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gefs: allow custom snapshot schedules

--- a/sys/man/8/gefs

+++ b/sys/man/8/gefs

@@ -22,9 +22,22 @@

 .B save trace

 .I filename

 .PP

+.B set

+[

+.I snap

+]

+.I key

+.I val

+.PP

+.B clr

+[

+.I snap

+]

+.I key

+.PP

 .B snap

 [

--Smdl

+-mdl

 ]

 [

 .I old 

@@ -83,6 +96,46 @@

 to modify the owner of the file.

 This may be useful during file system initialization.

 .PP

+.I Set

+or

+.I clr

+sets or clears a configuration key, respectively.

+If the

+.I snap

+name is passed, then the key is set in that snapshot.

+If not, then it is set globally.

+This key is a free form string which controls

+some aspect of file system behavior on that snapshot.

+All changes take effect after the file system is restarted.

+Currently, one configuration option is supported:

+.TP

+.BI retain 'timespec'

+sets the schedule for which snapshots are retained.

+The timespec is a sequence of counts and intervals,

+in the form <

+.BR count >@<

+.BR interval >< 

+.BR scale >.

+Every

+.BR interval ,

+a new snapshot is taken.

+Up to

+.B count

+snapshots are retained in the history, with old ones aging out.

+If the 

+.B count

+is omitted, then old snapshots are not trimmed.

+If the

+.B interval

+is omitted, it defaults to 1.

+.IP

+Snapshot timing is taken from the config key attached to the snapshot.

+If there is no key attached to the snapshot,

+the global config key is used.

+If there is no global config key, the default value

+.B `60@1m 24@1h @1d'

+is used.

+.PP

 .B Snap

 manages snapshots.

 It can be invoked as

@@ -123,10 +176,6 @@

 This flag only has an effect when tagging a new snapshot,

 and is ignored otherwise.

 .TP

-.B -S

-Disables automatic timed snapshots.

-This flag only has an effect when tagging a new snapshot,

-and is ignored otherwise.

 .PP

 .I Sync

 writes dirty blocks in memory to the disk.

@@ -239,7 +288,8 @@

 checkpoints:

 .IP

 .EX

-gefs# snap -Sm main mymutable

+gefs# snap -m main mymutable

+gefs# set mymutable retain ''

 .EE

 .PP

 To delete a snapshot:

@@ -246,6 +296,22 @@

 .IP

 .EX

 gefs# snap -d mysnap

+.EE

+.PP

+To set the snapshot retention on the main snapshot

+to 12 snapshots taken every five minutes,

+along with 48 snapshots taken every 2 hours,

+and a daily snapshot with no trimming:

+.IP

+.EX

+gefs# set main retain '12@5m 48@2h @d'

+.EE

+.PP

+To set the default snapshot retention to daily,

+with no minute or hour snapshots:

+.IP

+.EX

+gefs# set retain @d

 .EE

 .PP

 To create a new user:

--- a/sys/src/cmd/gefs/cons.c

+++ b/sys/src/cmd/gefs/cons.c

@@ -67,16 +67,8 @@

 			break;

 		flg = UNPACK32(s.kv.v+1+8);

 		fprint(fd, "snap %.*s", s.kv.nk-1, s.kv.k+1);

-		if(flg != 0)

-			fprint(fd, " [");

 		if(flg & Lmut)

-			fprint(fd, " mutable");

-		if(flg & Lauto)

-			fprint(fd, " auto");

-		if(flg & Ltsnap)

-			fprint(fd, " tsnap");

-		if(flg != 0)

-			fprint(fd, " ]");

+			fprint(fd, " [mutable]");

 		fprint(fd, "\n");

 	}

 	btexit(&s);

@@ -88,17 +80,12 @@

 	Amsg *a;

 	int i;

-	if((a = mallocz(sizeof(Amsg), 1)) == nil){

-		fprint(fd, "alloc sync msg: %r\n");

-		return;

-	}

+	a = emalloc(sizeof(Amsg), 1);

 	a->op = AOsnap;

 	a->fd = fd;

-	a->flag = Ltsnap;

 	while(ap[0][0] == '-'){

 		for(i = 1; ap[0][i]; i++){

 			switch(ap[0][i]){

-			case 'S':	a->flag &= ~Ltsnap;	break;

 			case 'm':	a->flag |= Lmut;	break;

 			case 'd':	a->delete++;		break;

 			case 'l':

@@ -364,11 +351,42 @@

 }

 static void

+setcfg(int fd, char **ap, int n)

+{

+	Amsg *a;

+

+	a = emalloc(sizeof(Amsg), 1);

+	a->op = AOsetcfg;

+	a->fd = fd;

+	if(n == 3)

+		strecpy(a->snap, a->snap+sizeof(a->snap), *ap++);

+	strecpy(a->key, a->key+sizeof(a->key), *ap++);

+	strecpy(a->val, a->val+sizeof(a->val), *ap);

+	chsend(fs->admchan, a);

+}

+

+static void

+clrcfg(int fd, char **ap, int n)

+{

+	Amsg *a;

+

+	a = emalloc(sizeof(Amsg), 1);

+	a->op = AOclrcfg;

+	a->fd = fd;

+	if(n == 2)

+		strecpy(a->snap, a->snap+sizeof(a->snap), *ap++);

+	strecpy(a->key, a->key+sizeof(a->key), *ap);

+	chsend(fs->admchan, a);

+}

+

+static void

 help(int fd, char**, int)

 {

 	char *msg =

 		"help -- show this help\n"

 		"check -- check for consistency\n"

+		"set [snap] key val -- set configuration key\n"

+		"clear [snap] key -- clear configuration key\n"

 		"df -- show disk usage\n"

 		"halt -- stop all writers, sync, and go read-only\n"

 		"permit [on|off] -- switch to/from permissive mode\n"

@@ -387,6 +405,8 @@

 Cmd cmdtab[] = {

 	/* admin */

 	{.name="check",		.sub=nil,	.minarg=0, .maxarg=0, .fn=fsckfs, .epoch=1},

+	{.name="set",		.sub=nil,	.minarg=2, .maxarg=3, .fn=setcfg},

+	{.name="clear",		.sub=nil,	.minarg=1, .maxarg=2, .fn=clrcfg},

 	{.name="df",		.sub=nil, 	.minarg=0, .maxarg=0, .fn=showdf},

 	{.name="halt",		.sub=nil,	.minarg=0, .maxarg=0, .fn=haltfs},

 	{.name="help",		.sub=nil,	.minarg=0, .maxarg=0, .fn=help},

--- a/sys/src/cmd/gefs/dat.h

+++ b/sys/src/cmd/gefs/dat.h

@@ -1,32 +1,33 @@

-typedef struct Blk	Blk;

 typedef struct Amsg	Amsg;

-typedef struct Gefs	Gefs;

+typedef struct Arange	Arange;

+typedef struct Arena	Arena;

+typedef struct Bfree	Bfree;

+typedef struct Blk	Blk;

+typedef struct Bptr	Bptr;

+typedef struct Bucket	Bucket;

+typedef struct Chan	Chan;

+typedef struct Conn	Conn;

+typedef struct Cron	Cron;

+typedef struct Dent	Dent;

+typedef struct Dlist	Dlist;

 typedef struct Errctx	Errctx;

-typedef struct Fmsg	Fmsg;

 typedef struct Fid	Fid;

-typedef struct Msg	Msg;

+typedef struct Fmsg	Fmsg;

+typedef struct Gefs	Gefs;

 typedef struct Key	Key;

-typedef struct Val	Val;

 typedef struct Kvp	Kvp;

-typedef struct Xdir	Xdir;

-typedef struct Bptr	Bptr;

 typedef struct Limbo	Limbo;

-typedef struct Bfree	Bfree;

+typedef struct Mount	Mount;

+typedef struct Msg	Msg;

+typedef struct Qent	Qent;

 typedef struct Scan	Scan;

