Move debug.ncnegfactor to vfs.ncnegfactor [1].
Provide some descriptions for the namecache related sysctls [1].
Based on the submission by: Rogier R. Mulhuijzen <drwilco drwilco net> [1]
MFC after: 2 weeks
X-MFC-note: remove debug.ncnegfactor in HEAD after MFC
use '-' in probe names, matching the probe names in Solaris.[1]
Add userland SDT probes definitions to sys/sdt.h.
Sponsored by: The FreeBSD Foundation
Discussed with: rwaston [1]
Assert this.
In the reported panic, vdestroy() fired the assertion "vp has namecache
for ..", because pseudofs may end up doing cache_enter() with reclaimed
dvp, after dotdot lookup temporary unlocked dvp.
Similar problem exists in ufs_lookup() for "." lookup, when vnode
lock needs to be upgraded.
Verify that dvp is not reclaimed before calling cache_enter().
Reported and tested by: pho
Reviewed by: kan
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
and calls to vn_vptocnp() by moving more of the common code to
vn_vptocnp(). Rename vn_vptocnp() to vn_vptocnp_locked() to signify that
cache is locked around the call.
Do not track buffer position by both the pointer and offset, use only
buflen to record the start of the free space.
Export vn_vptocnp() for external consumers as a wrapper around
vn_vptocnp_locked() that locks the cache and handles hold counts.
Tested by: pho
not populated in parent directory if negative entry was being
created, yet entry itself was added to the nc_neg list. It was
possible for parent vnode to get discarded later, leaving negative
entry pointing to now unused memory block.
Reported by: dho
Revewed by: kib
Check the condition and return ENOENT then.
In nfs_lookup(), respect ENOENT return from cache_lookup() when it is caused
by dvp reclaim.
Reported and tested by: pho
the size and cost of name cache entries, but make adding debugging
and tracing easier.
Add SDT DTrace probes for various namecache events:
vfs:namecache:enter:done - new entry in the name cache, passed parent
directory vnode pointer, name added to the cache, and child vnode
pointer.
vfs:namecache:enter_negative:done - new negative entry in the name cache,
passed parent vnode pointer, name added to the cache.
vfs:namecache:fullpath:enter - call to vn_fullpath1() is made, passed
the vnode to resolve to a name.
vfs:namecache:fullpath:hit - vn_fullpath1() successfully resolved a
search for the parent of an object using the namecache, passed the
discovered parent directory vnode pointer, name, and child vnode
pointer.
vfs:namecache:fullpath:miss - vn_fullpath1() failed to resolve a search
for the parent of an object using the namecache, passed the child
vnode pointer.
vfs:namecache:fullpath:return - vn_fullpath1() has completed, passed the
error number, and if that is zero, the vnode to resolve, and the
returned path.
vfs:namecache:lookup:hit - postive name cache entry hit, passed the
parent directory vnode pointer, name, and child vnode pointer.
vfs:namecache:lookup:hit_negative - negative name cache entry hit,
passed the parent directory vnode pointer and name.
vfs:namecache:lookup:miss - name cache miss, passed the parent directory
pointer and the full remaining component name (not terminated after the
cache miss component).
vfs:namecache:purge:done - name cache purge for a vnode, passed the vnode
pointer to purge.
vfs:namecache:purge_negative:done - name cache purge of negative entries
for children of a vnode, passed the vnode pointer to purge.
vfs:namecache:purgevfs - name cache purge for a mountpoint, passed the
mount pointer. Separate probes will also be invoked for each cache
entry zapped.
vfs:namecache:zap:done - name cache entry zapped, passed the parent
directory vnode pointer, name, and child vnode pointer.
vfs:namecache:zap_negative:done - negative name cache entry zapped,
passed the parent directory vnode pointer and name.
For any probes involving an extant name cache entry (enter, hit, zapp),
we use the nul-terminated string for the name component. For misses,
the remainder of the path, including later components, is provided as
an argument instead since there is no handy nul-terminated version of
the string around. This is arguably a bug.
MFC after: 1 month
Sponsored by: Google, Inc.
Reviewed by: jhb, kan, kib (earlier version)
in directory vnodes. Allow namecache dotdot entry to be created pointing
from child vnode to parent vnode if no existing links in opposite
direction exist. Use direct link from parent to child for dotdot lookups
otherwise.
This restores more efficient dotdot caching in NFS filesystems which
was lost when vnodes stoppped being type stable.
Reviewed by: kib
debug.hashstat.rawnchash sysctl in particular as taking 7 milliseconds on
a 3GHz Intel Xeon (4x2) running 7.1. It accounted for almost a quarter of
the total runtime of 'sysctl -a'. It also performs lots of copyout's while
holding the namecache lock (this does not attempt to fix that).
MFC after: 2 weeks
stale entries, we save a copy of the directory's modification time when
the first negative cache entry was added in the directory's NFS node.
When a negative cache entry is hit during a pathname lookup, the parent
directory's modification time is checked. If it has changed, all of the
negative cache entries for that parent are purged and the lookup falls
back to using the RPC. This required adding a new cache_purge_negative()
method to the name cache to purge only negative cache entries for a given
directory.
