nilfs2: add inode and other major structures

This adds the following common structures of the NILFS2 file system.

* nilfs_inode_info structure:
  gives on-memory inode.

* nilfs_sb_info structure:
  keeps per-mount state and a special inode for the ifile.
  This structure is attached to the super_block structure.

* the_nilfs structure:
  keeps shared state and locks among a read/write mount and snapshot
  mounts.  This keeps special inodes for the sufile, cpfile, dat, and
  another dat inode used during GC (gcdat).  This also has a hash table
  of dummy inodes to cache disk blocks during GC (gcinodes).

* nilfs_transaction_info structure:
  keeps per task state while nilfs is writing logs or doing indivisible
  inode or namespace operations.  This structure is used to identify
  context during log making and store nest level of the lock which
  ensures atomicity of file system operations.

Signed-off-by: Koji Sato <sato.koji@lab.ntt.co.jp>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 290 insertions, 0 deletions

diff --git a/fs/nilfs2/the_nilfs.h b/fs/nilfs2/the_nilfs.h
new file mode 100644
index 000000000000..dee8d83e0549
--- /dev/null
+++ b/fs/nilfs2/the_nilfs.h
@@ -0,0 +1,290 @@
+/*
+ * the_nilfs.h - the_nilfs shared structure.
+ *
+ * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Written by Ryusuke Konishi <ryusuke@osrg.net>
+ *
+ */
+
+#ifndef _THE_NILFS_H
+#define _THE_NILFS_H
+
+#include <linux/types.h>
+#include <linux/buffer_head.h>
+#include <linux/fs.h>
+#include <linux/blkdev.h>
+#include <linux/backing-dev.h>
+#include "sb.h"
+
+/* the_nilfs struct */
+enum {
+        THE_NILFS_INIT = 0,     /* Information from super_block is set */
+        THE_NILFS_LOADED,       /* Roll-back/roll-forward has done and
+                                   the latest checkpoint was loaded */
+        THE_NILFS_DISCONTINUED, /* 'next' pointer chain has broken */
+        THE_NILFS_COND_NONGC_WRITE,     /* Condition to wake up cleanerd */
+};
+
+/**
+ * struct the_nilfs - struct to supervise multiple nilfs mount points
+ * @ns_flags: flags
+ * @ns_count: reference count
+ * @ns_bdev: block device
+ * @ns_bdi: backing dev info
+ * @ns_writer: back pointer to writable nilfs_sb_info
+ * @ns_sem: semaphore for shared states
+ * @ns_writer_mutex: mutex protecting ns_writer attach/detach
+ * @ns_writer_refcount: number of referrers on ns_writer
+ * @ns_sbh: buffer head of the on-disk super block
+ * @ns_sbp: pointer to the super block data
+ * @ns_used_segments: list of full segments in volatile active state
+ * @ns_supers: list of nilfs super block structs
+ * @ns_seg_seq: segment sequence counter
+ * @ns_segnum: index number of the latest full segment.
+ * @ns_nextnum: index number of the full segment index to be used next
+ * @ns_pseg_offset: offset of next partial segment in the current full segment
+ * @ns_cno: next checkpoint number
+ * @ns_ctime: write time of the last segment
+ * @ns_nongc_ctime: write time of the last segment not for cleaner operation
+ * @ns_ndirtyblks: Number of dirty data blocks
+ * @ns_last_segment_lock: lock protecting fields for the latest segment
+ * @ns_last_pseg: start block number of the latest segment
+ * @ns_last_seq: sequence value of the latest segment
+ * @ns_last_cno: checkpoint number of the latest segment
+ * @ns_free_segments_count: counter of free segments
+ * @ns_segctor_sem: segment constructor semaphore
+ * @ns_dat: DAT file inode
+ * @ns_cpfile: checkpoint file inode
+ * @ns_sufile: segusage file inode
+ * @ns_gc_dat: shadow inode of the DAT file inode for GC
+ * @ns_gc_inodes: dummy inodes to keep live blocks
+ * @ns_gc_inodes_h: hash list to keep dummy inode holding live blocks
+ * @ns_cleanerd_wq: wait queue for cleanerd
+ * @ns_blocksize_bits: bit length of block size
+ * @ns_nsegments: number of segments in filesystem
+ * @ns_blocks_per_segment: number of blocks per segment
+ * @ns_r_segments_percentage: reserved segments percentage
