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From:   Andiry Xu <jix024@eng.ucsd.edu>
Date:   Wed, 14 Mar 2018 23:16:15 -0700
Message-ID: <CAD4SzjvseYcy0n7xcHtpQQM_+zHMPYXzn_UXBfk81dfV76CQug@mail.gmail.com>
Subject: Re: [RFC v2 04/83] NOVA inode definition.
To:     "Darrick J. Wong" <darrick.wong@oracle.com>
Cc:     Linux FS Devel <linux-fsdevel@vger.kernel.org>,
        linux-kernel@vger.kernel.org,
        "linux-nvdimm@lists.01.org" <linux-nvdimm@lists.01.org>,
        Dan Williams <dan.j.williams@intel.com>,
        "Rudoff, Andy" <andy.rudoff@intel.com>, coughlan@redhat.com,
        Steven Swanson <swanson@cs.ucsd.edu>,
        Dave Chinner <david@fromorbit.com>, jack@suse.com,
        swhiteho@redhat.com, miklos@szeredi.hu,
        Jian Xu <andiry.xu@gmail.com>, Andiry Xu <jix024@cs.ucsd.edu>
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On Wed, Mar 14, 2018 at 10:06 PM, Darrick J. Wong
<darrick.wong@oracle.com> wrote:
> 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.
>

Thanks, will do.

> (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?
>

OK.

>> +     u8      valid;           /* Is this inode valid? */
>> +     u8      deleted;         /* Is this inode deleted? */
>
> Would i_mode == 0 cover these?
>

Deleted flag comes from NOVA-Fortis code. I will check if i_mode can cover it.

>> +     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?
>

Yes, but 1G blocksize has not been tested.

>> +     __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.
>

Will fix.

>> +     __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?
>

This structure is born before the name NOVA was decided.

Thanks,
Andiry

> --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
>>