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(fault 6/9) Move getpages and associated logic into a dedicated function.

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Reviewed by:	kib
Differential Revision:	https://reviews.freebsd.org/D23311
This commit is contained in:
Jeff Roberson 2020-01-23 05:18:00 +00:00
parent 91eb2e908f
commit 5909dafea9
1 changed files with 108 additions and 97 deletions
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205
sys/vm/vm_fault.c
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@ -1001,6 +1001,95 @@ vm_fault_next(struct faultstate *fs)
return (true);
}
/*
* Call the pager to retrieve the page if there is a chance
* that the pager has it, and potentially retrieve additional
* pages at the same time.
*/
static int
vm_fault_getpages(struct faultstate *fs, int nera, int *behindp, int *aheadp)
{
vm_offset_t e_end, e_start;
int ahead, behind, cluster_offset, rv;
u_char behavior;
/*
* Prepare for unlocking the map. Save the map
* entry's start and end addresses, which are used to
* optimize the size of the pager operation below.
* Even if the map entry's addresses change after
* unlocking the map, using the saved addresses is
* safe.
*/
e_start = fs->entry->start;
e_end = fs->entry->end;
behavior = vm_map_entry_behavior(fs->entry);
/*
* Release the map lock before locking the vnode or
* sleeping in the pager. (If the current object has
* a shadow, then an earlier iteration of this loop
* may have already unlocked the map.)
*/
unlock_map(fs);
rv = vm_fault_lock_vnode(fs, false);
MPASS(rv == KERN_SUCCESS || rv == KERN_RESOURCE_SHORTAGE);
if (rv == KERN_RESOURCE_SHORTAGE)
return (rv);
KASSERT(fs->vp == NULL || !fs->map->system_map,
("vm_fault: vnode-backed object mapped by system map"));
/*
* Page in the requested page and hint the pager,
* that it may bring up surrounding pages.
*/
if (nera == -1 || behavior == MAP_ENTRY_BEHAV_RANDOM ||
P_KILLED(curproc)) {
behind = 0;
ahead = 0;
} else {
/* Is this a sequential fault? */
if (nera > 0) {
behind = 0;
ahead = nera;
} else {
/*
* Request a cluster of pages that is
* aligned to a VM_FAULT_READ_DEFAULT
* page offset boundary within the
* object. Alignment to a page offset
* boundary is more likely to coincide
* with the underlying file system
* block than alignment to a virtual
* address boundary.
*/
cluster_offset = fs->pindex % VM_FAULT_READ_DEFAULT;
behind = ulmin(cluster_offset,
atop(fs->vaddr - e_start));
ahead = VM_FAULT_READ_DEFAULT - 1 - cluster_offset;
}
ahead = ulmin(ahead, atop(e_end - fs->vaddr) - 1);
}
*behindp = behind;
*aheadp = ahead;
rv = vm_pager_get_pages(fs->object, &fs->m, 1, behindp, aheadp);
if (rv == VM_PAGER_OK)
return (KERN_SUCCESS);
if (rv == VM_PAGER_ERROR)
printf("vm_fault: pager read error, pid %d (%s)\n",
curproc->p_pid, curproc->p_comm);
/*
* If an I/O error occurred or the requested page was
* outside the range of the pager, clean up and return
* an error.
*/
if (rv == VM_PAGER_ERROR || rv == VM_PAGER_BAD)
return (KERN_OUT_OF_BOUNDS);
return (KERN_NOT_RECEIVER);
}
/*
* 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
@ -1043,10 +1132,8 @@ vm_fault(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type,
{
struct faultstate fs;
struct domainset *dset;
vm_offset_t e_end, e_start;
int ahead, alloc_req, behind, cluster_offset, faultcount;
int ahead, alloc_req, behind, faultcount;
int nera, oom, result, rv;
u_char behavior;
bool dead, hardfault;
VM_CNT_INC(v_vm_faults);
@ -1282,104 +1369,28 @@ vm_fault(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type,
* have the page, the number of additional pages to read will
* apply to subsequent objects in the shadow chain.
