/* * the_nilfs.c - 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> * */ #include <linux/buffer_head.h> #include <linux/slab.h> #include <linux/blkdev.h> #include <linux/backing-dev.h> #include <linux/crc32.h> #include "nilfs.h" #include "segment.h" #include "alloc.h" #include "cpfile.h" #include "sufile.h" #include "dat.h" #include "segbuf.h" static LIST_HEAD(nilfs_objects); static DEFINE_SPINLOCK(nilfs_lock); void nilfs_set_last_segment(struct the_nilfs *nilfs, sector_t start_blocknr, u64 seq, __u64 cno) { spin_lock(&nilfs->ns_last_segment_lock); nilfs->ns_last_pseg = start_blocknr; nilfs->ns_last_seq = seq; nilfs->ns_last_cno = cno; spin_unlock(&nilfs->ns_last_segment_lock); } /** * alloc_nilfs - allocate the_nilfs structure * @bdev: block device to which the_nilfs is related * * alloc_nilfs() allocates memory for the_nilfs and * initializes its reference count and locks. * * Return Value: On success, pointer to the_nilfs is returned. * On error, NULL is returned. */ static struct the_nilfs *alloc_nilfs(struct block_device *bdev) { struct the_nilfs *nilfs; nilfs = kzalloc(sizeof(*nilfs), GFP_KERNEL); if (!nilfs) return NULL; nilfs->ns_bdev = bdev; atomic_set(&nilfs->ns_count, 1); atomic_set(&nilfs->ns_ndirtyblks, 0); init_rwsem(&nilfs->ns_sem); init_rwsem(&nilfs->ns_super_sem); mutex_init(&nilfs->ns_mount_mutex); init_rwsem(&nilfs->ns_writer_sem); INIT_LIST_HEAD(&nilfs->ns_list); INIT_LIST_HEAD(&nilfs->ns_supers); spin_lock_init(&nilfs->ns_last_segment_lock); nilfs->ns_gc_inodes_h = NULL; init_rwsem(&nilfs->ns_segctor_sem); return nilfs; } /** * find_or_create_nilfs - find or create nilfs object * @bdev: block device to which the_nilfs is related * * find_nilfs() looks up an existent nilfs object created on the * device and gets the reference count of the object. If no nilfs object * is found on the device, a new nilfs object is allocated. * * Return Value: On success, pointer to the nilfs object is returned. * On error, NULL is returned. */ struct the_nilfs *find_or_create_nilfs(struct block_device *bdev) { struct the_nilfs *nilfs, *new = NULL; retry: spin_lock(&nilfs_lock); list_for_each_entry(nilfs, &nilfs_objects, ns_list) { if (nilfs->ns_bdev == bdev) { get_nilfs(nilfs); spin_unlock(&nilfs_lock); if (new) put_nilfs(new); return nilfs; /* existing object */ } } if (new) { list_add_tail(&new->ns_list, &nilfs_objects); spin_unlock(&nilfs_lock); return new; /* new object */ } spin_unlock(&nilfs_lock); new = alloc_nilfs(bdev); if (new) goto retry; return NULL; /* insufficient memory */ } /** * put_nilfs - release a reference to the_nilfs * @nilfs: the_nilfs structure to be released * * put_nilfs() decrements a reference counter of the_nilfs. * If the reference count reaches zero, the_nilfs is freed. */ void put_nilfs(struct the_nilfs *nilfs) { spin_lock(&nilfs_lock); if (!atomic_dec_and_test(&nilfs->ns_count)) { spin_unlock(&nilfs_lock); return; } list_del_init(&nilfs->ns_list); spin_unlock(&nilfs_lock); /* * Increment of ns_count never occurs below because the caller * of get_nilfs() holds at least one reference to the_nilfs. * Thus its exclusion