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* Virtualizes & untangles the bioops operations vector.phk2000-06-161-3/+2
| | | | Ref: Message-ID: <18317.961014572@critter.freebsd.dk> To: current@
* Separate the struct bio related stuff out of <sys/buf.h> intophk2000-05-051-0/+1
| | | | | | | | | | | | | | | <sys/bio.h>. <sys/bio.h> is now a prerequisite for <sys/buf.h> but it shall not be made a nested include according to bdes teachings on the subject of nested includes. Diskdrivers and similar stuff below specfs::strategy() should no longer need to include <sys/buf.> unless they need caching of data. Still a few bogus uses of struct buf to track down. Repocopy by: peter
* s/biowait/bufwait/gphk2000-04-291-1/+1
| | | | Prodded by: several.
* Complete the bio/buf divorce for all code below devfs::strategyphk2000-04-151-1/+1
| | | | | | | | | | Exceptions: Vinum untouched. This means that it cannot be compiled. Greg Lehey is on the case. CCD not converted yet, casts to struct buf (still safe) atapi-cd casts to struct buf to examine B_PHYS
* Move B_ERROR flag to b_ioflags and call it BIO_ERROR.phk2000-04-021-6/+10
| | | | | | | | | | | | | (Much of this done by script) Move B_ORDERED flag to b_ioflags and call it BIO_ORDERED. Move b_pblkno and b_iodone_chain to struct bio while we transition, they will be obsoleted once bio structs chain/stack. Add bio_queue field for struct bio aware disksort. Address a lot of stylistic issues brought up by bde.
* Change the write-behind code to take more care when startingdillon2000-04-021-8/+29
| | | | | | | | | | | | | | async I/O's. The sequential read heuristic has been extended to cover writes as well. We continue to call cluster_write() normally, thus blocks in the file will still be reallocated for large (but still random) I/O's, but I/O will only be initiated for truely sequential writes. This solves a number of annoying situations, especially with DBM (hash method) writes, and also has the side effect of fixing a number of (stupid) benchmarks. Reviewed-by: mckusick
* Remove B_READ, B_WRITE and B_FREEBUF and replace them with a newphk2000-03-201-12/+18
| | | | | | | | | | | | | | | | | | | | | field in struct buf: b_iocmd. The b_iocmd is enforced to have exactly one bit set. B_WRITE was bogusly defined as zero giving rise to obvious coding mistakes. Also eliminate the redundant struct buf flag B_CALL, it can just as efficiently be done by comparing b_iodone to NULL. Should you get a panic or drop into the debugger, complaining about "b_iocmd", don't continue. It is likely to write on your disk where it should have been reading. This change is a step in the direction towards a stackable BIO capability. A lot of this patch were machine generated (Thanks to style(9) compliance!) Vinum users: Greg has not had time to test this yet, be careful.
* useracc() the prequel:phk1999-10-291-1/+0
| | | | | | | | | | | Merge the contents (less some trivial bordering the silly comments) of <vm/vm_prot.h> and <vm/vm_inherit.h> into <vm/vm.h>. This puts the #defines for the vm_inherit_t and vm_prot_t types next to their typedefs. This paves the road for the commit to follow shortly: change useracc() to use VM_PROT_{READ|WRITE} rather than B_{READ|WRITE} as argument.
