1. Add new file "sys/kern/vfs_default.c" where default actions for
VOPs go. Implement proper defaults for ABORTOP, BWRITE, LEASE,
POLL, REVOKE and STRATEGY. Various stuff spread over the entire
tree belongs here.
2. Change VOP_BLKATOFF to a normal function in cd9660.
3. Kill VOP_BLKATOFF, VOP_TRUNCATE, VOP_VFREE, VOP_VALLOC. These
are private interface functions between UFS and the underlying
storage manager layer (FFS/LFS/MFS/EXT2FS). The functions now
live in struct ufsmount instead.
4. Remove a kludge of VOP_ functions in all filesystems, that did
nothing but obscure the simplicity and break the expandability.
If a filesystem doesn't implement VOP_FOO, it shouldn't have an
entry for it in its vnops table. The system will try to DTRT
if it is not implemented. There are still some cruft left, but
the bulk of it is done.
5. Fix another VCALL in vfs_cache.c (thanks Bruce!)
1. Use the default function to access all the specfs operations.
2. Use the default function to access all the fifofs operations.
3. Use the default function to access all the ufs operations.
4. Fix VCALL usage in vfs_cache.c
5. Use VOCALL to access specfs functions in devfs_vnops.c
6. Staticize most of the spec and fifofs vnops functions.
7. Make UFS panic if it lacks bits of the underlying storage handling.
1. Remove comment stating the blatantly obvious.
2. Align in two columns.
3. Sort all but the default element alphabetically.
4. Remove XXX comments pointing out entries not needed.
ip->i_flags.
Rev.1.18 completely broke ufs. My root directory went away about 10
seconds after booting. I think file system damage was null, since
IN_HASHED = 0x80 is not used in the disk flags (it would probably
be UF_SOMETHING if it were used).
Distribute all but the most fundamental malloc types. This time I also
remembered the trick to making things static: Put "static" in front of
them.
A couple of finer points by: bde
1. Clustered I/O is switched by the MNT_NOCLUSTERR and MNT_NOCLUSTERW
bits of the mnt_flag. The sysctl variables, vfs.foo.doclusterread
and vfs.foo.doclusterwrite are deleted. Only mount option can
control clustered I/O from userland.
2. When foofs_mount mounts block device, foofs_mount checks D_CLUSTERR
and D_CLUSTERW bits of the d_flags member in the block device switch
table. If D_NOCLUSTERR / D_NOCLUSTERW are set, MNT_NOCLUSTERR /
MNT_NOCLUSTERW bits will be set. In this case, MNT_NOCLUSTERR and
MNT_NOCLUSTERW cannot be cleared from userland.
3. Vnode driver disables both clustered read and write.
4. Union filesystem disables clutered write.
Reviewed by: bde
plus the previous changes to use the zone allocator decrease the useage
of malloc by half. The Zone allocator will be upgradeable to be able
to use per CPU-pools, and has more intelligent usage of SPLs. Additionally,
it has reasonable stats gathering capabilities, while making most calls
inline.
1. ffs_alloc() actually allowed writing one block less one frag (normally
7 frags or 7/8 blocks) beyond the limit.
2. freebufspace() gives the free space in frags, but `size' is in bytes,
so the change results in approximately `size' fragments too many being
reserved.
3. ffs_realloccg() has the same bug but wasn't changed.
PR: 3398
Submitted by: bde
Eyeballed by: phk
Introduce VFREE which indicates that vnode is on freelist.
Rename vholdrele() to vdrop().
Create vfree() and vbusy() to add/delete vnode from freelist.
Add vfree()/vbusy() to keep (v_holdcnt != 0 || v_usecount != 0)
vnodes off the freelist.
Generalize vhold()/v_holdcnt to mean "do not recycle".
Fix reassignbuf()s lack of use of vhold().
Use vhold() instead of checking v_cache_src list.
Remove vtouch(), the vnodes are always vget'ed soon enough
after for it to have any measuable effect.