+ * @ns_nrsvsegs: number of reserved segments
+ * @ns_first_data_block: block number of first data block
+ * @ns_inode_size: size of on-disk inode
+ * @ns_first_ino: first not-special inode number
+ * @ns_crc_seed: seed value of CRC32 calculation
+ */
+struct the_nilfs {
+        unsigned long           ns_flags;
+        atomic_t                ns_count;
+
+        struct block_device    *ns_bdev;
+        struct backing_dev_info *ns_bdi;
+        struct nilfs_sb_info   *ns_writer;
+        struct rw_semaphore     ns_sem;
+        struct mutex            ns_writer_mutex;
+        atomic_t                ns_writer_refcount;
+
+        /*
+         * used for
+         * - loading the latest checkpoint exclusively.
+         * - allocating a new full segment.
+         * - protecting s_dirt in the super_block struct
+         *   (see nilfs_write_super) and the following fields.
+         */
+        struct buffer_head     *ns_sbh;
+        struct nilfs_super_block *ns_sbp;
+        struct list_head        ns_used_segments;
+        unsigned                ns_mount_state;
+        struct list_head        ns_supers;
+
+        /*
+         * Following fields are dedicated to a writable FS-instance.
+         * Except for the period seeking checkpoint, code outside the segment
+         * constructor must lock a segment semaphore with transaction_begin()
+         * and transaction_end(), when accessing these fields.
+         * The writable FS-instance is sole during a lifetime of the_nilfs.
+         */
+        u64                     ns_seg_seq;
+        __u64                   ns_segnum;
+        __u64                   ns_nextnum;
+        unsigned long           ns_pseg_offset;
+        __u64                   ns_cno;
+        time_t                  ns_ctime;
+        time_t                  ns_nongc_ctime;
+        atomic_t                ns_ndirtyblks;
+
+        /*
+         * The following fields hold information on the latest partial segment
+         * written to disk with a super root.  These fields are protected by
+         * ns_last_segment_lock.
+         */
+        spinlock_t              ns_last_segment_lock;
+        sector_t                ns_last_pseg;
+        u64                     ns_last_seq;
+        __u64                   ns_last_cno;
+        unsigned long           ns_free_segments_count;
+
+        struct rw_semaphore     ns_segctor_sem;
+
+        /*
+         * Following fields are lock free except for the period before
+         * the_nilfs is initialized.
+         */
+        struct inode           *ns_dat;
+        struct inode           *ns_cpfile;
+        struct inode           *ns_sufile;
+        struct inode           *ns_gc_dat;
+
+        /* GC inode list and hash table head */
+        struct list_head        ns_gc_inodes;
+        struct hlist_head      *ns_gc_inodes_h;
+
+        /* cleanerd */
+        wait_queue_head_t       ns_cleanerd_wq;
+
+        /* Disk layout information (static) */
+        unsigned int            ns_blocksize_bits;
+        unsigned long           ns_nsegments;
+        unsigned long           ns_blocks_per_segment;
+        unsigned long           ns_r_segments_percentage;
+        unsigned long           ns_nrsvsegs;
+        unsigned long           ns_first_data_block;
+        int                     ns_inode_size;
+        int                     ns_first_ino;
+        u32                     ns_crc_seed;
+};
+
+#define NILFS_GCINODE_HASH_BITS         8
+#define NILFS_GCINODE_HASH_SIZE         (1<<NILFS_GCINODE_HASH_BITS)
+
+#define THE_NILFS_FNS(bit, name)                                        \
+static inline void set_nilfs_##name(struct the_nilfs *nilfs)            \
+{                                                                       \
+        set_bit(THE_NILFS_##bit, &(nilfs)->ns_flags);                   \
+}                                                                       \
