Re: [RFC v2 04/83] NOVA inode definition.

Darrick J. Wong
2018-03-15T05:13:13Z

On Sat, Mar 10, 2018 at 10:17:45AM -0800, Andiry Xu wrote:
> From: Andiry Xu <jix024@cs.ucsd.edu>
>
> inode.h defines the non-volatile and volatile NOVA inode data structures.
>
> The non-volatile NOVA inode (nova_inode) is aligned to 128 bytes and contains
> file/directory metadata information. The most important fields
> are log_head and log_tail. log_head points to the start of
> the log, and log_tail points to the end of the latest committed
> log entry. NOVA make updates to the inode by appending
> to the log tail and update the log_tail pointer atomically.
>
> The volatile NOVA inode (nova_inode_info) contains necessary
> information to limit access to the non-volatile NOVA inode during runtime.
> It has a radix tree to map file offset or filenames to the corresponding
> log entries.
>
> Signed-off-by: Andiry Xu <jix024@cs.ucsd.edu>
> ---
> fs/nova/inode.h | 187 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 187 insertions(+)
> create mode 100644 fs/nova/inode.h
>
> diff --git a/fs/nova/inode.h b/fs/nova/inode.h
> new file mode 100644
> index 0000000..f9187e3
> --- /dev/null
> +++ b/fs/nova/inode.h
> @@ -0,0 +1,187 @@
> +#ifndef __INODE_H
> +#define __INODE_H
> +
> +struct nova_inode_info_header;
> +struct nova_inode;
> +
> +#include "super.h"
> +
> +enum nova_new_inode_type {
> + TYPE_CREATE = 0,
> + TYPE_MKNOD,
> + TYPE_SYMLINK,
> + TYPE_MKDIR
> +};
> +
> +
> +/*
> + * Structure of an inode in PMEM
> + * Keep the inode size to within 120 bytes: We use the last eight bytes
> + * as inode table tail pointer.

I would've expected a
BUILD_BUG_ON(NOVA_INODE_SIZE - sizeof(struct nova_inode) == 8);
or something to enforce this.

(Or just equate inode number with byte offset? I looked ahead at the
directory entries and they seem to be 64-bit...)

I guess I'm being lazy and doing a on-disk-format-only review. :)

> + */
> +struct nova_inode {
> +
> + /* first 40 bytes */
> + u8 i_rsvd; /* reserved. used to be checksum */

Magic number?

> + u8 valid; /* Is this inode valid? */
> + u8 deleted; /* Is this inode deleted? */

Would i_mode == 0 cover these?

> + u8 i_blk_type; /* data block size this inode uses */

I would've thought these would just be bits of i_flags?

Also, if I have a 1G blocksize file and free space fragments to the
point that there's > 1G of free space but none of it contiguous, I guess
I can expect ENOSPC?

> + __le32 i_flags; /* Inode flags */
> + __le64 i_size; /* Size of data in bytes */
> + __le32 i_ctime; /* Inode modification time */
> + __le32 i_mtime; /* Inode b-tree Modification time */
> + __le32 i_atime; /* Access time */

Same y2038 grumble from the previous patch.