Add sysctl debug.freevnodes to keep track of things.
Move cache_purge() up in getnewvnodes to avoid race.
Decrement v_usecount after VOP_INACTIVE(), put a vhold() on
it during VOP_INACTIVE()
Unmacroize vhold()/vdrop()
Print out VDOOMED and VFREE flags (XXX: should use %b)
Reviewed by: dyson
This unifies several times in theory indentical 50 lines of code.
The filesystems have a new method: vop_cachedlookup, which is the
meat of the lookup, and use vfs_cache_lookup() for their vop_lookup
method. vfs_cache_lookup() will check the namecache and pass on
to the vop_cachedlookup method in case of a miss.
It's still the task of the individual filesystems to populate the
namecache with cache_enter().
Filesystems that do not use the namecache will just provide the
vop_lookup method as usual.
free list problem. Also, the vnode age flag is no longer used by the
vnode pager. (It is actually incorrect to use then.) Constructive
feedback welcome -- just be kind.
socket addresses in mbufs. (Socket buffers are the one exception.) A number
of kernel APIs needed to get fixed in order to make this happen. Also,
fix three protocol families which kept PCBs in mbufs to not malloc them
instead. Delete some old compatibility cruft while we're at it, and add
some new routines in the in_cksum family.
code. According to the crash dump, bpref is set to 445
and cgp->cg_nclusterblks is 444. Hence in the for loop,
the test fails immediately but the following failure check
(got == cgp->cg_nclusterblks) doesn't trigger because got >
cgp->cg_nclusterblks. This wreaks havoc in the code after that.
Fix: Move one source bit to the left :-)
Noticed by: Mike Hibler <mike@fast.cs.utah.edu>
Submitted by: Kirk McKusick <mckusick@McKusick.COM>
chown(). Previously, it wasn't marked for null chown()'s. We
permit null chown()s as a special case of "appropriate privilege"
- everyone has enough priviilege to not change ids (this is a better
argument than the one I gave for rev.1.13, that null changes aren't
really changes). However, POSIX.1 requires the update independently
of whether anything has changed.
Clear both the setuid and the setgid bits upon successful completion
of non-null chown()s by non-root. Previously, the setuid bit was
only changed for non-null changes of the uid, etc. POSIX.1 requires
clearing both unless the call was made by a process with "appropriate
privilege", in which case altering the bits is implementation-defined.
We define appropriate privilege as `process is root, or the change
is null', and the implementation-defined behaviour as not altering
the bits. There is no interpretation that permits clearing only
one of the bits.
Reviewed by: jdp
cause a problem of spiraling death due to buffer resource limitations.
The vfs_bio code in general had little ability to handle buffer resource
management, and now it does. Also, there are a lot more knobs for tuning the
vfs_bio code now. The knobs came free because of the need that there
always be some immediately available buffers (non-delayed or locked) for
use. Note that the buffer cache code is much less likely to get bogged
down with lots of delayed writes, even more so than before.
These changes add the ability to specify that a UFS file/directory
cannot be unlinked. This is basically a scaled back version
of the IMMUTABLE flag. The reason is to allow an administrator
to create a directory hierarchy that a group of users
can arbitrarily add/delete files from, but that the hierarchy
itself is safe from removal by them.
If the NOUNLINK definition is set to 0
then this results in no change to what happens normally.
(and results in identical binary (in the kernel)).
It can be proven that if this bit is never set by the admin,
no new behaviour is introduced..
Several "good idea" comments from reviewers plus one grumble
about creeping featurism.
This code is in production in 2.2 based systems
defining doff_t both here and in <ufs/ufs/dir.h> so that this file
is independent of <ufs/ufs/dir.h>. It still has old prerequisites
<sys/param.h> and <ufs/ufs/quota.h>, and a new Lite2 prerequisite of
<sys/lock.h>, sigh.
This might fix lsof, which was broken by namespace pollution giving
conflicting definitions of DIRBLKSIZ.
as shadows of their containing directory. This should solve the problem
of users not being able to delete their symlinks from /tmp once and for
all.
