by the inactive routine. Because the freeing causes the filesystem
to be modified, the close must be held up during periods when the
filesystem is suspended.
For snapshots to be consistent across crashes, they must write
blocks that they copy and claim those written blocks in their
on-disk block pointers before the old blocks that they referenced
can be allowed to be written.
Close a loophole that allowed unwritten blocks to be skipped when
doing ffs_sync with a request to wait for all I/O activity to be
completed.
to struct mount.
This makes the "struct netexport *" paramter to the vfs_export
and vfs_checkexport interface unneeded.
Consequently that all non-stacking filesystems can use
vfs_stdcheckexp().
At the same time, make it a pointer to a struct netexport
in struct mount, so that we can remove the bogus AF_MAX
and #include <net/radix.h> from <sys/mount.h>
fs_contigdirs, fs_avgfilesize and fs_avgfpdir. This could cause
panics if these fields were zeroed while a filesystem was mounted
read-only, and then remounted read-write.
Add code to ffs_reload() which copies the fs_contigdirs pointer
from the previous superblock, and reinitialises fs_avgf* if necessary.
Reviewed by: mckusick
VOP_BWRITE() was a hack which made it possible for NFS client
side to use struct buf with non-bio backing.
This patch takes a more general approach and adds a bp->b_op
vector where more methods can be added.
The success of this patch depends on bp->b_op being initialized
all relevant places for some value of "relevant" which is not
easy to determine. For now the buffers have grown a b_magic
element which will make such issues a tiny bit easier to debug.
sized blocks. To enable this option, use: `sysctl -w debug.bigcgs=1'.
Add debugging option to disable background writes of cylinder
groups. To enable this option, use: `sysctl -w debug.dobkgrdwrite=0'.
These debugging options should be tried on systems that are panicing
with corrupted cylinder group maps to see if it makes the problem
go away. The set of panics in question are:
ffs_clusteralloc: map mismatch
ffs_nodealloccg: map corrupted
ffs_nodealloccg: block not in map
ffs_alloccg: map corrupted
ffs_alloccg: block not in map
ffs_alloccgblk: cyl groups corrupted
ffs_alloccgblk: can't find blk in cyl
ffs_checkblk: partially free fragment
The following panics are less likely to be related to this problem,
but might be helped by these debugging options:
ffs_valloc: dup alloc
ffs_blkfree: freeing free block
ffs_blkfree: freeing free frag
ffs_vfree: freeing free inode
If you try these options, please report whether they helped reduce your
bitmap corruption panics to Kirk McKusick at <mckusick@mckusick.com>
and to Matt Dillon <dillon@earth.backplane.com>.
ACL_USER_OBJ and ACL_GROUP_OBJ fields, believing that modification of the
access ACL could be used by privileged processes to change file/directory
ownership. In fact, this is incorrect; ACL_*_OBJ (+ ACL_MASK and
ACL_OTHER) should have undefined ae_id fields; this commit attempts
to correct that misunderstanding.
o Modify arguments to vaccess_acl_posix1e() to accept the uid and gid
associated with the vnode, as those can no longer be extracted from
the ACL passed as an argument. Perform all comparisons against
the passed arguments. This actually has the effect of simplifying
a number of components of this call, as well as reducing the indent
level, but now seperates handling of ACL_GROUP_OBJ from ACL_GROUP.
o Modify acl_posix1e_check() to return EINVAL if the ae_id field of
any of the ACL_{USER_OBJ,GROUP_OBJ,MASK,OTHER} entries is a value
other than ACL_UNDEFINED_ID. As a temporary work-around to allow
clean upgrades, set the ae_id field to ACL_UNDEFINED_ID before
each check so that this cannot cause a failure in the short term
(this work-around will be removed when the userland libraries and
utilities are updated to take this change into account).
o Modify ufs_sync_acl_from_inode() so that it forces
ACL_{USER_OBJ,GROUP_OBJ,MASK,OTHER} ae_id fields to ACL_UNDEFINED_ID
when synchronizing the ACL from the inode.
o Modify ufs_sync_inode_from_acl to not propagate uid and gid
information to the inode from the ACL during ACL update. Also
modify the masking of permission bits that may be set from
ALLPERMS to (S_IRWXU|S_IRWXG|S_IRWXO), as ACLs currently do not
carry none-ACCESSPERMS (S_ISUID, S_ISGID, S_ISTXT).
o Modify ufs_getacl() so that when it emulates an access ACL from
the inode, it initializes the ae_id fields to ACL_UNDEFINED_ID.
o Clean up ufs_setacl() substantially since it is no longer possible
to perform chown/chgrp operations using vop_setacl(), so all the
access control for that can be eliminated.
o Modify ufs_access() so that it passes owner uid and gid information
into vaccess_acl_posix1e().