+static inline void clear_nilfs_##name(struct the_nilfs *nilfs)          \
+{                                                                       \
+        clear_bit(THE_NILFS_##bit, &(nilfs)->ns_flags);                 \
+}                                                                       \
+static inline int nilfs_##name(struct the_nilfs *nilfs)                 \
+{                                                                       \
+        return test_bit(THE_NILFS_##bit, &(nilfs)->ns_flags);           \
+}
+
+THE_NILFS_FNS(INIT, init)
+THE_NILFS_FNS(LOADED, loaded)
+THE_NILFS_FNS(DISCONTINUED, discontinued)
+THE_NILFS_FNS(COND_NONGC_WRITE, cond_nongc_write)
+
+void nilfs_set_last_segment(struct the_nilfs *, sector_t, u64, __u64);
+struct the_nilfs *alloc_nilfs(struct block_device *);
+void put_nilfs(struct the_nilfs *);
+int init_nilfs(struct the_nilfs *, struct nilfs_sb_info *, char *);
+int load_nilfs(struct the_nilfs *, struct nilfs_sb_info *);
+int nilfs_count_free_blocks(struct the_nilfs *, sector_t *);
+void nilfs_dispose_used_segments(struct the_nilfs *);
+int nilfs_checkpoint_is_mounted(struct the_nilfs *, __u64, int);
+int nilfs_near_disk_full(struct the_nilfs *);
+
+
+static inline void get_nilfs(struct the_nilfs *nilfs)
+{
+        /* Caller must have at least one reference of the_nilfs. */
+        atomic_inc(&nilfs->ns_count);
+}
+
+static inline struct nilfs_sb_info *nilfs_get_writer(struct the_nilfs *nilfs)
+{
+        if (atomic_inc_and_test(&nilfs->ns_writer_refcount))
+                mutex_lock(&nilfs->ns_writer_mutex);
+        return nilfs->ns_writer;
+}
+
+static inline void nilfs_put_writer(struct the_nilfs *nilfs)
+{
+        if (atomic_add_negative(-1, &nilfs->ns_writer_refcount))
+                mutex_unlock(&nilfs->ns_writer_mutex);
+}
+
+static inline void
+nilfs_attach_writer(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi)
+{
+        mutex_lock(&nilfs->ns_writer_mutex);
+        nilfs->ns_writer = sbi;
+        mutex_unlock(&nilfs->ns_writer_mutex);
+}
+
+static inline void
+nilfs_detach_writer(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi)
+{
+        mutex_lock(&nilfs->ns_writer_mutex);
+        if (sbi == nilfs->ns_writer)
+                nilfs->ns_writer = NULL;
+        mutex_unlock(&nilfs->ns_writer_mutex);
+}
+
+static inline void
+nilfs_get_segment_range(struct the_nilfs *nilfs, __u64 segnum,
+                        sector_t *seg_start, sector_t *seg_end)
+{
+        *seg_start = (sector_t)nilfs->ns_blocks_per_segment * segnum;
+        *seg_end = *seg_start + nilfs->ns_blocks_per_segment - 1;
+        if (segnum == 0)
+                *seg_start = nilfs->ns_first_data_block;
+}
+
+static inline sector_t
+nilfs_get_segment_start_blocknr(struct the_nilfs *nilfs, __u64 segnum)
+{
+        return (segnum == 0) ? nilfs->ns_first_data_block :
+                (sector_t)nilfs->ns_blocks_per_segment * segnum;
+}
+
+static inline __u64
+nilfs_get_segnum_of_block(struct the_nilfs *nilfs, sector_t blocknr)
+{
+        sector_t segnum = blocknr;
+
+        sector_div(segnum, nilfs->ns_blocks_per_segment);
+        return segnum;
+}
+
+static inline void
+nilfs_terminate_segment(struct the_nilfs *nilfs, sector_t seg_start,
+                        sector_t seg_end)
+{
+        /* terminate the current full segment (used in case of I/O-error) */
+        nilfs->ns_pseg_offset = seg_end - seg_start + 1;
+}
+
+static inline void nilfs_shift_to_next_segment(struct the_nilfs *nilfs)
+{
+        /* move forward with a full segment */
+        nilfs->ns_segnum = nilfs->ns_nextnum;
+        nilfs->ns_pseg_offset = 0;
+        nilfs->ns_seg_seq++;
+}
+
+static inline __u64 nilfs_last_cno(struct the_nilfs *nilfs)
+{
+        __u64 cno;
+
+        spin_lock(&nilfs->ns_last_segment_lock);
+        cno = nilfs->ns_last_cno;
+        spin_unlock(&nilfs->ns_last_segment_lock);
+        return cno;
+}
+
+#endif /* _THE_NILFS_H */