vfs: remove SLAB_MEM_SPREAD flag usage

The SLAB_MEM_SPREAD flag used to be implemented in SLAB, which was
removed as of v6.8-rc1 (see [1]), so it became a dead flag since the
commit 16a1d96 ("mm/slab: remove mm/slab.c and slab_def.h"). And
the series[1] went on to mark it obsolete explicitly to avoid confusion
for users. Here we can just remove all its users, which has no any
functional change.

Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
Link: https://lore.kernel.org/all/20240223-slab-cleanup-flags-v2-1-02f1753e8303@suse.cz [1]
Link: https://lore.kernel.org/r/20240224135315.830477-1-chengming.zhou@linux.dev
Signed-off-by: Christian Brauner <brauner@kernel.org>

Author: Chengming Zhou

fs/buffer.c

@@ -3122,7 +3122,7 @@ void __init buffer_init(void)
 	int ret;
 
 	bh_cachep = KMEM_CACHE(buffer_head,
-				SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|SLAB_MEM_SPREAD);
+				SLAB_RECLAIM_ACCOUNT|SLAB_PANIC);
 	/*
 	 * Limit the bh occupancy to 10% of ZONE_NORMAL
 	 */

fs/dcache.c

@@ -3136,7 +3136,7 @@ static void __init dcache_init(void)
 	 * of the dcache.
 	 */
 	dentry_cache = KMEM_CACHE_USERCOPY(dentry,
-		SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|SLAB_MEM_SPREAD|SLAB_ACCOUNT,
+		SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|SLAB_ACCOUNT,
 		d_iname);
 
 	/* Hash may have been set up in dcache_init_early */

fs/inode.c

@@ -2286,7 +2286,7 @@ void __init inode_init(void)
 					 sizeof(struct inode),
 					 0,
 					 (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|
-					 SLAB_MEM_SPREAD|SLAB_ACCOUNT),
+					 SLAB_ACCOUNT),
 					 init_once);
 
 	/* Hash may have been set up in inode_init_early */

fs/mbcache.c

@@ -426,8 +426,7 @@ EXPORT_SYMBOL(mb_cache_destroy);
 
 static int __init mbcache_init(void)
 {
-	mb_entry_cache = KMEM_CACHE(mb_cache_entry,
-					 SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD);
+	mb_entry_cache = KMEM_CACHE(mb_cache_entry, SLAB_RECLAIM_ACCOUNT);
 	if (!mb_entry_cache)
 		return -ENOMEM;
 	return 0;