Pointed out by: jedger
Obtained from: TrustedBSD Project
It is described in ufs/ffs/fs.h as follows:
/*
* Filesystem flags.
*
* Note that the FS_NEEDSFSCK flag is set and cleared only by the
* fsck utility. It is set when background fsck finds an unexpected
* inconsistency which requires a traditional foreground fsck to be
* run. Such inconsistencies should only be found after an uncorrectable
* disk error. A foreground fsck will clear the FS_NEEDSFSCK flag when
* it has successfully cleaned up the filesystem. The kernel uses this
* flag to enforce that inconsistent filesystems be mounted read-only.
*/
#define FS_UNCLEAN 0x01 /* filesystem not clean at mount */
#define FS_DOSOFTDEP 0x02 /* filesystem using soft dependencies */
#define FS_NEEDSFSCK 0x04 /* filesystem needs sync fsck before mount */
His description of the problem and solution follow. My own tests show
speedups on typical filesystem intensive workloads of 5% to 12% which
is very impressive considering the small amount of code change involved.
------
One day I noticed that some file operations run much faster on
small file systems then on big ones. I've looked at the ffs
algorithms, thought about them, and redesigned the dirpref algorithm.
First I want to describe the results of my tests. These results are old
and I have improved the algorithm after these tests were done. Nevertheless
they show how big the perfomance speedup may be. I have done two file/directory
intensive tests on a two OpenBSD systems with old and new dirpref algorithm.
The first test is "tar -xzf ports.tar.gz", the second is "rm -rf ports".
The ports.tar.gz file is the ports collection from the OpenBSD 2.8 release.
It contains 6596 directories and 13868 files. The test systems are:
1. Celeron-450, 128Mb, two IDE drives, the system at wd0, file system for
test is at wd1. Size of test file system is 8 Gb, number of cg=991,
size of cg is 8m, block size = 8k, fragment size = 1k OpenBSD-current
from Dec 2000 with BUFCACHEPERCENT=35
2. PIII-600, 128Mb, two IBM DTLA-307045 IDE drives at i815e, the system
at wd0, file system for test is at wd1. Size of test file system is 40 Gb,
number of cg=5324, size of cg is 8m, block size = 8k, fragment size = 1k
OpenBSD-current from Dec 2000 with BUFCACHEPERCENT=50
You can get more info about the test systems and methods at:
http://www.ptci.ru/gluk/dirpref/old/dirpref.html
Test Results
tar -xzf ports.tar.gz rm -rf ports
mode old dirpref new dirpref speedup old dirprefnew dirpref speedup
First system
normal 667 472 1.41 477 331 1.44
async 285 144 1.98 130 14 9.29
sync 768 616 1.25 477 334 1.43
softdep 413 252 1.64 241 38 6.34
Second system
normal 329 81 4.06 263.5 93.5 2.81
async 302 25.7 11.75 112 2.26 49.56
sync 281 57.0 4.93 263 90.5 2.9
softdep 341 40.6 8.4 284 4.76 59.66
"old dirpref" and "new dirpref" columns give a test time in seconds.
speedup - speed increasement in times, ie. old dirpref / new dirpref.
------
Algorithm description
The old dirpref algorithm is described in comments:
/*
* Find a cylinder to place a directory.
*
* The policy implemented by this algorithm is to select from
* among those cylinder groups with above the average number of
* free inodes, the one with the smallest number of directories.
*/
A new directory is allocated in a different cylinder groups than its
parent directory resulting in a directory tree that is spreaded across
all the cylinder groups. This spreading out results in a non-optimal
access to the directories and files. When we have a small filesystem
it is not a problem but when the filesystem is big then perfomance
degradation becomes very apparent.
What I mean by a big file system ?
