X-Git-Url: https://git.camperquake.de/gitweb.cgi?a=blobdiff_plain;f=module%2Fzfs%2Fdmu_traverse.c;h=775bb83583787313835ce2d83241d64a6ce87ab6;hb=3558fd73b5d863304102f6745c26e0b592aca60a;hp=023f90e12e342999aa8c3a767b076de8f755f047;hpb=572e285762521df27fe5b026f409ba1a21abb7ac;p=zfs.git

diff --git a/module/zfs/dmu_traverse.c b/module/zfs/dmu_traverse.c
index 023f90e..775bb83 100644
--- a/module/zfs/dmu_traverse.c
+++ b/module/zfs/dmu_traverse.c
@@ -59,6 +59,31 @@ typedef struct traverse_data {
 	void *td_arg;
 } traverse_data_t;
 
+typedef struct traverse_visitbp_data {
+	/* Function arguments */
+	traverse_data_t *tv_td;
+	const dnode_phys_t *tv_dnp;
+	arc_buf_t *tv_pbuf;
+	blkptr_t *tv_bp;
+	const zbookmark_t *tv_zb;
+	/* Local variables */
+	prefetch_data_t *tv_pd;
+	zbookmark_t tv_czb;
+	arc_buf_t *tv_buf;
+	boolean_t tv_hard;
+	objset_phys_t *tv_osp;
+	dnode_phys_t *tv_ldnp;
+	blkptr_t *tv_cbp;
+	uint32_t tv_flags;
+	int tv_err;
+	int tv_lasterr;
+	int tv_i;
+	int tv_epb;
+	int tv_depth;
+} traverse_visitbp_data_t;
+
+static inline int traverse_visitbp(traverse_data_t *td, const
+    dnode_phys_t *dnp, arc_buf_t *pbuf, blkptr_t *bp, const zbookmark_t *zb);
 static int traverse_dnode(traverse_data_t *td, const dnode_phys_t *dnp,
     arc_buf_t *buf, uint64_t objset, uint64_t object);
 
@@ -128,137 +153,191 @@ traverse_zil(traverse_data_t *td, zil_header_t *zh)
 	zil_free(zilog);
 }
 
-static int
-traverse_visitbp(traverse_data_t *td, const dnode_phys_t *dnp,
-    arc_buf_t *pbuf, blkptr_t *bp, const zbookmark_t *zb)
+#define TRAVERSE_VISITBP_MAX_DEPTH	20
+
+static void
+__traverse_visitbp_init(traverse_visitbp_data_t *tv,
+    traverse_data_t *td, const dnode_phys_t *dnp,
+    arc_buf_t *pbuf, blkptr_t *bp, const zbookmark_t *zb, int depth)
 {
-	zbookmark_t czb;
-	int err = 0, lasterr = 0;
-	arc_buf_t *buf = NULL;
-	prefetch_data_t *pd = td->td_pfd;
-	boolean_t hard = td->td_flags & TRAVERSE_HARD;
+	tv->tv_td = td;
+	tv->tv_dnp = dnp;
+	tv->tv_pbuf = pbuf;
+	tv->tv_bp = bp;
+	tv->tv_zb = zb;
+	tv->tv_err = 0;
+	tv->tv_lasterr = 0;
+	tv->tv_buf = NULL;
+	tv->tv_pd = td->td_pfd;
+	tv->tv_hard = td->td_flags & TRAVERSE_HARD;
+	tv->tv_flags = ARC_WAIT;
+	tv->tv_depth = depth;
+}
 
-	if (bp->blk_birth == 0) {
-		err = td->td_func(td->td_spa, NULL, NULL, pbuf, zb, dnp,
-		    td->td_arg);
-		return (err);
+static noinline int
+__traverse_visitbp(traverse_visitbp_data_t *tv)
+{
+	ASSERT3S(tv->tv_depth, <, TRAVERSE_VISITBP_MAX_DEPTH);
+
+	if (tv->tv_bp->blk_birth == 0) {
+		tv->tv_err = tv->tv_td->td_func(tv->tv_td->td_spa, NULL, NULL,
+		    tv->tv_pbuf, tv->tv_zb, tv->tv_dnp, tv->tv_td->td_arg);
+		return (tv->tv_err);
 	}
 
-	if (bp->blk_birth <= td->td_min_txg)
+	if (tv->tv_bp->blk_birth <= tv->tv_td->td_min_txg)
 		return (0);
 
