Author: smh
Date: Sun May 4 14:05:14 2014
New Revision: 265321
URL: http://svnweb.freebsd.org/changeset/base/265321
Log:
Use a zio flag to prevent recursion of vdev_queue_io_done which can
cause stack overflow for IO's which return ZIO_PIPELINE_CONTINUE
from the zio_vdev_io_start stage and hence don't suspend and complete
in a different thread.
This prevents double fault panic on slow machines running ZFS on
GELI volumes which return EOPNOTSUPP directly to BIO_DELETE requests.
MFC after: 1 month
X-MFC-With: r265152
Modified:
head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/zio.h
head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_queue.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 Sun May
4 12:32:37 2014 (r265320)
+++ head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/zio.h Sun May
4 14:05:14 2014 (r265321)
@@ -196,6 +196,7 @@ enum zio_flag {
ZIO_FLAG_NOPWRITE = 1 << 25,
ZIO_FLAG_REEXECUTED = 1 << 26,
ZIO_FLAG_DELEGATED = 1 << 27,
+ ZIO_FLAG_QUEUE_IO_DONE = 1 << 28,
};
#define ZIO_FLAG_MUSTSUCCEED 0
Modified: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_queue.c
==============================================================================
--- head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_queue.c Sun May
4 12:32:37 2014 (r265320)
+++ head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_queue.c Sun May
4 14:05:14 2014 (r265321)
@@ -796,14 +796,25 @@ vdev_queue_io_done(zio_t *zio)
vq->vq_io_complete_ts = gethrtime();
+ if (zio->io_flags & ZIO_FLAG_QUEUE_IO_DONE) {
+ /*
+ * Executing from a previous vdev_queue_io_done so
+ * to avoid recursion we just unlock and return.
+ */
+ mutex_exit(&vq->vq_lock);
+ return;
+ }
+
while ((nio = vdev_queue_io_to_issue(vq)) != NULL) {
mutex_exit(&vq->vq_lock);
+ nio->io_flags |= ZIO_FLAG_QUEUE_IO_DONE;
if (nio->io_done == vdev_queue_agg_io_done) {
zio_nowait(nio);
} else {
zio_vdev_io_reissue(nio);
zio_execute(nio);
}
+ nio->io_flags &= ~ZIO_FLAG_QUEUE_IO_DONE;
mutex_enter(&vq->vq_lock);
}
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