* [PATCH] fs: pack fields `i_state` and `i_fsnotify_mask`
@ 2026-11-11 15:36 Max Kellermann
2026-11-12 18:36 ` Jan Kara
0 siblings, 1 reply; 2+ messages in thread
From: Max Kellermann @ 2026-11-11 15:36 UTC (permalink / raw)
To: Alexander Viro, Christian Brauner, Jan Kara
Cc: Max Kellermann, linux-fsdevel, linux-kernel
Both were 32 bit fields followed by a 32 bit hole. This reduces size
of `struct inode` by 8 bytes.
Signed-off-by: Max Kellermann <max.kellermann@ionos.com>
---
include/linux/fs.h | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 5b3a100aba77..9ab028dabc1b 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -813,7 +813,11 @@ struct inode {
/* Misc */
struct inode_state_flags i_state;
- /* 32-bit hole */
+
+#ifdef CONFIG_FSNOTIFY
+ __u32 i_fsnotify_mask; /* all events this inode cares about */
+#endif
+
struct rw_semaphore i_rwsem;
/* Timestamp for writeback list ordering and age checks (jiffies). */
@@ -865,8 +869,6 @@ struct inode {
#ifdef CONFIG_FSNOTIFY
- __u32 i_fsnotify_mask; /* all events this inode cares about */
- /* 32-bit hole reserved for expanding i_fsnotify_mask */
struct fsnotify_mark_connector __rcu *i_fsnotify_marks;
#endif
--
2.53.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] fs: pack fields `i_state` and `i_fsnotify_mask`
2026-11-11 15:36 [PATCH] fs: pack fields `i_state` and `i_fsnotify_mask` Max Kellermann
@ 2026-11-12 18:36 ` Jan Kara
0 siblings, 0 replies; 2+ messages in thread
From: Jan Kara @ 2026-11-12 18:36 UTC (permalink / raw)
To: Max Kellermann
Cc: Alexander Viro, Christian Brauner, Jan Kara, linux-fsdevel,
linux-kernel
On Wed 11-11-26 16:36:30, Max Kellermann wrote:
> Both were 32 bit fields followed by a 32 bit hole. This reduces size
> of `struct inode` by 8 bytes.
>
> Signed-off-by: Max Kellermann <max.kellermann@ionos.com>
When moving i_fsnotify_mask please move it along with i_fsnotify_marks. It
should better be in the same cacheline because these two are accessed on
some performance sensitive paths.
Honza
> ---
> include/linux/fs.h | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 5b3a100aba77..9ab028dabc1b 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -813,7 +813,11 @@ struct inode {
>
> /* Misc */
> struct inode_state_flags i_state;
> - /* 32-bit hole */
> +
> +#ifdef CONFIG_FSNOTIFY
> + __u32 i_fsnotify_mask; /* all events this inode cares about */
> +#endif
> +
> struct rw_semaphore i_rwsem;
>
> /* Timestamp for writeback list ordering and age checks (jiffies). */
> @@ -865,8 +869,6 @@ struct inode {
>
>
> #ifdef CONFIG_FSNOTIFY
> - __u32 i_fsnotify_mask; /* all events this inode cares about */
> - /* 32-bit hole reserved for expanding i_fsnotify_mask */
> struct fsnotify_mark_connector __rcu *i_fsnotify_marks;
> #endif
>
> --
> 2.53.0
>
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
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