33c8e57c86
This will change the way to obtain nilfs object in nilfs_get_sb() function. Previously, a preliminary sget() call was performed, and the nilfs object was acquired from a super block instance found by the sget() call. This patch, instead, instroduces a new dedicated function find_or_create_nilfs(); as the name implies, the function finds an existent nilfs object from a global list or creates a new one if no object is found on the device. Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
301 lines
9.5 KiB
C
301 lines
9.5 KiB
C
/*
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* the_nilfs.h - the_nilfs shared structure.
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*
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* Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*
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* Written by Ryusuke Konishi <ryusuke@osrg.net>
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*
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*/
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#ifndef _THE_NILFS_H
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#define _THE_NILFS_H
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#include <linux/types.h>
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#include <linux/buffer_head.h>
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#include <linux/fs.h>
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#include <linux/blkdev.h>
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#include <linux/backing-dev.h>
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#include "sb.h"
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/* the_nilfs struct */
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enum {
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THE_NILFS_INIT = 0, /* Information from super_block is set */
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THE_NILFS_LOADED, /* Roll-back/roll-forward has done and
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the latest checkpoint was loaded */
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THE_NILFS_DISCONTINUED, /* 'next' pointer chain has broken */
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};
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/**
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* struct the_nilfs - struct to supervise multiple nilfs mount points
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* @ns_flags: flags
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* @ns_count: reference count
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* @ns_list: list head for nilfs_list
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* @ns_bdev: block device
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* @ns_bdi: backing dev info
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* @ns_writer: back pointer to writable nilfs_sb_info
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* @ns_sem: semaphore for shared states
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* @ns_writer_mutex: mutex protecting ns_writer attach/detach
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* @ns_writer_refcount: number of referrers on ns_writer
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* @ns_sbh: buffer heads of on-disk super blocks
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* @ns_sbp: pointers to super block data
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* @ns_sbwtime: previous write time of super blocks
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* @ns_sbsize: size of valid data in super block
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* @ns_supers: list of nilfs super block structs
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* @ns_seg_seq: segment sequence counter
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* @ns_segnum: index number of the latest full segment.
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* @ns_nextnum: index number of the full segment index to be used next
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* @ns_pseg_offset: offset of next partial segment in the current full segment
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* @ns_cno: next checkpoint number
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* @ns_ctime: write time of the last segment
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* @ns_nongc_ctime: write time of the last segment not for cleaner operation
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* @ns_ndirtyblks: Number of dirty data blocks
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* @ns_last_segment_lock: lock protecting fields for the latest segment
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* @ns_last_pseg: start block number of the latest segment
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* @ns_last_seq: sequence value of the latest segment
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* @ns_last_cno: checkpoint number of the latest segment
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* @ns_prot_seq: least sequence number of segments which must not be reclaimed
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* @ns_free_segments_count: counter of free segments
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* @ns_segctor_sem: segment constructor semaphore
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* @ns_dat: DAT file inode
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* @ns_cpfile: checkpoint file inode
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* @ns_sufile: segusage file inode
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* @ns_gc_dat: shadow inode of the DAT file inode for GC
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* @ns_gc_inodes: dummy inodes to keep live blocks
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* @ns_gc_inodes_h: hash list to keep dummy inode holding live blocks
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* @ns_blocksize_bits: bit length of block size
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* @ns_nsegments: number of segments in filesystem
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* @ns_blocks_per_segment: number of blocks per segment
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* @ns_r_segments_percentage: reserved segments percentage
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* @ns_nrsvsegs: number of reserved segments
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* @ns_first_data_block: block number of first data block
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* @ns_inode_size: size of on-disk inode
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* @ns_first_ino: first not-special inode number
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* @ns_crc_seed: seed value of CRC32 calculation
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*/
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struct the_nilfs {
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unsigned long ns_flags;
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atomic_t ns_count;
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struct list_head ns_list;
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struct block_device *ns_bdev;
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struct backing_dev_info *ns_bdi;
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struct nilfs_sb_info *ns_writer;
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struct rw_semaphore ns_sem;
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struct mutex ns_writer_mutex;
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atomic_t ns_writer_refcount;
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/*
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* used for
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* - loading the latest checkpoint exclusively.
