Date:   Sat, 10 Mar 2018 10:17:44 -0800
From:   Andiry Xu <jix024@....ucsd.edu>
To:     linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-nvdimm@...ts.01.org
Cc:     dan.j.williams@...el.com, andy.rudoff@...el.com,
        coughlan@...hat.com, swanson@...ucsd.edu, david@...morbit.com,
        jack@...e.com, swhiteho@...hat.com, miklos@...redi.hu,
        andiry.xu@...il.com, Andiry Xu <jix024@...ucsd.edu>
Subject: [RFC v2 03/83] Add super.h.

From: Andiry Xu <jix024@...ucsd.edu>

This header file defines NOVA persistent and volatile superblock
data structures.

It also defines NOVA block layout:

Page 0: Superblock
Page 1: Reserved inodes
Page 2 - 15: Reserved
Page 16 - 31: Inode table pointers
Page 32 - 47: Journal address pointers
Page 48 - 63: Reserved
Pages n-2: Replicate reserved inodes
Pages n-1: Replicate superblock

Other pages are for normal inodes, logs and data.

Signed-off-by: Andiry Xu <jix024@...ucsd.edu>
---
 fs/nova/super.h | 149 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 149 insertions(+)
 create mode 100644 fs/nova/super.h

diff --git a/fs/nova/super.h b/fs/nova/super.h
new file mode 100644
index 0000000..cb53908
--- /dev/null
+++ b/fs/nova/super.h
@@ -0,0 +1,149 @@
+#ifndef __SUPER_H
+#define __SUPER_H
+/*
+ * Structure of the NOVA super block in PMEM
+ *
+ * The fields are partitioned into static and dynamic fields. The static fields
+ * never change after file system creation. This was primarily done because
+ * nova_get_block() returns NULL if the block offset is 0 (helps in catching
+ * bugs). So if we modify any field using journaling (for consistency), we
+ * will have to modify s_sum which is at offset 0. So journaling code fails.
+ * This (static+dynamic fields) is a temporary solution and can be avoided
+ * once the file system becomes stable and nova_get_block() returns correct
+ * pointers even for offset 0.
+ */
+struct nova_super_block {
+	/* static fields. they never change after file system creation.
+	 * checksum only validates up to s_start_dynamic field below
+	 */
+	__le32		s_sum;			/* checksum of this sb */
+	__le32		s_magic;		/* magic signature */
+	__le32		s_padding32;
+	__le32		s_blocksize;		/* blocksize in bytes */
+	__le64		s_size;			/* total size of fs in bytes */
+	char		s_volume_name[16];	/* volume name */
+
+	/* all the dynamic fields should go here */
+	__le64		s_epoch_id;		/* Epoch ID */
+
+	/* s_mtime and s_wtime should be together and their order should not be
+	 * changed. we use an 8 byte write to update both of them atomically
+	 */
+	__le32		s_mtime;		/* mount time */
+	__le32		s_wtime;		/* write time */
+} __attribute((__packed__));
+
+#define NOVA_SB_SIZE 512       /* must be power of two */
+
+/* ======================= Reserved blocks ========================= */
+
+/*
+ * Page 0 contains super blocks;
+ * Page 1 contains reserved inodes;
+ * Page 2 - 15 are reserved.
+ * Page 16 - 31 contain pointers to inode tables.
+ * Page 32 - 47 contain pointers to journal pages.
+ */
+#define	HEAD_RESERVED_BLOCKS	64
+#define	NUM_JOURNAL_PAGES	16
+
+#define	SUPER_BLOCK_START       0 // Superblock
+#define	RESERVE_INODE_START	1 // Reserved inodes
+#define	INODE_TABLE_START	16 // inode table pointers
+#define	JOURNAL_START		32 // journal pointer table
+
+/* For replica super block and replica reserved inodes */
+#define	TAIL_RESERVED_BLOCKS	2
+
+/* ======================= Reserved inodes ========================= */
+
+/* We have space for 31 reserved inodes */
+#define NOVA_ROOT_INO		(1)
+#define NOVA_INODETABLE_INO	(2)	/* Fake inode associated with inode
+					 * stroage.  We need this because our
+					 * allocator requires inode to be
+					 * associated with each allocation.
+					 * The data actually lives in linked
+					 * lists in INODE_TABLE_START. */
+#define NOVA_BLOCKNODE_INO	(3)     /* Storage for allocator state */
+#define NOVA_LITEJOURNAL_INO	(4)     /* Storage for lightweight journals */
+#define NOVA_INODELIST_INO	(5)     /* Storage for Inode free list */
+
+
+/* Normal inode starts at 32 */
+#define NOVA_NORMAL_INODE_START      (32)
+
+
+
+/*
+ * NOVA super-block data in DRAM
+ */
+struct nova_sb_info {
+	struct super_block *sb;			/* VFS super block */
+	struct nova_super_block *nova_sb;	/* DRAM copy of SB */
+	struct block_device *s_bdev;
+	struct dax_device *s_dax_dev;
+
+	/*
+	 * base physical and virtual address of NOVA (which is also
+	 * the pointer to the super block)
+	 */
+	phys_addr_t	phys_addr;
+	void		*virt_addr;
+	void		*replica_reserved_inodes_addr;
+	void		*replica_sb_addr;
+
+	unsigned long	num_blocks;
+
+	/* Mount options */
+	unsigned long	bpi;
+	unsigned long	blocksize;
+	unsigned long	initsize;
+	unsigned long	s_mount_opt;
+	kuid_t		uid;    /* Mount uid for root directory */
+	kgid_t		gid;    /* Mount gid for root directory */
+	umode_t		mode;   /* Mount mode for root directory */
+	atomic_t	next_generation;
+	/* inode tracking */
+	unsigned long	s_inodes_used_count;
+	unsigned long	head_reserved_blocks;
+	unsigned long	tail_reserved_blocks;
+
+	struct mutex	s_lock;	/* protects the SB's buffer-head */
+
+	int cpus;
+
+	/* Current epoch. volatile guarantees visibility */
+	volatile u64 s_epoch_id;
+
+	/* ZEROED page for cache page initialized */
+	void *zeroed_page;
+};
+
+static inline struct nova_sb_info *NOVA_SB(struct super_block *sb)
+{
+	return sb->s_fs_info;
+}
+
+static inline struct nova_super_block
+*nova_get_redund_super(struct super_block *sb)
+{
+	struct nova_sb_info *sbi = NOVA_SB(sb);
+
+	return (struct nova_super_block *)(sbi->replica_sb_addr);
+}
+
+
+/* If this is part of a read-modify-write of the super block,
+ * nova_memunlock_super() before calling!
+ */
+static inline struct nova_super_block *nova_get_super(struct super_block *sb)
+{
+	struct nova_sb_info *sbi = NOVA_SB(sb);
+
+	return (struct nova_super_block *)sbi->virt_addr;
+}
+
+extern void nova_error_mng(struct super_block *sb, const char *fmt, ...);
+
+#endif
-- 
2.7.4

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