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
function null_destroy_proto() from null_insmntque_dtr(). Also
apply null_destroy_proto() in null_nodeget() when we raced and a vnode
is found in the hash, so the currently allocated protonode shall be
destroyed.
Lock the vnode interlock around reassigning the v_vnlock.
In fact, this path will not be exercised after several later commits,
since null_nodeget() cannot take shared-locked lowervp at all due to
insmntque() requirements.
Reported by: rea
Tested by: pho
MFC after: 1 week
a new jail parameter node with the following parameters:
allow.mount.devfs:
allow mounting the devfs filesystem inside a jail
allow.mount.nullfs:
allow mounting the nullfs filesystem inside a jail
Both parameters are disabled by default (equals the behavior before
devfs and nullfs in jails). Administrators have to explicitly allow
mounting devfs and nullfs for each jail. The value "-1" of the
devfs_ruleset parameter is removed in favor of the new allow setting.
Reviewed by: jamie
Suggested by: pjd
MFC after: 2 weeks
Several callers of null_nodeget() did the cleanup itself, but several
missed it, most prominent being null_bypass(). Remove the cleanup from
the callers, now null_nodeget() handles lowervp free itself.
Reported and tested by: pho
MFC after: 1 week
nullfs. The problem is that resulting vnode is only required to be
held on return from the successfull call to vop, instead of being
referenced.
Nullfs VOP_INACTIVE() method reclaims the vnode, which in combination
with the VOP_VPTOCNP() interface means that the directory vnode
returned from VOP_VPTOCNP() is reclaimed in advance, causing
vn_fullpath() to error with EBADF or like.
Change the interface for VOP_VPTOCNP(), now the dvp must be
referenced. Convert all in-tree implementations of VOP_VPTOCNP(),
which is trivial, because vhold(9) and vref(9) are similar in the
locking prerequisites. Out-of-tree fs implementation of VOP_VPTOCNP(),
if any, should have no trouble with the fix.
Tested by: pho
Reviewed by: mckusick
MFC after: 3 weeks (subject of re approval)
failure (the getnewvnode cannot return an error). In this case, the
null_insmntque_dtr() already unlocked the reclaimed vnode, so VOP_UNLOCK()
in the nullfs_mount() after null_nodeget() failure is wrong.
Tested by: pho
MFC after: 1 week
method, so that callers can indicate the minimum vnode
locking requirement. This will allow some file systems to choose
to return a LK_SHARED locked vnode when LK_SHARED is specified
for the flags argument. This patch only adds the flag. It
does not change any file system to use it and all callers
specify LK_EXCLUSIVE, so file system semantics are not changed.
Reviewed by: kib
of the lower level vnode is incremented to greater than 1 when
the upper level vnode's v_usecount is greater than one. This
is necessary for the NFS clients, so that they will do a silly
rename of the file instead of actually removing it when the
file is still in use. It is "racy", since the v_usecount is
incremented in many places in the kernel with
minimal synchronization, but an extraneous silly rename is
preferred to not doing a silly rename when it is required.
The only other file systems that currently check the value
of v_usecount in their VOP_REMOVE() functions are nwfs and
smbfs. These file systems choose to fail a remove when the
v_usecount is greater than 1 and I believe will function
more correctly with this patch, as well.
Tested by: to.my.trociny at gmail.com
Submitted by: to.my.trociny at gmail.com (earlier version)
Reviewed by: kib
MFC after: 2 weeks
vn_open_cred in default implementation. Valid struct ucred is needed for
audit and MAC, and curthread credentials may be wrong.
This further requires modifying the interface of vn_fullpath(9), but it
is out of scope of this change.
Reviewed by: rwatson
v_data is not-null before calling NULLVPTOLOWERVP(), and dropping the
interlock allows for reclaim to clean v_data and free the memory.
While there, remove unneeded semicolons and convert the infinite loops
to panics. I have a will to remove null_checkvp() altogether, or leave
it as a trivial stub, but not now.
Reported and tested by: pho
This should not really matter for correctness, since vp->v_lock is
not locked before the call, and null_lock() holds the interlock,
but makes the control flow for reclaim more clear.
Tested by: pho
permissions, such as VWRITE_ACL. For a filsystems that don't
implement it, there is a default implementation, which works
as a wrapper around VOP_ACCESS.
Reviewed by: rwatson@
the VFS. Now all the VFS_* functions and relating parts don't want the
context as long as it always refers to curthread.
In some points, in particular when dealing with VOPs and functions living
in the same namespace (eg. vflush) which still need to be converted,
pass curthread explicitly in order to retain the old behaviour.
Such loose ends will be fixed ASAP.
While here fix a bug: now, UFS_EXTATTR can be compiled alone without the
UFS_EXTATTR_AUTOSTART option.
VFS KPI is heavilly changed by this commit so thirdy parts modules needs
to be recompiled. Bump __FreeBSD_version in order to signal such
situation.
implementation instead. The bypass does not assume that returned vnode
is only held.
Reported by: Paul B. Mahol <onemda gmail com>, pluknet <pluknet gmail com>
Reviewed by: jhb
Tested by: pho, pluknet <pluknet gmail com>
to add more V* constants, and the variables changed by this patch were often
being assigned to mode_t variables, which is 16 bit.
Approved by: rwatson (mentor)
always curthread.
As KPI gets broken by this patch, manpages and __FreeBSD_version will be
updated by further commits.
Tested by: Andrea Barberio <insomniac at slackware dot it>
