1 6f4d00ee 2013-09-23 0intro #include "stdinc.h"
  2 6f4d00ee 2013-09-23 0intro 
  3 6f4d00ee 2013-09-23 0intro #include "9.h"
  4 6f4d00ee 2013-09-23 0intro 
  5 6f4d00ee 2013-09-23 0intro static struct {
  6 4b576658 2013-09-23 0intro 	QLock	lock;
  7 6f4d00ee 2013-09-23 0intro 
  8 6f4d00ee 2013-09-23 0intro 	Excl*	head;
  9 6f4d00ee 2013-09-23 0intro 	Excl*	tail;
 10 6f4d00ee 2013-09-23 0intro } ebox;
 11 6f4d00ee 2013-09-23 0intro 
 12 6f4d00ee 2013-09-23 0intro struct Excl {
 13 6f4d00ee 2013-09-23 0intro 	Fsys*	fsys;
 14 6f4d00ee 2013-09-23 0intro 	uvlong	path;
 15 6f4d00ee 2013-09-23 0intro 	ulong	time;
 16 6f4d00ee 2013-09-23 0intro 
 17 6f4d00ee 2013-09-23 0intro 	Excl*	next;
 18 6f4d00ee 2013-09-23 0intro 	Excl*	prev;
 19 6f4d00ee 2013-09-23 0intro };
 20 6f4d00ee 2013-09-23 0intro 
 21 6f4d00ee 2013-09-23 0intro enum {
 22 6f4d00ee 2013-09-23 0intro 	LifeTime	= (5*60),
 23 6f4d00ee 2013-09-23 0intro };
 24 6f4d00ee 2013-09-23 0intro 
 25 6f4d00ee 2013-09-23 0intro int
 26 6f4d00ee 2013-09-23 0intro exclAlloc(Fid* fid)
 27 6f4d00ee 2013-09-23 0intro {
 28 6f4d00ee 2013-09-23 0intro 	ulong t;
 29 6f4d00ee 2013-09-23 0intro 	Excl *excl;
 30 6f4d00ee 2013-09-23 0intro 
 31 6f4d00ee 2013-09-23 0intro 	assert(fid->excl == nil);
 32 6f4d00ee 2013-09-23 0intro 
 33 6f4d00ee 2013-09-23 0intro 	t = time(0L);
 34 4b576658 2013-09-23 0intro 	qlock(&ebox.lock);
 35 6f4d00ee 2013-09-23 0intro 	for(excl = ebox.head; excl != nil; excl = excl->next){
 36 6f4d00ee 2013-09-23 0intro 		if(excl->fsys != fid->fsys || excl->path != fid->qid.path)
 37 6f4d00ee 2013-09-23 0intro 			continue;
 38 6f4d00ee 2013-09-23 0intro 		/*
 39 6f4d00ee 2013-09-23 0intro 		 * Found it.
 40 6f4d00ee 2013-09-23 0intro 		 * Now, check if it's timed out.
 41 6f4d00ee 2013-09-23 0intro 		 * If not, return error, it's locked.
 42 6f4d00ee 2013-09-23 0intro 		 * If it has timed out, zap the old
 43 6f4d00ee 2013-09-23 0intro 		 * one and continue on to allocate a
 44 6f4d00ee 2013-09-23 0intro 		 * a new one.
 45 6f4d00ee 2013-09-23 0intro 		 */
 46 6f4d00ee 2013-09-23 0intro 		if(excl->time >= t){
 47 4b576658 2013-09-23 0intro 			qunlock(&ebox.lock);
 48 4b576658 2013-09-23 0intro 			werrstr("exclusive lock");
 49 6f4d00ee 2013-09-23 0intro 			return 0;
 50 6f4d00ee 2013-09-23 0intro 		}
 51 6f4d00ee 2013-09-23 0intro 		excl->fsys = nil;
 52 6f4d00ee 2013-09-23 0intro 	}
 53 6f4d00ee 2013-09-23 0intro 
 54 6f4d00ee 2013-09-23 0intro 	/*
 55 6f4d00ee 2013-09-23 0intro 	 * Not found or timed-out.
 56 6f4d00ee 2013-09-23 0intro 	 * Alloc a new one and initialise.