-	if (pd && !pd->pd_exited &&
-	    ((pd->pd_flags & TRAVERSE_PREFETCH_DATA) ||
-	    BP_GET_TYPE(bp) == DMU_OT_DNODE || BP_GET_LEVEL(bp) > 0)) {
-		mutex_enter(&pd->pd_mtx);
-		ASSERT(pd->pd_blks_fetched >= 0);
-		while (pd->pd_blks_fetched == 0 && !pd->pd_exited)
-			cv_wait(&pd->pd_cv, &pd->pd_mtx);
-		pd->pd_blks_fetched--;
-		cv_broadcast(&pd->pd_cv);
-		mutex_exit(&pd->pd_mtx);
+	if (tv->tv_pd && !tv->tv_pd->pd_exited &&
+	    ((tv->tv_pd->pd_flags & TRAVERSE_PREFETCH_DATA) ||
+	    BP_GET_TYPE(tv->tv_bp) == DMU_OT_DNODE ||
+	    BP_GET_LEVEL(tv->tv_bp) > 0)) {
+		mutex_enter(&tv->tv_pd->pd_mtx);
+		ASSERT(tv->tv_pd->pd_blks_fetched >= 0);
+		while (tv->tv_pd->pd_blks_fetched == 0 && !tv->tv_pd->pd_exited)
+			cv_wait(&tv->tv_pd->pd_cv, &tv->tv_pd->pd_mtx);
+		tv->tv_pd->pd_blks_fetched--;
+		cv_broadcast(&tv->tv_pd->pd_cv);
+		mutex_exit(&tv->tv_pd->pd_mtx);
 	}
 
-	if (td->td_flags & TRAVERSE_PRE) {
-		err = td->td_func(td->td_spa, NULL, bp, pbuf, zb, dnp,
-		    td->td_arg);
-		if (err == TRAVERSE_VISIT_NO_CHILDREN)
+	if (tv->tv_td->td_flags & TRAVERSE_PRE) {
+		tv->tv_err = tv->tv_td->td_func(tv->tv_td->td_spa, NULL,
+		    tv->tv_bp, tv->tv_pbuf, tv->tv_zb, tv->tv_dnp,
+		    tv->tv_td->td_arg);
+		if (tv->tv_err == TRAVERSE_VISIT_NO_CHILDREN)
 			return (0);
-		if (err)
-			return (err);
+		if (tv->tv_err)
+			return (tv->tv_err);
 	}
 
-	if (BP_GET_LEVEL(bp) > 0) {
-		uint32_t flags = ARC_WAIT;
-		int i;
-		blkptr_t *cbp;
-		int epb = BP_GET_LSIZE(bp) >> SPA_BLKPTRSHIFT;
+	if (BP_GET_LEVEL(tv->tv_bp) > 0) {
+		tv->tv_epb = BP_GET_LSIZE(tv->tv_bp) >> SPA_BLKPTRSHIFT;
 
-		err = dsl_read(NULL, td->td_spa, bp, pbuf,
-		    arc_getbuf_func, &buf,
-		    ZIO_PRIORITY_ASYNC_READ, ZIO_FLAG_CANFAIL, &flags, zb);
-		if (err)
-			return (err);
+		tv->tv_err = dsl_read(NULL, tv->tv_td->td_spa, tv->tv_bp,
+		    tv->tv_pbuf, arc_getbuf_func, &tv->tv_buf,
+		    ZIO_PRIORITY_ASYNC_READ, ZIO_FLAG_CANFAIL,
+		    &tv->tv_flags, tv->tv_zb);
+		if (tv->tv_err)
+			return (tv->tv_err);
 
