According to phk@, VOP_STRATEGY should never, _ever_, return

anything other than 0.  Make it so.  This fixes
"panic: VOP_STRATEGY failed bp=0xc320dd90 vp=0xc3b9f648",
encountered when writing to an orphaned filesystem.  Reason
for the panic was the following assert:
KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp));
at vfs_bio:bufstrategy().

Reviewed by:	scottl, phk
Approved by:	rwatson (mentor)
Sponsored by:	FreeBSD Foundation

share/man/man9/VOP_STRATEGY.9

@@ -53,7 +53,9 @@ This call either reads or writes data from a file, depending on the value of
 .Pp
 The call may block.
 .Sh RETURN VALUES
-Zero is returned on success, otherwise an error is returned.
+Always zero.
+Errors should be signalled by setting BIO_ERROR on b_ioflags field in struct buf,
+and setting b_error to the appropriate errno value.
 .Sh SEE ALSO
 .\" .Xr buf 9 ,
 .Xr vnode 9

sys/fs/hpfs/hpfs_vnops.c

@@ -661,7 +661,7 @@ hpfs_strategy(ap)
 			bp->b_error = error;
 			bp->b_ioflags |= BIO_ERROR;
 			bufdone(bp);
-			return (error);
+			return (0);
 		}
 		if ((long)bp->b_blkno == -1)
 			vfs_bio_clrbuf(bp);

sys/fs/msdosfs/msdosfs_vnops.c

@@ -1880,7 +1880,7 @@ msdosfs_strategy(ap)
 			bp->b_error = error;
 			bp->b_ioflags |= BIO_ERROR;
 			bufdone(bp);
-			return (error);
+			return (0);
 		}
 		if ((long)bp->b_blkno == -1)
 			vfs_bio_clrbuf(bp);

sys/fs/ntfs/ntfs_vnops.c

@@ -339,7 +339,7 @@ ntfs_strategy(ap)
 		}
 	}
 	bufdone(bp);
-	return (error);
+	return (0);
 }
 
 static int

sys/fs/nwfs/nwfs_vnops.c

@@ -804,7 +804,7 @@ static int nwfs_strategy (ap)
 	 */
 	if ((bp->b_flags & B_ASYNC) == 0 )
 		error = nwfs_doio(ap->a_vp, bp, cr, td);
-	return (error);
+	return (0);
 }
 
 

sys/fs/smbfs/smbfs_vnops.c

@@ -864,7 +864,7 @@ smbfs_strategy (ap)
 
 	if ((bp->b_flags & B_ASYNC) == 0 )
 		error = smbfs_doio(ap->a_vp, bp, cr, td);
-	return error;
+	return (0);
 }
 
 int

sys/gnu/fs/ext2fs/ext2_vnops.c

@@ -1399,7 +1399,7 @@ ext2_strategy(ap)
 			bp->b_error = error;
 			bp->b_ioflags |= BIO_ERROR;
 			bufdone(bp);
-			return (error);
+			return (0);
 		}
 		if ((long)bp->b_blkno == -1)
 			vfs_bio_clrbuf(bp);

sys/gnu/fs/reiserfs/reiserfs_vnops.c

@@ -350,8 +350,13 @@ reiserfs_strategy(struct vop_strategy_args /* {
 		bp->b_ioflags |= BIO_ERROR;
 	}
 
+	if (error) {
+		bp->b_ioflags |= BIO_ERROR;
+		bp->b_error = error;
+	}
+
 	bufdone(bp);
-	return (error);
+	return (0);
 }
 
 /*

sys/gnu/fs/xfs/FreeBSD/xfs_vnops.c

@@ -1136,7 +1136,7 @@ _xfs_strategy(
 			bp->b_error = error;
 			bp->b_ioflags |= BIO_ERROR;
 			bufdone(bp);
-			return (error);
+			return (0);
 		}
 		if ((long)bp->b_blkno == -1)
 			vfs_bio_clrbuf(bp);

sys/ufs/ufs/ufs_vnops.c

@@ -2013,7 +2013,7 @@ ufs_strategy(ap)
 			bp->b_error = error;
 			bp->b_ioflags |= BIO_ERROR;
 			bufdone(bp);
-			return (error);
+			return (0);
 		}
 		if ((long)bp->b_blkno == -1)
 			vfs_bio_clrbuf(bp);