-typedef struct Dent	Dent;

 typedef struct Scanp	Scanp;

-typedef struct Arena	Arena;

-typedef struct Arange	Arange;

-typedef struct Bucket	Bucket;

-typedef struct Chan	Chan;

 typedef struct Syncq	Syncq;

-typedef struct Qent	Qent;

 typedef struct Trace	Trace;

 typedef struct Tree	Tree;

-typedef struct Dlist	Dlist;

-typedef struct Mount	Mount;

 typedef struct User	User;

-typedef struct Conn	Conn;

+typedef struct Val	Val;

+typedef struct Xdir	Xdir;

 enum {

 	KiB	= 1024ULL,

@@ -107,6 +108,9 @@

 	Klabel,	/* name[] => snapid[]:			snapshot label */

 	Ksnap,	/* sid[8] => ref[8], tree[52]:		snapshot root */

 	Kdlist,	/* snap[8] gen[8] => hd[ptr],tl[ptr]	deadlist  */

+

+	/* configuration */

+	Kconf,	/* name[] => value[] */

 };

 enum {

@@ -121,12 +125,13 @@

 enum {

 	Lmut	= 1 << 0,	/* can we modify snaps via this label */

-	Lauto	= 1 << 1,	/* was this label generated automatically */

-	Ltsnap	= 1 << 2,	/* should we skip the timed snapshots */

+	_Lauto	= 1 << 1,	/* deprecated: was auto snap */

+	_Ltsnap	= 1 << 2,	/* deprecated: was skipping timed snaps */

 };

 enum {

-	Qdump = 1ULL << 63,

+	Qdump	= 1ULL << 63,

+	Qctl	= ~0ULL,

 };

 #define Zb (Bptr){-1, -1, -1}

@@ -326,6 +331,8 @@

 	AOhalt,

 	AOclear,

 	AOrclose,

+	AOsetcfg,

+	AOclrcfg,

 };

 enum {

@@ -405,8 +412,12 @@

 			char	new[128];

 			int	flag;

 			char	delete;

-

 		};

+		struct { /* AOsetcfg AOclrcfg */

+			char	snap[128];

+			char	key[32];

+			char	val[128];

+		};

 		struct {	/* AOclear, AOrclose */

 			Mount	*mnt;

 			Dent	*dent;

@@ -635,6 +646,15 @@

 	};

 };

+struct Cron {

+	int	i;

+	int	cnt;

+	vlong	div;

+	vlong	last;

+	char	*tag;

+	char	(*lbl)[128];

+};

+

 struct Mount {

 	Limbo;

 	Lock;

@@ -643,7 +663,6 @@

 	vlong	gen;

 	char	name[64];

 	Tree	*root;	/* EBR protected */

-

 	int	flag;

 	/* open directory entries */

@@ -650,9 +669,8 @@

 	Lock	dtablk;

 	Dent	*dtab[Ndtab];

-	/* snapshot history */

-	char	minutely[60][128];

-	char	hourly[24][128];

+	/* snapshot scheduling */

+	Cron	cron[3];

 };

 struct Conn {

--- a/sys/src/cmd/gefs/dump.c

+++ b/sys/src/cmd/gefs/dump.c

@@ -43,6 +43,9 @@

 		n = fmtprint(fmt, "dlist gen:%lld, bgen:%lld",

 			UNPACK64(k->k+1), UNPACK64(k->k+9));

 		break;

+	case Kconf:

+		n = fmtprint(fmt, "Conf %.*s", k->nk-1, k->k+1);

+		break;

 	default:

 		n = fmtprint(fmt, "??? %.*H", k->nk, k->k);

 		break;

@@ -165,6 +168,9 @@

 		n = fmtprint(fmt, "hd:%B, tl:%B",

 			unpackbp(v->v, v->nv),

 			unpackbp(v->v+Ptrsz, v->nv-Ptrsz));

+		break;

+	case Kconf:

+		n = fmtprint(fmt, "%.*s", v->nv, v->v);

 		break;

 	default:

 		n = fmtprint(fmt, "??? %.*H", v->nk, v->k);

--- a/sys/src/cmd/gefs/fs.c

+++ b/sys/src/cmd/gefs/fs.c

@@ -11,7 +11,7 @@

 static void	respond(Fmsg*, Fcall*);

 static void	rerror(Fmsg*, char*, ...);

 static void	clunkfid(Conn*, Fid*, Amsg**);

-

+static void	snapmsg(char*, char*);

 static void	authfree(AuthRpc*);

 int

@@ -573,49 +573,98 @@

 	return de;

 }

-static void

-loadautos(Mount *mnt)

+/*

+ * Load snapshots into history, trimming old ones if we have more

+ * snapshots than expected (eg, reducing the count in the config).

+ */

+void

+loadhist(Mount *mnt, Cron *c)

 {

 	char pfx[128];

-	int m, h, ns;

-	uint flg;

+	int i, ns;

 	Scan s;

-	m = 0;

-	h = 0;

+	if(c->cnt == 0)

+		return;

+	i = 0;

 	pfx[0] = Klabel;

-	ns = snprint(pfx+1, sizeof(pfx)-1, "%s@minute.", mnt->name);

+	ns = snprint(pfx+1, sizeof(pfx)-1, "%s@%s.", mnt->name, c->tag);

 	btnewscan(&s, pfx, ns+1);

 	btenter(&fs->snap, &s);

 	while(1){

 		if(!btnext(&s, &s.kv))

 			break;

-		flg = UNPACK32(s.kv.v+1+8);

-		if(flg & Lauto){

-			memcpy(mnt->minutely[m], s.kv.k+1, s.kv.nk-1);

-			mnt->minutely[m][s.kv.nk-1] = 0;

-			m = (m+1)%60;

-			continue;

-		}

+		if(c->lbl[i][0] != 0)

+			snapmsg(c->lbl[i], nil);

+		assert(s.kv.nk-1 < sizeof(c->lbl[i]));

+		memcpy(c->lbl[i], s.kv.k+1, s.kv.nk-1);

+		c->lbl[i][s.kv.nk-1] = 0;

+		i = (i+1) % c->cnt;

 	}

 	btexit(&s);

+	c->last = time(nil);

+	c->i = i;

+}

-	pfx[0] = Klabel;

-	ns = snprint(pfx+1, sizeof(pfx)-1, "%s@hour.", mnt->name);

-	btnewscan(&s, pfx, ns+1);

-	btenter(&fs->snap, &s);

-	while(1){

-		if(!btnext(&s, &s.kv))

-			break;

-		flg = UNPACK32(s.kv.v+1+8);

-		if(flg & Lauto){

-			memcpy(mnt->hourly[h], s.kv.k+1, s.kv.nk-1);

-			mnt->hourly[h][s.kv.nk-1] = 0;

-			h = (h+1)%24;

-			continue;

+/*

+ * Load up automatic snapshots. Don't error on bad config,

+ * so that the user can mount the snap and fix it.

+ */

+static void

+loadautos(Mount *mnt)

+{

+	static char *tagname[] = {"minute", "hour", "day"};

+	static int scale[] = {60, 3600, 24*3600};

+	char *p, pfx[128], rbuf[128];

+	int i, n, div, cnt, op;

+	Kvp kv;

+

+	pfx[0] = Kconf;

+	n = snprint(pfx+1, sizeof(pfx)-1, "retain");

+	kv.k = pfx;

+	kv.nk = n+1;

+	if(btlookup(mnt->root, &kv, &kv, rbuf, sizeof(rbuf)-1)

+	|| btlookup(&fs->snap, &kv, &kv, rbuf, sizeof(rbuf)-1)){

+		p[kv.nv] = 0;

+		p = kv.v;

+	}else

+		p = "60@m 24@h @d";

+	while(*p){

+		cnt = 0;

+		div = 1;

+		op = -1;

+

+		/* parse the conf. */

+		if(*p >= '0' && *p <= '9')