* Remove v_maxio from struct vnode.phk1999-09-291-4/+4
| | | | | | Replace it with mnt_iosize_max in struct mount. Nits from: bde
* Initialize vp->v_maxio to its default in getnetvnode() rather thanphk1999-09-201-8/+0
| | | | four different places in vfs_cluster.c
* If integration of a buffer into a cluster write operation fails, releasetegge1999-08-311-1/+3
| | | | | | the buffer instead of creating a future deadlock. PR: 12800 Submitted by: dillon
* $Id$ -> $FreeBSD$peter1999-08-281-1/+1
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* These changes appear to give us benefits with both small (32MB) andmckusick1999-07-081-13/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | large (1G) memory machine configurations. I was able to run 'dbench 32' on a 32MB system without bring the machine to a grinding halt. * buffer cache hash table now dynamically allocated. This will have no effect on memory consumption for smaller systems and will help scale the buffer cache for larger systems. * minor enhancement to pmap_clearbit(). I noticed that all the calls to it used constant arguments. Making it an inline allows the constants to propogate to deeper inlines and should produce better code. * removal of inherent vfs_ioopt support through the emplacement of appropriate #ifdef's, with John's permission. If we do not find a use for it by the end of the year we will remove it entirely. * removal of getnewbufloops* counters & sysctl's - no longer necessary for debugging, getnewbuf() is now optimal. * buffer hash table functions removed from sys/buf.h and localized to vfs_bio.c * VFS_BIO_NEED_DIRTYFLUSH flag and support code added ( bwillwrite() ), allowing processes to block when too many dirty buffers are present in the system. * removal of a softdep test in bdwrite() that is no longer necessary now that bdwrite() no longer attempts to flush dirty buffers. * slight optimization added to bqrelse() - there is no reason to test for available buffer space on B_DELWRI buffers. * addition of reverse-scanning code to vfs_bio_awrite(). vfs_bio_awrite() will attempt to locate clusterable areas in both the forward and reverse direction relative to the offset of the buffer passed to it. This will probably not make much of a difference now, but I believe we will start to rely on it heavily in the future if we decide to shift some of the burden of the clustering closer to the actual I/O initiation. * Removal of the newbufcnt and lastnewbuf counters that Kirk added. They do not fix any race conditions that haven't already been fixed by the gbincore() test done after the only call to getnewbuf(). getnewbuf() is a static, so there is no chance of it being misused by other modules. ( Unless Kirk can think of a specific thing that this code fixes. I went through it very carefully and didn't see anything ). * removal of VOP_ISLOCKED() check in flushbufqueues(). I do not think this check is necessary, the buffer should flush properly whether the vnode is locked or not. ( yes? ). * removal of extra arguments passed to getnewbuf() that are not necessary. * missed cluster_wbuild() that had to be a cluster_wbuild_wb() in vfs_cluster.c * vn_write() now calls bwillwrite() *PRIOR* to locking the vnode, which should greatly aid flushing operations in heavy load situations - both the pageout and update daemons will be able to operate more efficiently. * removal of b_usecount. We may add it back in later but for now it is useless. Prior implementations of the buffer cache never had enough buffers for it to be useful, and current implementations which make more buffers available might not benefit relative to the amount of sophistication required to implement a b_usecount. Straight LRU should work just as well, especially when most things are VMIO backed. I expect that (even though John will not like this assumption) directories will become VMIO backed some point soon. Submitted by: Matthew Dillon <dillon@backplane.com> Reviewed by: Kirk McKusick <mckusick@mckusick.com>
* The vfs.write_behind sysctl and related code support has been added tomckusick1999-07-041-3/+40
| | | | | | | | | | | | | | | | allow changes to the filesystem's write_behind behavior. By the default the filesystem aggressively issues write_behind's. Three values may be specified for vfs.write_behind. 0 disables write_behind, 1 results in historical operation (agressive write_behind), and 2 is an experimental backed-off write_behind. The values of 0 and 1 are recommended. The value of 0 is recommended in conjuction with an increase in the number of NBUF's and the number of dirty buffers allowed (vfs.{lo,hi}dirtybuffers). Note that a value of 0 will radically increase the dirty buffer load on the system. Future work on write_behind behavior will use values 2 and greater for testing purposes. Submitted by: Matthew Dillon <dillon@apollo.backplane.com> Reviewed by: Kirk McKusick <mckusick@mckusick.com>
* Hopefully fix the remaining glitches with the BUF_*() changes. This shouldpeter1999-06-291-3/+11
| | | | | | | | | | | | | (really this time) fix pageout to swap and a couple of clustering cases. This simplifies BUF_KERNPROC() so that it unconditionally reassigns the lock owner rather than testing B_ASYNC and having the caller decide when to do the reassign. At present this is required because some places use B_CALL/b_iodone to free the buffers without B_ASYNC being set. Also, vfs_cluster.c explicitly calls BUF_KERNPROC() when attaching the buffers rather than the parent walking the cluster_head tailq. Reviewed by: Kirk McKusick <mckusick@mckusick.com>
* Convert buffer locking from using the B_BUSY and B_WANTED flags to usingmckusick1999-06-261-18/+17
| | | | | | | lockmgr locks. This commit should be functionally equivalent to the old semantics. That is, all buffer locking is done with LK_EXCLUSIVE requests. Changes to take advantage of LK_SHARED and LK_RECURSIVE will be done in future commits.
