ext4: each filesystem creates and uses its own mb_cache

This patch adds new interfaces to create and destory cache,
ext4_xattr_create_cache() and ext4_xattr_destroy_cache(), and remove
the cache creation and destory calls from ex4_init_xattr() and
ext4_exitxattr() in fs/ext4/xattr.c.

fs/ext4/super.c has been changed so that when a filesystem is mounted
a cache is allocated and attched to its ext4_sb_info structure.

fs/mbcache.c has been changed so that only one slab allocator is
allocated and used by all mbcache structures.

Signed-off-by: T. Makphaibulchoke <[e-mail]>

fs/ext4/ext4.h

···
 	struct list_head s_es_lru;
 	unsigned long s_es_last_sorted;
 	struct percpu_counter s_extent_cache_cnt;
+	struct mb_cache *s_mb_cache;
 	spinlock_t s_es_lru_lock ____cacheline_aligned_in_smp;
 
 	/* Ratelimit ext4 messages. */

fs/ext4/super.c

···
 static struct ext4_lazy_init *ext4_li_info;
 static struct mutex ext4_li_mtx;
 static struct ext4_features *ext4_feat;
+static int ext4_mballoc_ready;
 
 static int ext4_load_journal(struct super_block *, struct ext4_super_block *,
 			     unsigned long journal_devnum);
···
 		sync_blockdev(sbi->journal_bdev);
 		invalidate_bdev(sbi->journal_bdev);
 		ext4_blkdev_remove(sbi);
+	}
+	if (sbi->s_mb_cache) {
+		ext4_xattr_destroy_cache(sbi->s_mb_cache);
+		sbi->s_mb_cache = NULL;
 	}
 	if (sbi->s_mmp_tsk)
 		kthread_stop(sbi->s_mmp_tsk);
···
 	percpu_counter_set(&sbi->s_dirtyclusters_counter, 0);
 
 no_journal:
+	if (ext4_mballoc_ready) {
+		sbi->s_mb_cache = ext4_xattr_create_cache(sb->s_id);
+		if (!sbi->s_mb_cache) {
+			ext4_msg(sb, KERN_ERR, "Failed to create an mb_cache");
+			goto failed_mount_wq;
+		}
+	}
+
 	/*
 	 * Get the # of file system overhead blocks from the
 	 * superblock if present.
···
 
 	err = ext4_init_mballoc();
 	if (err)
-		goto out3;
-
-	err = ext4_init_xattr();
-	if (err)
 		goto out2;
+	else
+		ext4_mballoc_ready = 1;
 	err = init_inodecache();
 	if (err)
 		goto out1;
···
 	unregister_as_ext3();
 	destroy_inodecache();
 out1:
-	ext4_exit_xattr();
-out2:
+	ext4_mballoc_ready = 0;
 	ext4_exit_mballoc();
-out3:
+out2:
 	ext4_exit_feat_adverts();
 out4:
 	if (ext4_proc_root)
···
 	unregister_as_ext3();
 	unregister_filesystem(&ext4_fs_type);
 	destroy_inodecache();
-	ext4_exit_xattr();
 	ext4_exit_mballoc();
 	ext4_exit_feat_adverts();
 	remove_proc_entry("fs/ext4", NULL);

fs/ext4/xattr.c

···
 # define ea_bdebug(bh, fmt, ...)	no_printk(fmt, ##__VA_ARGS__)
 #endif
 
-static void ext4_xattr_cache_insert(struct buffer_head *);
+static void ext4_xattr_cache_insert(struct mb_cache *, struct buffer_head *);
 static struct buffer_head *ext4_xattr_cache_find(struct inode *,
 						 struct ext4_xattr_header *,
 						 struct mb_cache_entry **);
···
 			      struct ext4_xattr_entry *);
 static int ext4_xattr_list(struct dentry *dentry, char *buffer,
 			   size_t buffer_size);
-
-static struct mb_cache *ext4_xattr_cache;
 
 static const struct xattr_handler *ext4_xattr_handler_map[] = {
 	[EXT4_XATTR_INDEX_USER]		     = &ext4_xattr_user_handler,
···
 #endif
 	NULL
 };
+
+#define EXT4_GET_MB_CACHE(inode)	(((struct ext4_sb_info *) \
+				inode->i_sb->s_fs_info)->s_mb_cache)
 
 static __le32 ext4_xattr_block_csum(struct inode *inode,
 				    sector_t block_nr,
···
 	struct ext4_xattr_entry *entry;
 	size_t size;
 	int error;
+	struct mb_cache *ext4_mb_cache = EXT4_GET_MB_CACHE(inode);
 
