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MFC r305129:

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Make swapoff reliable.
This commit is contained in:
kib 2016-09-14 10:51:06 +00:00
parent 2932b17b57
commit 6a85dd3622
1 changed files with 22 additions and 9 deletions
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31
sys/vm/swap_pager.c
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@ -1764,36 +1764,49 @@ static void
swap_pager_swapoff(struct swdevt *sp)
{
struct swblock *swap;
vm_object_t locked_obj, object;
vm_pindex_t pindex;
int i, j, retries;
GIANT_REQUIRED;
retries = 0;
locked_obj = NULL;
full_rescan:
mtx_lock(&swhash_mtx);
for (i = 0; i <= swhash_mask; i++) { /* '<=' is correct here */
restart:
for (swap = swhash[i]; swap != NULL; swap = swap->swb_hnext) {
vm_object_t object = swap->swb_object;
vm_pindex_t pindex = swap->swb_index;
object = swap->swb_object;
pindex = swap->swb_index;
for (j = 0; j < SWAP_META_PAGES; ++j) {
if (swp_pager_isondev(swap->swb_pages[j], sp)) {
/* avoid deadlock */
if (!swp_pager_isondev(swap->swb_pages[j], sp))
continue;
if (locked_obj != object) {
if (locked_obj != NULL)
VM_OBJECT_WUNLOCK(locked_obj);
locked_obj = object;
if (!VM_OBJECT_TRYWLOCK(object)) {
break;
} else {
mtx_unlock(&swhash_mtx);
swp_pager_force_pagein(object,
pindex + j);
VM_OBJECT_WUNLOCK(object);
/* Depends on type-stability. */
VM_OBJECT_WLOCK(object);
mtx_lock(&swhash_mtx);
goto restart;
}
}
MPASS(locked_obj == object);
mtx_unlock(&swhash_mtx);
swp_pager_force_pagein(object, pindex + j);
mtx_lock(&swhash_mtx);
goto restart;
}
}
}
mtx_unlock(&swhash_mtx);
if (locked_obj != NULL) {
VM_OBJECT_WUNLOCK(locked_obj);
locked_obj = NULL;
}
if (sp->sw_used) {
/*
* Objects may be locked or paging to the device being