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Fix a race involving vnode_pager_input_smlfs(). Specifically, in the case

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that vnode_pager_input_smlfs() zeroes the page, it should not mark the page
as valid until after the page is zeroed.  Otherwise, the page could be
mapped for read access (e.g., by vm_map_pmap_enter()) before the page is
zeroed.  Reviewed by: tegge

Eliminate gratuitous clearing of the page's dirty mask by
vnode_pager_input_smlfs().  Instead, assert that the page is clean.
Reviewed by: tegge

Eliminate some blank lines.

Eliminate pointless calls to pmap_clear_modify() and vm_page_undirty() from
vnode_pager_input_old().  The page is not mapped.  Therefore, it cannot have
any page table entries that are modified.

Eliminate an incorrect comment from vnode_pager_generic_getpages().
This commit is contained in:
Alan Cox 2009-05-09 08:30:44 +00:00
parent 126b14f7e8
commit 0d53a17bde
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=191935
1 changed files with 10 additions and 23 deletions
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33
sys/vm/vnode_pager.c
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@ -476,7 +476,7 @@ vnode_pager_input_smlfs(object, m)
vm_object_t object;
vm_page_t m;
{
int i;
int bits, i;
struct vnode *vp;
struct bufobj *bo;
struct buf *bp;
@ -498,7 +498,8 @@ vnode_pager_input_smlfs(object, m)
for (i = 0; i < PAGE_SIZE / bsize; i++) {
vm_ooffset_t address;
if (vm_page_bits(i * bsize, bsize) & m->valid)
bits = vm_page_bits(i * bsize, bsize);
if (m->valid & bits)
continue;
address = IDX_TO_OFF(m->pindex) + i * bsize;
@ -543,30 +544,21 @@ vnode_pager_input_smlfs(object, m)
relpbuf(bp, &vnode_pbuf_freecnt);
if (error)
break;
VM_OBJECT_LOCK(object);
vm_page_lock_queues();
vm_page_set_validclean(m, (i * bsize) & PAGE_MASK, bsize);
vm_page_unlock_queues();
VM_OBJECT_UNLOCK(object);
} else {
VM_OBJECT_LOCK(object);
vm_page_lock_queues();
vm_page_set_validclean(m, (i * bsize) & PAGE_MASK, bsize);
vm_page_unlock_queues();
VM_OBJECT_UNLOCK(object);
} else
bzero((caddr_t)sf_buf_kva(sf) + i * bsize, bsize);
}
KASSERT((m->dirty & bits) == 0,
("vnode_pager_input_smlfs: page %p is dirty", m));
VM_OBJECT_LOCK(object);
m->valid |= bits;
VM_OBJECT_UNLOCK(object);
}
sf_buf_free(sf);
if (error) {
return VM_PAGER_ERROR;
}
return VM_PAGER_OK;
}
/*
* old style vnode pager input routine
*/
@ -627,10 +619,7 @@ vnode_pager_input_old(object, m)
VM_OBJECT_LOCK(object);
}
vm_page_lock_queues();
pmap_clear_modify(m);
vm_page_undirty(m);
vm_page_unlock_queues();
KASSERT(m->dirty == 0, ("vnode_pager_input_old: page %p is dirty", m));
if (!error)
m->valid = VM_PAGE_BITS_ALL;
return error ? VM_PAGER_ERROR : VM_PAGER_OK;
@ -960,8 +949,6 @@ vnode_pager_generic_getpages(vp, m, bytecount, reqpage)
*/
vm_page_set_validclean(mt, 0,
object->un_pager.vnp.vnp_size - tfoff);
/* handled by vm_fault now */
/* vm_page_zero_invalid(mt, FALSE); */
}
if (i != reqpage) {