Remove an unnecessary trunc_page() from vmapbuf().

Reviewed by: tegge

o Check the b_bufsize passed to vmapbuf() returning an error
if it is invalid.
o Remove a debugging printf() from vmapbuf().

Suggested by: tegge

Preparation commit before I start on the bioqueue lockdown:

Collect all the bits of bioqueue handing in subr_disk.c, vfs_bio.c is big
enough as it is and disksort already lives in subr_disk.c.

Add support for reading directly from file to userland buffer when the
O_DIRECT descriptor status flag is set and both offset and length is a
multiple of the physical media sector size.

- Add vm_paddr_t, a physical address type. This is required for systems
where physical addresses larger than virtual addresses, such as i386s
with PAE.
- Use this to represent physical addresses

- Add vm_paddr_t, a physical address type. This is required for systems
where physical addresses larger than virtual addresses, such as i386s
with PAE.
- Use this to represent physical addresses in the MI vm system and in the
i386 pmap code. This also changes the paddr parameter to d_mmap_t.
- Fix printf formats to handle physical addresses >4G in the i386 memory
detection code, and due to kvtop returning vm_paddr_t instead of u_long.

Note that this is a name change only; vm_paddr_t is still the same as
vm_offset_t on all currently supported platforms.

Sponsored by: DARPA, Network Associates Laboratories
Discussed with: re, phk (cdevsw change)

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Including <sys/stdint.h> is (almost?) universally only to be able to use
%j in printfs, so put a newsted include in <sys/systm.h> where the printf
prototype lives and save everybody else the trouble.

- Add a lock for protecting against msleep(bp, ...) wakeup(bp) races.
- Create a new function bdone() which sets B_DONE and calls wakup(bp). This
is suitable for use as b_iodone for buf consumers

- Add a lock for protecting against msleep(bp, ...) wakeup(bp) races.
- Create a new function bdone() which sets B_DONE and calls wakup(bp). This
is suitable for use as b_iodone for buf consumers who are not going
through the buf cache.
- Create a new function bwait() which waits for the buf to be done at a set
priority and with a specific wmesg.
- Replace several cases where the above functionality was implemented
without locking with the new functions.

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- Remove a race between fsync like functions and flushbufqueues() by
requiring locked bufs in vfs_bio_awrite(). Previously the buf could
have been written out by fsync before we acquired the b

- Remove a race between fsync like functions and flushbufqueues() by
requiring locked bufs in vfs_bio_awrite(). Previously the buf could
have been written out by fsync before we acquired the buf lock if it
weren't for giant. The cluster_wbuild() handles this race properly but
the single write at the end of vfs_bio_awrite() would not.
- Modify flushbufqueues() so there is only one copy of the loop. Pass a
parameter in that says whether or not we should sync bufs with deps.
- Call flushbufqueues() a second time and then break if we couldn't find
any bufs without deps.

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- Add a new 'flags' parameter to getblk().
- Define one flag GB_LOCK_NOWAIT that tells getblk() to pass the LK_NOWAIT
flag to the initial BUF_LOCK(). This will eventually be used in cases
wer

- Add a new 'flags' parameter to getblk().
- Define one flag GB_LOCK_NOWAIT that tells getblk() to pass the LK_NOWAIT
flag to the initial BUF_LOCK(). This will eventually be used in cases
were we want to use a buffer only if it is not currently in use.
- Convert all consumers of the getblk() api to use this extra parameter.

Reviwed by: arch
Not objected to by: mckusick

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- Hold the vnode interlock across calls to bgetvp instead of acquiring it
internally. This is required to stop multiple bufs from being associated
with a single lblkno.

- gc USE_BUFHASH. The smp locking of the buf cache renders this useless.

When doing cleanup of excessive buffers in bdwrite (see kern/vfs_bio.c
delta 1.371) we must ensure that we do not get ourselves into a
recursive trap endlessly trying to clean up after ourselves.

Re

When doing cleanup of excessive buffers in bdwrite (see kern/vfs_bio.c
delta 1.371) we must ensure that we do not get ourselves into a
recursive trap endlessly trying to clean up after ourselves.

Reported by: Attila Nagy <bra@fsn.hu>
Sponsored by: DARPA & NAI Labs.

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- Add the missing NULL interlock argument to a recently added BUF_LOCK.

