shithub: unionfs

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store directory contents in a dynamic array instead of a linked list

this fixes a problem with reading big directories,
where a directory entry got skipped per read response
because of the weird way the walking was done in
tandem with dirread9p(2).
it should be a bit memory friendlier and faster, too.

--- a/unionfs.c

+++ b/unionfs.c

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

 typedef struct Union Union;

 typedef struct Fil Fil;

-typedef struct Flist Flist;

+typedef struct List List;

 typedef struct Fstate Fstate;

 typedef struct Qidmap Qidmap;

@@ -38,15 +38,15 @@

 	char *fspath;	/* internal path */

 };

-struct Flist {

-	Fil *file;

-	Flist *next;

+struct List {

+	long n, sz;

+	Fil **l;

 };

 struct Fstate {

 	int fd;

 	Fil *file;

-	Flist *dir, *idx;

+	List *flist;

 };

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

@@ -63,11 +63,20 @@

 	if((v = malloc(sz)) == nil)

 		sysfatal("emalloc: %r");

 	memset(v, 0, sz);

-

 	setmalloctag(v, getcallerpc(&sz));

+	

 	return v;

 }

+void*

+erealloc(void *v, ulong sz)

+{

+	if((v = realloc(v, sz)) == nil && sz != 0)

+		sysfatal("realloc: %r");

+	setrealloctag(v, getcallerpc(&v));

+	return v;

+}

+

 char*

 estrdup(char *s)

 {

@@ -233,34 +242,47 @@

 	free(f);

 }

-void

-flistadd(Flist **list, Fil *f)

+List*

+lnew(void)

 {

-	Flist *p;

+	List *l;

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

-	p->file = f;

-	p->next = *list;

-	*list = p;

+	l = emalloc(sizeof *l);

+	l->n = 0;

+	l->sz = 256;

+	l->l = emalloc(l->sz*sizeof(*l->l));

+

+	return l;

 }

 void

-flistfree(Flist *l)

+lfree(List *l)

 {

-	Flist *lp;

+	int i;

-	for(lp = l; lp != nil; l = lp){

-		lp = lp->next;

-		filefree(l->file);

-		free(l);

+	for(i = 0; i < l->n; i++)

+		filefree(l->l[i]);

+}

+

+int

+ladd(List *l, Fil *f)

+{

+	if(l->n == l->sz){

+		l->sz *= 2;

+		l->l = erealloc(l->l, l->sz*sizeof(*l->l));

 	}

+	l->l[l->n++] = f;

+

+	return l->n;

 }

 int

-flisthas(Flist *list, char *name)

+lhas(List *l, char *name)

 {

-	for(; list != nil; list = list->next)

-		if(strcmp(list->file->name, name) == 0)

+	int i;

+	

+	for(i = 0; i < l->n; i++)

+		if(strcmp(l->l[i]->name, name) == 0)

 			return 1;

 	return 0;

 }

@@ -281,8 +303,8 @@

 {

 	if(st->file)

 		filefree(st->file);

-	if(st->dir)

-		flistfree(st->dir);

+	if(st->flist)

+		lfree(st->flist);

 	close(st->fd);

 	free(st);

 }

@@ -397,7 +419,7 @@

 	walkandclone(r, walk1, clone, nil);

 }

-Flist*

+List*

 filereaddir(Fil *p)

 {

 	int fd;

@@ -406,9 +428,9 @@

 	char *path;

 	Union *u;

 	Fil *f;

-	Flist *list;

+	List *list;

-	list = nil;

+	list = lnew();

 	for(u = unionlist->next; u != unionlist; u = u->next){

 		path = mkpath(u->root, p->fspath, nil);

 		if((d = dirstat(path)) == nil){

@@ -425,10 +447,10 @@

 		if(n < 0)

 			continue;

 		for(i = 0; i < n; i++){

-			if(flisthas(list, dir[i].name))

+			if(lhas(list, dir[i].name))

 				continue;

 			f = filenew(&dir[i]);

-			flistadd(&list, f);

+			ladd(list, f);

 		}

 		free(dir);

 	}

@@ -447,10 +469,9 @@

 	st = r->fid->aux;

 	f = st->file;

-	if(f->mode&DMDIR){

-		st->dir = filereaddir(f);

-		st->idx = st->dir;

-	}else{

+	if(f->mode&DMDIR)

+		st->flist = filereaddir(f);

+	else{

 		if((st->fd = open(f->path, i->mode)) < 0){

 			responderror(r);

 			return;

@@ -567,17 +588,16 @@

 }

 int

-dirgen(int, Dir *dir, void *aux)

+dirgen(int i, Dir *dir, void *aux)

 {

 	Fstate *fs;

-	Flist *l;

+	List *l;

 	fs = aux;

-	l = fs->idx;

-	if(l == nil)

+	l = fs->flist;

+	if(i == l->n)

 		return -1;

-	dirfill(dir, l->file);

-	fs->idx = l->next;

+	dirfill(dir, l->l[i]);

 	return 0;

 }