ref: fb7dd4b3a868cb8987049c95bb32e6425a73c8b9
dir: /liblogfs/extentlist.c/
#include "logfsos.h"
#include "logfs.h"
#include "local.h"
typedef struct ExtentNode ExtentNode;
struct ExtentNode {
Extent e;
ExtentNode *next;
};
struct ExtentList {
ExtentNode *head;
};
char *
logfsextentlistnew(ExtentList **ep)
{
ExtentList *l;
l = logfsrealloc(nil, sizeof(*l));
if(l == nil)
return Enomem;
*ep = l;
return nil;
}
void
logfsextentlistreset(ExtentList *l)
{
ExtentNode *n;
n = l->head;
while(n) {
ExtentNode *next;
next = n->next;
logfsfreemem(n);
n = next;
}
l->head = nil;
}
void
logfsextentlistfree(ExtentList **lp)
{
ExtentList *l;
if(lp == nil || (l = *lp) == nil)
return;
logfsextentlistreset(l);
logfsfreemem(l);
*lp = nil;
}
char *
logfsextentlistinsert(ExtentList *l, Extent *add, Extent **new)
{
ExtentNode *old, *prev;
ExtentNode *saved = nil;
if(l == nil)
return "nil extentlist";
/* initially a's extents are non-empty, disjoint and sorted */
old = l->head;
prev = nil;
while(old) {
ExtentNode *next = old->next;
if(add->max <= old->e.min)
break;
if(old->e.min < add->max && add->min < old->e.max) { /* they intersect */
if(add->min <= old->e.min) {
/* add overlaps front of old */
if(add->max < old->e.max) {
int trimmed;
/* but doesn't overlap end */
/* retain tail of old */
if(saved == nil){
saved = logfsrealloc(nil, sizeof(*saved));
if(saved == nil)
return Enomem;
}
trimmed = add->max - old->e.min;
old->e.min += trimmed;
old->e.flashaddr += trimmed;
/* can't touch any further extents, so... */
break;
}
/* add.min ≤ old.min < old.max ≤ add.max ⇒ add completely covers old */
/* delete old */
if(prev)
prev->next = next;
else
l->head = next;
/* stash the deleted extent, so we can reuse it */
if(saved == nil)
saved = old;
else
logfsfreemem(old);
old = next;
continue;
}
else {
/* add.min > old.min, so overlaps end of old or splits it */
if(add->max < old->e.max) { /* add inside old, splitting it */
ExtentNode *frag;
/*
* will need at most two add extents, so ensure
* enough store exists before changing data structures
*/
if(saved == nil)
saved = logfsrealloc(nil, sizeof(*saved));
frag = logfsrealloc(nil, sizeof(*frag));
if(saved == nil || frag == nil)
return Enomem;
frag->next = next;
old->next = frag;
frag->e.min = add->max;
frag->e.max = old->e.max;
frag->e.flashaddr = old->e.flashaddr + (add->max - old->e.min);
old->e.max = add->min;
prev = old;
break;
}
else {
/*
* will need at most one add extent, so create one
* now before changing data structures
*/
if(saved == nil){
saved = logfsrealloc(nil, sizeof(*saved));
if(saved == nil)
return Enomem;
}
old->e.max = add->min; /* retain start of old */
}
/* old.max <= add.max ⇒ add covers tail of old */
}
}
prev = old;
old = next;
}
/*
* if here, and saved == nil, then there was no overlap
*/
if(saved == nil){
saved = logfsrealloc(nil, sizeof(*saved));
if(saved == nil)
return Enomem;
}
saved->e = *add;
if(prev) {
saved->next = prev->next;
prev->next = saved;
}
else {
saved->next = l->head;
l->head = saved;
}
if(new)
*new = &saved->e;
return nil;
}
Extent *
logfsextentlistmatch(ExtentList *l, Extent *e)
{
ExtentNode *m;
u32int flashmax;
if(l == nil)
return nil;
flashmax = e->flashaddr + (e->max - e->min);
for(m = l->head; m; m = m->next) {
u32int l = m->e.max - m->e.min;
if(e->min < m->e.max && m->e.min < e->max /* they intersect */
&& m->e.flashaddr < flashmax && e->flashaddr < m->e.flashaddr + l) /* the store intersects */
return &(m->e);
}
return nil;
}
int
logfsextentlistmatchall(ExtentList *l, int (*func)(void *magic, Extent *), void *magic, Extent *e)
{
ExtentNode *m;
u32int flashmax;
if(l == nil)
return 1;
flashmax = e->flashaddr + (e->max - e->min);
for(m = l->head; m; m = m->next) {
u32int l;
if(m->e.min >= e->max)
return 1;
l = m->e.max - m->e.min;
if(e->min < m->e.max /* they intersect */
&& m->e.flashaddr < flashmax && e->flashaddr < m->e.flashaddr + l) {
/* the store intersects */
int rv = (*func)(magic, &(m->e));
if(rv <= 0)
return rv;
}
}
return 1;
}
int
logfsextentlistwalk(ExtentList *l, int (*func)(void *magic, Extent *, int hole), void *magic)
{
ExtentNode *n;
u32int last = 0;
if(l == nil)
return 1;
for(n = l->head; n; n = n->next) {
int rv;
if(last < n->e.min) {
Extent hole;
hole.min = last;
hole.max = n->e.min;
hole.flashaddr = ~0;
rv = (*func)(magic, &hole, 1);
if(rv <= 0)
return rv;
}
rv = (*func)(magic, &n->e, 0);
if(rv <= 0)
return rv;
last = n->e.max;
}
return 1;
}
int
logfsextentlistwalkrange(ExtentList *l, int (*func)(void *magic, u32int baseoffset, u32int limitoffset, Extent *, u32int extentoffset), void *magic, u32int base, u32int limit)
{
ExtentNode *n;
u32int last = 0;
if(l == nil)
return 1;
for(n = l->head; n; n = n->next) {
Extent hole;
Extent *e;
if(last < n->e.min) {
hole.min = last;
hole.max = n->e.min;
e = &hole;
}
else {
again:
e = &n->e;
}
if(e->min >= limit)
return 1;
//print("walkrange %ud .. %ud\n", e->min, e->max);
if(e->max > base) {
ulong rangebase, rangelimit, extentoffset;
int rv;
rangebase = e->min;
if(rangebase < base) {
extentoffset = base - rangebase;
rangebase += extentoffset;
}
else
extentoffset = 0;
rangelimit = e->max;
if(rangelimit > limit)
rangelimit = limit;
rv = (*func)(magic, rangebase - base, rangelimit - base, e == &hole ? nil : e, extentoffset);
if(rv <= 0)
return rv;
}
last = e->max;
if(e == &hole)
goto again;
}
return 1;
}