* Reformat comment to match indentation of code around it.julian1999-06-171-8/+9
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* Changed trypbuf to a getpbuf to work around a problem where redundant writesdg1999-06-161-2/+2
| | | | | | | | | would occur when clustering them - caused by running out of buffers and taking a degenerate code path as a result. It appears that waiting instead for buffers to become available is okay. Submitted by: Matthew Dillon <dillon@apollo.backplane.com> Discovered by: Craig A Soules <soules+@andrew.cmu.edu>
* The VFS/BIO subsystem contained a number of hacks in order to optimizealc1999-05-021-3/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | piecemeal, middle-of-file writes for NFS. These hacks have caused no end of trouble, especially when combined with mmap(). I've removed them. Instead, NFS will issue a read-before-write to fully instantiate the struct buf containing the write. NFS does, however, optimize piecemeal appends to files. For most common file operations, you will not notice the difference. The sole remaining fragment in the VFS/BIO system is b_dirtyoff/end, which NFS uses to avoid cache coherency issues with read-merge-write style operations. NFS also optimizes the write-covers-entire-buffer case by avoiding the read-before-write. There is quite a bit of room for further optimization in these areas. The VM system marks pages fully-valid (AKA vm_page_t->valid = VM_PAGE_BITS_ALL) in several places, most noteably in vm_fault. This is not correct operation. The vm_pager_get_pages() code is now responsible for marking VM pages all-valid. A number of VM helper routines have been added to aid in zeroing-out the invalid portions of a VM page prior to the page being marked all-valid. This operation is necessary to properly support mmap(). The zeroing occurs most often when dealing with file-EOF situations. Several bugs have been fixed in the NFS subsystem, including bits handling file and directory EOF situations and buf->b_flags consistancy issues relating to clearing B_ERROR & B_INVAL, and handling B_DONE. getblk() and allocbuf() have been rewritten. B_CACHE operation is now formally defined in comments and more straightforward in implementation. B_CACHE for VMIO buffers is based on the validity of the backing store. B_CACHE for non-VMIO buffers is based simply on whether the buffer is B_INVAL or not (B_CACHE set if B_INVAL clear, and vise-versa). biodone() is now responsible for setting B_CACHE when a successful read completes. B_CACHE is also set when a bdwrite() is initiated and when a bwrite() is initiated. VFS VOP_BWRITE routines (there are only two - nfs_bwrite() and bwrite()) are now expected to set B_CACHE. This means that bowrite() and bawrite() also set B_CACHE indirectly. There are a number of places in the code which were previously using buf->b_bufsize (which is DEV_BSIZE aligned) when they should have been using buf->b_bcount. These have been fixed. getblk() now clears B_DONE on return because the rest of the system is so bad about dealing with B_DONE. Major fixes to NFS/TCP have been made. A server-side bug could cause requests to be lost by the server due to nfs_realign() overwriting other rpc's in the same TCP mbuf chain. The server's kernel must be recompiled to get the benefit of the fixes. Submitted by: Matthew Dillon <dillon@apollo.backplane.com>
* Reviewed by: Many at differnt times in differnt parts,julian1999-03-121-3/+3
| | | | | | | | | | | | | | | | | | | | | | including alan, john, me, luoqi, and kirk Submitted by: Matt Dillon <dillon@frebsd.org> This change implements a relatively sophisticated fix to getnewbuf(). There were two problems with getnewbuf(). First, the writerecursion can lead to a system stack overflow when you have NFS and/or VN devices in the system. Second, the free/dirty buffer accounting was completely broken. Not only did the nfs routines blow it trying to manually account for the buffer state, but the accounting that was done did not work well with the purpose of their existance: figuring out when getnewbuf() needs to sleep. The meat of the change is to kern/vfs_bio.c. The remaining diffs are all minor except for NFS, which includes both the fixes for bp interaction AND fixes for a 'biodone(): buffer already done' lockup. Sys/buf.h also contains a chaining structure which is not used by this patchset but is used by other patches that are coming soon. This patch deliniated by tags PRE_MAT_GETBUF and POST_MAT_GETBUF. (sorry for the missing T matt)
* Fix warnings in preparation for adding -Wall -Wcast-qual to thedillon1999-01-271-2/+2
| | | | kernel compile
* This is a rather large commit that encompasses the new swapper,dillon1999-01-211-4/+6
| | | | | | | | | | changes to the VM system to support the new swapper, VM bug fixes, several VM optimizations, and some additional revamping of the VM code. The specific bug fixes will be documented with additional forced commits. This commit is somewhat rough in regards to code cleanup issues. Reviewed by: "John S. Dyson" <root@dyson.iquest.net>, "David Greenman" <dg@root.com>
* KNFize, by bde.eivind1999-01-101-9/+8
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* Split DIAGNOSTIC -> DIAGNOSTIC, INVARIANTS, and INVARIANT_SUPPORT aseivind1999-01-081-18/+9
| | | | | | | | | discussed on -hackers. Introduce 'KASSERT(assertion, ("panic message", args))' for simple check + panic. Reviewed by: msmith
* Even the most recently allocated buffer may not have its b_blknomckusick1998-12-051-2/+5
| | | | | | field properly filled in, so we must do a VOP_BMAP on that buffer as well if it is not resolved. Submitted by: Luoqi Chen <luoqi@watermarkgroup.com>
* Because buffers may be tossed and recreated at will under the new VMmckusick1998-11-171-4/+9
| | | | | | system, the mapping from logical to physical block number may be lost. Hence we have to check for a reconstituted buffer and redo the call to VOP_BMAP if the physical block number has been lost.
* Fixed a missing include. <sys/kernel.h> is needed by the newbde1998-11-151-2/+2
| | | | | | | MALLOC_DEFINE() and MALLOC_DEFINE() is needed by the recently reenabled "reallocblks" code, but <sys/kernel.h> was only included if CLUSTERDEBUG was defined. This was too harmless. gcc only warns about garbage like `SYSINIT(blech);' at file scope ...
* Restored the "reallocblks" code to its former glory. What this does isdg1998-11-131-15/+4
| | | | | | basically do a on-the-fly defragmentation of the FFS filesystem, changing file block allocations to make them contiguous. Thanks to Kirk McKusick for providing hints on what needed to be done to get this working.
* Nitpicking and dusting performed on a train. Removes trivial warningsphk1998-10-251-2/+2
| | | | about unused variables, labels and other lint.
* Cosmetic changes to the PAGE_XXX macros to make them consistent withdfr1998-09-041-3/+3
| | | | the other objects in vm.
* Change various syscalls to use size_t arguments instead of u_int.dfr1998-08-241-9/+5
| | | | | | | | | | Add some overflow checks to read/write (from bde). Change all modifications to vm_page::flags, vm_page::busy, vm_object::flags and vm_object::paging_in_progress to use operations which are not interruptable. Reviewed by: Bruce Evans <bde@zeta.org.au>
* Protect all modifications to v_numoutput with splbio().dfr1998-08-131-1/+3
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* Protect all modifications to paging_in_progress with splvm(). The i386dfr1998-08-061-2/+6
| | | | | | | | | managed to avoid corruption of this variable by luck (the compiler used a memory read-modify-write instruction which wasn't interruptable) but other architectures cannot. With this change, I am now able to 'make buildworld' on the alpha (sfx: the crowd goes wild...)
* Fixed printf format errors.bde1998-07-291-12/+12
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* Fixed printf format errors.bde1998-07-111-5/+6
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* Don't depend on gcc's feature of casting lvalues.bde1998-07-071-4/+5
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* VOP_STRATEGY grows an (struct vnode *) argumentjulian1998-07-041-3/+3
| | | | | | as the value in b_vp is often not really what you want. (and needs to be frobbed). more cleanups will follow this. Reviewed by: Bruce Evans <bde@freebsd.org>
* Make flushing dirty pages work correctly on filesystems thatdyson1998-05-211-12/+8
| | | | | | unexpectedly do not complete writes even with sync I/O requests. This should help the behavior of mmaped files when using softupdates (and perhaps in other circumstances also.)
* Partially fixed write clustering for cases where cluster_wbuild() isbde1998-05-011-1/+4
| | | | | | | called from vfs_bio_awrite() without going through cluster_write() or ufs_bmaparray(), in particular for all writes to block disk devices. Only ufs_bmaparray() sets vp->v_maxio in a correct way, and it doesn't seem to be called early enough even for regular files.