+			cnt = strtol(p, &p, 10);

+		if(*p++ != '@')

+			goto Bad;

+		if(*p >= '0' && *p <= '9')

+			div = strtol(p, &p, 10);

+		if(*p == 'm' || *p == 'h' || *p == 'd')

+			op = *p++;

+		while(*p == ' ' || *p == '\t')

+			p++;

+		if(cnt < 0 || div <= 0){

+Bad:			memset(mnt->cron, 0, sizeof(mnt->cron));

+			fprint(2, "invalid time spec\n");

+			return;

 		}

+

+		switch(op){

+		case 'm':	i = 0;	break;

+		case 'h':	i = 1;	break;

+		case 'd':	i = 2;	break;

+		default:	abort();

+		}

+

+		mnt->cron[i].tag = tagname[i];

+		mnt->cron[i].div = scale[i]*div;

+		mnt->cron[i].cnt = cnt;

+		mnt->cron[i].lbl = emalloc(cnt*sizeof(char[128]), 1);

 	}

-	btexit(&s);

+	for(i = 0; i < nelem(mnt->cron); i++)

+		loadhist(mnt, &mnt->cron[i]);

 }

 Mount *

@@ -650,10 +699,10 @@

 	snprint(mnt->name, sizeof(mnt->name), "%s", name);

 	if((t = opensnap(name, &flg)) == nil)

 		error(Enosnap);

-	loadautos(mnt);

 	mnt->flag = flg;

 	mnt->root = t;

 	mnt->next = fs->mounts;

+	loadautos(mnt);

 	asetp(&fs->mounts, mnt);

 	poperror();

@@ -2655,6 +2704,43 @@

 }

 void

+setconf(int fd, int op, char *snap, char *key, char *val)

+{

+	char kbuf[128];

+	Mount *mnt;

+	Tree *t;

+	Msg m;

+

+	mnt = nil;

+	t = &fs->snap;

+	if(waserror()){

+		fprint(fd, "error setting config: %s\n", errmsg());

+		return;

+	}

+	if(snap[0] != 0){

+		mnt = getmount(snap);

+		t = mnt->root;

+	}

+	kbuf[0] = Kconf;

+	strecpy(kbuf+1, kbuf+sizeof(kbuf), key);

+	m.op = op;

+	m.k = kbuf;

+	m.nk = strlen(key)+1;

+	m.v = val;

+	m.nv = strlen(val);

+	qlock(&fs->mutlk);

+	if(!waserror()){

+		btupsert(t, &m, 1);

+		poperror();

+	}else

+		fprint(fd, "error setting config: %s\n", errmsg());

+	qunlock(&fs->mutlk);

+	if(mnt != nil)

+		clunkmount(mnt);

+	poperror();

+}

+

+void

 runsweep(int id, void*)

 {

 	char buf[Kvmax];

@@ -2672,6 +2758,12 @@

 	while(1){

 		am = chrecv(fs->admchan);

 		switch(am->op){

+		case AOsetcfg:

+			setconf(am->fd, Oinsert, am->snap, am->key, am->val);

+			break;

+		case AOclrcfg:

+			setconf(am->fd, Odelete, am->snap, am->key, "");

+			break;

 		case AOhalt:

 			if(!agetl(&fs->rdonly)){

 				ainc(&fs->rdonly);

@@ -2871,8 +2963,8 @@

 	}

 }

-void

-snapmsg(char *old, char *new, int flg)

+static void

+snapmsg(char *old, char *new)

 {

 	Amsg *a;

@@ -2879,7 +2971,6 @@

 	a = emalloc(sizeof(Amsg), 1);

 	a->op = AOsnap;

 	a->fd = -1;

-	a->flag = flg;

 	strecpy(a->old, a->old+sizeof(a->old), old);

 	if(new == nil)

 		a->delete = 1;

@@ -2888,19 +2979,43 @@

 	chsend(fs->admchan, a);

 }

+static void

+cronsync(char *name, Cron *c, Tm *tm, vlong now)