 		/* recursively visitbp() blocks below this */
-		cbp = buf->b_data;
-		for (i = 0; i < epb; i++, cbp++) {
-			SET_BOOKMARK(&czb, zb->zb_objset, zb->zb_object,
-			    zb->zb_level - 1,
-			    zb->zb_blkid * epb + i);
-			err = traverse_visitbp(td, dnp, buf, cbp, &czb);
-			if (err) {
-				if (!hard)
+		tv->tv_cbp = tv->tv_buf->b_data;
+		for (tv->tv_i = 0; tv->tv_i < tv->tv_epb;
+		     tv->tv_i++, tv->tv_cbp++) {
+			SET_BOOKMARK(&tv->tv_czb, tv->tv_zb->zb_objset,
+			    tv->tv_zb->zb_object, tv->tv_zb->zb_level - 1,
+			    tv->tv_zb->zb_blkid * tv->tv_epb + tv->tv_i);
+			__traverse_visitbp_init(tv + 1, tv->tv_td,
+			    tv->tv_dnp, tv->tv_buf, tv->tv_cbp,
+			    &tv->tv_czb, tv->tv_depth + 1);
+			tv->tv_err = __traverse_visitbp(tv + 1);
+			if (tv->tv_err) {
+				if (!tv->tv_hard)
 					break;
-				lasterr = err;
+				tv->tv_lasterr = tv->tv_err;
 			}
 		}
-	} else if (BP_GET_TYPE(bp) == DMU_OT_DNODE) {
-		uint32_t flags = ARC_WAIT;
-		int i;
-		int epb = BP_GET_LSIZE(bp) >> DNODE_SHIFT;
-
-		err = dsl_read(NULL, td->td_spa, bp, pbuf,
-		    arc_getbuf_func, &buf,
-		    ZIO_PRIORITY_ASYNC_READ, ZIO_FLAG_CANFAIL, &flags, zb);
-		if (err)
-			return (err);
+	} else if (BP_GET_TYPE(tv->tv_bp) == DMU_OT_DNODE) {
+		tv->tv_epb = BP_GET_LSIZE(tv->tv_bp) >> DNODE_SHIFT;
+
+		tv->tv_err = dsl_read(NULL, tv->tv_td->td_spa, tv->tv_bp,
+		    tv->tv_pbuf, arc_getbuf_func, &tv->tv_buf,
+		    ZIO_PRIORITY_ASYNC_READ, ZIO_FLAG_CANFAIL,
+		    &tv->tv_flags, tv->tv_zb);
+		if (tv->tv_err)
+			return (tv->tv_err);
 
 		/* recursively visitbp() blocks below this */
-		dnp = buf->b_data;
-		for (i = 0; i < epb; i++, dnp++) {
-			err = traverse_dnode(td, dnp, buf, zb->zb_objset,
-			    zb->zb_blkid * epb + i);
-			if (err) {
-				if (!hard)
+		tv->tv_dnp = tv->tv_buf->b_data;
+		for (tv->tv_i = 0; tv->tv_i < tv->tv_epb;
+		     tv->tv_i++, tv->tv_dnp++) {
+			tv->tv_err = traverse_dnode(tv->tv_td, tv->tv_dnp,
+			    tv->tv_buf, tv->tv_zb->zb_objset,
+			    tv->tv_zb->zb_blkid * tv->tv_epb + tv->tv_i);
+			if (tv->tv_err) {
+				if (!tv->tv_hard)
 					break;
-				lasterr = err;
+				tv->tv_lasterr = tv->tv_err;
 			}
 		}
-	} else if (BP_GET_TYPE(bp) == DMU_OT_OBJSET) {
-		uint32_t flags = ARC_WAIT;
-		objset_phys_t *osp;
-		dnode_phys_t *dnp;
-
-		err = dsl_read_nolock(NULL, td->td_spa, bp,
-		    arc_getbuf_func, &buf,
-		    ZIO_PRIORITY_ASYNC_READ, ZIO_FLAG_CANFAIL, &flags, zb);
-		if (err)
-			return (err);
-
-		osp = buf->b_data;
-		dnp = &osp->os_meta_dnode;
-		err = traverse_dnode(td, dnp, buf, zb->zb_objset,
-		    DMU_META_DNODE_OBJECT);
-		if (err && hard) {
-			lasterr = err;
-			err = 0;
+	} else if (BP_GET_TYPE(tv->tv_bp) == DMU_OT_OBJSET) {
+
+		tv->tv_err = dsl_read_nolock(NULL, tv->tv_td->td_spa,
+		    tv->tv_bp, arc_getbuf_func, &tv->tv_buf,
+		    ZIO_PRIORITY_ASYNC_READ, ZIO_FLAG_CANFAIL,
+		    &tv->tv_flags, tv->tv_zb);
+		if (tv->tv_err)
+			return (tv->tv_err);
+
+		tv->tv_osp = tv->tv_buf->b_data;
+		tv->tv_ldnp = &tv->tv_osp->os_meta_dnode;
+		tv->tv_err = traverse_dnode(tv->tv_td, tv->tv_ldnp, tv->tv_buf,
+		    tv->tv_zb->zb_objset, DMU_META_DNODE_OBJECT);
+		if (tv->tv_err && tv->tv_hard) {
+			tv->tv_lasterr = tv->tv_err;
+			tv->tv_err = 0;
 		}
-		if (err == 0 && arc_buf_size(buf) >= sizeof (objset_phys_t)) {
-			dnp = &osp->os_userused_dnode;
-			err = traverse_dnode(td, dnp, buf, zb->zb_objset,
+		if (tv->tv_err == 0 &&
+		    arc_buf_size(tv->tv_buf) >= sizeof (objset_phys_t)) {
+			tv->tv_ldnp = &tv->tv_osp->os_userused_dnode;
+			tv->tv_err = traverse_dnode(tv->tv_td, tv->tv_ldnp,
+			    tv->tv_buf, tv->tv_zb->zb_objset,
 			    DMU_USERUSED_OBJECT);
 		}
-		if (err && hard) {
-			lasterr = err;
-			err = 0;
+		if (tv->tv_err && tv->tv_hard) {
+			tv->tv_lasterr = tv->tv_err;
+			tv->tv_err = 0;
 		}
-		if (err == 0 && arc_buf_size(buf) >= sizeof (objset_phys_t)) {
-			dnp = &osp->os_groupused_dnode;
-			err = traverse_dnode(td, dnp, buf, zb->zb_objset,
+		if (tv->tv_err == 0 &&
+		    arc_buf_size(tv->tv_buf) >= sizeof (objset_phys_t)) {
+			tv->tv_ldnp = &tv->tv_osp->os_groupused_dnode;
+			tv->tv_err = traverse_dnode(tv->tv_td, tv->tv_ldnp,
+			    tv->tv_buf, tv->tv_zb->zb_objset,
 			    DMU_GROUPUSED_OBJECT);
 		}
 	}
 