1. A big filesystem is a filesystem which occupy 20-30 or more percent
of total drive space, i.e. first and last cylinder are physically
located relatively far from each other.
2. It has a relatively large number of cylinder groups, for example
more cylinder groups than 50% of the buffers in the buffer cache.
The first results in long access times, while the second results in
many buffers being used by metadata operations. Such operations use
cylinder group blocks and on-disk inode blocks. The cylinder group
block (fs->fs_cblkno) contains struct cg, inode and block bit maps.
It is 2k in size for the default filesystem parameters. If new and
parent directories are located in different cylinder groups then the
system performs more input/output operations and uses more buffers.
On filesystems with many cylinder groups, lots of cache buffers are
used for metadata operations.
My solution for this problem is very simple. I allocate many directories
in one cylinder group. I also do some things, so that the new allocation
method does not cause excessive fragmentation and all directory inodes
will not be located at a location far from its file's inodes and data.
The algorithm is:
/*
* Find a cylinder group to place a directory.
*
* The policy implemented by this algorithm is to allocate a
* directory inode in the same cylinder group as its parent
* directory, but also to reserve space for its files inodes
* and data. Restrict the number of directories which may be
* allocated one after another in the same cylinder group
* without intervening allocation of files.
*
* If we allocate a first level directory then force allocation
* in another cylinder group.
*/
My early versions of dirpref give me a good results for a wide range of
file operations and different filesystem capacities except one case:
those applications that create their entire directory structure first
and only later fill this structure with files.
My solution for such and similar cases is to limit a number of
directories which may be created one after another in the same cylinder
group without intervening file creations. For this purpose, I allocate
an array of counters at mount time. This array is linked to the superblock
fs->fs_contigdirs[cg]. Each time a directory is created the counter
increases and each time a file is created the counter decreases. A 60Gb
filesystem with 8mb/cg requires 10kb of memory for the counters array.
The maxcontigdirs is a maximum number of directories which may be created
without an intervening file creation. I found in my tests that the best
performance occurs when I restrict the number of directories in one cylinder
group such that all its files may be located in the same cylinder group.
There may be some deterioration in performance if all the file inodes
are in the same cylinder group as its containing directory, but their
data partially resides in a different cylinder group. The maxcontigdirs
value is calculated to try to prevent this condition. Since there is
no way to know how many files and directories will be allocated later
I added two optimization parameters in superblock/tunefs. They are:
int32_t fs_avgfilesize; /* expected average file size */
int32_t fs_avgfpdir; /* expected # of files per directory */
These parameters have reasonable defaults but may be tweeked for special
uses of a filesystem. They are only necessary in rare cases like better
tuning a filesystem being used to store a squid cache.
I have been using this algorithm for about 3 months. I have done
a lot of testing on filesystems with different capacities, average
filesize, average number of files per directory, and so on. I think
this algorithm has no negative impact on filesystem perfomance. It
works better than the default one in all cases. The new dirpref
will greatly improve untarring/removing/coping of big directories,
decrease load on cvs servers and much more. The new dirpref doesn't
speedup a compilation process, but also doesn't slow it down.
Obtained from: Grigoriy Orlov <gluk@ptci.ru>
to not using IO_SYNC. Expose a sysctl (debug.ufs_extattr_sync) for
enabling the use of IO_SYNC.
- Use of IO_SYNC substantially degrades ACL performance when a
default ACL is set on a directory, as there are four synchronous
writes initiated to define both supporting EAs for new
sub-directories, and to set the data; two for new files. Later, this
may be optimized to two writes for sub-directories, one for new
files.
- IO_SYNC does not substantially improve consistency properties due
to the poor consistency properties of existing permissions (which
ACLs are a superset of), due to interaction with soft updates,
and due to differences in handling consistency for data and file
system meta-data.
- In macro-benchmarks, this reduces the overhead of setting default
ACLs down to the same overhead as enabling ACLs on a file system
and not using them. Enabling ACLs still introduces a small
overhead (I measure 7% on a -j 2 buildworld with pre-allocated
EA backing store, but this is not rigorous testing, nor in any way
optimized).
- The sysctl will probably change to another administration method
(or at least, a better name) in the near future, but consistency
properties of EAs are still being worked out. The toggle is defined
right now to allow easier performance analysis and exploration
of possible guarantees.
