they will be fixed shortly.
Reviewed by: allanjude@, emaste@, kib@, wblock@ (earlier versions)
Phabric: D523
MFC after: 2 weeks
Relnotes: yes
Sponsored by: The FreeBSD Foundation
It could be claimed that two things were reasonable protected by
Giant. One is vfsconf list links, which is converted to the new
dedicated sx vfsconf_sx. Another is vfsconf.vfc_refcount, which is
now updated with atomics.
Note that vfc_refcount still has the same races now as it has under
the Giant, the unload of filesystem modules can happen while the
module is still in use.
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
not strlen as they are *not* strings.
Discovered by GSOC student, Mike Ma <mikemandarine@gmail.com> during his
fuse.glusterfs port to FreeBSD.
Final patch from mckusick@
Submitted by: mckusick@
Approved by: re (hrs)
MFC after: 2 weeks
waiting for an RPC reply from the server while holding the mount
point busy (mnt_lockref incremented). This happens because dounmount()
msleep()s waiting for mnt_lockref to become 0, before calling
VFS_UNMOUNT(). This patch adds a new VFS operation called VFS_PURGE(),
which the NFS client implements as purging RPCs in progress. Making
this call before checking mnt_lockref fixes the problem, by ensuring
that the VOP_xxx() calls will fail and unbusy the mount point.
Reported by: sbruno
Reviewed by: kib
MFC after: 2 weeks
about mount and unmount events. This is used by Juniper to implement a more
optimal implementation of NetBSD's veriexec.
This change differs from r253224 in the following way:
o The vfs_mounted handler is called before mountcheckdirs() and with
newdp locked. vp is unlocked.
o The event handlers are declared in <sys/eventhandler.h> and not in
<sys/mount.h>. The <sys/mount.h> header is used in user land code
that pretends to be kernel code and as such creates a very convoluted
environment. It's hard to untangle.
Submitted by: stevek@juniper.net
Discussed with: pjd@
Obtained from: Juniper Networks, Inc.
about mount and unmount events. This is used by Juniper to implement a more
optimal implementation of NetBSD's veriexec.
Submitted by: stevek@juniper.net
Obtained from: Juniper Networks, Inc