control is not required here. */ might_sleep(); if (nilfs_loaded(nilfs)) { nilfs_mdt_clear(nilfs->ns_sufile); nilfs_mdt_destroy(nilfs->ns_sufile); nilfs_mdt_clear(nilfs->ns_cpfile); nilfs_mdt_destroy(nilfs->ns_cpfile); nilfs_mdt_clear(nilfs->ns_dat); nilfs_mdt_destroy(nilfs->ns_dat); /* XXX: how and when to clear nilfs->ns_gc_dat? */ nilfs_mdt_destroy(nilfs->ns_gc_dat); } if (nilfs_init(nilfs)) { nilfs_destroy_gccache(nilfs); brelse(nilfs->ns_sbh[0]); brelse(nilfs->ns_sbh[1]); } kfree(nilfs); } static int nilfs_load_super_root(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi, sector_t sr_block) { static struct lock_class_key dat_lock_key; struct buffer_head *bh_sr; struct nilfs_super_root *raw_sr; struct nilfs_super_block **sbp = nilfs->ns_sbp; unsigned dat_entry_size, segment_usage_size, checkpoint_size; unsigned inode_size; int err; err = nilfs_read_super_root_block(sbi->s_super, sr_block, &bh_sr, 1); if (unlikely(err)) return err; down_read(&nilfs->ns_sem); dat_entry_size = le16_to_cpu(sbp[0]->s_dat_entry_size); checkpoint_size = le16_to_cpu(sbp[0]->s_checkpoint_size); segment_usage_size = le16_to_cpu(sbp[0]->s_segment_usage_size); up_read(&nilfs->ns_sem); inode_size = nilfs->ns_inode_size; err = -ENOMEM; nilfs->ns_dat = nilfs_mdt_new(nilfs, NULL, NILFS_DAT_INO); if (unlikely(!nilfs->ns_dat)) goto failed; nilfs->ns_gc_dat = nilfs_mdt_new(nilfs, NULL, NILFS_DAT_INO); if (unlikely(!nilfs->ns_gc_dat)) goto failed_dat; nilfs->ns_cpfile = nilfs_mdt_new(nilfs, NULL, NILFS_CPFILE_INO); if (unlikely(!nilfs->ns_cpfile)) goto failed_gc_dat; nilfs->ns_sufile = nilfs_mdt_new(nilfs, NULL, NILFS_SUFILE_INO); if (unlikely(!nilfs->ns_sufile)) goto failed_cpfile; err = nilfs_palloc_init_blockgroup(nilfs->ns_dat, dat_entry_size); if (unlikely(err)) goto failed_sufile; err = nilfs_palloc_init_blockgroup(nilfs->ns_gc_dat, dat_entry_size); if (unlikely(err)) goto failed_sufile; lockdep_set_class(&NILFS_MDT(nilfs->ns_dat)->mi_sem, &dat_lock_key); lockdep_set_class(&NILFS_MDT(nilfs->ns_gc_dat)->mi_sem, &dat_lock_key); nilfs_mdt_set_shadow(nilfs->ns_dat, nilfs->ns_gc_dat); nilfs_mdt_set_entry_size(nilfs->ns_cpfile, checkpoint_size, sizeof(struct nilfs_cpfile_header)); nilfs_mdt_set_entry_size(nilfs->ns_sufile, segment_usage_size, sizeof(struct nilfs_sufile_header)); err = nilfs_mdt_read_inode_direct( nilfs->ns_dat, bh_sr, NILFS_SR_DAT_OFFSET(inode_size)); if (unlikely(err)) goto failed_sufile; err = nilfs_mdt_read_inode_direct( nilfs->ns_cpfile, bh_sr, NILFS_SR_CPFILE_OFFSET(inode_size)); if (unlikely(err)) goto failed_sufile; err = nilfs_mdt_read_inode_direct( nilfs->ns_sufile, bh_sr, NILFS_SR_SUFILE_OFFSET(inode_size)); if (unlikely(err)) goto failed_sufile; raw_sr = (struct nilfs_super_root *)bh_sr->b_data; nilfs->ns_nongc_ctime = le64_to_cpu(raw_sr->sr_nongc_ctime); failed: brelse(bh_sr); return err; failed_sufile: nilfs_mdt_destroy(nilfs->ns_sufile); failed_cpfile: nilfs_mdt_destroy(nilfs->ns_cpfile); failed_gc_dat: nilfs_mdt_destroy(nilfs->ns_gc_dat); failed_dat: nilfs_mdt_destroy(nilfs->ns_dat); goto failed; } static void nilfs_init_recovery_info(struct nilfs_recovery_info *ri) { memset(ri, 0, sizeof(*ri)); INIT_LIST_HEAD(&ri->ri_used_segments); } static void nilfs_clear_recovery_info(struct nilfs_recovery_info *ri) { nilfs_dispose_segment_list(&ri->ri_used_segments); } /** * load_nilfs - load and recover the nilfs * @nilfs: the_nilfs structure to be released * @sbi: nilfs_sb_info used to recover past segment * * load_nilfs() searches and load the latest super root, * attaches the last segment, and does recovery if needed. * The caller must call this exclusively for simultaneous mounts. */ int load_nilfs(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi) { struct nilfs_recovery_info ri; unsigned int s_flags = sbi->s_super->s_flags; int really_read_only = bdev_read_only(nilfs->ns_bdev); unsigned valid_fs; int err = 0; nilfs_init_recovery_info(&ri); down_write(&nilfs->ns_sem); valid_fs = (nilfs->ns_mount_state & NILFS_VALID_FS); up_write(&nilfs->ns_sem); if (!valid_fs && (s_flags & MS_RDONLY)) { printk(KERN_INFO "NILFS: INFO: recovery " "required for readonly filesystem.\n"); if (really_read_only) { printk(KERN_ERR "NILFS: write access " "unavailable, cannot proceed.\n"); err = -EROFS; goto failed; } printk(KERN_INFO "NILFS: write access will " "be enabled during recovery.\n"); sbi->s_super->s_flags &= ~MS_RDONLY; } err = nilfs_search_super_root(nilfs, sbi, &ri); if (unlikely(err)) { printk(KERN_ERR "NILFS: error searching super root.\n"); goto failed; } err = nilfs_load_super_root(nilfs, sbi, ri.ri_super_root); if (unlikely(err)) { printk(KERN_ERR "NILFS: error loading super root.\n"); goto failed; } if (!valid_fs) { err = nilfs_recover_logical_segments(nilfs, sbi, &ri); if (unlikely(err)) { nilfs_mdt_destroy(nilfs->ns_cpfile); nilfs_mdt_destroy(nilfs->ns_sufile); nilfs_mdt_destroy(nilfs->ns_dat); goto failed; } if (ri.ri_need_recovery == NILFS_RECOVERY_SR_UPDATED) sbi->s_super->s_dirt = 1; } set_nilfs_loaded(nilfs); failed: nilfs_clear_recovery_info(&ri); sbi->s_super->s_flags = s_flags; return err; } static unsigned long long nilfs_max_size(unsigned int blkbits) { unsigned int max_bits; unsigned long long res = MAX_LFS_FILESIZE; /* page cache limit */ max_bits = blkbits + NILFS_BMAP_KEY_BIT; /* bmap size limit */ if (max_bits < 64) res = min_t(unsigned long long, res, (1ULL << max_bits) - 1); return res; } static int nilfs_store_disk_layout(struct the_nilfs *nilfs, struct nilfs_super_block *sbp) { if (le32_to_cpu(sbp->s_rev_level) != NILFS_CURRENT_REV) { printk(KERN_ERR "NILFS: revision mismatch " "(superblock rev.=%d.%d, current rev.=%d.%d). " "Please check the version of mkfs.nilfs.\n", le32_to_cpu(sbp->s_rev_level), le16_to_cpu(sbp->s_minor_rev_level), NILFS_CURRENT_REV, NILFS_MINOR_REV); return -EINVAL; } nilfs->ns_sbsize = le16_to_cpu(sbp->s_bytes); if (nilfs->ns_sbsize > BLOCK_SIZE) return -EINVAL; nilfs->ns_inode_size = le16_to_cpu(sbp->s_inode_size); nilfs->ns_first_ino = le32_to_cpu(sbp->s_first_ino); nilfs->ns_blocks_per_segment = le32_to_cpu(sbp->s_blocks_per_segment); if (nilfs->ns_blocks_per_segment < NILFS_SEG_MIN_BLOCKS) { printk(KERN_ERR "NILFS: too short segment. \n"); return -EINVAL; } nilfs->ns_first_data_block = le64_to_cpu(sbp->s_first_data_block); nilfs->ns_nsegments = le64_to_cpu(sbp->s_nsegments); nilfs->ns_r_segments_percentage = le32_to_cpu(sbp->s_r_segments_percentage); nilfs->ns_nrsvsegs = max_t(unsigned long, NILFS_MIN_NRSVSEGS, DIV_ROUND_UP(nilfs->ns_nsegments * nilfs->ns_r_segments_percentage, 100)); nilfs->ns_crc_seed = le32_to_cpu(sbp->s_crc_seed); return 0; } static int nilfs_valid_sb(struct nilfs_super_block *sbp) { static unsigned char sum[4]; const int sumoff = offsetof(struct nilfs_super_block, s_sum); size_t bytes; u32 crc; if (!sbp || le16_to_cpu(sbp->s_magic) != NILFS_SUPER_MAGIC) return 0; bytes = le16_to_cpu(sbp->s_bytes); if (bytes > BLOCK_SIZE) return 0; crc = crc32_le(le32_to_cpu(sbp->s_crc_seed), (unsigned char *)sbp, sumoff); crc = crc32_le(crc, sum, 4); crc = crc32_le(crc, (unsigned char *)sbp + sumoff + 4, bytes - sumoff - 4); return crc == le32_to_cpu(sbp->s_sum); } static int nilfs_sb2_bad_offset(struct nilfs_super_block *sbp, u64 offset) { return offset < ((le64_to_cpu(sbp->s_nsegments) * le32_to_cpu(sbp->s_blocks_per_segment)) << (le32_to_cpu(sbp->s_log_block_size) + 10)); } static void nilfs_release_super_block(struct the_nilfs *nilfs) { int i; for (i = 0; i < 2; i++) { if (nilfs->ns_sbp[i]) { brelse(nilfs->ns_sbh[i]); nilfs->ns_sbh[i] = NULL; nilfs->ns_sbp[i] = NULL; } } } void nilfs_fall_back_super_block(struct the_nilfs *nilfs) { brelse(nilfs->ns_sbh[0]); nilfs->ns_sbh[0] = nilfs->ns_sbh[1]; nilfs->ns_sbp[0] = nilfs->ns_sbp[1]; nilfs->ns_sbh[1] = NULL; nilfs->ns_sbp[1] = NULL; } void nilfs_swap_super_block(struct the_nilfs *nilfs) { struct buffer_head *tsbh = nilfs->ns_sbh[0]; struct nilfs_super_block *tsbp = nilfs->ns_sbp[0]; nilfs->ns_sbh[0] = nilfs->ns_sbh[1]; nilfs->ns_sbp[0] = nilfs->ns_sbp[1]; nilfs->ns_sbh[1] = tsbh; nilfs->ns_sbp[1] = tsbp; } static int nilfs_load_super_block(struct the_nilfs *nilfs, struct super_block *sb, int blocksize, struct nilfs_super_block **sbpp) { struct nilfs_super_block **sbp = nilfs->ns_sbp; struct buffer_head **sbh = nilfs->ns_sbh; u64 sb2off = NILFS_SB2_OFFSET_BYTES(nilfs->ns_bdev->bd_inode->i_size); int valid[2], swp = 0; sbp[0] = nilfs_read_super_block(sb, NILFS_SB_OFFSET_BYTES, blocksize, &sbh[0]); sbp[1] = nilfs_read_super_block(sb, sb2off, blocksize, &sbh[1]); if (!sbp[0]) { if (!sbp[1]) { printk(KERN_ERR "NILFS: unable to read superblock\n"); return -EIO; } printk(KERN_WARNING "NILFS warning: unable to read primary superblock\n"); } else if (!sbp[1]) printk(KERN_WARNING "NILFS warning: unable to read secondary superblock\n"); valid[0] = nilfs_valid_sb(sbp[0]); valid[1] = nilfs_valid_sb(sbp[1]); swp = valid[1] && (!valid[0] || le64_to_cpu(sbp[1]->s_wtime) > le64_to_cpu(sbp[0]->s_wtime)); if (valid[swp] && nilfs_sb2_bad_offset(sbp[swp], sb2off)) { brelse(sbh[1]); sbh[1] = NULL; sbp[1] = NULL; swp = 0; } if (!valid[swp]) { nilfs_release_super_block(nilfs); printk(KERN_ERR "NILFS: Can't find nilfs on dev %s.\n", sb->s_id); return -EINVAL; } if (swp) { printk(KERN_WARNING "NILFS warning: broken superblock. " "using spare superblock.