Symlinks do not have modes though, they are accessable to everything that
can read the directory (as before). They are made to show this fact at
lstat time (they appear as mode 0777 always, since that's how the the
lookup routines in the kernel treat them).
More commits will follow, eg: add a real lchown() syscall and man pages.
automatically have random generation numbers. The kenel way of handling those
also changed. Further it is advised to run fsirand on all your nfs exported
filesystems. the code is mostly copied from OpenBSD, with the randomization
chanegd to use /dev/urandom
Reviewed by: Garrett
Obtained from: OpenBSD
null casts. `time' is nonvolatile for accesses within a region locked
by splclock()/splx(). Accesses outside such a region are invalid, and
splx() must have the side effect of potentially changing all global
variables (since there are hundreds of sort of volatile variables like
`time'), so declaring `time' as volatile didn't have any real benefits.
form `tv = time'. Use a new function gettime(). The current version
just forces atomicicity without fixing precision or efficiency bugs.
Simplified some related valid accesses by using the central function.
of setting it (compiled into vfs_conf.c), but we have a dynamic system
in place. This could probably be better done via a runtime configure
flag in the VFS_SET() VFS declaration, perhaps VFCF_LOCAL, and have the
VFS code propagate this down into MNT_LOCAL at mount time. The other FS's
would need to be updated, havinf UFS and MSDOSFS filesystems without
MNT_LOCAL breaks a few things.. the man page rebuild scans for local
filesystems and currently fails, I suspect that other tools like find
and tar with their "local filesystem only" modes might be affected.
Restores the use of SBLOCK instead of the BSOFF/sectorsize calculation.
Using SBLOCK is bogus however in that it uses DEV_BSIZE instead of
the actual sector size, but that is taken care of in other places.
Changing the SBLOCK would be better, but it affects the system
in other places, and doing it this way makes it possible to
use filesystems that was made before the lite2 merge.
mount. This may have been a contributor to the 'null v_mount in
fsync()' problem
This is another, perhaps slightly less urgent, 2.2 last-minute candidate.
Reviewed by: sef
to not return without setting a return value when it
can't read a block error or detects a bad cylinder group,
since the caller is expecting a return value.
It will now panic at this point, since the thing
to do in this case would be to return a "bad block"
status to the caller, and the caller will panic
anyways when that happens.
Also updated to panic strings in this routine to read
"ffs_checkblk: ..." instead of "checkblk: ...".
changes, so don't expect to be able to run the kernel as-is (very well)
without the appropriate Lite/2 userland changes.
The system boots and can mount UFS filesystems.
Untested: ext2fs, msdosfs, NFS
Known problems: Incorrect Berkeley ID strings in some files.
Mount_std mounts will not work until the getfsent
library routine is changed.
Reviewed by: various people
Submitted by: Jeffery Hsu <hsu@freebsd.org>
This will make a number of things easier in the future, as well as (finally!)
avoiding the Id-smashing problem which has plagued developers for so long.
Boy, I'm glad we're not using sup anymore. This update would have been
insane otherwise.
Firstly, now our read-ahead clustering is on a file descriptor basis and not
on a per-vnode basis. This will allow multiple processes reading the
same file to take advantage of read-ahead clustering. Secondly, there
previously was a problem with large reads still using the ramp-up
algorithm. Of course, that was bogus, and now we read the entire
"chunk" off of the disk in one operation. The read-ahead clustering
algorithm should use less CPU than the previous also (I hope :-)).
NOTE: THAT LKMS MUST BE REBUILT!!!
makes MADV_SEQUENTIAL much more effective. I suggest that
we start using MADV_SEQUENTIAL on system utilities that mmap
their input files, and the I/O is predominantely sequential.
