static int
flushblock(VtCache *c, VtBlock *bb, uint8_t score[VtScoreSize], int ppb,
int epb,
int type)
{
uint32_t addr;
VtBlock *b;
VtEntry e;
int i;
addr = vtglobaltolocal(score);
if(addr == NilBlock)
return 0;
if(bb){
b = bb;
if(memcmp(b->score, score, VtScoreSize) != 0)
abort();
}else
if((b = vtcachelocal(c, addr, type)) == nil)
return -1;
switch(type){
case VtDataType:
break;
case VtDirType:
for(i=0; i<epb; i++){
if(vtentryunpack(&e, b->data, i) < 0)
goto Err;
if(!(e.flags&VtEntryActive))
continue;
if(flushblock(c, nil, e.score, e.psize/VtScoreSize, e.dsize/VtEntrySize,
e.type) < 0)
goto Err;
vtentrypack(&e, b->data, i);
}
break;
default: /* VtPointerTypeX */
for(i=0; i<ppb; i++){
if(flushblock(c, nil, b->data+VtScoreSize*i, ppb, epb, type-1) < 0)
goto Err;
}
break;
}
if(vtblockwrite(b) < 0)
goto Err;
memmove(score, b->score, VtScoreSize);
if(b != bb)
vtblockput(b);
return 0;
Err:
if(b != bb)
vtblockput(b);
return -1;
}
VtFile *
vtfileroot(VtCache *c, u32int addr, int mode)
{
VtFile *r;
VtBlock *b;
b = vtcachelocal(c, addr, VtDirType);
if(b == nil)
return nil;
r = vtfilealloc(c, b, nil, 0, mode);
vtblockput(b);
return r;
}
/*
* Retrieve the block containing the entry for r.
* If a snapshot has happened, we might need
* to get a new copy of the block. We avoid this
* in the common case by caching the score for
* the block and the last epoch in which it was valid.
*
* We use r->mode to tell the difference between active
* file system VtFiles (VtORDWR) and VtFiles for the
* snapshot file system (VtOREAD).
*/
static VtBlock*
fileloadblock(VtFile *r, int mode)
{
char e[ERRMAX];
u32int addr;
VtBlock *b;
switch(r->mode){
default:
assert(0);
case VtOWRITE:
assert(r->mode == VtORDWR);
if(r->local == 1){
b = vtcacheglobal(r->c, r->score, VtDirType);
if(b == nil)
return nil;
b->pc = getcallerpc(&r);
return b;
}
assert(r->parent != nil);
if(vtfilelock(r->parent, VtORDWR) < 0)
return nil;
b = vtfileblock(r->parent, r->offset/r->epb, VtORDWR);
if(b == nil)
b = vtfileblock(r->parent, r->offset/r->epb, VtOWRITE);
vtfileunlock(r->parent);
if(b == nil)
return nil;
memmove(r->score, b->score, VtScoreSize);
r->local = 1;
return b;
case VtORDWR:
assert(r->mode == VtORDWR);
if(r->local == 1){
b = vtcacheglobal(r->c, r->score, VtDirType);
if(b == nil)
return nil;
b->pc = getcallerpc(&r);
return b;
}
assert(r->parent != nil);
if(vtfilelock(r->parent, VtORDWR) < 0)
return nil;
b = vtfileblock(r->parent, r->offset/r->epb, VtORDWR);
vtfileunlock(r->parent);
if(b == nil)
return nil;
memmove(r->score, b->score, VtScoreSize);
r->local = 1;
return b;
case VtOREAD:
if(mode == VtORDWR){
werrstr("read/write lock of read-only file");
return nil;
}
addr = vtglobaltolocal(r->score);
if(addr == NilBlock)
return vtcacheglobal(r->c, r->score, VtDirType);
b = vtcachelocal(r->c, addr, VtDirType);
if(b)
return b;
/*
* If it failed because the epochs don't match, the block has been
* archived and reclaimed. Rewalk from the parent and get the
* new pointer. This can't happen in the VtORDWR case
* above because blocks in the current epoch don't get
* reclaimed. The fact that we're VtOREAD means we're
* a snapshot. (Or else the file system is read-only, but then
* the archiver isn't going around deleting blocks.)
*/
rerrstr(e, sizeof e);
if(strcmp(e, ELabelMismatch) == 0){
if(vtfilelock(r->parent, VtOREAD) < 0)
return nil;
b = vtfileblock(r->parent, r->offset/r->epb, VtOREAD);
vtfileunlock(r->parent);
if(b){
fprint(2, "vtfilealloc: lost %V found %V\n",
r->score, b->score);
memmove(r->score, b->score, VtScoreSize);
return b;
}
}
return nil;
}
}