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* - allocating a new full segment.
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* - protecting s_dirt in the super_block struct
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* (see nilfs_write_super) and the following fields.
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*/
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struct buffer_head *ns_sbh[2];
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struct nilfs_super_block *ns_sbp[2];
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time_t ns_sbwtime[2];
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unsigned ns_sbsize;
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unsigned ns_mount_state;
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struct list_head ns_supers;
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/*
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* Following fields are dedicated to a writable FS-instance.
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* Except for the period seeking checkpoint, code outside the segment
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* constructor must lock a segment semaphore while accessing these
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* fields.
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* The writable FS-instance is sole during a lifetime of the_nilfs.
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*/
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u64 ns_seg_seq;
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__u64 ns_segnum;
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__u64 ns_nextnum;
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unsigned long ns_pseg_offset;
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__u64 ns_cno;
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time_t ns_ctime;
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time_t ns_nongc_ctime;
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atomic_t ns_ndirtyblks;
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/*
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* The following fields hold information on the latest partial segment
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* written to disk with a super root. These fields are protected by
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* ns_last_segment_lock.
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*/
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spinlock_t ns_last_segment_lock;
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sector_t ns_last_pseg;
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u64 ns_last_seq;
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__u64 ns_last_cno;
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u64 ns_prot_seq;
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unsigned long ns_free_segments_count;
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struct rw_semaphore ns_segctor_sem;
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/*
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* Following fields are lock free except for the period before
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* the_nilfs is initialized.
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*/
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struct inode *ns_dat;
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struct inode *ns_cpfile;
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struct inode *ns_sufile;
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struct inode *ns_gc_dat;
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/* GC inode list and hash table head */
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struct list_head ns_gc_inodes;
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struct hlist_head *ns_gc_inodes_h;
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/* Disk layout information (static) */
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unsigned int ns_blocksize_bits;
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unsigned long ns_nsegments;
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unsigned long ns_blocks_per_segment;
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unsigned long ns_r_segments_percentage;
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unsigned long ns_nrsvsegs;
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unsigned long ns_first_data_block;
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int ns_inode_size;
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int ns_first_ino;
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u32 ns_crc_seed;
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};
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#define NILFS_GCINODE_HASH_BITS 8
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#define NILFS_GCINODE_HASH_SIZE (1<<NILFS_GCINODE_HASH_BITS)
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#define THE_NILFS_FNS(bit, name) \
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static inline void set_nilfs_##name(struct the_nilfs *nilfs) \
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{ \
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set_bit(THE_NILFS_##bit, &(nilfs)->ns_flags); \
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} \
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static inline void clear_nilfs_##name(struct the_nilfs *nilfs) \
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{ \
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clear_bit(THE_NILFS_##bit, &(nilfs)->ns_flags); \
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} \
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static inline int nilfs_##name(struct the_nilfs *nilfs) \
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{ \
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return test_bit(THE_NILFS_##bit, &(nilfs)->ns_flags); \
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}
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THE_NILFS_FNS(INIT, init)
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THE_NILFS_FNS(LOADED, loaded)
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THE_NILFS_FNS(DISCONTINUED, discontinued)
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/* Minimum interval of periodical update of superblocks (in seconds) */
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#define NILFS_SB_FREQ 10
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#define NILFS_ALTSB_FREQ 60 /* spare superblock */
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void nilfs_set_last_segment(struct the_nilfs *, sector_t, u64, __u64);
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struct the_nilfs *find_or_create_nilfs(struct block_device *);
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void put_nilfs(struct the_nilfs *);
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int init_nilfs(struct the_nilfs *, struct nilfs_sb_info *, char *);
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int load_nilfs(struct the_nilfs *, struct nilfs_sb_info *);
