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M7350/kernel/fs/nilfs2/the_nilfs.c
T f75098198c M7350v5_en_gpl
2024-09-09 08:57:42 +00:00

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21 KiB
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/*
* 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/random.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 int nilfs_valid_sb(struct nilfs_super_block *sbp);
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;
if (!nilfs_sb_dirty(nilfs)) {
if (nilfs->ns_prev_seq == nilfs->ns_last_seq)
goto stay_cursor;
set_nilfs_sb_dirty(nilfs);
}
nilfs->ns_prev_seq = nilfs->ns_last_seq;
stay_cursor:
spin_unlock(&nilfs->ns_last_segment_lock);
}
/**
* alloc_nilfs - allocate a nilfs object
* @bdev: block device to which the_nilfs is related
*
* Return Value: On success, pointer to the_nilfs is returned.
* On error, NULL is returned.
*/
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_ndirtyblks, 0);
init_rwsem(&nilfs->ns_sem);
mutex_init(&nilfs->ns_snapshot_mount_mutex);
INIT_LIST_HEAD(&nilfs->ns_dirty_files);
INIT_LIST_HEAD(&nilfs->ns_gc_inodes);
spin_lock_init(&nilfs->ns_inode_lock);
spin_lock_init(&nilfs->ns_next_gen_lock);
spin_lock_init(&nilfs->ns_last_segment_lock);
nilfs->ns_cptree = RB_ROOT;
spin_lock_init(&nilfs->ns_cptree_lock);
init_rwsem(&nilfs->ns_segctor_sem);
nilfs->ns_sb_update_freq = NILFS_SB_FREQ;
return nilfs;
}
/**
* destroy_nilfs - destroy nilfs object
* @nilfs: nilfs object to be released
*/
void destroy_nilfs(struct the_nilfs *nilfs)
{
might_sleep();
if (nilfs_init(nilfs)) {
nilfs_sysfs_delete_device_group(nilfs);
brelse(nilfs->ns_sbh[0]);
brelse(nilfs->ns_sbh[1]);
}
kfree(nilfs);
}
static int nilfs_load_super_root(struct the_nilfs *nilfs,
struct super_block *sb, sector_t sr_block)
{
struct buffer_head *bh_sr;
struct nilfs_super_root *raw_sr;
struct nilfs_super_block **sbp = nilfs->ns_sbp;
struct nilfs_inode *rawi;
unsigned dat_entry_size, segment_usage_size, checkpoint_size;
unsigned inode_size;
int err;
err = nilfs_read_super_root_block(nilfs, 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;
rawi = (void *)bh_sr->b_data + NILFS_SR_DAT_OFFSET(inode_size);
err = nilfs_dat_read(sb, dat_entry_size, rawi, &nilfs->ns_dat);
if (err)
goto failed;
rawi = (void *)bh_sr->b_data + NILFS_SR_CPFILE_OFFSET(inode_size);
err = nilfs_cpfile_read(sb, checkpoint_size, rawi, &nilfs->ns_cpfile);
if (err)
goto failed_dat;
rawi = (void *)bh_sr->b_data + NILFS_SR_SUFILE_OFFSET(inode_size);
err = nilfs_sufile_read(sb, segment_usage_size, rawi,
&nilfs->ns_sufile);
if (err)
goto failed_cpfile;
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_cpfile:
iput(nilfs->ns_cpfile);
failed_dat:
iput(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);
}
/**
* nilfs_store_log_cursor - load log cursor from a super block
* @nilfs: nilfs object
* @sbp: buffer storing super block to be read
*
* nilfs_store_log_cursor() reads the last position of the log
* containing a super root from a given super block, and initializes
* relevant information on the nilfs object preparatory for log
* scanning and recovery.