Prevent large files from monopolizing the system buffers. Keep
track of the number of dirty buffers held by a vnode. When a
bdwrite is done on a buffer, check the existing number of dirty
buffers ass

Prevent large files from monopolizing the system buffers. Keep
track of the number of dirty buffers held by a vnode. When a
bdwrite is done on a buffer, check the existing number of dirty
buffers associated with its vnode. If the number rises above
vfs.dirtybufthresh (currently 90% of vfs.hidirtybuffers), one
of the other (hopefully older) dirty buffers associated with
the vnode is written (using bawrite). In the event that this
approach fails to curb the growth in it the vnode's number of
dirty buffers (due to soft updates rollback dependencies),
the more drastic approach of doing a VOP_FSYNC on the vnode
is used. This code primarily affects very large and actively
written files such as snapshots. This change should eliminate
hanging when taking snapshots or doing background fsck on
very large filesystems.

Hopefully, one day it will be possible to cache filesystem
metadata in the VM cache as is done with file data. As it
stands, only the buffer cache can be used which limits total
metadata storage to about 20Mb no matter how much memory is
available on the system. This rather small memory gets badly
thrashed causing a lot of extra I/O. For example, taking a
snapshot of a 1Tb filesystem minimally requires about 35,000
write operations, but because of the cache thrashing (we only
have about 350 buffers at our disposal) ends up doing about
237,540 I/O's thus taking twenty-five minutes instead of four
if it could run entirely in the cache.

Reported by: Attila Nagy <bra@fsn.hu>
Sponsored by: DARPA & NAI Labs.

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- Add an interlock argument to BUF_LOCK and BUF_TIMELOCK.
- Remove the buftimelock mutex and acquire the buf's interlock to protect
these fields instead.
- Hold the vnode interlock while locking

- Add an interlock argument to BUF_LOCK and BUF_TIMELOCK.
- Remove the buftimelock mutex and acquire the buf's interlock to protect
these fields instead.
- Hold the vnode interlock while locking bufs on the clean/dirty queues.
This reduces some cases from one BUF_LOCK with a LK_NOWAIT and another
BUF_LOCK with a LK_TIMEFAIL to a single lock.

Reviewed by: arch, mckusick

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Back out M_* changes, per decision of the TRB.

Approved by: trb

- Introduce a new function bremfreel() that does a bremfree with the buf
queue lock already held.
- In getblk() and flushbufqueues() use bremfreel() while we still have the
buf queue lock held

- Introduce a new function bremfreel() that does a bremfree with the buf
queue lock already held.
- In getblk() and flushbufqueues() use bremfreel() while we still have the
buf queue lock held to keep the lists consistent.
- Add LK_NOWAIT to two cases where we're essentially asserting that the bufs
are not locked while acquiring the locks. This will make sure that we get
the appropriate panic() and not another one for sleeping with a lock held.

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- Add a comment about a race that will happen without Giant.

- Unlock the nblock after the loop in bwillwrite().

- In getnewbuf() unlock the bq lock prior to sleeping when we're out of
buffers.

Submitted by: tegge

- Correct another atomic op.

Spotted by: alc

- Move some code out from #ifdef INVARIANTS.

- Cleanup unlocked accesses to buf flags by introducing a new b_vflag member
that is protected by the vnode lock.
- Move B_SCANNED into b_vflags and call it BV_SCANNED.
- Create a vop_stdfsync()

- Cleanup unlocked accesses to buf flags by introducing a new b_vflag member
that is protected by the vnode lock.
- Move B_SCANNED into b_vflags and call it BV_SCANNED.
- Create a vop_stdfsync() modeled after spec's sync.
- Replace spec_fsync, msdos_fsync, and hpfs_fsync with the stdfsync and some
fs specific processing. This gives all of these filesystems proper
behavior wrt MNT_WAIT/NOWAIT and the use of the B_SCANNED flag.
- Annotate the locking in buf.h

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- spell add 'add' and not 'subtract' in an atomic op.

Spotted by: alc
Pointy hat to: jeff

- Lock down the buffer cache's infrastructure code. This includes locks on
buf lists, synchronization variables, and atomic ops for the counters.
This change does not remove giant from any cod

- Lock down the buffer cache's infrastructure code. This includes locks on
buf lists, synchronization variables, and atomic ops for the counters.
This change does not remove giant from any code although some pushdown
may be possible.
- In vfs_bio_awrite() don't access buf fields without the buf lock.

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