-	if (buf)
-		(void) arc_buf_remove_ref(buf, &buf);
+	if (tv->tv_buf)
+		(void) arc_buf_remove_ref(tv->tv_buf, &tv->tv_buf);
 
-	if (err == 0 && lasterr == 0 && (td->td_flags & TRAVERSE_POST)) {
-		err = td->td_func(td->td_spa, NULL, bp, pbuf, zb, dnp,
-		    td->td_arg);
+	if (tv->tv_err == 0 && tv->tv_lasterr == 0 &&
+	    (tv->tv_td->td_flags & TRAVERSE_POST)) {
+		tv->tv_err = tv->tv_td->td_func(tv->tv_td->td_spa, NULL,
+		    tv->tv_bp, tv->tv_pbuf, tv->tv_zb, tv->tv_dnp,
+		    tv->tv_td->td_arg);
 	}
 
-	return (err != 0 ? err : lasterr);
+	return (tv->tv_err != 0 ? tv->tv_err : tv->tv_lasterr);
+}
+
+/*
+ * Due to  limited stack space recursive functions are frowned upon in
+ * the Linux kernel.  However, they often are the most elegant solution
+ * to a problem.  The following code preserves the recursive function
+ * traverse_visitbp() but moves the local variables AND function
+ * arguments to the heap to minimize the stack frame size.  Enough
+ * space is initially allocated on the stack for 16 levels of recursion.
+ * This change does ugly-up-the-code but it reduces the worst case
+ * usage from roughly 2496 bytes to 576 bytes on x86_64 archs.
+ */
+static int
+traverse_visitbp(traverse_data_t *td, const dnode_phys_t *dnp,
+    arc_buf_t *pbuf, blkptr_t *bp, const zbookmark_t *zb)
+{
+	traverse_visitbp_data_t *tv;
+	int error;
+
+	tv = kmem_zalloc(sizeof(traverse_visitbp_data_t) *
+	    TRAVERSE_VISITBP_MAX_DEPTH, KM_SLEEP);
+	__traverse_visitbp_init(tv, td, dnp, pbuf, bp, zb, 0);
+
+	error = __traverse_visitbp(tv);
+
+	kmem_free(tv, sizeof(traverse_visitbp_data_t) *
+	    TRAVERSE_VISITBP_MAX_DEPTH);
+
+	return (error);
 }
 
 static int
@@ -356,24 +435,28 @@ static int
 traverse_impl(spa_t *spa, dsl_dataset_t *ds, blkptr_t *rootbp,
     uint64_t txg_start, int flags, blkptr_cb_t func, void *arg)
 {
-	traverse_data_t td;
-	prefetch_data_t pd = { 0 };
-	zbookmark_t czb;
+	traverse_data_t *td;
+	prefetch_data_t *pd;
+	zbookmark_t *czb;
 	int err;
 
