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From:   Andiry Xu <jix024@eng.ucsd.edu>
To:     linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-nvdimm@lists.01.org
Cc:     dan.j.williams@intel.com, andy.rudoff@intel.com,
        coughlan@redhat.com, swanson@cs.ucsd.edu, david@fromorbit.com,
        jack@suse.com, swhiteho@redhat.com, miklos@szeredi.hu,
        andiry.xu@gmail.com, Andiry Xu <jix024@cs.ucsd.edu>
Subject: [RFC v2 69/83] Super: Add module param inplace_data_updates.
Date:   Sat, 10 Mar 2018 10:18:50 -0800
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From: Andiry Xu <jix024@cs.ucsd.edu>

Provide inplace data updates option if people prefer inplace
updates to copy-on-write.

Signed-off-by: Andiry Xu <jix024@cs.ucsd.edu>
---
 fs/nova/nova.h  | 1 +
 fs/nova/super.c | 7 ++++++-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/fs/nova/nova.h b/fs/nova/nova.h
index 1c2205e..6c94a9b 100644
--- a/fs/nova/nova.h
+++ b/fs/nova/nova.h
@@ -138,6 +138,7 @@ extern unsigned int nova_dbgmask;
 
 
 extern int measure_timing;
+extern int inplace_data_updates;
 
 
 extern unsigned int blk_type_to_shift[NOVA_BLOCK_TYPE_MAX];
diff --git a/fs/nova/super.c b/fs/nova/super.c
index 9710be8..980b1d7 100644
--- a/fs/nova/super.c
+++ b/fs/nova/super.c
@@ -43,10 +43,14 @@
 
 int measure_timing;
 int support_clwb;
+int inplace_data_updates;
 
 module_param(measure_timing, int, 0444);
 MODULE_PARM_DESC(measure_timing, "Timing measurement");
 
+module_param(inplace_data_updates, int, 0444);
+MODULE_PARM_DESC(inplace_data_updates, "Perform data updates in-place (i.e., not atomically)");
+
 module_param(nova_dbgmask, int, 0444);
 MODULE_PARM_DESC(nova_dbgmask, "Control debugging output");
 
@@ -541,7 +545,8 @@ static int nova_fill_super(struct super_block *sb, void *data, int silent)
 		goto out;
 	}
 
-	nova_dbg("measure timing %d\n", measure_timing);
+	nova_dbg("measure timing %d, inplace data update %d\n",
+			measure_timing, inplace_data_updates);
 
 	get_random_bytes(&random, sizeof(u32));
 	atomic_set(&sbi->next_generation, random);
-- 
2.7.4