Obtained from: TrustedBSD Project
under heavy use when default ACLs were bgin inherited by new files
or directories. This is done by removing a bug in default ACL
reading, and improving error handling for this failure case:
- Move the setting of the buffer length (len) variable to above the
ACL type (ap->a_type) switch rather than having it only for
ACL_TYPE_ACCESS. Otherwise, the len variable is unitialized in
the ACL_TYPE_DEFAULT case, which generally worked right, but could
result in failure.
- Add a check for a short/long read of the ACL_TYPE_DEFAULT type from
the underlying EA, resulting in EPERM rather than passing a
potentially corrupted ACL back to the caller (resulting "cleaner"
failures if the EA is damaged: right now, the caller will almost
always panic in the presence of a corrupted EA). This code is similar
to code in the ACL_TYPE_ACCESS handling in the previous switch case.
- While I'm fixing this code, remove a redundant bzero() of the ACL
reader buffer; it need only be initialized above the acl_type
switch.
Obtained from: TrustedBSD Project
implementation is still experimental, and while fairly broadly tested,
is not yet intended for production use. Support for POSIX.1e ACLs on
UFS will not be MFC'd to RELENG_4.
This implementation works by providing implementations of VOP_[GS]ETACL()
for FFS, as well as modifying the appropriate access control and file
creation routines. In this implementation, ACLs are backed into extended
attributes; the base ACL (owner, group, other) permissions remain in the
inode for performance and compatibility reasons, so only the extended and
default ACLs are placed in extended attributes. The logic for ACL
evaluation is provided by the fs-independent kern/kern_acl.c.
o Introduce UFS_ACL, a compile-time configuration option that enables
support for ACLs on FFS (and potentially other UFS-based file systems).
o Introduce ufs_getacl(), ufs_setacl(), ufs_aclcheck(), which
respectively get, set, and check the ACLs on the passed vnode.
o Introduce ufs_sync_acl_from_inode(), ufs_sync_inode_from_acl() to
maintain access control information between inode permissions and
extended attribute data.
o Modify ufs_access() to load a file access ACL and invoke
vaccess_acl_posix1e() if ACLs are available on the file system
o Modify ufs_mkdir() and ufs_makeinode() to associate ACLs with newly
created directories and files, inheriting from the parent directory's
default ACL.
o Enable these new vnode operations and conditionally compiled code
paths if UFS_ACL is defined.
A few notes:
o This implementation is fairly widely tested, but still should be
considered experimental.
o Currently, ACLs are not exported via NFS, instead, the summarizing
file mode/etc from the inode is. This results in conservative
protection behavior, similar to the behavior of ACL-nonaware programs
acting locally.
o It is possible that underlying binary data formats associated with
this implementation may change. Consumers of the implementation
should expect to find their local configuration obsoleted in the
next few months, resulting in possible loss of ACL data during an
upgrade.
o The extended attributes interface and implementation is still
undergoing modification to address portable interface concerns, as
well as performance.
o Many applications do not yet correctly handle ACLs. In general,
due to the POSIX.1e ACL model, behavior of ACL-unaware applications
will be conservative with respects to file protection; some caution
is recommended.
o Instructions for configuring and maintaining ACLs on UFS will be
committed in the near future; in the mean time it is possible to
reference the README included in the last UFS ACL distribution
placed in the TrustedBSD web site:
http://www.TrustedBSD.org/downloads/
Substantial debugging, hardware, travel, or connectivity support for this
project was provided by: BSDi, Safeport Network Services, and NAI Labs.
Significant coding contributions were made by Chris Faulhaber. Additional
support was provided by Brian Feldman, Thomas Moestl, and Ilmar Habibulin.
Reviewed by: jedgar, keichii, mckusick, trustedbsd-discuss, freebsd-fs
Obtained from: TrustedBSD Project
which resulted in the output of warning messages at boot if
UFS_EXTATTR_AUTOSTART was enabled but ".attribute" and possible
sub-directories weren't in a mounted MFS or UFS file systems.
Pointed out by: dcs
Obtained from: TrustedBSD Project
(as is done in unmount).
Remove a snapshot inode from the superblock list when its last
name goes away rather than when its last reference goes away.