Below is a test with 'cmp' on two relatively large binary files,
where the files are so large that the caching is ineffective:
+ ls -l t1.xxx t2.xxx
-rw-r--r-- 1 root wheel 65598384 Dec 10 12:13 t1.xxx
-rw-r--r-- 1 root wheel 65598384 Dec 10 12:14 t2.xxx
+ time cmp t1.xxx t2.xxx
3.78user 0.70system 1:33.43elapsed 4%CPU
+ time cmpmadv t1.xxx t2.xxx
4.21user 1.05system 0:30.93elapsed 17%CPU
This change is as a result of an observation made by BDE.
the sd & od drivers. There is also slight changes to fdisk & newfs
in order to comply with different sectorsizes.
Currently sectors of size 512, 1024 & 2048 are supported, the only
restriction beeing in fdisk, which hunts for the sectorsize of
the device.
This is based on patches to od.c and the other system files by
John Gumb & Barry Scott, minor changes and the sd.c patches by
me.
There also exist some patches for the msdos filesys code, but I
havn't been able to test those (yet).
John Gumb (john@talisker.demon.co.uk)
Barry Scott (barry@scottb.demon.co.uk)
We encountered an interesting situation where the superblock for
a file system got written to disk with the "fs_fmod" flag set to
one. It appears that this flag is normally supposed to be cleared
during ffs_sync(), but we experienced a crash, or some other weird
occurrence that left it on the disk set to 1.
Later this partition was mounted read-only... and the fs_fmod
field was never cleared, causing ffs_sync() to panic "rofs mod"
when trying to unmount that filesystem (ffs_vfsops.c: line 790).
fix:
set this bit to 0 when you load the superblock from disk.
(see more complete mail on this to hackers)
1. When a directory is renamed to an existing (empty) directory,
it is possible for the target vnode to become the source vnode
underneath you (because another process may complete the same
rename). It was assumed that this can't happen, and the bogus
errno EINVAL was returned. This was fairly harmless.
Fix: return ENOENT instead, as if the source directory was renamed
a little earlier.
2. The same metamorphosis is possible for non-directories. It was
assumed that this can't happen, and the code for handling "just
removing a link name" happened to be used. This would have worked
except for fatal bugs in the link name removal - the link name was
assumed to still be there, and a null pointer was followed.
Fix: check the result of relookup(). This fixes PR 1930.
Notes:
(a) POSIX seems to say that removing link names shall have no effect.
BSD (4.4Lite2 at least) does something reasonable instead.
(b) The relookup() may find a file unrelated to the original.
Removing this isn't correct. Consider 3 existing files A, B and
C, and concurrent renames: AB = rename(A, B), another AB, and
CA = rename("c", "a"). If rename() is atomic, then only the
following results are possible:
AB, AB (fails), CA: A = original C, B = original A, C = gone
AB, CA, AB: A = gone, B = original C, C = gone
CA, AB, AB (fails): A = gone, B = original C, C = gone
but ufs_rename() can give:
A,AB,CA,B (sorta): A = gone, B = original A, C = gone
This usually doesn't matter, since getting into a race is usually
an error.
---
These fixes should be in 2.1.6 and 2.2.
ufs_read() and ufs_write().
Found by: looking at warnings for comparing the result of lblktosize()
(which is usually daddr_t = long) with file sizes (which are u_quad_t
for ufs). File sizes should probably be off_t's to avoid warnings
when the are compared with file offsets, so the fixed lblktosize()
casts to off_t instead of u_quad_t.
Added definition of smalllblksize(). It is the same as the old
lblksize() and is more efficient for small block numbers on 32-bit
machines.
Use smalllblktosize() instead of its expansion in blksize() and
dblksize(). This keeps the line length short and makes it more
obvious that the shift can't overflow.
It is needed for implementation details but very little of it is
needed for the interface. Include it in the few places that didn't
already include it.
Include <sys/ioccom.h> in <sys/disklabel.h> (as already in
<sys/diskslice.h>) so that all the disk-related headers are almost
self-sufficient.
/*
* Structure defined by POSIX.4 to be like a timeval.
*/
struct timespec {
time_t ts_sec; /* seconds */
long ts_nsec; /* and nanoseconds */
};
The correct names of the fields are tv_sec and tv_nsec.
