Add FAILFAST support

ZFS works best when it is notified as soon as possible when a device
failure occurs.  This allows it to immediately start any recovery
actions which may be needed.  In theory Linux supports a flag which
can be set on bio's called FAILFAST which provides this quick
notification by disabling the retry logic in the lower scsi layers.

That's the theory at least.  In practice is turns out that while the
flag exists you oddly have to set it with the BIO_RW_AHEAD flag.
And even when it's set it you may get retries in the low level
drivers decides that's the right behavior, or if you don't get the
right error codes reported to the scsi midlayer.

Unfortunately, without additional kernels patchs there's not much
which can be done to improve this.  Basically, this just means that
it may take 2-3 minutes before a ZFS is notified properly that a
device has failed.  This can be improved and I suspect I'll be
submitting patches upstream to handle this.

8 files changed, 8 insertions, 0 deletions

diff --git a/lib/libspl/include/Makefile.in b/lib/libspl/include/Makefile.in
index ec0dd912c..1a0a7f8b1 100644
--- a/lib/libspl/include/Makefile.in
+++ b/lib/libspl/include/Makefile.in
@@ -44,6 +44,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bdev-logical-size.m4 \
 	$(top_srcdir)/config/kernel-bio-empty-barrier.m4 \
 	$(top_srcdir)/config/kernel-bio-end-io-t-args.m4 \
+	$(top_srcdir)/config/kernel-bio-failfast.m4 \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
diff --git a/lib/libspl/include/ia32/Makefile.in b/lib/libspl/include/ia32/Makefile.in
index 4c39db696..4b97ee1b4 100644
--- a/lib/libspl/include/ia32/Makefile.in
+++ b/lib/libspl/include/ia32/Makefile.in
@@ -42,6 +42,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bdev-logical-size.m4 \
 	$(top_srcdir)/config/kernel-bio-empty-barrier.m4 \
 	$(top_srcdir)/config/kernel-bio-end-io-t-args.m4 \
+	$(top_srcdir)/config/kernel-bio-failfast.m4 \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
diff --git a/lib/libspl/include/ia32/sys/Makefile.in b/lib/libspl/include/ia32/sys/Makefile.in
index 2cf46c908..1b2fb35ee 100644
--- a/lib/libspl/include/ia32/sys/Makefile.in
+++ b/lib/libspl/include/ia32/sys/Makefile.in
@@ -44,6 +44,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bdev-logical-size.m4 \
 	$(top_srcdir)/config/kernel-bio-empty-barrier.m4 \
 	$(top_srcdir)/config/kernel-bio-end-io-t-args.m4 \
+	$(top_srcdir)/config/kernel-bio-failfast.m4 \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
diff --git a/lib/libspl/include/rpc/Makefile.in b/lib/libspl/include/rpc/Makefile.in
index 5c946ee67..f5385d9d1 100644
--- a/lib/libspl/include/rpc/Makefile.in
+++ b/lib/libspl/include/rpc/Makefile.in
@@ -44,6 +44,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bdev-logical-size.m4 \
 	$(top_srcdir)/config/kernel-bio-empty-barrier.m4 \
 	$(top_srcdir)/config/kernel-bio-end-io-t-args.m4 \
+	$(top_srcdir)/config/kernel-bio-failfast.m4 \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
diff --git a/lib/libspl/include/sys/Makefile.in b/lib/libspl/include/sys/Makefile.in
index 28fa39110..cb930aacf 100644
--- a/lib/libspl/include/sys/Makefile.in
+++ b/lib/libspl/include/sys/Makefile.in
@@ -44,6 +44,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bdev-logical-size.m4 \
 	$(top_srcdir)/config/kernel-bio-empty-barrier.m4 \
 	$(top_srcdir)/config/kernel-bio-end-io-t-args.m4 \
+	$(top_srcdir)/config/kernel-bio-failfast.m4 \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
diff --git a/lib/libspl/include/sys/dktp/Makefile.in b/lib/libspl/include/sys/dktp/Makefile.in
index 02b107e99..713aa88b6 100644
--- a/lib/libspl/include/sys/dktp/Makefile.in
+++ b/lib/libspl/include/sys/dktp/Makefile.in
@@ -44,6 +44,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bdev-logical-size.m4 \
 	$(top_srcdir)/config/kernel-bio-empty-barrier.m4 \
 	$(top_srcdir)/config/kernel-bio-end-io-t-args.m4 \
+	$(top_srcdir)/config/kernel-bio-failfast.m4 \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
diff --git a/lib/libspl/include/sys/sysevent/Makefile.in b/lib/libspl/include/sys/sysevent/Makefile.in
index 71cb626ed..858e38877 100644
--- a/lib/libspl/include/sys/sysevent/Makefile.in
+++ b/lib/libspl/include/sys/sysevent/Makefile.in
@@ -44,6 +44,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bdev-logical-size.m4 \
 	$(top_srcdir)/config/kernel-bio-empty-barrier.m4 \
 	$(top_srcdir)/config/kernel-bio-end-io-t-args.m4 \
+	$(top_srcdir)/config/kernel-bio-failfast.m4 \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
diff --git a/lib/libspl/include/util/Makefile.in b/lib/libspl/include/util/Makefile.in
index 07cdb7835..1cdbb5740 100644
--- a/lib/libspl/include/util/Makefile.in
+++ b/lib/libspl/include/util/Makefile.in
@@ -44,6 +44,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bdev-logical-size.m4 \
 	$(top_srcdir)/config/kernel-bio-empty-barrier.m4 \
 	$(top_srcdir)/config/kernel-bio-end-io-t-args.m4 \
+	$(top_srcdir)/config/kernel-bio-failfast.m4 \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \