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From: Andiry Xu <jix024@eng.ucsd.edu>
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>
Subject: Re: [RFC v2 03/83] Add super.h.
Date: Wed, 14 Mar 2018 23:11:48 -0700
Message-ID: <CAD4SzjtHmBTisX6vQYuEnJf0fKsF==w5GHqsdks6xGv1go7Lzw@mail.gmail.com> (raw)
In-Reply-To: <20180315045401.GB4860@magnolia>

On Wed, Mar 14, 2018 at 9:54 PM, Darrick J. Wong
<darrick.wong@oracle.com> wrote:
> On Sat, Mar 10, 2018 at 10:17:44AM -0800, Andiry Xu wrote:
>> From: Andiry Xu <jix024@cs.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@cs.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 */
>
> Hmmm, 32-bit timestamps?  2038 isn't that far away...
>

I will try fixing this in the next version.

>> +} __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)
>
> I've been wondering this whole time, why not make the inode number the
> byte offset into the pmem?  Then you don't have to lose the last 8 bytes
> of each inode block to point to the next one.
>

During failure recovery, NOVA scans the inode logs. To find all the
inodes, it follows the inode block list. Making inode number the byte
offset cannot locate all the inodes during recovery.

One option is to organize the inodes in a B+tree, which makes the code
more complex.

Thanks,
Andiry

> --D
>
>> +
>> +
>> +
>> +/*
>> + * 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
>>