 	ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld",
 		  name_index, name, buffer, (long)buffer_size);
···
 		error = -EIO;
 		goto cleanup;
 	}
-	ext4_xattr_cache_insert(bh);
+	ext4_xattr_cache_insert(ext4_mb_cache, bh);
 	entry = BFIRST(bh);
 	error = ext4_xattr_find_entry(&entry, name_index, name, bh->b_size, 1);
 	if (error == -EIO)
···
 	struct inode *inode = dentry->d_inode;
 	struct buffer_head *bh = NULL;
 	int error;
+	struct mb_cache *ext4_mb_cache = EXT4_GET_MB_CACHE(inode);
 
 	ea_idebug(inode, "buffer=%p, buffer_size=%ld",
 		  buffer, (long)buffer_size);
···
 		error = -EIO;
 		goto cleanup;
 	}
-	ext4_xattr_cache_insert(bh);
+	ext4_xattr_cache_insert(ext4_mb_cache, bh);
 	error = ext4_xattr_list_entries(dentry, BFIRST(bh), buffer, buffer_size);
 
 cleanup:
···
 {
 	struct mb_cache_entry *ce = NULL;
 	int error = 0;
+	struct mb_cache *ext4_mb_cache = EXT4_GET_MB_CACHE(inode);
 
-	ce = mb_cache_entry_get(ext4_xattr_cache, bh->b_bdev, bh->b_blocknr);
+	ce = mb_cache_entry_get(ext4_mb_cache, bh->b_bdev, bh->b_blocknr);
 	error = ext4_journal_get_write_access(handle, bh);
 	if (error)
 		goto out;
···
 	struct ext4_xattr_search *s = &bs->s;
 	struct mb_cache_entry *ce = NULL;
 	int error = 0;
+	struct mb_cache *ext4_mb_cache = EXT4_GET_MB_CACHE(inode);
 
 #define header(x) ((struct ext4_xattr_header *)(x))
 
 	if (i->value && i->value_len > sb->s_blocksize)
 		return -ENOSPC;
 	if (s->base) {
-		ce = mb_cache_entry_get(ext4_xattr_cache, bs->bh->b_bdev,
+		ce = mb_cache_entry_get(ext4_mb_cache, bs->bh->b_bdev,
 					bs->bh->b_blocknr);
 		error = ext4_journal_get_write_access(handle, bs->bh);
 		if (error)
···
 				if (!IS_LAST_ENTRY(s->first))
 					ext4_xattr_rehash(header(s->base),
 							  s->here);
-				ext4_xattr_cache_insert(bs->bh);
+				ext4_xattr_cache_insert(ext4_mb_cache,
+					bs->bh);
 			}
 			unlock_buffer(bs->bh);
 			if (error == -EIO)
···
 			memcpy(new_bh->b_data, s->base, new_bh->b_size);
 			set_buffer_uptodate(new_bh);
 			unlock_buffer(new_bh);
-			ext4_xattr_cache_insert(new_bh);
+			ext4_xattr_cache_insert(ext4_mb_cache, new_bh);
 			error = ext4_handle_dirty_xattr_block(handle,
 							      inode, new_bh);
 			if (error)
···
  * Returns 0, or a negative error number on failure.
  */
 static void
-ext4_xattr_cache_insert(struct buffer_head *bh)
+ext4_xattr_cache_insert(struct mb_cache *ext4_mb_cache, struct buffer_head *bh)
 {
 	__u32 hash = le32_to_cpu(BHDR(bh)->h_hash);
 	struct mb_cache_entry *ce;
 	int error;
 
