svn commit: r192704 - user/kmacy/releng_7_2_fcs/sys/cddl/contrib/opensolaris/uts/common/fs/zfs

[Kip Macy]

Author: kmacy
Date: Sun May 24 23:24:49 2009
New Revision: 192704
URL: http://svn.freebsd.org/changeset/base/192704

Log:
  don't block I/O progress waiting for a pre-fetch stream
  if we find a matching stream but can't get the lock skip the prefetch

Modified:
  user/kmacy/releng_7_2_fcs/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dmu_zfetch.c

Modified: user/kmacy/releng_7_2_fcs/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dmu_zfetch.c
==============================================================================
--- user/kmacy/releng_7_2_fcs/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dmu_zfetch.c	Sun May 24 22:17:59 2009	(r192703)
+++ user/kmacy/releng_7_2_fcs/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dmu_zfetch.c	Sun May 24 23:24:49 2009	(r192704)
@@ -50,11 +50,11 @@ uint64_t	zfetch_array_rd_sz = 1024 * 102
 
 SYSCTL_DECL(_vfs_zfs);
 TUNABLE_INT("vfs.zfs.prefetch_disable", &zfs_prefetch_disable);
-SYSCTL_INT(_vfs_zfs, OID_AUTO, prefetch_disable, CTLFLAG_RDTUN,
+SYSCTL_INT(_vfs_zfs, OID_AUTO, prefetch_disable, CTLFLAG_RW,
     &zfs_prefetch_disable, 0, "Disable prefetch");
 SYSCTL_NODE(_vfs_zfs, OID_AUTO, zfetch, CTLFLAG_RW, 0, "ZFS ZFETCH");
 TUNABLE_INT("vfs.zfs.zfetch.max_streams", &zfetch_max_streams);
-SYSCTL_UINT(_vfs_zfs_zfetch, OID_AUTO, max_streams, CTLFLAG_RDTUN,
+SYSCTL_UINT(_vfs_zfs_zfetch, OID_AUTO, max_streams, CTLFLAG_RW,
     &zfetch_max_streams, 0, "Max # of streams per zfetch");
 TUNABLE_INT("vfs.zfs.zfetch.min_sec_reap", &zfetch_min_sec_reap);
 SYSCTL_UINT(_vfs_zfs_zfetch, OID_AUTO, min_sec_reap, CTLFLAG_RDTUN,
@@ -339,8 +339,10 @@ top:
 
 			reset = !prefetched && zs->zst_len > 1;
 
-			mutex_enter(&zs->zst_lock);
-
+			if (mutex_tryenter(&zs->zst_lock) == 0) {
+				rc = 1;
+				goto out;
+			}
 			if (zh->zst_offset != zs->zst_offset + zs->zst_len) {
 				mutex_exit(&zs->zst_lock);
 				goto top;
@@ -364,8 +366,10 @@ top:
 
 			reset = !prefetched && zs->zst_len > 1;
 
-			mutex_enter(&zs->zst_lock);
-
+			if (mutex_tryenter(&zs->zst_lock) == 0) {
+				rc = 1;
+				goto out;
+			}
 			if (zh->zst_offset != zs->zst_offset - zh->zst_len) {
 				mutex_exit(&zs->zst_lock);
 				goto top;
@@ -392,8 +396,10 @@ top:
 		    zs->zst_len) && (zs->zst_len != zs->zst_stride)) {
 			/* strided forward access */
 
-			mutex_enter(&zs->zst_lock);
-
+			if (mutex_tryenter(&zs->zst_lock) == 0) {
+				rc = 1;
+				goto out;
+			}
 			if ((zh->zst_offset - zs->zst_offset - zs->zst_stride >=
 			    zs->zst_len) || (zs->zst_len == zs->zst_stride)) {
 				mutex_exit(&zs->zst_lock);
@@ -409,8 +415,10 @@ top:
 		    zs->zst_len) && (zs->zst_len != zs->zst_stride)) {
 			/* strided reverse access */
 
-			mutex_enter(&zs->zst_lock);
-
+			if (mutex_tryenter(&zs->zst_lock) == 0) {
+				rc = 1;
+				goto out;
+			}
 			if ((zh->zst_offset - zs->zst_offset + zs->zst_stride >=
 			    zs->zst_len) || (zs->zst_len == zs->zst_stride)) {
 				mutex_exit(&zs->zst_lock);