*/
static int nilfs_store_log_cursor(struct the_nilfs *nilfs,
struct nilfs_super_block *sbp)
{
int ret = 0;
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_prev_seq = nilfs->ns_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");
ret = -EINVAL;
}
return ret;
}
/**
* load_nilfs - load and recover the nilfs
* @nilfs: the_nilfs structure to be released
* @sb: super block isntance 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 super_block *sb)
{
struct nilfs_recovery_info ri;
unsigned int s_flags = sb->s_flags;
int really_read_only = bdev_read_only(nilfs->ns_bdev);
int valid_fs = nilfs_valid_fs(nilfs);
int err;
if (!valid_fs) {
printk(KERN_WARNING "NILFS warning: mounting unchecked fs\n");
if (s_flags & MS_RDONLY) {
printk(KERN_INFO "NILFS: INFO: recovery "
"required for readonly filesystem.\n");
printk(KERN_INFO "NILFS: write access will "
"be enabled during recovery.\n");
}
}
nilfs_init_recovery_info(&ri);
err = nilfs_search_super_root(nilfs, &ri);
if (unlikely(err)) {
struct nilfs_super_block **sbp = nilfs->ns_sbp;
int blocksize;
if (err != -EINVAL)
goto scan_error;
if (!nilfs_valid_sb(sbp[1])) {
printk(KERN_WARNING
"NILFS warning: unable to fall back to spare"
"super block\n");
goto scan_error;
}
printk(KERN_INFO
"NILFS: try rollback from an earlier position\n");
/*
* restore super block with its spare and reconfigure
* relevant states of the nilfs object.
*/
memcpy(sbp[0], sbp[1], nilfs->ns_sbsize);
nilfs->ns_crc_seed = le32_to_cpu(sbp[0]->s_crc_seed);
nilfs->ns_sbwtime = le64_to_cpu(sbp[0]->s_wtime);
/* verify consistency between two super blocks */
blocksize = BLOCK_SIZE << le32_to_cpu(sbp[0]->s_log_block_size);
if (blocksize != nilfs->ns_blocksize) {
printk(KERN_WARNING
"NILFS warning: blocksize differs between "
"two super blocks (%d != %d)\n",
blocksize, nilfs->ns_blocksize);
goto scan_error;
}
err = nilfs_store_log_cursor(nilfs, sbp[0]);
if (err)
goto scan_error;
/* drop clean flag to allow roll-forward and recovery */
nilfs->ns_mount_state &= ~NILFS_VALID_FS;
valid_fs = 0;
err = nilfs_search_super_root(nilfs, &ri);
if (err)
goto scan_error;
}
err = nilfs_load_super_root(nilfs, sb, ri.ri_super_root);
if (unlikely(err)) {
printk(KERN_ERR "NILFS: error loading super root.\n");
goto failed;
}
if (valid_fs)
goto skip_recovery;
if (s_flags & MS_RDONLY) {
__u64 features;
if (nilfs_test_opt(nilfs, NORECOVERY)) {
printk(KERN_INFO "NILFS: norecovery option specified. "
"skipping roll-forward recovery\n");
goto skip_recovery;
}
features = le64_to_cpu(nilfs->ns_sbp[0]->s_feature_compat_ro) &
~NILFS_FEATURE_COMPAT_RO_SUPP;
if (features) {
printk(KERN_ERR "NILFS: couldn't proceed with "
"recovery because of unsupported optional "
"features (%llx)\n",
(unsigned long long)features);
err = -EROFS;
goto failed_unload;
}
if (really_read_only) {
printk(KERN_ERR "NILFS: write access "
"unavailable, cannot proceed.\n");
err = -EROFS;
goto failed_unload;
}
sb->s_flags &= ~MS_RDONLY;
} else if (nilfs_test_opt(nilfs, NORECOVERY)) {
printk(KERN_ERR "NILFS: recovery cancelled because norecovery "
"option was specified for a read/write mount\n");
err = -EINVAL;
goto failed_unload;
}
err = nilfs_salvage_orphan_logs(nilfs, sb, &ri);
if (err)
goto failed_unload;
down_write(&nilfs->ns_sem);
nilfs->ns_mount_state |= NILFS_VALID_FS; /* set "clean" flag */
err = nilfs_cleanup_super(sb);
up_write(&nilfs->ns_sem);
if (err) {
printk(KERN_ERR "NILFS: failed to update super block. "
"recovery unfinished.\n");
goto failed_unload;
}
printk(KERN_INFO "NILFS: recovery complete.\n");
skip_recovery:
nilfs_clear_recovery_info(&ri);
sb->s_flags = s_flags;
return 0;
scan_error:
printk(KERN_ERR "NILFS: error searching super root.\n");
goto failed;
failed_unload:
iput(nilfs->ns_cpfile);
iput(nilfs->ns_sufile);
iput(nilfs->ns_dat);
failed:
nilfs_clear_recovery_info(&ri);
sb->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;