-	ce = mb_cache_entry_alloc(ext4_xattr_cache, GFP_NOFS);
+	ce = mb_cache_entry_alloc(ext4_mb_cache, GFP_NOFS);
 	if (!ce) {
 		ea_bdebug(bh, "out of memory");
 		return;
···
 {
 	__u32 hash = le32_to_cpu(header->h_hash);
 	struct mb_cache_entry *ce;
+	struct mb_cache *ext4_mb_cache = EXT4_GET_MB_CACHE(inode);
 
 	if (!header->h_hash)
 		return NULL;  /* never share */
 	ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
 again:
-	ce = mb_cache_entry_find_first(ext4_xattr_cache, inode->i_sb->s_bdev,
+	ce = mb_cache_entry_find_first(ext4_mb_cache, inode->i_sb->s_bdev,
 				       hash);
 	while (ce) {
 		struct buffer_head *bh;
···
 
 #undef BLOCK_HASH_SHIFT
 
-int __init
-ext4_init_xattr(void)
+#define	HASH_BUCKET_BITS	10
+
+struct mb_cache *
+ext4_xattr_create_cache(char *name)
 {
-	ext4_xattr_cache = mb_cache_create("ext4_xattr", 6);
-	if (!ext4_xattr_cache)
-		return -ENOMEM;
-	return 0;
+	return mb_cache_create(name, HASH_BUCKET_BITS);
 }
 
-void
-ext4_exit_xattr(void)
+void ext4_xattr_destroy_cache(struct mb_cache *cache)
 {
-	if (ext4_xattr_cache)
-		mb_cache_destroy(ext4_xattr_cache);
-	ext4_xattr_cache = NULL;
+	if (cache)
+		mb_cache_destroy(cache);
 }
+

fs/ext4/xattr.h

···
 extern int ext4_expand_extra_isize_ea(struct inode *inode, int new_extra_isize,
 			    struct ext4_inode *raw_inode, handle_t *handle);
 
-extern int __init ext4_init_xattr(void);
-extern void ext4_exit_xattr(void);
-
 extern const struct xattr_handler *ext4_xattr_handlers[];
 
 extern int ext4_xattr_ibody_find(struct inode *inode, struct ext4_xattr_info *i,
···
 extern int ext4_xattr_ibody_inline_set(handle_t *handle, struct inode *inode,
 				       struct ext4_xattr_info *i,
 				       struct ext4_xattr_ibody_find *is);
+
+extern struct mb_cache *ext4_xattr_create_cache(char *name);
+extern void ext4_xattr_destroy_cache(struct mb_cache *);
 
 #ifdef CONFIG_EXT4_FS_SECURITY
 extern int ext4_init_security(handle_t *handle, struct inode *inode,

fs/mbcache.c

···
 
 static DECLARE_WAIT_QUEUE_HEAD(mb_cache_queue);
 static struct blockgroup_lock *mb_cache_bg_lock;
+static struct kmem_cache *mb_cache_kmem_cache;
 
 MODULE_AUTHOR("Andreas Gruenbacher <[e-mail]>");
 MODULE_DESCRIPTION("Meta block cache (for extended attributes)");
···
 		goto fail;
 	for (n=0; n<bucket_count; n++)
 		INIT_HLIST_BL_HEAD(&cache->c_index_hash[n]);
-	cache->c_entry_cache = kmem_cache_create(name,
-		sizeof(struct mb_cache_entry), 0,
-		SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD, NULL);
-	if (!cache->c_entry_cache)
-		goto fail2;
+	if (!mb_cache_kmem_cache) {
+		mb_cache_kmem_cache = kmem_cache_create(name,
+			sizeof(struct mb_cache_entry), 0,
+			SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD, NULL);
+		if (!mb_cache_kmem_cache)
+			goto fail2;
+	}
+	cache->c_entry_cache = mb_cache_kmem_cache;
 
 	/*
 	 * Set an upper limit on the number of cache entries so that the hash
···
 			  atomic_read(&cache->c_entry_count));
 	}
 
+	if (list_empty(&mb_cache_list)) {
+		kmem_cache_destroy(mb_cache_kmem_cache);
+		mb_cache_kmem_cache = NULL;
+	}
 	kfree(cache->c_index_hash);
 	kfree(cache->c_block_hash);
 	kfree(cache);