  reply index

Thread overview: 119+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-10 18:17 [RFC v2 00/83] NOVA: a new file system for persistent memory Andiry Xu
2018-03-10 18:17 ` [RFC v2 01/83] Introduction and documentation of NOVA filesystem Andiry Xu
2018-03-19 20:43   ` Randy Dunlap
2018-03-19 23:00     ` Andiry Xu
2018-04-22  8:05   ` Pavel Machek
2018-03-10 18:17 ` [RFC v2 02/83] Add nova_def.h Andiry Xu
2018-03-10 18:17 ` [RFC v2 03/83] Add super.h Andiry Xu
2018-03-15  4:54   ` Darrick J. Wong
2018-03-15  6:11     ` Andiry Xu [this message]
2018-03-15  9:05       ` Arnd Bergmann
2018-03-15 17:51         ` Andiry Xu
2018-03-15 20:04           ` Andreas Dilger
2018-03-15 20:38           ` Arnd Bergmann
2018-03-16  2:59             ` Theodore Y. Ts'o
2018-03-16  6:17               ` Andiry Xu
2018-03-16  6:30                 ` Darrick J. Wong
2018-03-16  9:19               ` Arnd Bergmann
2018-03-10 18:17 ` [RFC v2 04/83] NOVA inode definition Andiry Xu
2018-03-15  5:06   ` Darrick J. Wong
2018-03-15  6:16     ` Andiry Xu
2018-03-10 18:17 ` [RFC v2 05/83] Add NOVA filesystem definitions and useful helper routines Andiry Xu
2018-03-11 12:00   ` Nikolay Borisov
2018-03-11 19:22     ` Eric Biggers
2018-03-11 21:45       ` Andiry Xu
2018-03-19 19:39       ` Andiry Xu
2018-03-19 20:30         ` Eric Biggers
2018-03-19 21:59           ` Andiry Xu
2018-03-10 18:17 ` [RFC v2 06/83] Add inode get/read methods Andiry Xu
2018-04-23  6:12   ` Darrick J. Wong
2018-04-23 15:55     ` Andiry Xu
2018-03-10 18:17 ` [RFC v2 07/83] Initialize inode_info and rebuild inode information in nova_iget() Andiry Xu
2018-03-10 18:17 ` [RFC v2 08/83] NOVA superblock operations Andiry Xu
2018-03-10 18:17 ` [RFC v2 09/83] Add Kconfig and Makefile Andiry Xu
2018-03-11 12:15   ` Nikolay Borisov
2018-03-11 21:32     ` Andiry Xu
2018-03-10 18:17 ` [RFC v2 10/83] Add superblock integrity check Andiry Xu
2018-03-10 18:17 ` [RFC v2 11/83] Add timing and I/O statistics for performance analysis and profiling Andiry Xu
2018-03-10 18:17 ` [RFC v2 12/83] Add timing for mount and init Andiry Xu
2018-03-10 18:17 ` [RFC v2 13/83] Add remount_fs and show_options methods Andiry Xu
2018-03-10 18:17 ` [RFC v2 14/83] Add range node kmem cache Andiry Xu
2018-03-11 11:55   ` Nikolay Borisov
2018-03-11 21:31     ` Andiry Xu
2018-03-10 18:17 ` [RFC v2 15/83] Add free list data structure Andiry Xu
2018-03-10 18:17 ` [RFC v2 16/83] Initialize block map and free lists in nova_init() Andiry Xu
2018-03-11 12:12   ` Nikolay Borisov
2018-03-11 21:30     ` Andiry Xu
2018-03-10 18:17 ` [RFC v2 17/83] Add statfs support Andiry Xu
2018-03-10 18:17 ` [RFC v2 18/83] Add freelist statistics printing Andiry Xu
2018-03-10 18:18 ` [RFC v2 19/83] Add pmem block free routines Andiry Xu
2018-03-10 18:18 ` [RFC v2 20/83] Pmem block allocation routines Andiry Xu
2018-03-10 18:18 ` [RFC v2 21/83] Add log structure Andiry Xu
2018-03-10 18:18 ` [RFC v2 22/83] Inode log pages allocation and reclaimation Andiry Xu
2018-03-10 18:18 ` [RFC v2 23/83] Save allocator to pmem in put_super Andiry Xu
2018-03-10 18:18 ` [RFC v2 24/83] Initialize and allocate inode table Andiry Xu
2018-03-10 18:18 ` [RFC v2 25/83] Support get normal inode address and inode table extentsion Andiry Xu
2018-03-10 18:18 ` [RFC v2 26/83] Add inode_map to track inuse inodes Andiry Xu
2018-03-10 18:18 ` [RFC v2 27/83] Save the inode inuse list to pmem upon umount Andiry Xu
2018-03-10 18:18 ` [RFC v2 28/83] Add NOVA address space operations Andiry Xu
2018-03-10 18:18 ` [RFC v2 29/83] Add write_inode and dirty_inode routines Andiry Xu
2018-03-10 18:18 ` [RFC v2 30/83] New NOVA inode allocation Andiry Xu
2018-03-10 18:18 ` [RFC v2 31/83] Add new vfs " Andiry Xu
2018-03-10 18:18 ` [RFC v2 32/83] Add log entry definitions Andiry Xu
2018-03-10 18:18 ` [RFC v2 33/83] Inode log and entry printing for debug purpose Andiry Xu
2018-03-10 18:18 ` [RFC v2 34/83] Journal: NOVA light weight journal definitions Andiry Xu