\n"); nilfs_swap_super_block(nilfs); } nilfs->ns_sbwtime[0] = le64_to_cpu(sbp[0]->s_wtime); nilfs->ns_sbwtime[1] = valid[!swp] ? le64_to_cpu(sbp[1]->s_wtime) : 0; nilfs->ns_prot_seq = le64_to_cpu(sbp[valid[1] & !swp]->s_last_seq); *sbpp = sbp[0]; return 0; } /** * init_nilfs - initialize a NILFS instance. * @nilfs: the_nilfs structure * @sbi: nilfs_sb_info * @sb: super block * @data: mount options * * init_nilfs() performs common initialization per block device (e.g. * reading the super block, getting disk layout information, initializing * shared fields in the_nilfs). It takes on some portion of the jobs * typically done by a fill_super() routine. This division arises from * the nature that multiple NILFS instances may be simultaneously * mounted on a device. * For multiple mounts on the same device, only the first mount * invokes these tasks. * * Return Value: On success, 0 is returned. On error, a negative error * code is returned. */ int init_nilfs(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi, char *data) { struct super_block *sb = sbi->s_super; struct nilfs_super_block *sbp; struct backing_dev_info *bdi; int blocksize; int err; down_write(&nilfs->ns_sem); if (nilfs_init(nilfs)) { /* Load values from existing the_nilfs */ sbp = nilfs->ns_sbp[0]; err = nilfs_store_magic_and_option(sb, sbp, data); if (err) goto out; blocksize = BLOCK_SIZE << le32_to_cpu(sbp->s_log_block_size); if (sb->s_blocksize != blocksize && !sb_set_blocksize(sb, blocksize)) { printk(KERN_ERR "NILFS: blocksize %d unfit to device\n", blocksize); err = -EINVAL; } sb->s_maxbytes = nilfs_max_size(sb->s_blocksize_bits); goto out; } blocksize = sb_min_blocksize(sb, BLOCK_SIZE); if (!blocksize) { printk(KERN_ERR "NILFS: unable to set blocksize\n"); err = -EINVAL; goto out; } err = nilfs_load_super_block(nilfs, sb, blocksize, &sbp); if (err) goto out; err = nilfs_store_magic_and_option(sb, sbp, data); if (err) goto failed_sbh; blocksize = BLOCK_SIZE << le32_to_cpu(sbp->s_log_block_size); if (sb->s_blocksize != blocksize) { int hw_blocksize = bdev_logical_block_size(sb->s_bdev); if (blocksize < hw_blocksize) { printk(KERN_ERR "NILFS: blocksize %d too small for device " "(sector-size = %d).\n", blocksize, hw_blocksize); err = -EINVAL; goto failed_sbh; } nilfs_release_super_block(nilfs); sb_set_blocksize(sb, blocksize); err = nilfs_load_super_block(nilfs, sb, blocksize, &sbp); if (err) goto out; /* not failed_sbh; sbh is released automatically when reloading fails. */ } nilfs->ns_blocksize_bits = sb->s_blocksize_bits; err = nilfs_store_disk_layout(nilfs, sbp); if (err) goto failed_sbh; sb->s_maxbytes = nilfs_max_size(sb->s_blocksize_bits); nilfs->ns_mount_state = le16_to_cpu(sbp->s_state); bdi = nilfs->ns_bdev->bd_inode->i_mapping->backing_dev_info; nilfs->ns_bdi = bdi ? : &default_backing_dev_info; /* Finding last segment */ nilfs->ns_last_pseg = le64_to_cpu(sbp->s_last_pseg); nilfs->ns_last_cno = le64_to_cpu(sbp->s_last_cno); nilfs->ns_last_seq = le64_to_cpu(sbp->s_last_seq); nilfs->ns_seg_seq = nilfs->ns_last_seq; nilfs->ns_segnum = nilfs_get_segnum_of_block(nilfs, nilfs->ns_last_pseg); nilfs->ns_cno = nilfs->ns_last_cno + 1; if (nilfs->ns_segnum >= nilfs->ns_nsegments) { printk(KERN_ERR "NILFS invalid last segment number.