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diff --git a/fs/nilfs2/the_nilfs.h b/fs/nilfs2/the_nilfs.h
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+/*
+ * 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 */
+};
+
+/**
+ * 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 heads of on-disk super blocks
+ * @ns_sbp: pointers to super block data
+ * @ns_sbwtime: previous write time of super blocks
+ * @ns_sbsize: size of valid data in super block
+ * @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_prot_seq: least sequence number of segments which must not be reclaimed
+ * @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_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[2];
+ struct nilfs_super_block *ns_sbp[2];
+ time_t ns_sbwtime[2];
+ unsigned ns_sbsize;
+ 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 while 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;
+ u64 ns_prot_seq;
+ 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;
+
+ /* 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)
+
+/* Minimum interval of periodical update of superblocks (in seconds) */
+#define NILFS_SB_FREQ 10
+#define NILFS_ALTSB_FREQ 60 /* spare superblock */
+
+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 *);
+int nilfs_checkpoint_is_mounted(struct the_nilfs *, __u64, int);
+int nilfs_near_disk_full(struct the_nilfs *);
+void nilfs_fall_back_super_block(struct the_nilfs *);
+void nilfs_swap_super_block(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;
+}
+
+static inline int nilfs_segment_is_active(struct the_nilfs *nilfs, __u64 n)
+{
+ return n == nilfs->ns_segnum || n == nilfs->ns_nextnum;
+}
+
+#endif /* _THE_NILFS_H */