Submitted by: mohans, Rick Macklem, Ricardo Labiaga @ NetApp
Reviewed by: mohans
mutex to a reader/writer lock. Lookup operations first grab a read lock and
perform the lookup. If the operation results in a need to modify the cache,
then it tries to do an upgrade. If that fails, it drops the read lock,
obtains a write lock, and redoes the lookup.
inside the SYSCTL() macros and thus does not need to be done for
all of the nodes scattered across the source tree.
- Mark the name-cache related sysctl's (including debug.hashstat.*) MPSAFE.
- Mark vm.loadavg MPSAFE.
- Remove GIANT_REQUIRED from vmtotal() (everything in this routine already
has sufficient locking) and mark vm.vmtotal MPSAFE.
- Mark the vm.stats.(sys|vm).* sysctls MPSAFE.
In normal operation, the number of cache entries is roughly equal to the
number of active vnodes. However, when most of the recently accessed
vnodes have many hard links, the number of cache entries can be 32000
times as large, exhausting kernel memory and provoking a panic in
kmem_malloc().
MFC after: 2 weeks
did not compared nc_dvp with supplied parent directory vnode pointer.
Add the check and note that now branches for vp != NULL and vp == NULL
are the same, thus can be merged.
Reported and reviewed by: kan
Tested by: pho
MFC after: 2 weeks
looked up would have v_dd set to a non-NULL value. This fixes a panic
seen when running installworld on a diskless system with a separate /usr
file system.
Submitted by: cracauer
Approved by: kib
on a best-effort basis. Teach vn_fullpath to use this new VOP if a
regular VFS cache lookup fails. This VOP is designed to supplement the
VFS cache to provide a better chance that a vnode-to-name lookup will
succeed.
Currently, an implementation for devfs is being committed. The default
implementation is to return ENOENT.
A big thanks to kib for the mentorship on this, and to pho for running it
through his stress test suite.
Reviewed by: arch
Approved by: kib
entries for one name. Then, creating inode with that name would remove
one entry, leaving others dormant. Reclaiming the vnode would uncover
negative entries, causing false return of ENOENT from the calls like
stat, that do not create inode.
Prevent creation of the duplicated negative entries.
Reported and debugged with: pho
Reviewed by: jhb
X-MFC: after shared lookup changes
advance of teaching vn_fullpath1() how to query file systems for
vnode-to-name mappings when cache lookups fail.
Thanks to kib for guidance and patience on this process.
Reviewed by: kib
Approved by: kib
unmounts. When we upgrade a vnode lock from shared to exclusive during
a name cache lookup, fail the lookup with EBADF if the vnode is invalidated
while we are waiting for the exclusive lock.
Also, for correctness (though I'm not sure it can occur in practice),
downgrade an exclusively locked vnode if it should be share locked.
Tested by: pho
not in the namecache when shared lookups are enabled (vfs.lookup_shared=1,
it is currently off by default) and the filesystem supports shared lookups
(e.g. NFS client). Specifically, if multiple concurrent LOOKUPs both miss
in the name cache in parallel, each of the lookups may each end up adding an
entry to the namecache resulting in duplicate entries in the namecache
for the same pathname. A subsequent removal of the mapping of that
pathname to that vnode (via remove or rename) would only evict one of the
entries from the name cache. As a result, subseqent lookups for that
pathname would still return the old vnode.
This race was observed with shared lookups over NFS where a file was updated
by writing a new file out to a temporary file name and then renaming that
temporary file to the "real" file to effect atomic updates of a file. Other
processes on the same client that were periodically reading the file would
occasionally receive an ESTALE error from open(2) because the VOP_GETATTR()
in nfs_open() would receive that error when given the stale vnode.
The fix here is to check for duplicates in cache_enter() and just return
if an entry for this same directory and leaf file name for this vnode is
already in the cache. The check for duplicates is done by walking the
per-vnode list of name cache entries. It is expected that this list should
be very small in the common case (usually 0 or 1 entries during a
cache_enter() since most files only have 1 "leaf" name).
Reviewed by: ups, scottl
MFC after: 2 months
processes are not producing absolute pathname tokens. It is required
that audited pathnames are generated relative to the global root mount
point. This modification changes our implementation of audit_canon_path(9)
and introduces a new function: vn_fullpath_global(9) which performs a
vnode -> pathname translation relative to the global mount point based
on the contents of the name cache. Much like vn_fullpath,
vn_fullpath_global is a wrapper function which called vn_fullpath1.
Further, the string parsing routines have been converted to use the
sbuf(9) framework. This change also removes the conditional acquisition
of Giant, since the vn_fullpath1 method will not dip into file system
dependent code.
The vnode locking was modified to use vhold()/vdrop() instead the vref()
and vrele(). This will modify the hold count instead of modifying the
user count. This makes more sense since it's the kernel that requires
the reference to the vnode. This also makes sure that the vnode does not
get recycled we hold the reference to it. [1]
Discussed with: rwatson
Reviewed by: kib [1]
MFC after: 2 weeks
no longer needed, but for now we still want to be consistent with other
similar checks in the tree.
- Call ASSERT_VOP_ELOCKED() only when vget() returns 0.
Reviewed by: jeff
after each SYSINIT() macro invocation. This makes a number of
lightweight C parsers much happier with the FreeBSD kernel
source, including cflow's prcc and lxr.
MFC after: 1 month
Discussed with: imp, rink
