+ shmem-shrink-shmem_inode_info-dir_offsets-in-a-union.patch added to mm-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: shmem: shrink shmem_inode_info: dir_offsets in a union
has been added to the -mm mm-unstable branch.  Its filename is
     shmem-shrink-shmem_inode_info-dir_offsets-in-a-union.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/shmem-shrink-shmem_inode_info-dir_offsets-in-a-union.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Hugh Dickins <hughd@google.com>
Subject: shmem: shrink shmem_inode_info: dir_offsets in a union
Date: Fri, 29 Sep 2023 20:25:38 -0700 (PDT)

Patch series "shmem,tmpfs: general maintenance".

Mostly just cosmetic mods in mm/shmem.c, but the last two enforcing the
"size=" limit better.  8/8 goes into percpu counter territory, and could
stand alone.


This patch (of 8):

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.

Link: https://lkml.kernel.org/r/c7441dc6-f3bb-dd60-c670-9f5cbd9f266@google.com
Link: https://lkml.kernel.org/r/86ebb4b-c571-b9e8-27f5-cb82ec50357e@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Carlos Maiolino <cem@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Darrick J. Wong <djwong@kernel.org>
Cc: Dave Chinner <dchinner@redhat.com>
Cc: Tim Chen <tim.c.chen@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/linux/shmem_fs.h |   16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

--- a/include/linux/shmem_fs.h~shmem-shrink-shmem_inode_info-dir_offsets-in-a-union
+++ a/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;
 };
 
_

Patches currently in -mm which might be from hughd@google.com are

shmem-shrink-shmem_inode_info-dir_offsets-in-a-union.patch
shmem-remove-vma-arg-from-shmem_get_folio_gfp.patch
shmem-factor-shmem_falloc_wait-out-of-shmem_fault.patch
shmem-trivial-tidyups-removing-extra-blank-lines-etc.patch
shmem-shmem_acct_blocks-and-shmem_inode_acct_blocks.patch
shmem-move-memcg-charge-out-of-shmem_add_to_page_cache.patch
shmem-_add_to_page_cache-before-shmem_inode_acct_blocks.patch
shmempercpu_counter-add-_limited_addfbc-limit-amount.patch