-	td.td_spa = spa;
-	td.td_objset = ds ? ds->ds_object : 0;
-	td.td_rootbp = rootbp;
-	td.td_min_txg = txg_start;
-	td.td_func = func;
-	td.td_arg = arg;
-	td.td_pfd = &pd;
-	td.td_flags = flags;
+	td = kmem_alloc(sizeof(traverse_data_t), KM_SLEEP);
+	pd = kmem_zalloc(sizeof(prefetch_data_t), KM_SLEEP);
+	czb = kmem_alloc(sizeof(zbookmark_t), KM_SLEEP);
+
+	td->td_spa = spa;
+	td->td_objset = ds ? ds->ds_object : 0;
+	td->td_rootbp = rootbp;
+	td->td_min_txg = txg_start;
+	td->td_func = func;
+	td->td_arg = arg;
+	td->td_pfd = pd;
+	td->td_flags = flags;
 
-	pd.pd_blks_max = zfs_pd_blks_max;
-	pd.pd_flags = flags;
-	mutex_init(&pd.pd_mtx, NULL, MUTEX_DEFAULT, NULL);
-	cv_init(&pd.pd_cv, NULL, CV_DEFAULT, NULL);
+	pd->pd_blks_max = zfs_pd_blks_max;
+	pd->pd_flags = flags;
+	mutex_init(&pd->pd_mtx, NULL, MUTEX_DEFAULT, NULL);
+	cv_init(&pd->pd_cv, NULL, CV_DEFAULT, NULL);
 
 	/* See comment on ZIL traversal in dsl_scan_visitds. */
 	if (ds != NULL && !dsl_dataset_is_snapshot(ds)) {
@@ -383,27 +466,31 @@ traverse_impl(spa_t *spa, dsl_dataset_t *ds, blkptr_t *rootbp,
 		if (err)
 			return (err);
 
-		traverse_zil(&td, &os->os_zil_header);
+		traverse_zil(td, &os->os_zil_header);
 	}
 
 	if (!(flags & TRAVERSE_PREFETCH) ||
 	    0 == taskq_dispatch(system_taskq, traverse_prefetch_thread,
-	    &td, TQ_NOQUEUE))
-		pd.pd_exited = B_TRUE;
+	    td, TQ_NOQUEUE))
+		pd->pd_exited = B_TRUE;
 
-	SET_BOOKMARK(&czb, td.td_objset,
+	SET_BOOKMARK(czb, td->td_objset,
 	    ZB_ROOT_OBJECT, ZB_ROOT_LEVEL, ZB_ROOT_BLKID);
-	err = traverse_visitbp(&td, NULL, NULL, rootbp, &czb);
+	err = traverse_visitbp(td, NULL, NULL, rootbp, czb);
+
+	mutex_enter(&pd->pd_mtx);
+	pd->pd_cancel = B_TRUE;
+	cv_broadcast(&pd->pd_cv);
+	while (!pd->pd_exited)
+		cv_wait(&pd->pd_cv, &pd->pd_mtx);
+	mutex_exit(&pd->pd_mtx);
 
-	mutex_enter(&pd.pd_mtx);
-	pd.pd_cancel = B_TRUE;
-	cv_broadcast(&pd.pd_cv);
-	while (!pd.pd_exited)
-		cv_wait(&pd.pd_cv, &pd.pd_mtx);
-	mutex_exit(&pd.pd_mtx);
+	mutex_destroy(&pd->pd_mtx);
+	cv_destroy(&pd->pd_cv);
 
-	mutex_destroy(&pd.pd_mtx);
-	cv_destroy(&pd.pd_cv);
+	kmem_free(czb, sizeof(zbookmark_t));
+	kmem_free(pd, sizeof(struct prefetch_data));
+	kmem_free(td, sizeof(struct traverse_data));
 
 	return (err);
 }
@@ -480,3 +567,8 @@ traverse_pool(spa_t *spa, uint64_t txg_start, int flags,
 		err = 0;
 	return (err != 0 ? err : lasterr);
 }
+
+#if defined(_KERNEL) && defined(HAVE_SPL)
+EXPORT_SYMBOL(traverse_dataset);
+EXPORT_SYMBOL(traverse_pool);
+#endif