Author: kib
Date: Sat Jun 17 17:10:50 2017
New Revision: 320057
URL: https://svnweb.freebsd.org/changeset/base/320057
Log:
MFC r319539:
Mitigate several problems with the softdep_request_cleanup() on busy
host.
Approved by: re (gjb)
Modified:
stable/11/sys/ufs/ffs/ffs_softdep.c
stable/11/sys/ufs/ffs/softdep.h
Directory Properties:
stable/11/ (props changed)
Modified: stable/11/sys/ufs/ffs/ffs_softdep.c
==============================================================================
--- stable/11/sys/ufs/ffs/ffs_softdep.c Sat Jun 17 14:46:14 2017
(r320056)
+++ stable/11/sys/ufs/ffs/ffs_softdep.c Sat Jun 17 17:10:50 2017
(r320057)
@@ -901,6 +901,7 @@ static int pagedep_find(struct pagedep_hashhead *, ino
struct pagedep **);
static void pause_timer(void *);
static int request_cleanup(struct mount *, int);
+static int softdep_request_cleanup_flush(struct mount *, struct ufsmount *);
static void schedule_cleanup(struct mount *);
static void softdep_ast_cleanup_proc(struct thread *);
static int process_worklist_item(struct mount *, int, int);
@@ -13266,10 +13267,9 @@ softdep_request_cleanup(fs, vp, cred, resource)
{
struct ufsmount *ump;
struct mount *mp;
- struct vnode *lvp, *mvp;
long starttime;
ufs2_daddr_t needed;
- int error;
+ int error, failed_vnode;
/*
* If we are being called because of a process doing a
@@ -13360,41 +13360,88 @@ retry:
* to the worklist that we can then process to reap addition
* resources. We walk the vnodes associated with the mount point
* until we get the needed worklist requests that we can reap.
+ *
+ * If there are several threads all needing to clean the same
+ * mount point, only one is allowed to walk the mount list.
+ * When several threads all try to walk the same mount list,
+ * they end up competing with each other and often end up in
+ * livelock. This approach ensures that forward progress is
+ * made at the cost of occational ENOSPC errors being returned
+ * that might otherwise have been avoided.
*/
+ error = 1;
if ((resource == FLUSH_BLOCKS_WAIT &&
fs->fs_cstotal.cs_nbfree <= needed) ||
(resource == FLUSH_INODES_WAIT && fs->fs_pendinginodes > 0 &&
fs->fs_cstotal.cs_nifree <= needed)) {
- MNT_VNODE_FOREACH_ALL(lvp, mp, mvp) {
- if (TAILQ_FIRST(&lvp->v_bufobj.bo_dirty.bv_hd) == 0) {
- VI_UNLOCK(lvp);
- continue;
+ ACQUIRE_LOCK(ump);
+ if ((ump->um_softdep->sd_flags & FLUSH_RC_ACTIVE) == 0) {
+ ump->um_softdep->sd_flags |= FLUSH_RC_ACTIVE;
+ FREE_LOCK(ump);
+ failed_vnode = softdep_request_cleanup_flush(mp, ump);
+ ACQUIRE_LOCK(ump);
+ ump->um_softdep->sd_flags &= ~FLUSH_RC_ACTIVE;
+ FREE_LOCK(ump);
+ if (ump->softdep_on_worklist > 0) {
+ stat_cleanup_retries += 1;
+ if (!failed_vnode)
+ goto retry;
}
- if (vget(lvp, LK_EXCLUSIVE | LK_INTERLOCK | LK_NOWAIT,
- curthread))
- continue;
- if (lvp->v_vflag & VV_NOSYNC) { /* unlinked */
- vput(lvp);
- continue;
- }
- (void) ffs_syncvnode(lvp, MNT_NOWAIT, 0);
- vput(lvp);
+ } else {
+ FREE_LOCK(ump);
+ error = 0;
}
- lvp = ump->um_devvp;
- if (vn_lock(lvp, LK_EXCLUSIVE | LK_NOWAIT) == 0) {
- VOP_FSYNC(lvp, MNT_NOWAIT, curthread);
- VOP_UNLOCK(lvp, 0);
- }
- if (ump->softdep_on_worklist > 0) {
- stat_cleanup_retries += 1;
- goto retry;
- }
stat_cleanup_failures += 1;
}
if (time_second - starttime > stat_cleanup_high_delay)
stat_cleanup_high_delay = time_second - starttime;
UFS_LOCK(ump);
- return (1);
+ return (error);
+}
+
+/*
+ * Scan the vnodes for the specified mount point flushing out any
+ * vnodes that can be locked without waiting. Finally, try to flush
+ * the device associated with the mount point if it can be locked
+ * without waiting.
+ *
+ * We return 0 if we were able to lock every vnode in our scan.
+ * If we had to skip one or more vnodes, we return 1.
+ */
+static int
+softdep_request_cleanup_flush(mp, ump)
+ struct mount *mp;
+ struct ufsmount *ump;
+{
+ struct thread *td;
+ struct vnode *lvp, *mvp;
+ int failed_vnode;
+
+ failed_vnode = 0;
+ td = curthread;
+ MNT_VNODE_FOREACH_ALL(lvp, mp, mvp) {
+ if (TAILQ_FIRST(&lvp->v_bufobj.bo_dirty.bv_hd) == 0) {
+ VI_UNLOCK(lvp);
+ continue;
+ }
+ if (vget(lvp, LK_EXCLUSIVE | LK_INTERLOCK | LK_NOWAIT,
+ td) != 0) {
+ failed_vnode = 1;
+ continue;
+ }
+ if (lvp->v_vflag & VV_NOSYNC) { /* unlinked */
+ vput(lvp);
+ continue;
+ }
+ (void) ffs_syncvnode(lvp, MNT_NOWAIT, 0);
+ vput(lvp);
+ }
+ lvp = ump->um_devvp;
+ if (vn_lock(lvp, LK_EXCLUSIVE | LK_NOWAIT) == 0) {
+ VOP_FSYNC(lvp, MNT_NOWAIT, td);
+ VOP_UNLOCK(lvp, 0);
+ }
+ return (failed_vnode);
}
static bool
Modified: stable/11/sys/ufs/ffs/softdep.h
==============================================================================
--- stable/11/sys/ufs/ffs/softdep.h Sat Jun 17 14:46:14 2017
(r320056)
+++ stable/11/sys/ufs/ffs/softdep.h Sat Jun 17 17:10:50 2017
(r320057)
@@ -1065,6 +1065,7 @@ struct mount_softdeps {
#define FLUSH_EXIT 0x0001 /* time to exit */
#define FLUSH_CLEANUP 0x0002 /* need to clear out softdep structures */
#define FLUSH_STARTING 0x0004 /* flush thread not yet started */
+#define FLUSH_RC_ACTIVE 0x0008 /* a thread is flushing the mount point
*/
/*
* Keep the old names from when these were in the ufsmount structure.
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