From 5e405595e5bf4c09fab9ca1e7dbe5b62872757b5 Mon Sep 17 00:00:00 2001
From: Dan Williams <dan.j.williams@intel.com>
Date: Thu, 24 Aug 2017 16:42:48 -0700
Subject: ext4: perform dax_device lookup at mount

The ->iomap_begin() operation is a hot path, so cache the
fs_dax_get_by_host() result at mount time to avoid the incurring the
hash lookup overhead on a per-i/o basis.

Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Reviewed-by: Jan Kara <jack@suse.cz>
Reported-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 fs/ext4/ext4.h | 1 +
 1 file changed, 1 insertion(+)

(limited to 'fs/ext4/ext4.h')

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index a2bb7d2870e4..194e622dc3dd 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1528,6 +1528,7 @@ struct ext4_sb_info {
 
 	/* Barrier between changing inodes' journal flags and writepages ops. */
 	struct percpu_rw_semaphore s_journal_flag_rwsem;
+	struct dax_device *s_daxdev;
 };
 
 static inline struct ext4_sb_info *EXT4_SB(struct super_block *sb)
-- 
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