Reminded by: James Drobina <jdrobina@infinet.com>
is that it doesn't say _what_ did it! (the core dumped console message
is very useful for listing the process name and pid). This adds similar
information.
the file access time update on reads and can be useful in reducing
filesystem overhead in cases where the access time is not important (like
Usenet news spools).
The interface into the "VMIO" system has changed to be more consistant
and robust. Essentially, it is now no longer necessary to call vn_open
to get merged VM/Buffer cache operation, and exceptional conditions
such as merged operation of VBLK devices is simpler and more correct.
This code corrects a potentially large set of problems including the
problems with ktrace output and loaded systems, file create/deletes,
etc.
Most of the changes to NFS are cosmetic and name changes, eliminating
a layer of subroutine calls. The direct calls to vput/vrele have
been re-instituted for better cross platform compatibility.
Reviewed by: davidg
process won't possibly block before filling in the fsnode pointer (v_data)
which might be dereferenced during a sync since the vnode is put on the
mnt_vnodelist by getnewvnode.
Pointed out by Matt Day <mday@artisoft.com>
and B_READ before writing. This was was fatal. They also broke the
clearing of B_INVAL before doing i/o. This didn't actually matter.
Submitted by: mostly by joerg
be called with the directory referenced, and this reference will
be dropped iff relookup() fails, so the value returned must not be
ignored.
Reviewed by: davidg
Speed up for vfs_bio -- addition of a routine bqrelse to greatly diminish
overhead for merged cache.
Efficiency improvement for vfs_cluster. It used to do alot of redundant
calls to cluster_rbuild.
Correct the ordering for vrele of .text and release of credentials.
Use the selective tlb update for 486/586/P6.
Numerous fixes to the size of objects allocated for files. Additionally,
fixes in the various pagers.
Fixes for proper positioning of vnode_pager_setsize in msdosfs and ext2fs.
Fixes in the swap pager for exhausted resources. The pageout code
will not as readily thrash.
Change the page queue flags (PG_ACTIVE, PG_INACTIVE, PG_FREE, PG_CACHE) into
page queue indices (PQ_ACTIVE, PQ_INACTIVE, PQ_FREE, PQ_CACHE),
thereby improving efficiency of several routines.
Eliminate even more unnecessary vm_page_protect operations.
Significantly speed up process forks.
Make vm_object_page_clean more efficient, thereby eliminating the pause
that happens every 30seconds.
Make sequential clustered writes B_ASYNC instead of B_DELWRI even in the
case of filesystems mounted async.
Fix a panic with busy pages when write clustering is done for non-VMIO
buffers.
This fixes PR943.
ffs/ffs_vfsops.c:
ffs_statfs() multiplied by (100 - minfree) as part of calculating the
minfree percentage (complemented in 100%), so with the standard minfree
of 8, it was broken for file systems of size >= 1TB/92 = 11GB. Use the
standard freespace() macro instead. This also fixes a rounding bug (the
"Avail" count was sometimes 1 too small).
ffs/* (not fixed):
The freespace() macro multiplies by minfree, so with the standard
minfree of 8, it is broken for file systems of size >= 1TB/8 = 128GB.
This bug is more serious since it affects block allocation.
ffs/ffs_alloc.c (not fixed):
Ordinary users are sometimes allowed to allocate 1 (partial) block
too many so that the "Avail" count goes negative. E.g., if there is
1 fragment available and the file is fairly large, one more full
block is allocated.
df/df.c:
ufs_df() used/uses essentially the same code as ffs_statfs(), so it
had/has the same bugs.
ufs_df() gratuitously replaced "Avail" counts of < 0 by 0, so it
gave different results for non-mounted file systems in this case.
is possible to boot a kernel with an empty in-core MFS image, and have
it load the image from floppy directly. This is admittedly a hack and
would be better replaced by a self-loading ram-disk.
