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Add FAILFAST support

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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.
This commit is contained in:
Brian Behlendorf
2010-10-01 10:57:56 -07:00
parent c5343ba71b
commit 2959d94a0a
49 changed files with 241 additions and 10 deletions
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configure
Vendored
+136
View File
@@ -12613,6 +12613,74 @@ fi
{ $as_echo "$as_me:$LINENO: checking whether BIO_RW_FAILFAST_* are defined" >&5
$as_echo_n "checking whether BIO_RW_FAILFAST_* are defined... " >&6; }
cat confdefs.h - <<_ACEOF >conftest.c
/* confdefs.h. */
_ACEOF
cat confdefs.h >>conftest.$ac_ext
cat >>conftest.$ac_ext <<_ACEOF
/* end confdefs.h. */
#include <linux/bio.h>
int
main (void)
{
int flags;
flags = ((1 << BIO_RW_FAILFAST_DEV) |
(1 << BIO_RW_FAILFAST_TRANSPORT) |
(1 << BIO_RW_FAILFAST_DRIVER));
;
return 0;
}
_ACEOF
rm -Rf build && mkdir -p build
echo "obj-m := conftest.o" >build/Makefile
if { ac_try='cp conftest.c build && make modules -C $LINUX_OBJ EXTRA_CFLAGS="-Werror-implicit-function-declaration $EXTRA_KCFLAGS" $ARCH_UM M=$PWD/build'
{ (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
(eval $ac_try) 2>&5
ac_status=$?
$as_echo "$as_me:$LINENO: \$? = $ac_status" >&5
(exit $ac_status); }; } >/dev/null && { ac_try='test -s build/conftest.o'
{ (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
(eval $ac_try) 2>&5
ac_status=$?
$as_echo "$as_me:$LINENO: \$? = $ac_status" >&5
(exit $ac_status); }; }; then
{ $as_echo "$as_me:$LINENO: result: yes" >&5
$as_echo "yes" >&6; }
cat >>confdefs.h <<\_ACEOF
#define HAVE_BIO_RW_FAILFAST 1
_ACEOF
else
$as_echo "$as_me: failed program was:" >&5
sed 's/^/| /' conftest.$ac_ext >&5
{ $as_echo "$as_me:$LINENO: result: no" >&5
$as_echo "no" >&6; }
fi
rm -Rf build
{ $as_echo "$as_me:$LINENO: checking whether bio_end_io_t wants 2 args" >&5
$as_echo_n "checking whether bio_end_io_t wants 2 args... " >&6; }
tmp_flags="$EXTRA_KCFLAGS"
@@ -15616,6 +15684,74 @@ fi
{ $as_echo "$as_me:$LINENO: checking whether BIO_RW_FAILFAST_* are defined" >&5
$as_echo_n "checking whether BIO_RW_FAILFAST_* are defined... " >&6; }
cat confdefs.h - <<_ACEOF >conftest.c
/* confdefs.h. */
_ACEOF
cat confdefs.h >>conftest.$ac_ext
cat >>conftest.$ac_ext <<_ACEOF
/* end confdefs.h. */
#include <linux/bio.h>
int
main (void)
{
int flags;
flags = ((1 << BIO_RW_FAILFAST_DEV) |
(1 << BIO_RW_FAILFAST_TRANSPORT) |
(1 << BIO_RW_FAILFAST_DRIVER));
;
return 0;
}
_ACEOF
rm -Rf build && mkdir -p build
echo "obj-m := conftest.o" >build/Makefile
if { ac_try='cp conftest.c build && make modules -C $LINUX_OBJ EXTRA_CFLAGS="-Werror-implicit-function-declaration $EXTRA_KCFLAGS" $ARCH_UM M=$PWD/build'
{ (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
(eval $ac_try) 2>&5
ac_status=$?
$as_echo "$as_me:$LINENO: \$? = $ac_status" >&5
(exit $ac_status); }; } >/dev/null && { ac_try='test -s build/conftest.o'
{ (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
(eval $ac_try) 2>&5
ac_status=$?
$as_echo "$as_me:$LINENO: \$? = $ac_status" >&5
(exit $ac_status); }; }; then
{ $as_echo "$as_me:$LINENO: result: yes" >&5
$as_echo "yes" >&6; }
cat >>confdefs.h <<\_ACEOF
#define HAVE_BIO_RW_FAILFAST 1
_ACEOF
else
$as_echo "$as_me: failed program was:" >&5
sed 's/^/| /' conftest.$ac_ext >&5
{ $as_echo "$as_me:$LINENO: result: no" >&5
$as_echo "no" >&6; }
fi
rm -Rf build
{ $as_echo "$as_me:$LINENO: checking whether bio_end_io_t wants 2 args" >&5
$as_echo_n "checking whether bio_end_io_t wants 2 args... " >&6; }
tmp_flags="$EXTRA_KCFLAGS"