svn commit: r216793 - head/sys/dev/md

[Konstantin Belousov]

Author: kib
Date: Wed Dec 29 11:39:15 2010
New Revision: 216793
URL: http://svn.freebsd.org/changeset/base/216793

Log:
  Add sysctl vm.md_malloc_wait, non-zero value of which switches malloc-backed
  md(4) to using M_WAITOK malloc calls.
  
  M_NOWAITOK allocations may fail when enough memory could be freed, but not
  immediately. E.g. SU UFS becomes quite unhappy when metadata write return
  error, that would happen for failed malloc() call.
  
  Reported and tested by:	pho
  MFC after:	1 week

Modified:
  head/sys/dev/md/md.c

Modified: head/sys/dev/md/md.c
==============================================================================
--- head/sys/dev/md/md.c	Wed Dec 29 11:19:39 2010	(r216792)
+++ head/sys/dev/md/md.c	Wed Dec 29 11:39:15 2010	(r216793)
@@ -103,6 +103,8 @@ static MALLOC_DEFINE(M_MDSECT, "md_secto
 
 static int md_debug;
 SYSCTL_INT(_debug, OID_AUTO, mddebug, CTLFLAG_RW, &md_debug, 0, "");
+static int md_malloc_wait;
+SYSCTL_INT(_vm, OID_AUTO, md_malloc_wait, CTLFLAG_RW, &md_malloc_wait, 0, "");
 
 #if defined(MD_ROOT) && defined(MD_ROOT_SIZE)
 /*
@@ -208,11 +210,12 @@ new_indir(u_int shift)
 {
 	struct indir *ip;
 
-	ip = malloc(sizeof *ip, M_MD, M_NOWAIT | M_ZERO);
+	ip = malloc(sizeof *ip, M_MD, (md_malloc_wait ? M_WAITOK : M_NOWAIT)
+	    | M_ZERO);
 	if (ip == NULL)
 		return (NULL);
 	ip->array = malloc(sizeof(uintptr_t) * NINDIR,
-	    M_MDSECT, M_NOWAIT | M_ZERO);
+	    M_MDSECT, (md_malloc_wait ? M_WAITOK : M_NOWAIT) | M_ZERO);
 	if (ip->array == NULL) {
 		free(ip, M_MD);
 		return (NULL);
@@ -456,6 +459,7 @@ mdstart_malloc(struct md_s *sc, struct b
 			} else {
 				if (osp <= 255) {
 					sp = (uintptr_t)uma_zalloc(sc->uma,
+					    md_malloc_wait ? M_WAITOK :
 					    M_NOWAIT);
 					if (sp == 0) {
 						error = ENOSPC;
@@ -850,7 +854,8 @@ mdcreate_malloc(struct md_s *sc, struct 
 
 		nsectors = sc->mediasize / sc->sectorsize;
 		for (u = 0; u < nsectors; u++) {
-			sp = (uintptr_t)uma_zalloc(sc->uma, M_NOWAIT | M_ZERO);
+			sp = (uintptr_t)uma_zalloc(sc->uma, md_malloc_wait ?
+			    M_WAITOK : M_NOWAIT | M_ZERO);
 			if (sp != 0)
 				error = s_write(sc->indir, u, sp);
 			else