Axe Giant from vn_fullpath(9). The vnode -> pathname lookup should be
filesystem agnostic. We are not touching any file system specific functions
in this code path. Since we have a cache lock, there is really no need to
keep Giant around here.
This eliminates Giant acquisitions for any syscall which is auditing pathnames.
cache_zap() to clear the v_dd pointers when a directory vnode is forcibly
discarded. For this to work, all vnodes with v_dd pointers to a directory
must also have name cache entries linked via v_cache_dst to that dvp
otherwise we could not find them at cache_purge() time. The following
code snipit could break this guarantee by unlinking a directory before
fetching it's dotdot. The dotdot lookup would initialize the v_dd field
of the unlinked directory which could never be cleared. To fix this
we don't initialize v_dd for orphaned vnodes.
printf("rmdir: %d\n", rmdir("../foo")); /* foo is cwd */
printf("chdir: %d\n", chdir(".."));
printf("%s\n", getwd(NULL));
Sponsored by: Isilon Systems, Inc.
Discovered by: kkenn
Approved by: re (blanket vfs)
vnodes whose names it caches, so we no longer need a `generation
number' to tell us if a referenced vnode is invalid. Replace the use
of the parent's v_id in the hash function with the address of the
parent vnode.
Tested by: Peter Holm
Glanced at by: jeff, phk
except for places where people forget to update one of them. We now
collect only one set of stats for both of these routines. Other
changes in this commit include:
- Start acquiring Giant again in vn_fullpath(), since it is required
when crossing a mount point.
- Expand the scope of the cache lock to avoid dropping it and
picking it up again for every pathname component. This also
makes it trivial to avoid races in stats collection.
- Assert that nc_dvp == v_dd for directories instead of returning
an error to userland when this is not true. AFAIK, it should
always be true when v_dd is non-null.
- For vn_fullpath(), handle the first (non-directory) vnode
separately.
Glanced at by: jeff, phk
to cache_lookup(). This allows us to acquire the vnode interlock before
dropping the cache lock. This protects the vnodes identity until we
have locked it.
Sponsored by: Isilon Systems, Inc.
config option have now been fixed. All filesystems are properly locked
and checked via DEBUG_VFS_LOCKS. Remove the workaround code.
Sponsored by: Isilon Systems, Inc.
vnode lock is much simpler than I originally thought it would be.
Now, the cache lock is always acquired before the vnode lock.
- Provide some gotos in __getcwd() to simplify the unlocking a bit.
- Move Giant acquisition down into __getcwd().
Sponsored By: Isilon Systems, Inc.
small but noticeable increase in performance for name lookup operations.
The code uses two zones, one for short names (less than 32 characters)
and one for long names (up to NAME_MAX). Since most file names are
fairly short, this saves a considerable amount of space that would
otherwise be wasted if we always allocated NAME_MAX bytes. The cutoff
value of 32 characters was picked arbitrarily and may benefit from some
tweaking; it could also be made into a tunable.
Submitted by: hmp
but I decided that it was important for this patch to not bit-rot, and
since it is mainly moving code around, the total amount of entropy is
epsilon /phk)
This is a patch to move the common parts of linux_getcwd() back into
kern/vfs_cache.c so that the standard FreeBSD libc getcwd() can use it's
extended functionality. The linux syscall linux_getcwd() in
compat/linux/linux_getcwd.c has been rewritten to use it too. It should
be possible to simplify libc's getcwd() after this. No doubt this code
needs some cleaning up, since I've left in the sysctl variables I used
for debugging.
PR: 48169
Submitted by: James Whitwell <abacau@yahoo.com.au>
- v_vflag is protected by the vnode lock and is used when synchronization
with VOP calls is needed.
- v_iflag is protected by interlock and is used for dealing with vnode
management issues. These flags include X/O LOCK, FREE, DOOMED, etc.
- All accesses to v_iflag and v_vflag have either been locked or marked with
mp_fixme's.
- Many ASSERT_VOP_LOCKED calls have been added where the locking was not
clear.
- Many functions in vfs_subr.c were restructured to provide for stronger
locking.