\n"); err = -EINVAL; goto failed_sbh; } /* Dummy values */ nilfs->ns_free_segments_count = nilfs->ns_nsegments - (nilfs->ns_segnum + 1); /* Initialize gcinode cache */ err = nilfs_init_gccache(nilfs); if (err) goto failed_sbh; set_nilfs_init(nilfs); err = 0; out: up_write(&nilfs->ns_sem); return err; failed_sbh: nilfs_release_super_block(nilfs); goto out; } int nilfs_count_free_blocks(struct the_nilfs *nilfs, sector_t *nblocks) { struct inode *dat = nilfs_dat_inode(nilfs); unsigned long ncleansegs; int err; down_read(&NILFS_MDT(dat)->mi_sem); /* XXX */ err = nilfs_sufile_get_ncleansegs(nilfs->ns_sufile, &ncleansegs); up_read(&NILFS_MDT(dat)->mi_sem); /* XXX */ if (likely(!err)) *nblocks = (sector_t)ncleansegs * nilfs->ns_blocks_per_segment; return err; } int nilfs_near_disk_full(struct the_nilfs *nilfs) { struct inode *sufile = nilfs->ns_sufile; unsigned long ncleansegs, nincsegs; int ret; ret = nilfs_sufile_get_ncleansegs(sufile, &ncleansegs); if (likely(!ret)) { nincsegs = atomic_read(&nilfs->ns_ndirtyblks) / nilfs->ns_blocks_per_segment + 1; if (ncleansegs <= nilfs->ns_nrsvsegs + nincsegs) ret++; } return ret; } /** * nilfs_find_sbinfo - find existing nilfs_sb_info structure * @nilfs: nilfs object * @rw_mount: mount type (non-zero value for read/write mount) * @cno: checkpoint number (zero for read-only mount) * * nilfs_find_sbinfo() returns the nilfs_sb_info structure which * @rw_mount and @cno (in case of snapshots) matched. If no instance * was found, NULL is returned. Although the super block instance can * be unmounted after this function returns, the nilfs_sb_info struct * is kept on memory until nilfs_put_sbinfo() is called. */ struct nilfs_sb_info *nilfs_find_sbinfo(struct the_nilfs *nilfs, int rw_mount, __u64 cno) { struct nilfs_sb_info *sbi; down_read(&nilfs->ns_super_sem); /* * The SNAPSHOT flag and sb->s_flags are supposed to be * protected with nilfs->ns_super_sem. */ sbi = nilfs->ns_current; if (rw_mount) { if (sbi && !(sbi->s_super->s_flags & MS_RDONLY)) goto found; /* read/write mount */ else goto out; } else if (cno == 0) { if (sbi && (sbi->s_super->s_flags & MS_RDONLY)) goto found; /* read-only mount */ else goto out; } list_for_each_entry(sbi, &nilfs->ns_supers, s_list) { if (nilfs_test_opt(sbi, SNAPSHOT) && sbi->s_snapshot_cno == cno) goto found; /* snapshot mount */ } out: up_read(&nilfs->ns_super_sem); return NULL; found: atomic_inc(&sbi->s_count); up_read(&nilfs->ns_super_sem); return sbi; } int nilfs_checkpoint_is_mounted(struct the_nilfs *nilfs, __u64 cno, int snapshot_mount) { struct nilfs_sb_info *sbi; int ret = 0; down_read(&nilfs->ns_super_sem); if (cno == 0 || cno > nilfs->ns_cno) goto out_unlock; list_for_each_entry(sbi, &nilfs->ns_supers, s_list) { if (sbi->s_snapshot_cno == cno && (!snapshot_mount || nilfs_test_opt(sbi, SNAPSHOT))) { /* exclude read-only mounts */ ret++; break; } } /* for protecting recent checkpoints */ if (cno >= nilfs_last_cno(nilfs)) ret++; out_unlock: up_read(&nilfs->ns_super_sem); return ret; }