That way it will be properly reclaimed by fsck after a crash
rather than reenabled when the filesystem is mounted.
is under-tested, and that MFS appears to be in the process of being
deprecated in favor of FFS over md. Note also that UFS_EXTATTR_AUTOSTART
doesn't make much sense on MFS unless the MFSROOT is compiled in, so
manual configuration is generally required.
Obtained from: TrustedBSD Project
options UFS_EXTATTR and UFS_EXTATTR_AUTOSTART respectively. This change
reflects the fact that our EA support is implemented entirely at the
UFS layer (modulo FFS start/stop/autostart hooks for mount and unmount
events). This also better reflects the fact that [shortly] MFS will also
support EAs, as well as possibly IFS.
o Consumers of the EA support in FFS are reminded that as a result, they
must change kernel config files to reflect the new option names.
Obtained from: TrustedBSD Project
off of the file system root: "user" for user attributes, and "system"
for system attributes. When the scan occurs, attribute backing files
discovered in those directories will be started in the respective
namespaces. This re-introduces support for auto-starting of user
attributes, which was removed when the "$" prefix for system attributes
was replaced with explicit namespacing.
For users of the TrustedBSD UFS POSIX.1e ACL code, you'll need to:
mv ${FSROOT}/'$posix1e.acl_access' ${FSROOT}/system/posix1e.acl_access
mv ${FSROOT}/'$posix1e.acl_default' ${FSROOT}/system/posix1e.acl_default
For users of the TrustedBSD POSIX.1e Capability code, you'll need to:
mv ${FSROOT}/'$posix1e.cap' ${FSROOT}/system/posix1e.cap
For users of the TrustedBSD MAC code, you'll need to:
mv ${FSROOT}/'$freebsd.mac' ${FSROOT}/system/freebsd.mac
Updated versions of relevant patches will be released in the near
future.
Obtained from: TrustedBSD Project
introduce a new argument, "namespace", rather than relying on a first-
character namespace indicator. This is in line with more recent
thinking on EA interfaces on various mailing lists, including the
posix1e, Linux acl-devel, and trustedbsd-discuss forums. Two namespaces
are defined by default, EXTATTR_NAMESPACE_SYSTEM and
EXTATTR_NAMESPACE_USER, where the primary distinction lies in the
access control model: user EAs are accessible based on the normal
MAC and DAC file/directory protections, and system attributes are
limited to kernel-originated or appropriately privileged userland
requests.
o These API changes occur at several levels: the namespace argument is
introduced in the extattr_{get,set}_file() system call interfaces,
at the vnode operation level in the vop_{get,set}extattr() interfaces,
and in the UFS extended attribute implementation. Changes are also
introduced in the VFS extattrctl() interface (system call, VFS,
and UFS implementation), where the arguments are modified to include
a namespace field, as well as modified to advoid direct access to
userspace variables from below the VFS layer (in the style of recent
changes to mount by adrian@FreeBSD.org). This required some cleanup
and bug fixing regarding VFS locks and the VFS interface, as a vnode
pointer may now be optionally submitted to the VFS_EXTATTRCTL()
call. Updated documentation for the VFS interface will be committed
shortly.
o In the near future, the auto-starting feature will be updated to
search two sub-directories to the ".attribute" directory in appropriate
file systems: "user" and "system" to locate attributes intended for
those namespaces, as the single filename is no longer sufficient
to indicate what namespace the attribute is intended for. Until this
is committed, all attributes auto-started by UFS will be placed in
the EXTATTR_NAMESPACE_SYSTEM namespace.
o The default POSIX.1e attribute names for ACLs and Capabilities have
been updated to no longer include the '$' in their filename. As such,
if you're using these features, you'll need to rename the attribute
backing files to the same names without '$' symbols in front.
o Note that these changes will require changes in userland, which will
be committed shortly. These include modifications to the extended
attribute utilities, as well as to libutil for new namespace
string conversion routines. Once the matching userland changes are
committed, a buildworld is recommended to update all the necessary
include files and verify that the kernel and userland environments
are in sync. Note: If you do not use extended attributes (most people
won't), upgrading is not imperative although since the system call
API has changed, the new userland extended attribute code will no longer
compile with old include files.
o Couple of minor cleanups while I'm there: make more code compilation
conditional on FFS_EXTATTR, which should recover a bit of space on
kernels running without EA's, as well as update copyright dates.