Idea stolen from: BSD/OS
behavior by default. Also, change the options line to reflect this.
If there are no problems reported this will become the only behavior and the
knob will be removed in a month or so.
Demanded by: obrien
The stat() and open() calls have been changed to make use of this new functionality. Using shared locks in
these cases is sufficient and can significantly reduce their latency if IO is pending to these vnodes. Also,
this reduces the number of exclusive locks that are floating around in the system, which helps reduce the
number of deadlocks that occur.
A new kernel option "LOOKUP_SHARED" has been added. It defaults to off so this patch can be turned on for
testing, and should eventually go away once it is proven to be stable. I have personally been running this
patch for over a year now, so it is believed to be fully stable.
Reviewed by: jake, obrien
Approved by: jake
Includes some minor whitespace changes, and re-ordering to be able to document
properly (e.g, grouping of variables and the SYSCTL macro calls for them, where
the documentation has been added.)
Reviewed by: phk (but all errors are mine)
Seigo Tanimura (tanimura) posted the initial delta.
I've polished it quite a bit reducing the need for locking and
adapting it for KSE.
Locks:
1 mutex in each filedesc
protects all the fields.
protects "struct file" initialization, while a struct file
is being changed from &badfileops -> &pipeops or something
the filedesc should be locked.
1 mutex in each struct file
protects the refcount fields.
doesn't protect anything else.
the flags used for garbage collection have been moved to
f_gcflag which was the FILLER short, this doesn't need
locking because the garbage collection is a single threaded
container.
could likely be made to use a pool mutex.
1 sx lock for the global filelist.
struct file * fhold(struct file *fp);
/* increments reference count on a file */
struct file * fhold_locked(struct file *fp);
/* like fhold but expects file to locked */
struct file * ffind_hold(struct thread *, int fd);
/* finds the struct file in thread, adds one reference and
returns it unlocked */
struct file * ffind_lock(struct thread *, int fd);
/* ffind_hold, but returns file locked */
I still have to smp-safe the fget cruft, I'll get to that asap.
to avoid removing higher level directory vnodes from the namecache has
no perceivable effect and will be removed. This is especially true
when vmiodirenable is turned on, which it is by default now. ( vmiodirenable
makes a huge difference in directory caching ). The vfs.vmiodirenable and
vfs.nameileafonly sysctls have been left in to allow further testing, but
I expect to rip out vfs.nameileafonly soon too.
I have also determined through testing that the real problem with numvnodes
getting too large is due to the VM Page cache preventing the vnode from
being reclaimed. The directory stuff made only a tiny dent relative
to Poul's original code, enough so that some tests succeeded. But tests
with several million small files show that the bigger problem is the VM Page
cache. This will have to be addressed by a future commit.
MFC after: 3 days
Note ALL MODULES MUST BE RECOMPILED
make the kernel aware that there are smaller units of scheduling than the
process. (but only allow one thread per process at this time).
This is functionally equivalent to teh previousl -current except
that there is a thread associated with each process.
Sorry john! (your next MFC will be a doosie!)
Reviewed by: peter@freebsd.org, dillon@freebsd.org
X-MFC after: ha ha ha ha
has been forcibly unmounted. If the filesystem root vnode is reached
and it has no associated mountpoint (vp->v_mount == NULL), __getcwd
would return without freeing 'buf'. Add the missing free() call.
PR: kern/30306
Submitted by: Mike Potanin <potanin@mccme.ru>
MFC after: 1 week
other "system" header files.
Also help the deprecation of lockmgr.h by making it a sub-include of
sys/lock.h and removing sys/lockmgr.h form kernel .c files.
Sort sys/*.h includes where possible in affected files.
OK'ed by: bde (with reservations)
available.
Only directory vnodes holding no child directory vnodes held in
v_cache_src are recycled, so that directory vnodes near the root of
the filesystem hierarchy remain in namecache and directory vnodes are
not reclaimed in cascade.
The period of vnode reclaiming attempt and the number of vnodes
attempted to reclaim can be tuned via sysctl(2).
Suggested by: tegge
Approved by: phk
