svn commit: r328444 - head/sys/kern

[Kirk McKusick]

Author: mckusick
Date: Fri Jan 26 18:17:11 2018
New Revision: 328444
URL: https://svnweb.freebsd.org/changeset/base/328444

Log:
  For many years the message "fsync: giving up on dirty" has occationally
  appeared on UFS/FFS filesystems. In some cases it was promptly followed
  by a panic of "softdep_deallocate_dependencies: dangling deps". This fix
  should eliminate both of these occurences.
  
  Submitted by: Andreas Longwitz <longwitz at incore.de>
  Reviewed by:  kib
  Tested by:    Peter Holm (pho)
  PR:           225423
  MFC after:    1 week

Modified:
  head/sys/kern/vfs_default.c

Modified: head/sys/kern/vfs_default.c
==============================================================================
--- head/sys/kern/vfs_default.c	Fri Jan 26 17:56:20 2018	(r328443)
+++ head/sys/kern/vfs_default.c	Fri Jan 26 18:17:11 2018	(r328444)
@@ -631,13 +631,21 @@ vop_stdfsync(ap)
 		struct thread *a_td;
 	} */ *ap;
 {
-	struct vnode *vp = ap->a_vp;
-	struct buf *bp;
+	struct vnode *vp;
+	struct buf *bp, *nbp;
 	struct bufobj *bo;
-	struct buf *nbp;
-	int error = 0;
-	int maxretry = 1000;     /* large, arbitrarily chosen */
+	struct mount *mp;
+	int error, maxretry;
 
+	error = 0;
+	maxretry = 10000;     /* large, arbitrarily chosen */
+	vp = ap->a_vp;
+	mp = NULL;
+	if (vp->v_type == VCHR) {
+		VI_LOCK(vp);
+		mp = vp->v_rdev->si_mountpt;
+		VI_UNLOCK(vp);
+	}
 	bo = &vp->v_bufobj;
 	BO_LOCK(bo);
 loop1:
@@ -680,6 +688,8 @@ loop2:
 			bremfree(bp);
 			bawrite(bp);
 		}
+		if (maxretry < 1000)
+			pause("dirty", hz < 1000 ? 1 : hz / 1000);
 		BO_LOCK(bo);
 		goto loop2;
 	}
@@ -701,7 +711,8 @@ loop2:
 			TAILQ_FOREACH(bp, &bo->bo_dirty.bv_hd, b_bobufs)
 				if ((error = bp->b_error) != 0)
 					break;
-			if (error == 0 && --maxretry >= 0)
+			if ((mp != NULL && mp->mnt_secondary_writes > 0) ||
+			    (error == 0 && --maxretry >= 0))
 				goto loop1;
 			error = EAGAIN;
 		}