+{

+	char *p, *e, buf[128];

+

+	if(c->div == 0)

+		return;

+	if(now/c->div == c->last/c->div)

+		return;

+

+	if(c->cnt == 0){

+		p = buf;

+		e = p + sizeof(buf);

+	}else{

+		if(c->lbl[c->i][0] != 0)

+			snapmsg(c->lbl[c->i], nil);

+		p = c->lbl[c->i];

+		e = p + sizeof(c->lbl[c->i]);

+		c->i = (c->i+1)%c->cnt;

+	}

+	seprint(p, e, "%s@%s.%τ",

+		name, c->tag,

+		tmfmt(tm, "YYYY.MM.DD[_]hh:mm:ss"));

+	snapmsg(name, p);

+	c->last = now;

+}

+

 void

 runtasks(int, void *)

 {

-	char buf[128];

-	Tm now, then;

+	vlong now;

 	Mount *mnt;

-	int m, h;

 	Amsg *a;

+	Tm tm;

+	int i;

-	m = 0;

-	h = 0;

-	tmnow(&then, nil);

-	tmnow(&now, nil);

+	tmnow(&tm, nil);

 	while(1){

 		sleep(5000);

 		if(fs->rdonly)

@@ -2914,35 +3029,14 @@

 		a->fd = -1;

 		chsend(fs->admchan, a);

-		tmnow(&now, nil);

+		tmnow(&tm, nil);

+		now = tmnorm(&tm);

 		for(mnt = agetp(&fs->mounts); mnt != nil; mnt = mnt->next){

-			if(!(mnt->flag & Ltsnap))

+			if(!(mnt->flag & Lmut))

 				continue;

-			if(now.yday != then.yday){

-				snprint(buf, sizeof(buf),

-					"%s@day.%τ", mnt->name, tmfmt(&now, "YYYY.MM.DD[_]hh:mm:ss"));

-				snapmsg(mnt->name, buf, Lauto);

-			}

-			if(now.hour != then.hour){

-				if(mnt->hourly[h][0] != 0)

-					snapmsg(mnt->hourly[h], nil, 0);

-				snprint(mnt->hourly[h], sizeof(mnt->hourly[h]),

-					"%s@hour.%τ", mnt->name, tmfmt(&now, "YYYY.MM.DD[_]hh:mm:ss"));

-				snapmsg(mnt->name, mnt->hourly[h], Lauto);

-			}

-			if(now.min != then.min){

-				if(mnt->minutely[m][0] != 0)

-					snapmsg(mnt->minutely[m], nil, 0);

-				snprint(mnt->minutely[m], sizeof(mnt->minutely[m]),

-					"%s@minute.%τ", mnt->name, tmfmt(&now, "YYYY.MM.DD[_]hh:mm:ss"));

-				snapmsg(mnt->name, mnt->minutely[m], Lauto);

-			}

+			for(i = 0; i < nelem(mnt->cron); i++)

+				cronsync(mnt->name, &mnt->cron[i], &tm, now);

 		}

-		if(now.hour != then.hour)

-			h = (h+1)%24;

-		if(now.min != then.min)

-			m = (m+1)%60;

-		then = now;

 		poperror();

 	}

 }

--- a/sys/src/cmd/gefs/ream.c

+++ b/sys/src/cmd/gefs/ream.c

@@ -91,11 +91,11 @@

 	Tree t;

 	Kvp kv;

-	lbl2kv("adm", 1, Lmut|Ltsnap, &kv, buf, sizeof(buf));

+	lbl2kv("adm", 1, Lmut, &kv, buf, sizeof(buf));

 	setval(s, &kv);

 	lbl2kv("empty", 0, 0, &kv, buf, sizeof(buf));

 	setval(s, &kv);

-	lbl2kv("main", 2, Lmut|Ltsnap, &kv, buf, sizeof(buf));

+	lbl2kv("main", 2, Lmut, &kv, buf, sizeof(buf));

 	setval(s, &kv);

 	p = buf;

-- 

⑨