Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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.
+17
-1
+17
-1
drivers/md/raid5.c
+17
-1
drivers/md/raid5.c
···
64
64
#define cpu_to_group(cpu) cpu_to_node(cpu)
65
65
#define ANY_GROUP NUMA_NO_NODE
66
66
67
+
static bool devices_handle_discard_safely = false;
68
+
module_param(devices_handle_discard_safely, bool, 0644);
69
+
MODULE_PARM_DESC(devices_handle_discard_safely,
70
+
"Set to Y if all devices in each array reliably return zeroes on reads from discarded regions");
67
71
static struct workqueue_struct *raid5_wq;
68
72
/*
69
73
* Stripe cache
···
6212
6208
mddev->queue->limits.discard_granularity = stripe;
6213
6209
/*
6214
6210
* unaligned part of discard request will be ignored, so can't
6215
-
* guarantee discard_zerors_data
6211
+
* guarantee discard_zeroes_data
6216
6212
*/
6217
6213
mddev->queue->limits.discard_zeroes_data = 0;
6218
6214
···
6237
6233
!bdev_get_queue(rdev->bdev)->
6238
6234
limits.discard_zeroes_data)
6239
6235
discard_supported = false;
6236
+
/* Unfortunately, discard_zeroes_data is not currently
6237
+
* a guarantee - just a hint. So we only allow DISCARD
6238
+
* if the sysadmin has confirmed that only safe devices
6239
+
* are in use by setting a module parameter.
6240
+
*/
6241
+
if (!devices_handle_discard_safely) {
6242
+
if (discard_supported) {
6243
+
pr_info("md/raid456: discard support disabled due to uncertainty.\n");
6244
+
pr_info("Set raid456.devices_handle_discard_safely=Y to override.\n");
6245
+
}
6246
+
discard_supported = false;
6247
+
}
6240
6248
}
6241
6249
6242
6250
if (discard_supported &&