shithub: unionfs

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Improve Qid mapping strategy and implementation

--- a/mkfile

+++ b/mkfile

@@ -8,6 +8,7 @@

 	unionfs.h

 OFILES=\

 	util.$O\

+	qmap.$O\

 	unionfs.$O

 </sys/src/cmd/mkone

--- a/unionfs.c

+++ b/unionfs.c

@@ -7,74 +7,9 @@

 Union u0 = {.next = &u0, .prev = &u0};

 Union *unionlist = &u0;

-QLock qidtablock;

-Qtab *qidtab[Nqtab];

 F *root;

 Srv thefs;

-int

-qthash(uvlong path)

-{

-	int h, n;

-	

-	h = 0;

-	for(n = 0; n < 64; n += Nqbit){

-		h ^= path;

-		path >>= Nqbit;

-	}

-	return h & (Nqtab-1);

-}

-

-uvlong

-uniqpath(uvlong path)

-{

-	static u16int salt;

-	int h, have;

-	Qtab *q;

-

-	for(;;){

-		have = 0;

-		h = qthash(path);

-		for(q = qidtab[h]; q != nil; q = q->next)

-			if(q->uniqpath == path){

-				have = 1;

-				break;

-			}

-		if(have == 0)

-			return path;

-		path = ((uvlong)salt<<48) | (path&((uvlong)1<<48)-1);

-		++salt;

-	}

-}

-

-Qtab*

-qtadd(Dir *d)

-{

-	int h;

-	Qtab *q;

-

-	qlock(&qidtablock);

-	h = qthash(d->qid.path);

-	for(q = qidtab[h]; q != nil; q = q->next)

-		if(q->type == d->type

-		&& q->dev == d->dev

-		&& q->path == d->qid.path)

-			goto done;

-

-	q = emalloc(sizeof(*q));

-	q->type = d->type;

-	q->dev = d->dev;

-	q->path = d->qid.path;

-	q->uniqpath = uniqpath(q->path);

-

-	h = qthash(q->path);

-	q->next = qidtab[h];

-	qidtab[h] = q;

-done:

-	qunlock(&qidtablock);

-	return q;

-}

-

 void

 unionlink(Union *p, Union *n)

 {

@@ -92,9 +27,8 @@

 	f = emalloc(sizeof(*f));

 	f->ref = 1;

-	f->qtab = qtadd(d);

 	f->Dir = *d;

-	f->qid.path = f->qtab->uniqpath;

+	f->qid = qencode(d);

 	f->name = estrdup(d->name);

 	f->uid = estrdup(d->uid);

 	f->gid = estrdup(d->gid);

@@ -305,7 +239,7 @@

 clone(Fid *old, Fid *new, void*)

 {

 	Fstate *fs;

-	

+

 	fs = old->aux;

 	new->aux = fstatenew(fs->file);

 	return nil;

--- a/unionfs.h

+++ b/unionfs.h

@@ -1,6 +1,4 @@

 enum {

-	Nqbit = 5,

-	Nqtab = 1<<Nqbit,

 	Nftab = 32,

 	Nftlist = 32,

 };

@@ -9,7 +7,6 @@

 typedef struct F F;

 typedef struct Ftab Ftab;

 typedef struct Fstate Fstate;

-typedef struct Qtab Qtab;

 struct Union {

 	char *root;

@@ -17,17 +14,9 @@

 	Union *prev, *next;

 };

-struct Qtab {

-	ushort type;

-	uint dev;

-	uvlong path, uniqpath;

-	Qtab *next;

-};

-

 struct F {

 	Ref;

 	Dir;

-	Qtab *qtab;

 	char *path;   /* real path */

 	char *fspath; /* internal path */

 };

@@ -44,6 +33,7 @@

 };

 void usage(void);

+Qid qencode(Dir*);

 char *mkpath(char*, ...);

 Ref *copyref(Ref*);

 void *emalloc(ulong);