static VtBlock *
blockwalk(VtBlock *p, int index, VtCache *c, int mode, VtEntry *e)
{
VtBlock *b;
int type;
uchar *score;
VtEntry oe;
switch(p->type){
case VtDataType:
assert(0);
case VtDirType:
type = e->type;
score = e->score;
break;
default:
type = p->type - 1;
score = p->data+index*VtScoreSize;
break;
}
/*print("walk from %V/%d ty %d to %V ty %d\n", p->score, index, p->type, score, type); */
if(mode == VtOWRITE && vtglobaltolocal(score) == NilBlock){
print("VtOWRITE && NilBlock\n");
b = vtcacheallocblock(c, type);
print("vtcachealloblcok returns %p\n", b);
if(b)
goto HaveCopy;
}else
b = vtcacheglobal(c, score, type);
if(b == nil || mode == VtOREAD)
return b;
if(vtglobaltolocal(b->score) != NilBlock)
return b;
oe = *e;
/*
* Copy on write.
*/
e->flags |= VtEntryLocal;
b = vtblockcopy(b/*, e->tag, fs->ehi, fs->elo*/);
if(b == nil)
return nil;
HaveCopy:
if(p->type == VtDirType){
memmove(e->score, b->score, VtScoreSize);
vtentrypack(e, p->data, index);
}else{
memmove(p->data+index*VtScoreSize, b->score, VtScoreSize);
}
return b;
}
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;
}
/*
* 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;
}
}
int
vtfileflushbefore(VtFile *r, u64int offset)
{
VtBlock *b, *bb;
VtEntry e;
int i, base, depth, ppb, epb, doflush;
int index[VtPointerDepth+1], j, ret;
VtBlock *bi[VtPointerDepth+2];
uchar *score;
assert(ISLOCKED(r));
if(offset == 0)
return 0;
b = fileload(r, &e);
if(b == nil)
return -1;
/*
* compute path through tree for the last written byte and the next one.
*/
ret = -1;
memset(bi, 0, sizeof bi);
depth = DEPTH(e.type);
bi[depth+1] = b;
i = mkindices(&e, (offset-1)/e.dsize, index);
if(i < 0)
goto Err;
if(i > depth)
goto Err;
ppb = e.psize / VtScoreSize;
epb = e.dsize / VtEntrySize;
/*
* load the blocks along the last written byte
*/
index[depth] = r->offset % r->epb;
for(i=depth; i>=0; i--){
bb = blockwalk(b, index[i], r->c, VtORDWR, &e);
if(bb == nil)
goto Err;
bi[i] = bb;
b = bb;
}
ret = 0;
/*
* walk up the path from leaf to root, flushing anything that
* has been finished.
*/
base = e.type&~VtTypeDepthMask;
for(i=0; i<=depth; i++){
doflush = 0;
if(i == 0){
/* leaf: data or dir block */
if(offset%e.dsize == 0)
doflush = 1;
}else{
/*
* interior node: pointer blocks.
* specifically, b = bi[i] is a block whose index[i-1]'th entry
* points at bi[i-1].
*/
b = bi[i];
/*
* the index entries up to but not including index[i-1] point at
* finished blocks, so flush them for sure.
*/
for(j=0; j<index[i-1]; j++)
if(flushblock(r->c, nil, b->data+j*VtScoreSize, ppb, epb, base+i-1) < 0)
goto Err;
/*
* if index[i-1] is the last entry in the block and is global
* (i.e. the kid is flushed), then we can flush this block.
*/
if(j==ppb-1 && vtglobaltolocal(b->data+j*VtScoreSize)==NilBlock)
doflush = 1;
}
if(doflush){
if(i == depth)
score = e.score;
else
score = bi[i+1]->data+index[i]*VtScoreSize;
if(flushblock(r->c, bi[i], score, ppb, epb, base+i) < 0)
goto Err;
}
}
Err:
/* top: entry. do this always so that the score is up-to-date */
vtentrypack(&e, bi[depth+1]->data, index[depth]);
for(i=0; i<nelem(bi); i++)
if(bi[i])
vtblockput(bi[i]);
return ret;
}