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int nilfs_count_free_blocks(struct the_nilfs *, sector_t *);
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int nilfs_checkpoint_is_mounted(struct the_nilfs *, __u64, int);
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int nilfs_near_disk_full(struct the_nilfs *);
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void nilfs_fall_back_super_block(struct the_nilfs *);
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void nilfs_swap_super_block(struct the_nilfs *);
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static inline void get_nilfs(struct the_nilfs *nilfs)
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{
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/* Caller must have at least one reference of the_nilfs. */
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atomic_inc(&nilfs->ns_count);
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}
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static inline struct nilfs_sb_info *nilfs_get_writer(struct the_nilfs *nilfs)
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{
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if (atomic_inc_and_test(&nilfs->ns_writer_refcount))
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mutex_lock(&nilfs->ns_writer_mutex);
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return nilfs->ns_writer;
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}
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static inline void nilfs_put_writer(struct the_nilfs *nilfs)
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{
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if (atomic_add_negative(-1, &nilfs->ns_writer_refcount))
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mutex_unlock(&nilfs->ns_writer_mutex);
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}
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static inline void
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nilfs_attach_writer(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi)
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{
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mutex_lock(&nilfs->ns_writer_mutex);
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nilfs->ns_writer = sbi;
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mutex_unlock(&nilfs->ns_writer_mutex);
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}
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static inline void
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nilfs_detach_writer(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi)
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{
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mutex_lock(&nilfs->ns_writer_mutex);
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if (sbi == nilfs->ns_writer)
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nilfs->ns_writer = NULL;
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mutex_unlock(&nilfs->ns_writer_mutex);
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}
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static inline void
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nilfs_get_segment_range(struct the_nilfs *nilfs, __u64 segnum,
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sector_t *seg_start, sector_t *seg_end)
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{
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*seg_start = (sector_t)nilfs->ns_blocks_per_segment * segnum;
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*seg_end = *seg_start + nilfs->ns_blocks_per_segment - 1;
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if (segnum == 0)
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*seg_start = nilfs->ns_first_data_block;
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}
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static inline sector_t
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nilfs_get_segment_start_blocknr(struct the_nilfs *nilfs, __u64 segnum)
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{
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return (segnum == 0) ? nilfs->ns_first_data_block :
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(sector_t)nilfs->ns_blocks_per_segment * segnum;
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}
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static inline __u64
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nilfs_get_segnum_of_block(struct the_nilfs *nilfs, sector_t blocknr)
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{
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sector_t segnum = blocknr;
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sector_div(segnum, nilfs->ns_blocks_per_segment);
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return segnum;
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}
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static inline void
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nilfs_terminate_segment(struct the_nilfs *nilfs, sector_t seg_start,
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sector_t seg_end)
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{
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/* terminate the current full segment (used in case of I/O-error) */
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nilfs->ns_pseg_offset = seg_end - seg_start + 1;
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}
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static inline void nilfs_shift_to_next_segment(struct the_nilfs *nilfs)
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{
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/* move forward with a full segment */
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nilfs->ns_segnum = nilfs->ns_nextnum;
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nilfs->ns_pseg_offset = 0;
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nilfs->ns_seg_seq++;
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}
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static inline __u64 nilfs_last_cno(struct the_nilfs *nilfs)
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{
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__u64 cno;
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spin_lock(&nilfs->ns_last_segment_lock);
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cno = nilfs->ns_last_cno;
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spin_unlock(&nilfs->ns_last_segment_lock);
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return cno;
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}
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static inline int nilfs_segment_is_active(struct the_nilfs *nilfs, __u64 n)
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{
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return n == nilfs->ns_segnum || n == nilfs->ns_nextnum;
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}
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#endif /* _THE_NILFS_H */
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