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Message-ID: <20231003130635.hn2ljuorlf7rdodx@quack3>
Date: Tue, 3 Oct 2023 15:06:35 +0200
From: Jan Kara <jack@...e.cz>
To: Hugh Dickins <hughd@...gle.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
Christian Brauner <brauner@...nel.org>,
Carlos Maiolino <cem@...nel.org>,
Chuck Lever <chuck.lever@...cle.com>, Jan Kara <jack@...e.cz>,
Matthew Wilcox <willy@...radead.org>,
Johannes Weiner <hannes@...xchg.org>,
Axel Rasmussen <axelrasmussen@...gle.com>,
linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-mm@...ck.org
Subject: Re: [PATCH 1/8] shmem: shrink shmem_inode_info: dir_offsets in a
union
On Fri 29-09-23 20:25:38, Hugh Dickins wrote:
> Shave 32 bytes off (the 64-bit) shmem_inode_info. There was a 4-byte
> pahole after stop_eviction, better filled by fsflags. And the 24-byte
> dir_offsets can only be used by directories, whereas shrinklist and
> swaplist only by shmem_mapping() inodes (regular files or long symlinks):
> so put those into a union. No change in mm/shmem.c is required for this.
>
> Signed-off-by: Hugh Dickins <hughd@...gle.com>
Looks good to me. Feel free to add:
Reviewed-by: Jan Kara <jack@...e.cz>
Honza
> ---
> include/linux/shmem_fs.h | 16 ++++++++++------
> 1 file changed, 10 insertions(+), 6 deletions(-)
>
> diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h
> index 6b0c626620f5..2caa6b86106a 100644
> --- a/include/linux/shmem_fs.h
> +++ b/include/linux/shmem_fs.h
> @@ -23,18 +23,22 @@ struct shmem_inode_info {
> unsigned long flags;
> unsigned long alloced; /* data pages alloced to file */
> unsigned long swapped; /* subtotal assigned to swap */
> - pgoff_t fallocend; /* highest fallocate endindex */
> - struct list_head shrinklist; /* shrinkable hpage inodes */
> - struct list_head swaplist; /* chain of maybes on swap */
> + union {
> + struct offset_ctx dir_offsets; /* stable directory offsets */
> + struct {
> + struct list_head shrinklist; /* shrinkable hpage inodes */
> + struct list_head swaplist; /* chain of maybes on swap */
> + };
> + };
> + struct timespec64 i_crtime; /* file creation time */
> struct shared_policy policy; /* NUMA memory alloc policy */
> struct simple_xattrs xattrs; /* list of xattrs */
> + pgoff_t fallocend; /* highest fallocate endindex */
> + unsigned int fsflags; /* for FS_IOC_[SG]ETFLAGS */
> atomic_t stop_eviction; /* hold when working on inode */
> - struct timespec64 i_crtime; /* file creation time */
> - unsigned int fsflags; /* flags for FS_IOC_[SG]ETFLAGS */
> #ifdef CONFIG_TMPFS_QUOTA
> struct dquot *i_dquot[MAXQUOTAS];
> #endif
> - struct offset_ctx dir_offsets; /* stable entry offsets */
> struct inode vfs_inode;
> };
>
> --
> 2.35.3
>
--
Jan Kara <jack@...e.com>
SUSE Labs, CR
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