Obtained from: TrustedBSD Project
"options FFS_EXTATTR". When extended attribute auto-starting
is enabled, FFS will scan the .attribute directory off of the
root of each file system, as it is mounted. If .attribute
exists, EA support will be started for the file system. If
there are files in the directory, FFS will attempt to start
them as attribute backing files for attributes baring the same
name. All attributes are started before access to the file
system is permitted, so this permits race-free enabling of
attributes. For attributes backing support for security
features, such as ACLs, MAC, Capabilities, this is vital, as
it prevents the file system attributes from getting out of
sync as a result of file system operations between mount-time
and the enabling of the extended attribute. The userland
extattrctl tool will still function exactly as previously.
Files must be placed directly in .attribute, which must be
directly off of the file system root: symbolic links are
not permitted. FFS_EXTATTR will continue to be able
to function without FFS_EXTATTR_AUTOSTART for sites that do not
want/require auto-starting. If you're using the UFS_ACL code
available from www.TrustedBSD.org, using FFS_EXTATTR_AUTOSTART
is recommended.
o This support is implemented by adding an invocation of
ufs_extattr_autostart() to ffs_mountfs(). In addition,
several new supporting calls are introduced in
ufs_extattr.c:
ufs_extattr_autostart(): start EAs on the specified mount
ufs_extattr_lookup(): given a directory and filename,
return the vnode for the file.
ufs_extattr_enable_with_open(): invoke ufs_extattr_enable()
after doing the equililent of vn_open()
on the passed file.
ufs_extattr_iterate_directory(): iterate over a directory,
invoking ufs_extattr_lookup() and
ufs_extattr_enable_with_open() on each
entry.
o This feature is not widely tested, and therefore may contain
bugs, caution is advised. Several changes are in the pipeline
for this feature, including breaking out of EA namespaces into
subdirectories of .attribute (this is waiting on the updated
EA API), as well as a per-filesystem flag indicating whether
or not EAs should be auto-started. This is required because
administrators may not want .attribute auto-started on all
file systems, especially if non-administrators have write access
to the root of a file system.
Obtained from: TrustedBSD Project
structure rather than assuming that the device vnode would reside
in the FFS filesystem (which is obviously a broken assumption with
the device filesystem).
An initial tidyup of the mount() syscall and VFS mount code.
This code replaces the earlier work done by jlemon in an attempt to
make linux_mount() work.
* the guts of the mount work has been moved into vfs_mount().
* move `type', `path' and `flags' from being userland variables into being
kernel variables in vfs_mount(). `data' remains a pointer into
userspace.
* Attempt to verify the `type' and `path' strings passed to vfs_mount()
aren't too long.
* rework mount() and linux_mount() to take the userland parameters
(besides data, as mentioned) and pass kernel variables to vfs_mount().
(linux_mount() already did this, I've just tidied it up a little more.)
* remove the copyin*() stuff for `path'. `data' still requires copyin*()
since its a pointer into userland.
* set `mount->mnt_statf_mntonname' in vfs_mount() rather than in each
filesystem. This variable is generally initialised with `path', and
each filesystem can override it if they want to.
* NOTE: f_mntonname is intiailised with "/" in the case of a root mount.
that was introduced in revision 1.80. The problem manifested
itself with a `locking against myself' panic and could also
result in soft updates inconsistences associated with inodedeps.
The two problems are:
1) One of the background operations could manipulate the bitmap
while holding it locked with intent to create. This held lock
results in a `locking against myself' panic, when the background
processing that we have been coopted to do tries to lock the bitmap
which we are already holding locked. To understand how to fix this
problem, first, observe that we can do the background cleanups in
inodedep_lookup only when allocating inodedeps (DEPALLOC is set in
the call to inodedep_lookup). Second observe that calls to
inodedep_lookup with DEPALLOC set can only happen from the following
calls into the softdep code:
softdep_setup_inomapdep
softdep_setup_allocdirect
softdep_setup_remove
softdep_setup_freeblocks
softdep_setup_directory_change
softdep_setup_directory_add
softdep_change_linkcnt
Only the first two of these can come from ffs_alloc.c while holding
a bitmap locked. Thus, inodedep_lookup must not go off to do
request_cleanups when being called from these functions. This change
adds a flag, NODELAY, that can be passed to inodedep_lookup to let
it know that it should not do background processing in those cases.
