Author: avg
Date: Wed Jun 28 13:59:20 2017
New Revision: 320452
URL: https://svnweb.freebsd.org/changeset/base/320452
Log:
fix an architectural problem introduced in r320156, ZFS ABD import
The implementation of ZFS refcount_t uses the emulated illumos mutex
(the sx lock) and the waiting memory allocation when ZFS_DEBUG is
enabled. This makes refcount_t unsuitable for use in GEOM g_up
thread where sleeping is prohibited.
When importing the ABD change I modified vdev_geom using illumos
vdev_disk as an example. As a result, I added a call to abd_return_buf
in vdev_geom_io_intr. The latter is called on g_up thread while the
former uses refcount_t.
This change fixes the problem by deferring the abd_return_buf call to
the previously unused vdev_geom_io_done that is called on a ZFS zio
taskqueue thread where sleeping is allowed.
A side bonus of this change is that now a vdev zio has a pointer
to its corresponding bio while the zio is active.
Reported by: Shawn Webb <shawn.w...@hardenedbsd.org>
Tested by: Shawn Webb <shawn.w...@hardenedbsd.org>
MFC after: 1 week
X-MFC with: r320156
Modified:
head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/zio.h
head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_geom.c
Modified: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/zio.h
==============================================================================
--- head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/zio.h Wed Jun
28 13:56:15 2017 (r320451)
+++ head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/zio.h Wed Jun
28 13:59:20 2017 (r320452)
@@ -453,6 +453,10 @@ struct zio {
avl_node_t io_alloc_node;
zio_alloc_list_t io_alloc_list;
+#ifdef __FreeBSD__
+ struct bio *io_bio;
+#endif
+
/* Internal pipeline state */
enum zio_flag io_flags;
enum zio_stage io_stage;
Modified: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_geom.c
==============================================================================
--- head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_geom.c Wed Jun
28 13:56:15 2017 (r320451)
+++ head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_geom.c Wed Jun
28 13:59:20 2017 (r320452)
@@ -989,13 +989,6 @@ vdev_geom_io_intr(struct bio *bp)
break;
}
- if (zio->io_type == ZIO_TYPE_READ) {
- abd_return_buf_copy(zio->io_abd, bp->bio_data, zio->io_size);
- } else if (zio->io_type == ZIO_TYPE_WRITE) {
- abd_return_buf(zio->io_abd, bp->bio_data, zio->io_size);
- }
-
- g_destroy_bio(bp);
zio_delay_interrupt(zio);
}
@@ -1087,6 +1080,7 @@ sendreq:
break;
}
bp->bio_done = vdev_geom_io_intr;
+ zio->io_bio = bp;
g_io_request(bp, cp);
}
@@ -1094,6 +1088,15 @@ sendreq:
static void
vdev_geom_io_done(zio_t *zio)
{
+ struct bio *bp = zio->io_bio;
+
+ if (zio->io_type == ZIO_TYPE_READ) {
+ abd_return_buf_copy(zio->io_abd, bp->bio_data, zio->io_size);
+ } else if (zio->io_type == ZIO_TYPE_WRITE) {
+ abd_return_buf(zio->io_abd, bp->bio_data, zio->io_size);
+ }
+
+ g_destroy_bio(bp);
}
static void
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