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(fault 2/9) Move map lookup into a dedicated function.

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Reviewed by:	kib, markj
Differential Revision:	https://reviews.freebsd.org/D23302
This commit is contained in:
Jeff Roberson 2020-01-23 05:05:39 +00:00
parent 2c2f4413cc
commit c308a3a6c9
1 changed files with 53 additions and 36 deletions
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89
sys/vm/vm_fault.c
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@ -747,6 +747,54 @@ vm_fault_readahead(struct faultstate *fs)
return (nera);
}
static int
vm_fault_lookup(struct faultstate *fs)
{
int result;
KASSERT(!fs->lookup_still_valid,
("vm_fault_lookup: Map already locked."));
result = vm_map_lookup(&fs->map, fs->vaddr, fs->fault_type |
VM_PROT_FAULT_LOOKUP, &fs->entry, &fs->first_object,
&fs->first_pindex, &fs->prot, &fs->wired);
if (result != KERN_SUCCESS) {
unlock_vp(fs);
return (result);
}
fs->map_generation = fs->map->timestamp;
if (fs->entry->eflags & MAP_ENTRY_NOFAULT) {
panic("%s: fault on nofault entry, addr: %#lx",
__func__, (u_long)fs->vaddr);
}
if (fs->entry->eflags & MAP_ENTRY_IN_TRANSITION &&
fs->entry->wiring_thread != curthread) {
vm_map_unlock_read(fs->map);
vm_map_lock(fs->map);
if (vm_map_lookup_entry(fs->map, fs->vaddr, &fs->entry) &&
(fs->entry->eflags & MAP_ENTRY_IN_TRANSITION)) {
unlock_vp(fs);
fs->entry->eflags |= MAP_ENTRY_NEEDS_WAKEUP;
vm_map_unlock_and_wait(fs->map, 0);
} else
vm_map_unlock(fs->map);
return (KERN_RESOURCE_SHORTAGE);
}
MPASS((fs->entry->eflags & MAP_ENTRY_GUARD) == 0);
if (fs->wired)
fs->fault_type = fs->prot | (fs->fault_type & VM_PROT_COPY);
else
KASSERT((fs->fault_flags & VM_FAULT_WIRE) == 0,
("!fs->wired && VM_FAULT_WIRE"));
fs->lookup_still_valid = true;
return (KERN_SUCCESS);
}
/*
* Wait/Retry if the page is busy. We have to do this if the page is
* either exclusive or shared busy because the vm_pager may be using
@ -807,6 +855,8 @@ vm_fault(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type,
fs.vaddr = vaddr;
fs.m_hold = m_hold;
fs.fault_flags = fault_flags;
fs.map = map;
fs.lookup_still_valid = false;
faultcount = 0;
nera = -1;
hardfault = false;
@ -820,44 +870,13 @@ vm_fault(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type,
* Find the backing store object and offset into it to begin the
* search.
*/
fs.map = map;
result = vm_map_lookup(&fs.map, fs.vaddr, fs.fault_type |
VM_PROT_FAULT_LOOKUP, &fs.entry, &fs.first_object,
&fs.first_pindex, &fs.prot, &fs.wired);
result = vm_fault_lookup(&fs);
if (result != KERN_SUCCESS) {
unlock_vp(&fs);
if (result == KERN_RESOURCE_SHORTAGE)
goto RetryFault;
return (result);
}
fs.map_generation = fs.map->timestamp;
if (fs.entry->eflags & MAP_ENTRY_NOFAULT) {
panic("%s: fault on nofault entry, addr: %#lx",
__func__, (u_long)fs.vaddr);
}
if (fs.entry->eflags & MAP_ENTRY_IN_TRANSITION &&
fs.entry->wiring_thread != curthread) {
vm_map_unlock_read(fs.map);
vm_map_lock(fs.map);
if (vm_map_lookup_entry(fs.map, fs.vaddr, &fs.entry) &&
(fs.entry->eflags & MAP_ENTRY_IN_TRANSITION)) {
unlock_vp(&fs);
fs.entry->eflags |= MAP_ENTRY_NEEDS_WAKEUP;
vm_map_unlock_and_wait(fs.map, 0);
} else
vm_map_unlock(fs.map);
goto RetryFault;
}
MPASS((fs.entry->eflags & MAP_ENTRY_GUARD) == 0);
if (fs.wired)
fs.fault_type = fs.prot | (fs.fault_type & VM_PROT_COPY);
else
KASSERT((fs.fault_flags & VM_FAULT_WIRE) == 0,
("!fs.wired && VM_FAULT_WIRE"));
/*
* Try to avoid lock contention on the top-level object through
* special-case handling of some types of page faults, specifically,
@ -891,8 +910,6 @@ vm_fault(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type,
vm_object_reference_locked(fs.first_object);
vm_object_pip_add(fs.first_object, 1);
fs.lookup_still_valid = true;
fs.m_cow = fs.m = fs.first_m = NULL;
/*