*/
if (nera == -1 && !P_KILLED(curproc)) {
if (nera == -1 && !P_KILLED(curproc))
nera = vm_fault_readahead(&fs);
/*
* Prepare for unlocking the map. Save the map
* entry's start and end addresses, which are used to
* optimize the size of the pager operation below.
* Even if the map entry's addresses change after
* unlocking the map, using the saved addresses is
* safe.
*/
e_start = fs.entry->start;
e_end = fs.entry->end;
behavior = vm_map_entry_behavior(fs.entry);
rv = vm_fault_getpages(&fs, nera, &behind, &ahead);
if (rv == KERN_SUCCESS) {
faultcount = behind + 1 + ahead;
hardfault = true;
break; /* break to PAGE HAS BEEN FOUND. */
}
if (rv == KERN_RESOURCE_SHORTAGE)
goto RetryFault;
VM_OBJECT_WLOCK(fs.object);
if (rv == KERN_OUT_OF_BOUNDS) {
fault_page_free(&fs.m);
unlock_and_deallocate(&fs);
return (rv);
}
/*
* Call the pager to retrieve the page if there is a chance
* that the pager has it, and potentially retrieve additional
* pages at the same time.
*/
if (fs.object->type != OBJT_DEFAULT) {
/*
* Release the map lock before locking the vnode or
* sleeping in the pager. (If the current object has
* a shadow, then an earlier iteration of this loop
* may have already unlocked the map.)
*/
unlock_map(&fs);
rv = vm_fault_lock_vnode(&fs, false);
MPASS(rv == KERN_SUCCESS ||
rv == KERN_RESOURCE_SHORTAGE);
if (rv == KERN_RESOURCE_SHORTAGE)
goto RetryFault;
KASSERT(fs.vp == NULL || !fs.map->system_map,
("vm_fault: vnode-backed object mapped by system map"));
/*
* Page in the requested page and hint the pager,
* that it may bring up surrounding pages.
*/
if (nera == -1 || behavior == MAP_ENTRY_BEHAV_RANDOM ||
P_KILLED(curproc)) {
behind = 0;
ahead = 0;
} else {
/* Is this a sequential fault? */
if (nera > 0) {
behind = 0;
ahead = nera;
} else {
/*
* Request a cluster of pages that is
* aligned to a VM_FAULT_READ_DEFAULT
* page offset boundary within the
* object. Alignment to a page offset
* boundary is more likely to coincide
* with the underlying file system
* block than alignment to a virtual
* address boundary.
*/
cluster_offset = fs.pindex %
VM_FAULT_READ_DEFAULT;
behind = ulmin(cluster_offset,
atop(vaddr - e_start));
ahead = VM_FAULT_READ_DEFAULT - 1 -
cluster_offset;
}
ahead = ulmin(ahead, atop(e_end - vaddr) - 1);
}
rv = vm_pager_get_pages(fs.object, &fs.m, 1,
&behind, &ahead);
if (rv == VM_PAGER_OK) {
faultcount = behind + 1 + ahead;
hardfault = true;
break; /* break to PAGE HAS BEEN FOUND. */
}
VM_OBJECT_WLOCK(fs.object);
if (rv == VM_PAGER_ERROR)
printf("vm_fault: pager read error, pid %d (%s)\n",
curproc->p_pid, curproc->p_comm);
/*
* If an I/O error occurred or the requested page was
* outside the range of the pager, clean up and return
* an error.
*/
if (rv == VM_PAGER_ERROR || rv == VM_PAGER_BAD) {
fault_page_free(&fs.m);
unlock_and_deallocate(&fs);
return (KERN_OUT_OF_BOUNDS);
}
}
/*
* The page was not found in the current object. Try to traverse
* into a backing object or zero fill if none is found.
* The page was not found in the current object. Try to
* traverse into a backing object or zero fill if none is
* found.
*/
if (!vm_fault_next(&fs)) {
/* Don't try to prefault neighboring pages. */