One fix for raid5 discard issue.

-----BEGIN PGP SIGNATURE-----
 Version: GnuPG v2.0.22 (GNU/Linux)
 
 iQIVAwUAVC40bznsnt1WYoG5AQJs0w//T8Z3vBhXwC3SjREbH42x8pWxFXgzhUdW
 WGKwYYwHFQfL05rP3eg+X+Sh+X3s3E3/+lFzDVE/JGjBdSG/A5X+j5jRH6ENl16u
 32wQjZwKliYxSiUPWbbPzl0BDi3nyhpR1CMsgTWpU6qkMuGy2npNZFK/cQIy4/Je
 ygXLwncKPfAVszaMrx9oBeghpwTnJR3Se1RAYhxc4qQLm+jXfUTQ9Ool3J2InZo3
 st7weyuvPrtr+Em65ta0j/VIOzTP5dIallq+LSL5e0lhn5Pc99XBaM60lEzH9mwP
 t8ZDuV6HL8rXktCOwNtkmEQeW/7uOpmwKG0yt6nPFKghsclJvbyrtxOWKnOrPAd8
 0rvUAX7EXX/OQyEjguhJQ1ZK9E4HxglGay7trVyXeLdK3kOUaVjAlG/5y8FrEusU
 K/uOnHwIiCDxTZ86imTcRcXxOG5eWVscsWwVFIHf2IN4J1NKJ7rQB6LP4WEKzHGE
 y3CgSy/c7yyuksMlYZE9q1GRc5i8pI5tGg3tV2S2uvgjuNIw6dkAF1UjW5Mpgy3x
 OFue/SxsYWuBeSqMANuJQDeCOLttwSZV/Ho3Kac+nA7l0LTXkVIYFj0bSGIIUxjI
 scF+r04u35/jib0QALdeTw9FB46V5GYZ7d0bd/lEMxe24dsPreCKiI/xDvpr5NQn
 8flYcaBK+PI=
 =Qyea
 -----END PGP SIGNATURE-----

Merge tag 'md/3.17-final-fix' of git://neil.brown.name/md

Pull raid5 discard fix from Neil Brown:
 "One fix for raid5 discard issue"

* tag 'md/3.17-final-fix' of git://neil.brown.name/md:
  md/raid5: disable 'DISCARD' by default due to safety concerns.
This commit is contained in:
Linus Torvalds 2014-10-03 08:40:37 -07:00
commit ee042ec880
1 changed files with 17 additions and 1 deletions

View File

@ -64,6 +64,10 @@
#define cpu_to_group(cpu) cpu_to_node(cpu)
#define ANY_GROUP NUMA_NO_NODE
static bool devices_handle_discard_safely = false;
module_param(devices_handle_discard_safely, bool, 0644);
MODULE_PARM_DESC(devices_handle_discard_safely,
"Set to Y if all devices in each array reliably return zeroes on reads from discarded regions");
static struct workqueue_struct *raid5_wq;
/*
* Stripe cache
@ -6208,7 +6212,7 @@ static int run(struct mddev *mddev)
mddev->queue->limits.discard_granularity = stripe;
/*
* unaligned part of discard request will be ignored, so can't
* guarantee discard_zerors_data
* guarantee discard_zeroes_data
*/
mddev->queue->limits.discard_zeroes_data = 0;
@ -6233,6 +6237,18 @@ static int run(struct mddev *mddev)
!bdev_get_queue(rdev->bdev)->
limits.discard_zeroes_data)
discard_supported = false;
/* Unfortunately, discard_zeroes_data is not currently
* a guarantee - just a hint. So we only allow DISCARD
* if the sysadmin has confirmed that only safe devices
* are in use by setting a module parameter.
*/
if (!devices_handle_discard_safely) {
if (discard_supported) {
pr_info("md/raid456: discard support disabled due to uncertainty.\n");
pr_info("Set raid456.devices_handle_discard_safely=Y to override.\n");
}
discard_supported = false;
}
}
if (discard_supported &&