d1c34fef9c
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>
177 lines
5.8 KiB
C
177 lines
5.8 KiB
C
/*
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* Copyright (c) 1990 University of Utah.
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* Copyright (c) 1991, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* the Systems Programming Group of the University of Utah Computer
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* Science Department.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)vm_pager.h 8.4 (Berkeley) 1/12/94
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* $Id: vm_pager.h,v 1.21 1999/03/14 09:20:00 julian Exp $
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*/
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/*
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* Pager routine interface definition.
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*/
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#ifndef _VM_PAGER_
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#define _VM_PAGER_
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#include <sys/queue.h>
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TAILQ_HEAD(pagerlst, vm_object);
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struct buf;
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struct pagerops {
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void (*pgo_init) __P((void)); /* Initialize pager. */
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vm_object_t (*pgo_alloc) __P((void *, vm_ooffset_t, vm_prot_t, vm_ooffset_t)); /* Allocate pager. */
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void (*pgo_dealloc) __P((vm_object_t)); /* Disassociate. */
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int (*pgo_getpages) __P((vm_object_t, vm_page_t *, int, int)); /* Get (read) page. */
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void (*pgo_putpages) __P((vm_object_t, vm_page_t *, int, int, int *)); /* Put (write) page. */
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boolean_t (*pgo_haspage) __P((vm_object_t, vm_pindex_t, int *, int *)); /* Does pager have page? */
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void (*pgo_pageunswapped) __P((vm_page_t));
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void (*pgo_strategy) __P((vm_object_t, struct buf *));
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};
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/*
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* get/put return values
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* OK operation was successful
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* BAD specified data was out of the accepted range
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* FAIL specified data was in range, but doesn't exist
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* PEND operations was initiated but not completed
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* ERROR error while accessing data that is in range and exists
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* AGAIN temporary resource shortage prevented operation from happening
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*/
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#define VM_PAGER_OK 0
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#define VM_PAGER_BAD 1
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#define VM_PAGER_FAIL 2
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#define VM_PAGER_PEND 3
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#define VM_PAGER_ERROR 4
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#define VM_PAGER_AGAIN 5
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#define VM_PAGER_PUT_SYNC 0x1
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#define VM_PAGER_PUT_INVAL 0x2
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#ifdef KERNEL
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#ifdef MALLOC_DECLARE
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MALLOC_DECLARE(M_VMPGDATA);
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#endif
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extern vm_map_t pager_map;
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extern int pager_map_size;
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extern struct pagerops *pagertab[];
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vm_object_t vm_pager_allocate __P((objtype_t, void *, vm_ooffset_t, vm_prot_t, vm_ooffset_t));
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void vm_pager_bufferinit __P((void));
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void vm_pager_deallocate __P((vm_object_t));
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static __inline int vm_pager_get_pages __P((vm_object_t, vm_page_t *, int, int));
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static __inline boolean_t vm_pager_has_page __P((vm_object_t, vm_pindex_t, int *, int *));
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void vm_pager_init __P((void));
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vm_object_t vm_pager_object_lookup __P((struct pagerlst *, void *));
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vm_offset_t vm_pager_map_pages __P((vm_page_t *, int, boolean_t));
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vm_offset_t vm_pager_map_page __P((vm_page_t));
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void vm_pager_sync __P((void));
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void vm_pager_unmap_pages __P((vm_offset_t, int));
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void vm_pager_unmap_page __P((vm_offset_t));
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void vm_pager_strategy __P((vm_object_t object, struct buf *bp));
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struct buf *getchainbuf(struct buf *bp, struct vnode *vp, int flags);
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void flushchainbuf(struct buf *nbp);
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void waitchainbuf(struct buf *bp, int count, int done);
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void autochaindone(struct buf *bp);
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/*
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* vm_page_get_pages:
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*
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* Retrieve pages from the VM system in order to map them into an object
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* ( or into VM space somewhere ). If the pagein was successful, we
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* must fully validate it.
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*/
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static __inline int
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vm_pager_get_pages(
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vm_object_t object,
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vm_page_t *m,
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int count,
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int reqpage
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) {
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int r;
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r = (*pagertab[object->type]->pgo_getpages)(object, m, count, reqpage);
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if (r == VM_PAGER_OK && m[reqpage]->valid != VM_PAGE_BITS_ALL) {
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vm_page_zero_invalid(m[reqpage], TRUE);
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}
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return(r);
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}
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static __inline void
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vm_pager_put_pages(
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vm_object_t object,
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vm_page_t *m,
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int count,
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int flags,
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int *rtvals
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) {
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(*pagertab[object->type]->pgo_putpages)
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(object, m, count, flags, rtvals);
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}
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static __inline boolean_t
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vm_pager_has_page(
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vm_object_t object,
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vm_pindex_t offset,
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int *before,
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int *after
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) {
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return ((*pagertab[object->type]->pgo_haspage) (object, offset, before, after));
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}
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/*
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* vm_pager_page_unswapped
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*
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* called at splvm() to destroy swap associated with the page.
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*
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* This function may not block.
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*/
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static __inline void
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vm_pager_page_unswapped(vm_page_t m)
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{
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if (pagertab[m->object->type]->pgo_pageunswapped)
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(*pagertab[m->object->type]->pgo_pageunswapped)(m);
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}
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#endif
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#endif /* _VM_PAGER_ */
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