[049/227] fs: introduce alloc_inode_sb() to allocate filesystems specific inode

Commit Message

Andrew Morton March 22, 2022, 9:41 p.m. UTC

From: Muchun Song <[e-mail]>
Subject: fs: introduce alloc_inode_sb() to allocate filesystems specific inode

The allocated inode cache is supposed to be added to its memcg list_lru
which should be allocated as well in advance.  That can be done by
kmem_cache_alloc_lru() which allocates object and list_lru.  The file
systems is main user of it.  So introduce alloc_inode_sb() to allocate
file system specific inodes and set up the inode reclaim context properly.
The file system is supposed to use alloc_inode_sb() to allocate inodes. 
In the later patches, we will convert all users to the new API.

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Muchun Song <[e-mail]>
Reviewed-by: Roman Gushchin <[e-mail]>
Cc: Alex Shi <[e-mail]>
Cc: Anna Schumaker <[e-mail]>
Cc: Chao Yu <[e-mail]>
Cc: Dave Chinner <[e-mail]>
Cc: Fam Zheng <[e-mail]>
Cc: Jaegeuk Kim <[e-mail]>
Cc: Johannes Weiner <[e-mail]>
Cc: Kari Argillander <[e-mail]>
Cc: Matthew Wilcox (Oracle) <[e-mail]>
Cc: Michal Hocko <[e-mail]>
Cc: Qi Zheng <[e-mail]>
Cc: Shakeel Butt <[e-mail]>
Cc: Theodore Ts'o <[e-mail]>
Cc: Trond Myklebust <[e-mail]>
Cc: Vladimir Davydov <[e-mail]>
Cc: Vlastimil Babka <[e-mail]>
Cc: Wei Yang <[e-mail]>
Cc: Xiongchun Duan <[e-mail]>
Cc: Yang Shi <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
---

 Documentation/filesystems/porting.rst |    6 ++++++
 fs/inode.c                            |    2 +-
 include/linux/fs.h                    |   11 +++++++++++
 3 files changed, 18 insertions(+), 1 deletion(-)

Patch

--- a/Documentation/filesystems/porting.rst~fs-introduce-alloc_inode_sb-to-allocate-filesystems-specific-inode
+++ a/Documentation/filesystems/porting.rst
@@ -45,6 +45,12 @@  typically between calling iget_locked()
 
 At some point that will become mandatory.
 
+**mandatory**
+
+The foo_inode_info should always be allocated through alloc_inode_sb() rather
+than kmem_cache_alloc() or kmalloc() related to set up the inode reclaim context
+correctly.
+
 ---
 
 **mandatory**
--- a/fs/inode.c~fs-introduce-alloc_inode_sb-to-allocate-filesystems-specific-inode
+++ a/fs/inode.c
@@ -259,7 +259,7 @@  static struct inode *alloc_inode(struct
 	if (ops->alloc_inode)
 		inode = ops->alloc_inode(sb);
 	else
-		inode = kmem_cache_alloc(inode_cachep, GFP_KERNEL);
+		inode = alloc_inode_sb(sb, inode_cachep, GFP_KERNEL);
 
 	if (!inode)
 		return NULL;
--- a/include/linux/fs.h~fs-introduce-alloc_inode_sb-to-allocate-filesystems-specific-inode
+++ a/include/linux/fs.h
@@ -42,6 +42,7 @@ 
 #include <linux/mount.h>
 #include <linux/cred.h>
 #include <linux/mnt_idmapping.h>
+#include <linux/slab.h>
 
 #include <asm/byteorder.h>
 #include <uapi/linux/fs.h>
@@ -3114,6 +3115,16 @@  extern void free_inode_nonrcu(struct ino
 extern int should_remove_suid(struct dentry *);
 extern int file_remove_privs(struct file *);
 
+/*
+ * This must be used for allocating filesystems specific inodes to set
+ * up the inode reclaim context correctly.
+ */
+static inline void *
+alloc_inode_sb(struct super_block *sb, struct kmem_cache *cache, gfp_t gfp)
+{
+	return kmem_cache_alloc_lru(cache, &sb->s_inode_lru, gfp);
+}
+
 extern void __insert_inode_hash(struct inode *, unsigned long hashval);
 static inline void insert_inode_hash(struct inode *inode)
 {