This patch fixes places where they should be called atomically changing
their locking requirements (both assume per-proc spinlock held) and
introducing rufetchcalc which wrappers both calls to be performed in
atomic way.
Reviewed by: jeff
Approved by: jeff (mentor)
- Use thread_lock() rather than sched_lock for per-thread scheduling
sychronization.
- Use the per-process spinlock rather than the sched_lock for per-process
scheduling synchronization.
Tested by: kris, current@
Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc.
Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
Now, we assume no more sched_lock protection for some of them and use the
distribuited loads method for vmmeter (distribuited through CPUs).
Reviewed by: alc, bde
Approved by: jeff (mentor)
argument from being file descriptor index into the pointer to struct file:
part 2. Convert calls missed in the first big commit.
Noted by: rwatson
Pointy hat to: kib
Probabilly, a general approach is not the better solution here, so we should
solve the sched_lock protection problems separately.
Requested by: alc
Approved by: jeff (mentor)
Change the VOP_OPEN(), vn_open() vnode operation and d_fdopen() cdev operation
argument from being file descriptor index into the pointer to struct file.
Proposed and reviewed by: jhb
Reviewed by: daichi (unionfs)
Approved by: re (kensmith)
function calls are no more generated for vop_lock.
Rename _vop_lock to vop_lock1 to satisfy tools/vnode_if.awk assumption
about vop naming conventions. This restores pre/post-condition calls.
vmcnts. This can be used to abstract away pcpu details but also changes
to use atomics for all counters now. This means sched lock is no longer
responsible for protecting counts in the switch routines.
Contributed by: Attilio Rao <attilio@FreeBSD.org>
where similar data structures exist to support devfs and the MAC
Framework, but are named differently.
Obtained from: TrustedBSD Project
Sponsored by: SPARTA, Inc.
be applied to dev entries. This leaves us with file times like "Jan 1 1970."
Work around this problem by replacing the tv_sec == 0 check with a
<= 3600 check. It's doubtful anyone will be booting within an hour of the
Epoch, let alone care about a few seconds worth of nonzero timestamps. It's
a hackish work around, but it does work and I have not experienced any
negatives in my testing.
Discussed with: bde
"Ok with me: phk
requests where uio_offset is not 0 to begin with. This fixes a long-
standing bug where e.g. 'cat /proc/$$/regs' would loop forever.
MFC after: 3 weeks
The pfs_info mutex is only needed to lock pi_unrhdr. Everything else
in struct pfs_info is modified only while Giant is held (during
vfs_init() / vfs_uninit()); add assertions to that effect.
Simplify pfs_destroy somewhat.
Remove superfluous arguments from pfs_fileno_{alloc,free}(), and the
assertions which were added in the previous commit to ensure they were
consistent.
Assert that Giant is held while the vnode cache is initialized and
destroyed. Also assert that the cache is empty when it is destroyed.
Rename the vnode cache mutex for consistency.
Fix a long-standing bug in pfs_getattr(): it would uncritically return
the node's pn_fileno as st_ino. This would result in st_ino being 0
if the node had not previously been visited by readdir(), and also in
an incorrect st_ino for process directories and any files contained
therein. Correct this by abstracting the fileno manipulations
previously done in pfs_readdir() into a new function, pfs_fileno(),
which is used by both pfs_getattr() and pfs_readdir().
specific nodes when the process exits)
Move the vnode-cache-walking loop which was duplicated in pfs_exit() and
pfs_disable() into its own function, pfs_purge(), which looks for vnodes
marked as dead and / or belonging to the specified pfs_node and reclaims
them. Note that this loop is still extremely inefficient.
Add a comment in pfs_vncache_alloc() explaining why we have to purge the
vnode from the vnode cache before returning, in case anyone should be
tempted to remove the call to cache_purge().
Move the special handling for pfstype_root nodes into pfs_fileno_alloc()
and pfs_fileno_free() (the root node's fileno must always be 2). This
also fixes a bug where pfs_fileno_free() would reclaim the root node's
fileno, triggering a panic in the unr code, as that fileno was never
allocated from unr to begin with.
When destroying a pfs_node, release its fileno and purge it from the
vnode cache. I wish we could put off the call to pfs_purge() until
after the entire tree had been destroyed, but then we'd have vnodes
referencing freed pfs nodes. This probably doesn't matter while we're
still under Giant, but might become an issue later.
When destroying a pseudofs instance, destroy the tree before tearing
down the fileno allocator.
In pfs_mount(), acquire the mountpoint interlock when required.
MFC after: 3 weeks
and flags with an sxlock. This leads to a significant and measurable
performance improvement as a result of access to shared locking for
frequent lookup operations, reduced general overhead, and reduced overhead
in the event of contention. All of these are imported for threaded
applications where simultaneous access to a shared file descriptor array
occurs frequently. Kris has reported 2x-4x transaction rate improvements
on 8-core MySQL benchmarks; smaller improvements can be expected for many
workloads as a result of reduced overhead.
- Generally eliminate the distinction between "fast" and regular
acquisisition of the filedesc lock; the plan is that they will now all
be fast. Change all locking instances to either shared or exclusive
locks.
- Correct a bug (pointed out by kib) in fdfree() where previously msleep()
was called without the mutex held; sx_sleep() is now always called with
the sxlock held exclusively.
- Universally hold the struct file lock over changes to struct file,
rather than the filedesc lock or no lock. Always update the f_ops
field last. A further memory barrier is required here in the future
(discussed with jhb).
- Improve locking and reference management in linux_at(), which fails to
properly acquire vnode references before using vnode pointers. Annotate
improper use of vn_fullpath(), which will be replaced at a future date.