* In kern_physio.c fix tsleep priority messup.dyson1998-03-191-11/+22
| | | | | | | | | | | | | | | | | | | | | | In vfs_bio.c, remove b_generation count usage, remove redundant reassignbuf, remove redundant spl(s), manage page PG_ZERO flags more correctly, utilize in invalid value for b_offset until it is properly initialized. Add asserts for #ifdef DIAGNOSTIC, when b_offset is improperly used. when a process is not performing I/O, and just waiting on a buffer generally, make the sleep priority low. only check page validity in getblk for B_VMIO buffers. In vfs_cluster, add b_offset asserts, correct pointer calculation for clustered reads. Improve readability of certain parts of the code. Remove redundant spl(s). In vfs_subr, correct usage of vfs_bio_awrite (From Andrew Gallatin <gallatin@cs.duke.edu>). More vtruncbuf problems fixed.
* Remove a soft-update hook that was accidentally added to the READ path.julian1998-03-161-26/+53
| | | | also add some comments, and a couple of very minor cosmetic changes.
* Some VM improvements, including elimination of alot of Sig-11dyson1998-03-161-16/+25
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | problems. Tor Egge and others have helped with various VM bugs lately, but don't blame him -- blame me!!! pmap.c: 1) Create an object for kernel page table allocations. This fixes a bogus allocation method previously used for such, by grabbing pages from the kernel object, using bogus pindexes. (This was a code cleanup, and perhaps a minor system stability issue.) pmap.c: 2) Pre-set the modify and accessed bits when prudent. This will decrease bus traffic under certain circumstances. vfs_bio.c, vfs_cluster.c: 3) Rather than calculating the beginning virtual byte offset multiple times, stick the offset into the buffer header, so that the calculated offset can be reused. (Long long multiplies are often expensive, and this is a probably unmeasurable performance improvement, and code cleanup.) vfs_bio.c: 4) Handle write recursion more intelligently (but not perfectly) so that it is less likely to cause a system panic, and is also much more robust. vfs_bio.c: 5) getblk incorrectly wrote out blocks that are incorrectly sized. The problem is fixed, and writes blocks out ONLY when B_DELWRI is true. vfs_bio.c: 6) Check that already constituted buffers have fully valid pages. If not, then make sure that the B_CACHE bit is not set. (This was a major source of Sig-11 type problems.) vfs_bio.c: 7) Fix a potential system deadlock due to an incorrectly specified sleep priority while waiting for a buffer write operation. The change that I made opens the system up to serious problems, and we need to examine the issue of process sleep priorities. vfs_cluster.c, vfs_bio.c: 8) Make clustered reads work more correctly (and more completely) when buffers are already constituted, but not fully valid. (This was another system reliability issue.) vfs_subr.c, ffs_inode.c: 9) Create a vtruncbuf function, which is used by filesystems that can truncate files. The vinvalbuf forced a file sync type operation, while vtruncbuf only invalidates the buffers past the new end of file, and also invalidates the appropriate pages. (This was a system reliabiliy and performance issue.) 10) Modify FFS to use vtruncbuf. vm_object.c: 11) Make the object rundown mechanism for OBJT_VNODE type objects work more correctly. Included in that fix, create pager entries for the OBJT_DEAD pager type, so that paging requests that might slip in during race conditions are properly handled. (This was a system reliability issue.) vm_page.c: 12) Make some of the page validation routines be a little less picky about arguments passed to them. Also, support page invalidation change the object generation count so that we handle generation counts a little more robustly. vm_pageout.c: 13) Further reduce pageout daemon activity when the system doesn't need help from it. There should be no additional performance decrease even when the pageout daemon is running. (This was a significant performance issue.) vnode_pager.c: 14) Teach the vnode pager to handle race conditions during vnode deallocations.