What was happening, was that the main mfs loop was sleeping, and when it was
being awoken by a wakeup when it was supposed to process some IO requests.
The problem was that if it was being woken out of the tsleep() by a signal
at shutdown, it was going straight into dounmount() without servicing any
pending IO requests, causing dounmount() to fail because there were busy
buffers (and they could not be "processed" because the processing loop was
trying to unmount rather than dispatching into mfs_doio()).
This (dare I say it :-) appears to be a layering problem....
1) Make cluster buffer list be a non-malloced chain. This eliminates
yet another 'evil' M_WAITOK and generally cleans up the code.
2) Fix write clustering for ext2fs. It was just broken. Also, ffs
clustering had an efficiency problem that more bawrites were happening
than should have been.
3) Make changes to buf.h to support the above, plus remove b_pfcent
at the request of David Greenman.
Note that the reallocblocks code is disabled pending rewrite for
the cluster buffer list changes.
structs and prototypes for syscalls.
Ifdefed duplicated decentralized declarations of args structs. It's
convenient to have this visible but they are hard to maintain. Some
are already different from the central declarations. 4.4lite2 puts
them in comments in the function headers but I wanted to avoid the
large changes for that.
it 1138 times (:-() in casts and a few more times in declarations.
This change is null for the i386.
The type has to be `typedef int vop_t(void *)' and not `typedef
int vop_t()' because `gcc -Wstrict-prototypes' warns about the
latter. Since vnode op functions are called with args of different
(struct pointer) types, neither of these function types is any use
for type checking of the arg, so it would be preferable not to use
the complete function type, especially since using the complete
type requires adding 1138 casts to avoid compiler warnings and
another 40+ casts to reverse the function pointer conversions before
calling the functions.
earlier discussions with DG, and a recent email exchange with SEF, I
decided to allow UFS to run wide-open on an experimental basis. We
will probably support eventually multiple async modes, and this is
the fastest the we can expect. Just use the -o async flag on the
UFS mount. Good luck...
dangerous than the original MNT_ASYNC. There might be some minor
security considerations due to data writes not being posted as promptly
as before. Meta-data operations are still not quite as fast as Linux,
but streaming I/O is still higher.
filesystem layer, as was done in lite-2. Merged in some other cosmetic
changes while I was at it. Rewrote most of msdosfs_access() to be more
like ufs_access() and to include the FS read-only check.
Obtained from: partially from 4.4BSD-lite2
fix a change where a shortcut resulted in teh wrong answer..
e.g.
touch a
touch b
mv a b
resulted in b being removed and a being moved to b
in the shortcut..
touch a
ln a b
mv a b
the wrong link was removed..
leaving a instead of b, giving a different result to when
both files were separate.
bp->b_flags has been broken for many years:
a) they didn't set B_BUSY for doing i/o. This has been fatal since
1995/07/25 when biodone() started checking that B_BUSY is set.
b) they didn't set B_INVAL for releasing the buffer. This at best
just put a useless buffer in the LRU queue for a little while.
Fix a couple of spelling errors and complete a couple of function
pointer declarations.
Submitted by: terry (terry lambert)
This is a composite of 3 patch sets submitted by terry.
they are:
New low-level init code that supports loadbal modules better
some cleanups in the namei code to help terry in 16-bit character support
some changes to the mount-root code to make it a little more
modular..
NOTE: mounting root off cdrom or NFS MIGHT be broken as I haven't been able
to test those cases..
certainly mounting root of disk still works just fine..
mfs should work but is untested. (tomorrows task)
The low level init stuff includes a total rewrite of init_main.c
to make it possible for new modules to have an init phase by simply
adding an entry to a TEXT_SET (or is it DATA_SET) list. thus a new module can
be added to the kernel without editing any other files other than the
'files' file.
disksort is called at non-interrupt time and can be actively traversing
the list when that happens, there is a very small window of vulnerability.
Close it by protecting disksort with splbio().
wrong vp's ops vector being used by changing the VOP_LINK's argument order.