In fcntl(), we conservatively acquire an exclusive lock, even though in
some cases a shared lock may be sufficient, which should be revisited.
The dropping of the filedesc lock in fdgrowtable() is no longer required
as the sxlock can be held over the sleep operation; we should consider
removing that (pointed out by attilio).
Tested by: kris
Discussed with: jhb, kris, attilio, jeff
late stages of unmount). On failure, the vnode is recycled.
Add insmntque1(), to allow for file system specific cleanup when
recycling vnode on failure.
Change getnewvnode() to no longer call insmntque(). Previously,
embryonic vnodes were put onto the list of vnode belonging to a file
system, which is unsafe for a file system marked MPSAFE.
Change vfs_hash_insert() to no longer lock the vnode. The caller now
has that responsibility.
Change most file systems to lock the vnode and call insmntque() or
insmntque1() after a new vnode has been sufficiently setup. Handle
failed insmntque*() calls by propagating errors to callers, possibly
after some file system specific cleanup.
Approved by: re (kensmith)
Reviewed by: kib
In collaboration with: kib
function which is called from pfs_destroy() before the node is reclaimed.
Modify pfs_create_{dir,file,link}() to accept a pointer to a destructor
function in addition to the usual attr / fill / vis pointers.
This breaks both the programming and binary interfaces between pseudofs
and its consumers. It is believed that there are no pseudofs consumers
outside the source tree, so that the impact of this change is minimal.
Submitted by: Aniruddha Bohra <bohra@cs.rutgers.edu>
This way we may support multiple structures in v_data vnode field within
one file system without using black magic.
Vnode-to-file-handle should be VOP in the first place, but was made VFS
operation to keep interface as compatible as possible with SUN's VFS.
BTW. Now Solaris also implements vnode-to-file-handle as VOP operation.
VFS_VPTOFH() was left for API backward compatibility, but is marked for
removal before 8.0-RELEASE.
Approved by: mckusick
Discussed with: many (on IRC)
Tested with: ufs, msdosfs, cd9660, nullfs and zfs
the value of p_textvp. This way, we always unlock the locked vnode.
While there, vhold() the vnode around the vn_lock().
Reported and tested by: Guy Helmer (ghelmer palisadesys com)
Approved by: des (procfs maintainer)
MFC after: 1 week
#ifdef MSDOSFS_LARGE to run-time checks to see if "-o large" was specified.
Test case provided by Oliver Fromme:
truncate -s 200G test.img
mdconfig -a -t vnode -f test.img -u 9
newfs_msdos -s 419430400 -n 1 /dev/md9 zip250
mount -t msdosfs /dev/md9 /mnt # should fail
mount -t msdosfs -o large /dev/md9 /mnt # should succeed
PR: 105964
Requested by: Oliver Fromme <olli lurza secnetix de>
Tested by: trhodes
MFC after: 2 weeks
--------------------------
[Deadlock] is caused by a lock order reversal in vfs_lookup(), where
[some] process is trying to lock a directory vnode, that is the parent
directory of covered vnode) while holding an exclusive vnode lock on
covering vnode.
A simplified scenario:
root fs var fs
/ A / (/var) D
/var B /log (/var/log) E
vfs lock C vfs lock F
Within each file system, the lock order is clear: C->A->B and F->D->E
When traversing across mounts, the system can choose between two lock orders,
but everything must then follow that lock order:
L1: C->A->B
|
+->F->D->E
L2: F->D->E
|
+->C->A->B
The lookup() process for namei("/var") mixes those two lock orders:
VOP_LOOKUP() obtains B while A is held
vfs_busy() obtains a shared lock on F while A and B are held (follows L1,
violates L2)
vput() releases lock on B
VOP_UNLOCK() releases lock on A
VFS_ROOT() obtains lock on D while shared lock on F is held
vfs_unbusy() releases shared lock on F
vn_lock() obtains lock on A while D is held (violates L1, follows L2)
dounmount() follows L1 (B is locked while F is drained).
Without unmount activity, vfs_busy() will always succeed without blocking
and the deadlock isn't triggered (the system behaves as if L2 is followed).
With unmount, you can get 4 processes in a deadlock:
p1: holds D, want A (in lookup())
p2: holds shared lock on F, want D (in VFS_ROOT())
p3: holds B, want drain lock on F (in dounmount())
p4: holds A, want B (in VOP_LOOKUP())
You can have more than one instance of p2.
The reversal was introduced in revision 1.81 of src/sys/kern/vfs_lookup.c and
MFCed to revision 1.80.2.1, probably to avoid a cascade of vnode locks when nfs
servers are dead (VFS_ROOT() just hangs) spreading to the root fs root vnode.
- Tor Egge
To fix the LOR, ups@ noted that when crossing the mount point, ni_dvp
is actually not used by the callers of namei. Thus, placeholder deadfs
vnode vp_crossmp is introduced that is filled into ni_dvp.
Idea by: ups
Reviewed by: tegge, ups, jeff, rwatson (mac interaction)
Tested by: Peter Holm
MFC after: 2 weeks
from just before extending a file. This has the desired effect
of keeping the write speed constant. And yes, that helps a lot
copying large files always at full speed now, and I have seen
improvements using benchmarks/bonnie.
Stolen from: NetBSD
Reviewed by: bde
The code is modelled after cd9660, including support for simple read-ahead
courtesy of clustered read.
Fix udf_strategy to DTRT.
This change fixes sendfile(2) not to send out garbage.
Reviewed by: scottl
MFC after: 1 month