* Reviewed by: dyson@freebsd.org (john Dyson), dg@root.com (david greenman)julian1998-03-081-3/+8
| | | | | Submitted by: Kirk McKusick (mcKusick@mckusick.com) Obtained from: WHistle development tree
* This mega-commit is meant to fix numerous interrelated problems. Theredyson1998-03-071-12/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | has been some bitrot and incorrect assumptions in the vfs_bio code. These problems have manifest themselves worse on NFS type filesystems, but can still affect local filesystems under certain circumstances. Most of the problems have involved mmap consistancy, and as a side-effect broke the vfs.ioopt code. This code might have been committed seperately, but almost everything is interrelated. 1) Allow (pmap_object_init_pt) prefaulting of buffer-busy pages that are fully valid. 2) Rather than deactivating erroneously read initial (header) pages in kern_exec, we now free them. 3) Fix the rundown of non-VMIO buffers that are in an inconsistent (missing vp) state. 4) Fix the disassociation of pages from buffers in brelse. The previous code had rotted and was faulty in a couple of important circumstances. 5) Remove a gratuitious buffer wakeup in vfs_vmio_release. 6) Remove a crufty and currently unused cluster mechanism for VBLK files in vfs_bio_awrite. When the code is functional, I'll add back a cleaner version. 7) The page busy count wakeups assocated with the buffer cache usage were incorrectly cleaned up in a previous commit by me. Revert to the original, correct version, but with a cleaner implementation. 8) The cluster read code now tries to keep data associated with buffers more aggressively (without breaking the heuristics) when it is presumed that the read data (buffers) will be soon needed. 9) Change to filesystem lockmgr locks so that they use LK_NOPAUSE. The delay loop waiting is not useful for filesystem locks, due to the length of the time intervals. 10) Correct and clean-up spec_getpages. 11) Implement a fully functional nfs_getpages, nfs_putpages. 12) Fix nfs_write so that modifications are coherent with the NFS data on the server disk (at least as well as NFS seems to allow.) 13) Properly support MS_INVALIDATE on NFS. 14) Properly pass down MS_INVALIDATE to lower levels of the VM code from vm_map_clean. 15) Better support the notion of pages being busy but valid, so that fewer in-transit waits occur. (use p->busy more for pageouts instead of PG_BUSY.) Since the page is fully valid, it is still usable for reads. 16) It is possible (in error) for cached pages to be busy. Make the page allocation code handle that case correctly. (It should probably be a printf or panic, but I want the system to handle coding errors robustly. I'll probably add a printf.) 17) Correct the design and usage of vm_page_sleep. It didn't handle consistancy problems very well, so make the design a little less lofty. After vm_page_sleep, if it ever blocked, it is still important to relookup the page (if the object generation count changed), and verify it's status (always.) 18) In vm_pageout.c, vm_pageout_clean had rotted, so clean that up. 19) Push the page busy for writes and VM_PROT_READ into vm_pageout_flush. 20) Fix vm_pager_put_pages and it's descendents to support an int flag instead of a boolean, so that we can pass down the invalidate bit.
* Back out DIAGNOSTIC changes.eivind1998-02-061-2/+1
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* Turn DIAGNOSTIC into a new-style option.eivind1998-02-041-1/+2
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* Change the busy page mgmt, so that when pages are freed, theydyson1998-01-311-2/+13
| | | | | | | | | | | | | | MUST be PG_BUSY. It is bogus to free a page that isn't busy, because it is in a state of being "unavailable" when being freed. The additional advantage is that the page_remove code has a better cross-check that the page should be busy and unavailable for other use. There were some minor problems with the collapse code, and this plugs those subtile "holes." Also, the vfs_bio code wasn't checking correctly for PG_BUSY pages. I am going to develop a more consistant scheme for grabbing pages, busy or otherwise. For now, we are stuck with the current morass.
* Make the debug options new-style.eivind1998-01-311-1/+3
| | | | | This also zaps a DPT option from lint; it wasn't referenced from anywhere.
* Add better support for larger I/O clusters, including larger physicaldyson1998-01-241-5/+11
| | | | | I/O. The support is not mature yet, and some of the underlying implementation needs help. However, support does exist for IDE devices now.
* Make our v_usecount vnode reference count work identically to thedyson1998-01-061-6/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | original BSD code. The association between the vnode and the vm_object no longer includes reference counts. The major difference is that vm_object's are no longer freed gratuitiously from the vnode, and so once an object is created for the vnode, it will last as long as the vnode does. When a vnode object reference count is incremented, then the underlying vnode reference count is incremented also. The two "objects" are now more intimately related, and so the interactions are now much less complex. When vnodes are now normally placed onto the free queue with an object still attached. The rundown of the object happens at vnode rundown time, and happens with exactly the same filesystem semantics of the original VFS code. There is absolutely no need for vnode_pager_uncache and other travesties like that anymore. A side-effect of these changes is that SMP locking should be much simpler, the I/O copyin/copyout optimizations work, NFS should be more ponderable, and further work on layered filesystems should be less frustrating, because of the totally coherent management of the vnode objects and vnodes. Please be careful with your system while running this code, but I would greatly appreciate feedback as soon a reasonably possible.
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