The special-case hack doesn't go far enough and breaks the generic
bypass routine used in some non-leaf filesystems. Pointed out by Kirk
McKusick.
proc or any VM system structure will have to be rebuilt!!!
Much needed overhaul of the VM system. Included in this first round of
changes:
1) Improved pager interfaces: init, alloc, dealloc, getpages, putpages,
haspage, and sync operations are supported. The haspage interface now
provides information about clusterability. All pager routines now take
struct vm_object's instead of "pagers".
2) Improved data structures. In the previous paradigm, there is constant
confusion caused by pagers being both a data structure ("allocate a
pager") and a collection of routines. The idea of a pager structure has
escentially been eliminated. Objects now have types, and this type is
used to index the appropriate pager. In most cases, items in the pager
structure were duplicated in the object data structure and thus were
unnecessary. In the few cases that remained, a un_pager structure union
was created in the object to contain these items.
3) Because of the cleanup of #1 & #2, a lot of unnecessary layering can now
be removed. For instance, vm_object_enter(), vm_object_lookup(),
vm_object_remove(), and the associated object hash list were some of the
things that were removed.
4) simple_lock's removed. Discussion with several people reveals that the
SMP locking primitives used in the VM system aren't likely the mechanism
that we'll be adopting. Even if it were, the locking that was in the code
was very inadequate and would have to be mostly re-done anyway. The
locking in a uni-processor kernel was a no-op but went a long way toward
making the code difficult to read and debug.
5) Places that attempted to kludge-up the fact that we don't have kernel
thread support have been fixed to reflect the reality that we are really
dealing with processes, not threads. The VM system didn't have complete
thread support, so the comments and mis-named routines were just wrong.
We now use tsleep and wakeup directly in the lock routines, for instance.
6) Where appropriate, the pagers have been improved, especially in the
pager_alloc routines. Most of the pager_allocs have been rewritten and
are now faster and easier to maintain.
7) The pagedaemon pageout clustering algorithm has been rewritten and
now tries harder to output an even number of pages before and after
the requested page. This is sort of the reverse of the ideal pagein
algorithm and should provide better overall performance.
8) Unnecessary (incorrect) casts to caddr_t in calls to tsleep & wakeup
have been removed. Some other unnecessary casts have also been removed.
9) Some almost useless debugging code removed.
10) Terminology of shadow objects vs. backing objects straightened out.
The fact that the vm_object data structure escentially had this
backwards really confused things. The use of "shadow" and "backing
object" throughout the code is now internally consistent and correct
in the Mach terminology.
11) Several minor bug fixes, including one in the vm daemon that caused
0 RSS objects to not get purged as intended.
12) A "default pager" has now been created which cleans up the transition
of objects to the "swap" type. The previous checks throughout the code
for swp->pg_data != NULL were really ugly. This change also provides
the rudiments for future backing of "anonymous" memory by something
other than the swap pager (via the vnode pager, for example), and it
allows the decision about which of these pagers to use to be made
dynamically (although will need some additional decision code to do
this, of course).
13) (dyson) MAP_COPY has been deprecated and the corresponding "copy
object" code has been removed. MAP_COPY was undocumented and non-
standard. It was furthermore broken in several ways which caused its
behavior to degrade to MAP_PRIVATE. Binaries that use MAP_COPY will
continue to work correctly, but via the slightly different semantics
of MAP_PRIVATE.
14) (dyson) Sharing maps have been removed. It's marginal usefulness in a
threads design can be worked around in other ways. Both #12 and #13
were done to simplify the code and improve readability and maintain-
ability. (As were most all of these changes)
TODO:
1) Rewrite most of the vnode pager to use VOP_GETPAGES/PUTPAGES. Doing
this will reduce the vnode pager to a mere fraction of its current size.
2) Rewrite vm_fault and the swap/vnode pagers to use the clustering
information provided by the new haspage pager interface. This will
substantially reduce the overhead by eliminating a large number of
VOP_BMAP() calls. The VOP_BMAP() filesystem interface should be
improved to provide both a "behind" and "ahead" indication of
contiguousness.
