If there is no saved write cache policy for a JBOD, we
would like the write cache policy to default to write back
for the best performance. However, we currently have code
in check_current_config that reads the current write
cache policy and saves it in the ipr_dev struct. Then iprinit
calls ipr_get_dev_attr which sets the write_cache_policy attribute
in the local ipr_disk_attr structure, we call ipr_modify_dev_attr,
which looks for a saved write cache policy and we don't find one,
then we change the cache policy to write back. Then we call
ipr_set_dev_attr, see that the now current write cache setting
does not match what the attribute was after calling ipr_get_dev_attr
earlier, and then ends up reverting the cache policy back to
what it was originally, which is write through.
To fix this we do a few things:
1. Removing this write_cache_policy field in the ipr_dev struct.
2. Remove the special code in init_gpdd_dev to set the write cache policy
and move it into ipr_set_dev_attr.
3. Enhance ipr_modify_dev_attr to set write_cache_policy to the default
value of write back if there is no saved write cache policy.
Signed-off-by: Brian King <brk...@linux.vnet.ibm.com>
---
iprlib.c | 39 ++++++++++++++++++---------------------
iprlib.h | 1 -
2 files changed, 18 insertions(+), 22 deletions(-)
diff -puN iprlib.h~iprutils_fix_wcache_policy iprlib.h
--- iprutils.patches/iprlib.h~iprutils_fix_wcache_policy 2017-06-09
16:21:23.225725484 -0500
+++ iprutils.patches-bjking1/iprlib.h 2017-06-09 16:21:34.568667807 -0500
@@ -1483,7 +1483,6 @@ struct ipr_dev {
u8 active_suspend;
u32 is_suspend_cand:1;
u32 is_resume_cand:1;
- u8 write_cache_policy:1;
u8 supports_4k:1;
u8 supports_5xx:1;
u8 read_c7:1;
diff -puN iprlib.c~iprutils_fix_wcache_policy iprlib.c
--- iprutils.patches/iprlib.c~iprutils_fix_wcache_policy 2017-06-09
16:21:38.594647336 -0500
+++ iprutils.patches-bjking1/iprlib.c 2017-06-09 20:20:17.013028680 -0500
@@ -3593,6 +3593,7 @@ static int ipr_set_dev_wcache_policy (co
char *cache_type;
char current_type[100];
+ memset(current_type, 0, sizeof(current_type));
sprintf(path, "/sys/class/scsi_disk/%s",
dev->scsi_dev_data->sysfs_device_name);
@@ -6646,15 +6647,6 @@ void check_current_config(bool allow_reb
strcpy(ioa->dev[device_count].gen_name,
scsi_dev_data->gen_name);
- if (scsi_dev_data->type == TYPE_DISK) {
- if
(ipr_dev_wcache_policy(&(ioa->dev[device_count])) == IPR_DEV_CACHE_WRITE_BACK)
-
ioa->dev[device_count].write_cache_policy =
-
IPR_DEV_CACHE_WRITE_BACK;
- else
-
ioa->dev[device_count].write_cache_policy =
-
IPR_DEV_CACHE_WRITE_THROUGH;
- }
-
/* find array config data matching resource
entry */
k = 0;
for_each_qac_entry(common_record, qac_data) {
@@ -7487,7 +7479,13 @@ int ipr_get_dev_attr(struct ipr_dev *dev
attr->tcq_enabled = is_tagged(dev);
attr->format_timeout = get_format_timeout(dev);
- attr->write_cache_policy = dev->write_cache_policy;
+
+ if (ipr_is_gscsi(dev) || ipr_is_volume_set(dev)) {
+ if (ipr_dev_wcache_policy(dev) == IPR_DEV_CACHE_WRITE_BACK)
+ attr->write_cache_policy = IPR_DEV_CACHE_WRITE_BACK;
+ else
+ attr->write_cache_policy = IPR_DEV_CACHE_WRITE_THROUGH;
+ }
return 0;
}
@@ -7655,6 +7653,8 @@ int ipr_modify_dev_attr(struct ipr_dev *
rc = ipr_get_saved_dev_attr(dev, IPR_WRITE_CACHE_POLICY, temp);
if (rc == RC_SUCCESS)
sscanf(temp, "%d", &attr->write_cache_policy);
+ else
+ attr->write_cache_policy = IPR_DEV_CACHE_WRITE_BACK;
return 0;
}
@@ -7738,12 +7738,14 @@ int ipr_set_dev_attr(struct ipr_dev *dev
}
}
- if (attr->write_cache_policy != old_attr.write_cache_policy
- || !attr->write_cache_policy) {
- ipr_set_dev_wcache_policy(dev, attr->write_cache_policy);
- if (save) {
- sprintf(temp, "%d", attr->write_cache_policy);
- ipr_save_dev_attr(dev, IPR_WRITE_CACHE_POLICY, temp, 1);
+ if (ipr_is_gscsi(dev) || ipr_is_volume_set(dev)) {
+ if (attr->write_cache_policy != old_attr.write_cache_policy
+ || !attr->write_cache_policy) {
+ ipr_set_dev_wcache_policy(dev,
attr->write_cache_policy);
+ if (save) {
+ sprintf(temp, "%d", attr->write_cache_policy);
+ ipr_save_dev_attr(dev, IPR_WRITE_CACHE_POLICY,
temp, 1);
+ }
}
}
@@ -9723,11 +9725,6 @@ static void init_gpdd_dev(struct ipr_dev
if (ipr_modify_dev_attr(dev, &attr))
return;
- rc = ipr_get_saved_dev_attr(dev, IPR_WRITE_CACHE_POLICY, saved_cache);
- policy = (rc || strtoul (saved_cache, NULL, 10)) ?
- IPR_DEV_CACHE_WRITE_BACK : IPR_DEV_CACHE_WRITE_THROUGH;
- ipr_set_dev_wcache_policy(dev, policy);
-
if (ipr_set_dev_attr(dev, &attr, 0))
return;
}
_
------------------------------------------------------------------------------
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot
_______________________________________________
Iprdd-devel mailing list
Iprdd-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/iprdd-devel
