kern_execve() locks text vnode exclusive to be able to set and clear
VV_TEXT flag. VV_TEXT is mutually exclusive with the v_writecount > 0
condition.
The change removes VV_TEXT, replacing it with the condition
v_writecount <= -1, and puts v_writecount under the vnode interlock.
Each text reference decrements v_writecount. To clear the text
reference when the segment is unmapped, it is recorded in the
vm_map_entry backed by the text file as MAP_ENTRY_VN_TEXT flag, and
v_writecount is incremented on the map entry removal
The operations like VOP_ADD_WRITECOUNT() and VOP_SET_TEXT() check that
v_writecount does not contradict the desired change. vn_writecheck()
is now racy and its use was eliminated everywhere except access.
Atomic check for writeability and increment of v_writecount is
performed by the VOP. vn_truncate() now increments v_writecount
around VOP_SETATTR() call, lack of which is arguably a bug on its own.
nullfs bypasses v_writecount to the lower vnode always, so nullfs
vnode has its own v_writecount correct, and lower vnode gets all
references, since object->handle is always lower vnode.
On the text vnode' vm object dealloc, the v_writecount value is reset
to zero, and deadfs vop_unset_text short-circuit the operation.
Reclamation of lowervp always reclaims all nullfs vnodes referencing
lowervp first, so no stray references are left.
Reviewed by: markj, trasz
Tested by: mjg, pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 month
Differential revision: https://reviews.freebsd.org/D19923
If vflush() did not completely flushed the mount vnodes queue, either
retry for forced unmounts, or give up for non-forced. This situation
can occur when new vnodes are instantiated while vflush() worked.
Reported and tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
The vp vnode is unlocked during the execution of the VOP method and
can be reclaimed, zeroing vp->v_data. Caching allows to use the
correct mount point.
Reported and tested by: pho
PR: 235549
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
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
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.
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
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
the vnode is inactivated. This contradicts with the nullfs caching
which keeps upper vnode around, as consequence keeping the use
reference to lower vnode.
Add a filesystem flag to request nullfs to not cache when mounted over
that filesystem, and set the flag for nfs v4 mounts.
Reported by: asomers
Reviewed by: rmacklem
Tested by: asomers, rmacklem
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
The lower vnode is already referenced and nodeget is supposed to consume
the reference. Thus the extra vref call was causing a leak.
Reported by: pho
Reviewed by: kib
MFC after: 1 week
The previous code was forcing an expensive walk in vop_stdvptocnp,
which was causing performance issues on highly contended zfs.
No objections: kib
MFC after: 2 weeks
filesystem to the nullfs mount.
MNTK_NO_IOPF must be present on the nullfs struct mount so that struct
file fo_read and fo_write fops operate in the mode requested by the
lower mount.
MNTK_UNMAPPED_BUFS allows VOP_GETPAGES() to use unmapped buffers. It
does not matter for VOP_GETPAGES() calls from vm_fault() since handle
of the vm_object always points to the lower vnode. But it may be
useful for other situations where VOP_GETPAGES() is used.
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
unlinked. Otherwise the vnode stays cached, causing leak. This is
similar to r292961 for regular files.
Reported and tested by: pho (previous version)
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
lower vnode. Otherwise, reference to the lower vnode from the upper
one prevents final unlink.
PR: 178238
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
This obviates the need for a MNTK_SUSPENDABLE flag, since passthrough
filesystems like nullfs and unionfs no longer need to inherit this
information from their lower layer(s). This change also restores the
pre-r273336 behaviour of using the presence of a susp_clean VFS method to
request suspension support.
Reviewed by: kib, mjg
Differential Revision: https://reviews.freebsd.org/D2937
use VOP_FSYNC() to perform the NFS server's Commit operation.
This patch adds a mnt_kern_flag called MNTK_USES_BCACHE which
is set by file systems that use the buffer cache. If this flag
is not set, the NFS server always does a VOP_FSYNC().
This should be ok for old file system modules that do not set
MNTK_USES_BCACHE, since calling VOP_FSYNC() is correct, although
it might not be optimal for file systems that use the buffer cache.
Reviewed by: kib
MFC after: 2 weeks
two.
nullfs and unionfs need to request suspension if underlying filesystem(s)
use it. Utilize mnt_kern_flag for this purpose.
This is a fixup for 273271.
No strong objections from: kib
Pointy hat to: mjg
MFC after: 2 weeks
nullfs vnode shares vnode lock with lower vnode, this allows the
reclamation of nullfs directory vnode in null_lookup(). In this
situation, VOP must return ENOENT.
More, since after the reclamation, the locks of nullfs directory vnode
and lower vnode are no longer shared, the relock of the ldvp does not
restore the correct locking state of dvp, and leaks ldvp lock.
Correct this by unlocking ldvp and locking dvp.
Use cached value of dvp->v_mount.
Reported by: bdrewery
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
forcing filesystem VOP_LINK() methods to repeat the code. In
tmpfs_link(), remove redundand check for the type of the source,
already done by VFS.
Note that NFS server already performs this check before calling
VOP_LINK().
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
transmission which could be tricked into rounding up to the nearest
page size, leaking up to a page of kernel memory. [13:11]
In IPv6 and NetATM, stop SIOCSIFADDR, SIOCSIFBRDADDR, SIOCSIFDSTADDR
and SIOCSIFNETMASK at the socket layer rather than pass them on to the
link layer without validation or credential checks. [SA-13:12]
Prevent cross-mount hardlinks between different nullfs mounts of the
same underlying filesystem. [SA-13:13]
Security: CVE-2013-5666
Security: FreeBSD-SA-13:11.sendfile
Security: CVE-2013-5691
Security: FreeBSD-SA-13:12.ifioctl
Security: CVE-2013-5710
Security: FreeBSD-SA-13:13.nullfs
Approved by: re
for the case when the nullfs vnode is not reclaimed. Otherwise, later
reclamation would not unlock the lower vnode.
Reported by: antoine
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
null_hashget() obtains the reference on the nullfs vnode, which must
be dropped.
- Fix a wart which existed from the introduction of the nullfs
caching, do not unlock lower vnode in the nullfs_reclaim_lowervp().
It should be innocent, but now it is also formally safe. Inform the
nullfs_reclaim() about this using the NULLV_NOUNLOCK flag set on
nullfs inode.
- Add a callback to the upper filesystems for the lower vnode
unlinking. When inactivating a nullfs vnode, check if the lower
vnode was unlinked, indicated by nullfs flag NULLV_DROP or VV_NOSYNC
on the lower vnode, and reclaim upper vnode if so. This allows
nullfs to purge cached vnodes for the unlinked lower vnode, avoiding
excessive caching.
Reported by: G??ran L??wkrantz <goran.lowkrantz@ismobile.com>
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
Include some flags of the nullfs mount itself:
MNT_RDONLY, MNT_NOEXEC, MNT_NOSUID, MNT_UNION, MNT_NOSYMFOLLOW.
This allows userland code calling statfs() or fstatfs() to see these flags.
In particular, this allows opendir() to detect that a -t nullfs -o union
mount needs deduplication (otherwise at least . and .. are returned twice)
and allows rtld to detect a -t nullfs -o noexec mount as noexec.
Turn off the MNT_ROOTFS flag from the underlying filesystem because the
nullfs mount is definitely not the root filesystem.
Reviewed by: kib
MFC after: 1 week
in r245004. Although the report was for noatime option which is
non-functional for the nullfs, other standard options like nosuid or
noexec are useful with it.
Reported by: Dewayne Geraghty <dewayne.geraghty@heuristicsystems.com.au>
MFC after: 3 days
existing nullfs vnode by the lower vnode is only 16 slots. Since the
default mode for the nullfs is to cache the vnodes, hash has extremely
huge chains.
Size the nullfs hashtbl based on the current value of
desiredvnodes. Use vfs_hash_index() to calculate the hash bucket for a
given vnode.
Pointy hat to: kib
Diagnosed and reviewed by: peter
Tested by: peter, pho (previous version)
Sponsored by: The FreeBSD Foundation
MFC after: 5 days
get back the leased write reference from the lower vnode. There is no
other path which can correct v_writecount on the lowervp.
Reported by: flo
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 3 days
the free nullfs vnodes, switching nullfs behaviour to pre-r240285.
The option is mostly intended as the last-resort when higher pressure
on the vnode cache due to doubling of the vnode counts is not
desirable.
Note that disabling the cache costs more than 2x wall time in the
metadata-hungry scenarious. The default is "cache".
Tested and benchmarked by: pho (previous version)
MFC after: 2 weeks
received granular locking) but the comment present in UFS has been
copied all over other filesystems code incorrectly for several times.
Removes comments that makes no sense now.
Reviewed by: kib
MFC after: 3 days
was still possible to open for write from the lower filesystem. There
is a symmetric situation where the binary could already has file
descriptors opened for write, but it can be executed from the nullfs
overlay.
Handle the issue by passing one v_writecount reference to the lower
vnode if nullfs vnode has non-zero v_writecount. Note that only one
write reference can be donated, since nullfs only keeps one use
reference on the lower vnode. Always use the lower vnode v_writecount
for the checks.
Introduce the VOP_GET_WRITECOUNT to read v_writecount, which is
currently always bypassed to the lower vnode, and VOP_ADD_WRITECOUNT
to manipulate the v_writecount value, which manages a single bypass
reference to the lower vnode. Caling the VOPs instead of directly
accessing v_writecount provide the fix described in the previous
paragraph.
Tested by: pho
MFC after: 3 weeks
it. There are two problems which shall be addressed for shared
lookups use to have measurable effect on nullfs scalability:
1. When vfs_lookup() calls VOP_LOOKUP() for nullfs, which passes lookup
operation to lower fs, resulting vnode is often only shared-locked. Then
null_nodeget() cannot instantiate covering vnode for lower vnode, since
insmntque1() and null_hashins() require exclusive lock on the lower.
Change the assert that lower vnode is exclusively locked to only
require any lock. If null hash failed to find pre-existing nullfs
vnode for lower vnode and the vnode is shared-locked, the lower vnode
lock is upgraded.
2. Nullfs reclaims its vnodes on deactivation. This is due to nullfs
inability to detect reclamation of the lower vnode. Reclamation of a
nullfs vnode at deactivation time prevents a reference to the lower
vnode to become stale.
Change nullfs VOP_INACTIVE to not reclaim the vnode, instead use the
VFS_RECLAIM_LOWERVP to get notification and reclaim upper vnode
together with the reclamation of the lower vnode.
Note that nullfs reclamation procedure calls vput() on the lowervp
vnode, temporary unlocking the vnode being reclaimed. This seems to be
fine for MPSAFE filesystems, but not-MPSAFE code often put partially
initialized vnode on some globally visible list, and later can decide
that half-constructed vnode is not needed. If nullfs mount is created
above such filesystem, then other threads might catch such not
properly initialized vnode. Instead of trying to overcome this case,
e.g. by recursing the lower vnode lock in null_reclaim_lowervp(), I
decided to rely on nearby removal of the support for non-MPSAFE
filesystems.
In collaboration with: pho
MFC after: 3 weeks
instead of accepting half-constructed vnode. Previous code cannot decide
what to do with such vnode anyway, and although processing it for hash
removal, paniced later when getting rid of nullfs reference on lowervp.
While there, remove initializations from the declaration block.
Tested by: pho
MFC after: 1 week