> + __le16 i_mode; /* File mode */
> + __le16 i_links_count; /* Links count */
> +
> + __le64 i_xattr; /* Extended attribute block */
> +
> + /* second 40 bytes */
> + __le32 i_uid; /* Owner Uid */
> + __le32 i_gid; /* Group Id */
> + __le32 i_generation; /* File version (for NFS) */
> + __le32 i_create_time; /* Create time */
> + __le64 nova_ino; /* nova inode number */
> +
> + __le64 log_head; /* Log head pointer */
> + __le64 log_tail; /* Log tail pointer */
> +
> + /* last 40 bytes */
> + __le64 create_epoch_id; /* Transaction ID when create */
> + __le64 delete_epoch_id; /* Transaction ID when deleted */
> +
> + struct {
> + __le32 rdev; /* major/minor # */
> + } dev; /* device inode */
> +
> + __le32 csum; /* CRC32 checksum */
> + /* Leave 8 bytes for inode table tail pointer */
> +} __attribute((__packed__));
> +
> +/*
> + * NOVA-specific inode state kept in DRAM
> + */
> +struct nova_inode_info_header {
> + /* For files, tree holds a map from file offsets to
> + * write log entries.
> + *
> + * For directories, tree holds a map from a hash of the file name to
> + * dentry log entry.
> + */
> + struct radix_tree_root tree;
> + struct rw_semaphore i_sem; /* Protect log and tree */
> + unsigned short i_mode; /* Dir or file? */
> + unsigned int i_flags;
> + unsigned long log_pages; /* Num of log pages */
> + unsigned long i_size;
> + unsigned long i_blocks;
> + unsigned long ino;
> + unsigned long pi_addr;
> + unsigned long valid_entries; /* For thorough GC */
> + unsigned long num_entries; /* For thorough GC */
> + u64 last_setattr; /* Last setattr entry */
> + u64 last_link_change; /* Last link change entry */
> + u64 last_dentry; /* Last updated dentry */
> + u64 trans_id; /* Transaction ID */
> + u64 log_head; /* Log head pointer */
> + u64 log_tail; /* Log tail pointer */
> + u8 i_blk_type;
> +};
> +
> +/*
> + * DRAM state for inodes
> + */
> +struct nova_inode_info {
> + struct nova_inode_info_header header;
> + struct inode vfs_inode;
> +};
> +
> +
> +static inline struct nova_inode_info *NOVA_I(struct inode *inode)
> +{
> + return container_of(inode, struct nova_inode_info, vfs_inode);
> +}
> +
> +static inline void sih_lock(struct nova_inode_info_header *header)

"sih"? What happened to the "nova" prefix?

--D

> +{
> + down_write(&header->i_sem);
> +}
> +
> +static inline void sih_unlock(struct nova_inode_info_header *header)
> +{
> + up_write(&header->i_sem);
> +}
> +
> +static inline void sih_lock_shared(struct nova_inode_info_header *header)
> +{
> + down_read(&header->i_sem);
> +}
> +
> +static inline void sih_unlock_shared(struct nova_inode_info_header *header)
> +{
> + up_read(&header->i_sem);
> +}
> +
> +static inline unsigned int
> +nova_inode_blk_shift(struct nova_inode_info_header *sih)
> +{
> + return blk_type_to_shift[sih->i_blk_type];
> +}
> +
> +static inline uint32_t nova_inode_blk_size(struct nova_inode_info_header *sih)
> +{
> + return blk_type_to_size[sih->i_blk_type];
> +}
> +
> +static inline u64 nova_get_reserved_inode_addr(struct super_block *sb,
> + u64 inode_number)
> +{
> + return (NOVA_DEF_BLOCK_SIZE_4K * RESERVE_INODE_START) +
> + inode_number * NOVA_INODE_SIZE;
> +}
> +
> +static inline struct nova_inode *nova_get_reserved_inode(struct super_block *sb,
> + u64 inode_number)
> +{
> + struct nova_sb_info *sbi = NOVA_SB(sb);
> + u64 addr;
> +
> + addr = nova_get_reserved_inode_addr(sb, inode_number);
> +
> + return (struct nova_inode *)(sbi->virt_addr + addr);
> +}
> +
> +static inline struct nova_inode *nova_get_inode_by_ino(struct super_block *sb,
> + u64 ino)
> +{
> + if (ino == 0 || ino >= NOVA_NORMAL_INODE_START)
> + return NULL;
> +
> + return nova_get_reserved_inode(sb, ino);
> +}
> +
> +static inline struct nova_inode *nova_get_inode(struct super_block *sb,
> + struct inode *inode)
> +{
> + struct nova_inode_info *si = NOVA_I(inode);
> + struct nova_inode_info_header *sih = &si->header;
> + struct nova_inode fake_pi;
> + void *addr;
> + int rc;
> +
> + addr = nova_get_block(sb, sih->pi_addr);
> + rc = memcpy_mcsafe(&fake_pi, addr, sizeof(struct nova_inode));
> + if (rc)
> + return NULL;
> +
> + return (struct nova_inode *)addr;
> +}
> +
> +static inline int nova_persist_inode(struct nova_inode *pi)
> +{
> + nova_flush_buffer(pi, sizeof(struct nova_inode), 1);
> + return 0;
> +}
> +
> +#endif
> --
> 2.7.4
>