2018-03-10 18:18 ` [RFC v2 35/83] Journal: Lite journal helper routines Andiry Xu
2018-03-10 18:18 ` [RFC v2 36/83] Journal: Lite journal recovery Andiry Xu
2018-03-10 18:18 ` [RFC v2 37/83] Journal: Lite journal create and commit Andiry Xu
2018-03-10 18:18 ` [RFC v2 38/83] Journal: NOVA lite journal initialization Andiry Xu
2018-03-10 18:18 ` [RFC v2 39/83] Log operation: dentry append Andiry Xu
2018-03-10 18:18 ` [RFC v2 40/83] Log operation: file write entry append Andiry Xu
2018-03-10 18:18 ` [RFC v2 41/83] Log operation: setattr " Andiry Xu
2018-03-10 18:18 ` [RFC v2 42/83] Log operation: link change append Andiry Xu
2018-03-10 18:18 ` [RFC v2 43/83] Log operation: in-place update log entry Andiry Xu
2018-03-10 18:18 ` [RFC v2 44/83] Log operation: invalidate log entries Andiry Xu
2018-03-10 18:18 ` [RFC v2 45/83] Log operation: file inode log lookup and assign Andiry Xu
2018-03-10 18:18 ` [RFC v2 46/83] Dir: Add Directory radix tree insert/remove methods Andiry Xu
2018-03-10 18:18 ` [RFC v2 47/83] Dir: Add initial dentries when initializing a directory inode log Andiry Xu
2018-03-10 18:18 ` [RFC v2 48/83] Dir: Readdir operation Andiry Xu
2018-03-10 18:18 ` [RFC v2 49/83] Dir: Append create/remove dentry Andiry Xu
2018-03-10 18:18 ` [RFC v2 50/83] Inode: Add nova_evict_inode Andiry Xu
2018-03-10 18:18 ` [RFC v2 51/83] Rebuild: directory inode Andiry Xu
2018-03-10 18:18 ` [RFC v2 52/83] Rebuild: file inode Andiry Xu
2018-03-10 18:18 ` [RFC v2 53/83] Namei: lookup Andiry Xu
2018-03-10 18:18 ` [RFC v2 54/83] Namei: create and mknod Andiry Xu
2018-03-10 18:18 ` [RFC v2 55/83] Namei: mkdir Andiry Xu
2018-03-10 18:18 ` [RFC v2 56/83] Namei: link and unlink Andiry Xu
2018-03-10 18:18 ` [RFC v2 57/83] Namei: rmdir Andiry Xu
2018-03-10 18:18 ` [RFC v2 58/83] Namei: rename Andiry Xu
2018-03-10 18:18 ` [RFC v2 59/83] Namei: setattr Andiry Xu
2018-03-10 18:18 ` [RFC v2 60/83] Add special inode operations Andiry Xu
2018-03-10 18:18 ` [RFC v2 61/83] Super: Add nova_export_ops Andiry Xu
2018-03-10 18:18 ` [RFC v2 62/83] File: getattr and file inode operations Andiry Xu
2018-03-10 18:18 ` [RFC v2 63/83] File operation: llseek Andiry Xu
2018-03-10 18:18 ` [RFC v2 64/83] File operation: open, fsync, flush Andiry Xu
2018-03-10 18:18 ` [RFC v2 65/83] File operation: read Andiry Xu
2018-03-10 18:18 ` [RFC v2 66/83] Super: Add file write item cache Andiry Xu
2018-03-10 18:18 ` [RFC v2 67/83] Dax: commit list of file write items to log Andiry Xu
2018-03-10 18:18 ` [RFC v2 68/83] File operation: copy-on-write write Andiry Xu
2018-03-10 18:18 ` [RFC v2 69/83] Super: Add module param inplace_data_updates Andiry Xu
2018-03-10 18:18 ` [RFC v2 70/83] File operation: Inplace write Andiry Xu
2018-03-10 18:18 ` [RFC v2 71/83] Symlink support Andiry Xu
2018-03-10 18:18 ` [RFC v2 72/83] File operation: fallocate Andiry Xu
2018-03-10 18:18 ` [RFC v2 73/83] Dax: Add iomap operations Andiry Xu
2018-03-10 18:18 ` [RFC v2 74/83] File operation: Mmap Andiry Xu
2018-03-10 18:18 ` [RFC v2 75/83] File operation: read/write iter Andiry Xu
2018-03-10 18:18 ` [RFC v2 76/83] Ioctl support Andiry Xu
2018-03-10 18:18 ` [RFC v2 77/83] GC: Fast garbage collection Andiry Xu
2018-03-10 18:18 ` [RFC v2 78/83] GC: Thorough " Andiry Xu
2018-03-10 18:19 ` [RFC v2 79/83] Normal recovery Andiry Xu
2018-03-10 18:19 ` [RFC v2 80/83] Failure recovery: bitmap operations Andiry Xu
2018-03-10 18:19 ` [RFC v2 81/83] Failure recovery: Inode pages recovery routines Andiry Xu
2018-03-10 18:19 ` [RFC v2 82/83] Failure recovery: Per-CPU recovery Andiry Xu
2018-03-10 18:19 ` [RFC v2 83/83] Sysfs support Andiry Xu
2018-03-15  0:33   ` Randy Dunlap
2018-03-15  6:07     ` Andiry Xu
2018-03-22 15:00   ` David Sterba
2018-03-23  0:31     ` Andiry Xu
2018-03-11  2:14 ` [RFC v2 00/83] NOVA: a new file system for persistent memory Theodore Y. Ts'o
2018-03-11  4:58   ` Andiry Xu

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