2) The return value from request_cleanup when helping out with the
cleanup was 0 instead of 1. This meant that despite the fact that
we may have slept while doing the cleanups, the code did not recheck
for the appearance of an inodedep (e.g., goto top in inodedep_lookup).
This lead to the softdep inconsistency in which we ended up with
two inodedep's for the same inode.
Reviewed by: Peter Wemm <peter@yahoo-inc.com>,
Matt Dillon <dillon@earth.backplane.com>
- All processes go into the same array of queues, with different
scheduling classes using different portions of the array. This
allows user processes to have their priorities propogated up into
interrupt thread range if need be.
- I chose 64 run queues as an arbitrary number that is greater than
32. We used to have 4 separate arrays of 32 queues each, so this
may not be optimal. The new run queue code was written with this
in mind; changing the number of run queues only requires changing
constants in runq.h and adjusting the priority levels.
- The new run queue code takes the run queue as a parameter. This
is intended to be used to create per-cpu run queues. Implement
wrappers for compatibility with the old interface which pass in
the global run queue structure.
- Group the priority level, user priority, native priority (before
propogation) and the scheduling class into a struct priority.
- Change any hard coded priority levels that I found to use
symbolic constants (TTIPRI and TTOPRI).
- Remove the curpriority global variable and use that of curproc.
This was used to detect when a process' priority had lowered and
it should yield. We now effectively yield on every interrupt.
- Activate propogate_priority(). It should now have the desired
effect without needing to also propogate the scheduling class.
- Temporarily comment out the call to vm_page_zero_idle() in the
idle loop. It interfered with propogate_priority() because
the idle process needed to do a non-blocking acquire of Giant
and then other processes would try to propogate their priority
onto it. The idle process should not do anything except idle.
vm_page_zero_idle() will return in the form of an idle priority
kernel thread which is woken up at apprioriate times by the vm
system.
- Update struct kinfo_proc to the new priority interface. Deliberately
change its size by adjusting the spare fields. It remained the same
size, but the layout has changed, so userland processes that use it
would parse the data incorrectly. The size constraint should really
be changed to an arbitrary version number. Also add a debug.sizeof
sysctl node for struct kinfo_proc.
mtx_enter(lock, type) becomes:
mtx_lock(lock) for sleep locks (MTX_DEF-initialized locks)
mtx_lock_spin(lock) for spin locks (MTX_SPIN-initialized)
similarily, for releasing a lock, we now have:
mtx_unlock(lock) for MTX_DEF and mtx_unlock_spin(lock) for MTX_SPIN.
We change the caller interface for the two different types of locks
because the semantics are entirely different for each case, and this
makes it explicitly clear and, at the same time, it rids us of the
extra `type' argument.
The enter->lock and exit->unlock change has been made with the idea
that we're "locking data" and not "entering locked code" in mind.
Further, remove all additional "flags" previously passed to the
lock acquire/release routines with the exception of two:
MTX_QUIET and MTX_NOSWITCH
The functionality of these flags is preserved and they can be passed
to the lock/unlock routines by calling the corresponding wrappers:
mtx_{lock, unlock}_flags(lock, flag(s)) and
mtx_{lock, unlock}_spin_flags(lock, flag(s)) for MTX_DEF and MTX_SPIN
locks, respectively.
Re-inline some lock acq/rel code; in the sleep lock case, we only
inline the _obtain_lock()s in order to ensure that the inlined code
fits into a cache line. In the spin lock case, we inline recursion and
actually only perform a function call if we need to spin. This change
has been made with the idea that we generally tend to avoid spin locks
and that also the spin locks that we do have and are heavily used
(i.e. sched_lock) do recurse, and therefore in an effort to reduce
function call overhead for some architectures (such as alpha), we
inline recursion for this case.
Create a new malloc type for the witness code and retire from using
the M_DEV type. The new type is called M_WITNESS and is only declared
if WITNESS is enabled.
Begin cleaning up some machdep/mutex.h code - specifically updated the
"optimized" inlined code in alpha/mutex.h and wrote MTX_LOCK_SPIN
and MTX_UNLOCK_SPIN asm macros for the i386/mutex.h as we presently
need those.
Finally, caught up to the interface changes in all sys code.
Contributors: jake, jhb, jasone (in no particular order)
