[PATCH v2 89/89] fs: move i_generation into new hole created after timestamp conversion

From: Jeff Layton <jlayton@kernel.org>
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Subject: [PATCH v2 89/89] fs: move i_generation into new hole created after timestamp conversion
Date: Wed,  4 Oct 2023 14:55:30 -0400	[thread overview]
Message-ID: <20231004185530.82088-3-jlayton@kernel.org> (raw)
In-Reply-To: <20231004185530.82088-1-jlayton@kernel.org>

The recent change to use discrete integers instead of struct timespec64
shaved 8 bytes off of struct inode, but it also moves the i_lock
into the previous cacheline, away from the fields that it protects.

Move i_generation above the i_lock, which moves the new 4 byte hole to
just after the i_fsnotify_mask in my setup.

Suggested-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
---
 include/linux/fs.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 485b5e21c8e5..686c9f33e725 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -677,6 +677,7 @@ struct inode {
 	u32			i_atime_nsec;
 	u32			i_mtime_nsec;
 	u32			i_ctime_nsec;
+	u32			i_generation;
 	spinlock_t		i_lock;	/* i_blocks, i_bytes, maybe i_size */
 	unsigned short          i_bytes;
 	u8			i_blkbits;
@@ -733,7 +734,6 @@ struct inode {
 		unsigned		i_dir_seq;
 	};
 
-	__u32			i_generation;
 
 #ifdef CONFIG_FSNOTIFY
 	__u32			i_fsnotify_mask; /* all events this inode cares about */
-- 
2.41.0