3) Implement the extended features of pager_haspage in swap_pager_haspage().
It currently just says 0 pages ahead/behind.
4) Re-implement the swap device (swstrategy) in a more elegant way, perhaps
via a much more general mechanism that could also be used for disk
striping of regular filesystems.
5) Do something to improve the architecture of vm_object_collapse(). The
fact that it makes calls into the swap pager and knows too much about
how the swap pager operates really bothers me. It also doesn't allow
for collapsing of non-swap pager objects ("unnamed" objects backed by
other pagers).
2) Removed unnecessary vm_object_lookup()/pager_cache(object, TRUE) pairs
after vnode_pager_alloc() calls - the object is already guaranteed to be
persistent.
3) Removed some gratuitous casts.
1) Files weren't properly synced on filesystems other than UFS. In some
cases, this lead to lost data. Most likely would be noticed on NFS.
The fix is to make the VM page sync/object_clean general rather than
in each filesystem.
2) Mixing regular and mmaped file I/O on NFS was very broken. It caused
chunks of files to end up as zeroes rather than the intended contents.
The fix was to fix several race conditions and to kludge up the
"b_dirtyoff" and "b_dirtyend" that NFS relies upon - paying attention
to page modifications that occurred via the mmapping.
Reviewed by: David Greenman
Submitted by: John Dyson
These changes solve the problem in a general way by moving the
initialization out of the individual fs_mountroot's and into swaponvp().
Submitted by: Poul-Henning Kamp
when the single user shell was terminated. These changes disallow mounting
or R/W upgrading filesystems that are dirty unless "-f" (force) option
is used with mount. /etc/rc has been modified to abort the startup if
one or more non-nfs partitions fail to mount.
Reviewed by: Poul-Henning Kamp, Rod Grimes
I ran into another manifestation of the problem reported in PR 211 and
fixed it. Try this:
as non-root:
cd /tmp; mkdir x y x/z
as root:
chown root /tmp/x/z
as non-root:
cd /tmp/x; mv z ../y # EACCES as expected
as root:
cd /tmp/x; mv z ../y # EINVAL NOT as expected
This is because ufs_rename() sets IN_RENAME and fails to clear it.
Reviewed by: davidg
Submitted by: bde
(2GB). If this limit is not imposed, then filesystem corruption will
ensue when files larger than 2GB are created. This is temporary,
and the underlying limitation will be removed later.
don't lock the vnode - it doesn't appear to ever be necessary for VCHR
vnode/inodes. This fixes a bug introduced in the previous commit that
caused tty timestamps to act strange (causing 'w' and 'finger' to show
the tty wasn't idle when it may have been for hours).
Fixed remaining known bugs in the buffer IO and VM system.
vfs_bio.c:
Fixed some race conditions and locking bugs. Improved performance
by removing some (now) unnecessary code and fixing some broken
logic.
Fixed process accounting of # of FS outputs.
Properly handle NFS interrupts (B_EINTR).
(various)
Replaced calls to clrbuf() with calls to an optimized routine
called vfs_bio_clrbuf().
(various FS sync)
Sync out modified vnode_pager backed pages.
ffs_vnops.c:
Do two passes: Sync out file data first, then indirect blocks.
vm_fault.c:
Fixed deadly embrace caused by acquiring locks in the wrong order.
vnode_pager.c:
Changed to use buffer I/O system for writing out modified pages. This
should fix the problem with the modification date previous not getting
updated. Also dramatically simplifies the code. Note that this is
going to change in the future and be implemented via VOP_PUTPAGES().
vm_object.c:
Fixed a pile of bugs related to cleaning (vnode) objects. The performance
of vm_object_page_clean() is terrible when dealing with huge objects,
but this will change when we implement a binary tree to keep the object
pages sorted.
vm_pageout.c:
Fixed broken clustering of pageouts. Fixed race conditions and other
lockup style bugs in the scanning of pages. Improved performance.