 57 6f4d00ee 2013-09-23 0intro 	 */
 58 4b576658 2013-09-23 0intro 	excl = vtmallocz(sizeof(Excl));
 59 6f4d00ee 2013-09-23 0intro 	excl->fsys = fid->fsys;
 60 6f4d00ee 2013-09-23 0intro 	excl->path = fid->qid.path;
 61 6f4d00ee 2013-09-23 0intro 	excl->time = t+LifeTime;
 62 6f4d00ee 2013-09-23 0intro 	if(ebox.tail != nil){
 63 6f4d00ee 2013-09-23 0intro 		excl->prev = ebox.tail;
 64 6f4d00ee 2013-09-23 0intro 		ebox.tail->next = excl;
 65 6f4d00ee 2013-09-23 0intro 	}
 66 6f4d00ee 2013-09-23 0intro 	else{
 67 6f4d00ee 2013-09-23 0intro 		ebox.head = excl;
 68 6f4d00ee 2013-09-23 0intro 		excl->prev = nil;
 69 6f4d00ee 2013-09-23 0intro 	}
 70 6f4d00ee 2013-09-23 0intro 	ebox.tail = excl;
 71 6f4d00ee 2013-09-23 0intro 	excl->next = nil;
 72 4b576658 2013-09-23 0intro 	qunlock(&ebox.lock);
 73 6f4d00ee 2013-09-23 0intro 
 74 6f4d00ee 2013-09-23 0intro 	fid->excl = excl;
 75 6f4d00ee 2013-09-23 0intro 	return 1;
 76 6f4d00ee 2013-09-23 0intro }
 77 6f4d00ee 2013-09-23 0intro 
 78 6f4d00ee 2013-09-23 0intro int
 79 6f4d00ee 2013-09-23 0intro exclUpdate(Fid* fid)
 80 6f4d00ee 2013-09-23 0intro {
 81 6f4d00ee 2013-09-23 0intro 	ulong t;
 82 6f4d00ee 2013-09-23 0intro 	Excl *excl;
 83 6f4d00ee 2013-09-23 0intro 
 84 6f4d00ee 2013-09-23 0intro 	excl = fid->excl;
 85 6f4d00ee 2013-09-23 0intro 
 86 6f4d00ee 2013-09-23 0intro 	t = time(0L);
 87 4b576658 2013-09-23 0intro 	qlock(&ebox.lock);
 88 6f4d00ee 2013-09-23 0intro 	if(excl->time < t || excl->fsys != fid->fsys){
 89 4b576658 2013-09-23 0intro 		qunlock(&ebox.lock);
 90 4b576658 2013-09-23 0intro 		werrstr("exclusive lock broken");
 91 6f4d00ee 2013-09-23 0intro 		return 0;
 92 6f4d00ee 2013-09-23 0intro 	}
 93 6f4d00ee 2013-09-23 0intro 	excl->time = t+LifeTime;
 94 4b576658 2013-09-23 0intro 	qunlock(&ebox.lock);
 95 6f4d00ee 2013-09-23 0intro 
 96 6f4d00ee 2013-09-23 0intro 	return 1;
 97 6f4d00ee 2013-09-23 0intro }
 98 6f4d00ee 2013-09-23 0intro 
 99 6f4d00ee 2013-09-23 0intro void
100 6f4d00ee 2013-09-23 0intro exclFree(Fid* fid)
101 6f4d00ee 2013-09-23 0intro {
102 6f4d00ee 2013-09-23 0intro 	Excl *excl;
103 6f4d00ee 2013-09-23 0intro 
104 6f4d00ee 2013-09-23 0intro 	if((excl = fid->excl) == nil)
105 6f4d00ee 2013-09-23 0intro 		return;
106 6f4d00ee 2013-09-23 0intro 	fid->excl = nil;
107 6f4d00ee 2013-09-23 0intro 
108 4b576658 2013-09-23 0intro 	qlock(&ebox.lock);
109 6f4d00ee 2013-09-23 0intro 	if(excl->prev != nil)
110 6f4d00ee 2013-09-23 0intro 		excl->prev->next = excl->next;
111 6f4d00ee 2013-09-23 0intro 	else
112 6f4d00ee 2013-09-23 0intro 		ebox.head = excl->next;
113 6f4d00ee 2013-09-23 0intro 	if(excl->next != nil)
114 6f4d00ee 2013-09-23 0intro 		excl->next->prev = excl->prev;
115 6f4d00ee 2013-09-23 0intro 	else
116 6f4d00ee 2013-09-23 0intro 		ebox.tail = excl->prev;
117 4b576658 2013-09-23 0intro 	qunlock(&ebox.lock);
118 6f4d00ee 2013-09-23 0intro 
119 4b576658 2013-09-23 0intro 	vtfree(excl);
120 6f4d00ee 2013-09-23 0intro }
121 6f4d00ee 2013-09-23 0intro 
122 6f4d00ee 2013-09-23 0intro void
123 6f4d00ee 2013-09-23 0intro exclInit(void)
124 6f4d00ee 2013-09-23 0intro {
125 6f4d00ee 2013-09-23 0intro }