}
/**
* nilfs_nrsvsegs - calculate the number of reserved segments
* @nilfs: nilfs object
* @nsegs: total number of segments
*/
unsigned long nilfs_nrsvsegs(struct the_nilfs *nilfs, unsigned long nsegs)
{
return max_t(unsigned long, NILFS_MIN_NRSVSEGS,
DIV_ROUND_UP(nsegs * nilfs->ns_r_segments_percentage,
100));
}
void nilfs_set_nsegments(struct the_nilfs *nilfs, unsigned long nsegs)
{
nilfs->ns_nsegments = nsegs;
nilfs->ns_nrsvsegs = nilfs_nrsvsegs(nilfs, nsegs);
}
static int nilfs_store_disk_layout(struct the_nilfs *nilfs,
struct nilfs_super_block *sbp)
{
if (le32_to_cpu(sbp->s_rev_level) < NILFS_MIN_SUPP_REV) {
printk(KERN_ERR "NILFS: unsupported revision "
"(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);
if (nilfs->ns_inode_size > nilfs->ns_blocksize) {
printk(KERN_ERR "NILFS: too large inode size: %d bytes.\n",
nilfs->ns_inode_size);
return -EINVAL;
} else if (nilfs->ns_inode_size < NILFS_MIN_INODE_SIZE) {
printk(KERN_ERR "NILFS: too small inode size: %d bytes.\n",
nilfs->ns_inode_size);
return -EINVAL;
}
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_r_segments_percentage =
le32_to_cpu(sbp->s_r_segments_percentage);
if (nilfs->ns_r_segments_percentage < 1 ||
nilfs->ns_r_segments_percentage > 99) {
printk(KERN_ERR "NILFS: invalid reserved segments percentage.\n");
return -EINVAL;
}
nilfs_set_nsegments(nilfs, le64_to_cpu(sbp->s_nsegments));
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 "
"(blocksize = %d)\n", blocksize);
} else if (!sbp[1]) {
printk(KERN_WARNING
"NILFS warning: unable to read secondary superblock "
"(blocksize = %d)\n", blocksize);
}
/*
* Compare two super blocks and set 1 in swp if the secondary
* super block is valid and newer. Otherwise, set 0 in swp.
*/
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_last_cno) >
le64_to_cpu(sbp[0]->s_last_cno));
if (valid[swp] && nilfs_sb2_bad_offset(sbp[swp], sb2off)) {
brelse(sbh[1]);
sbh[1] = NULL;
sbp[1] = NULL;
valid[1] = 0;
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 (!valid[!swp])
printk(KERN_WARNING "NILFS warning: broken superblock. "
"using spare superblock (blocksize = %d).\n", blocksize);
if (swp)
nilfs_swap_super_block(nilfs);
nilfs->ns_sbwcount = 0;
nilfs->ns_sbwtime = le64_to_cpu(sbp[0]->s_wtime);
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
* @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).
*
* Return Value: On success, 0 is returned. On error, a negative error
* code is returned.
*/
int init_nilfs(struct the_nilfs *nilfs, struct super_block *sb, char *data)
{
struct nilfs_super_block *sbp;
int blocksize;
int err;
down_write(&nilfs->ns_sem);
blocksize = sb_min_blocksize(sb, NILFS_MIN_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;
err = nilfs_check_feature_compatibility(sb, sbp);
if (err)
goto failed_sbh;
blocksize = BLOCK_SIZE << le32_to_cpu(sbp->s_log_block_size);
if (blocksize < NILFS_MIN_BLOCK_SIZE ||
blocksize > NILFS_MAX_BLOCK_SIZE) {
printk(KERN_ERR "NILFS: couldn't mount because of unsupported "
"filesystem blocksize %d\n", blocksize);
err = -EINVAL;
goto failed_sbh;
}
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;
nilfs->ns_blocksize = blocksize;
get_random_bytes(&nilfs->ns_next_generation,
sizeof(nilfs->ns_next_generation));
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);
err = nilfs_store_log_cursor(nilfs, sbp);
if (err)
goto failed_sbh;
err = nilfs_sysfs_create_device_group(sb);
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_discard_segments(struct the_nilfs *nilfs, __u64 *segnump,
size_t nsegs)
{
sector_t seg_start, seg_end;
sector_t start = 0, nblocks = 0;
unsigned int sects_per_block;
__u64 *sn;
int ret = 0;
sects_per_block = (1 << nilfs->ns_blocksize_bits) /
bdev_logical_block_size(nilfs->ns_bdev);
for (sn = segnump; sn < segnump + nsegs; sn++) {
nilfs_get_segment_range(nilfs, *sn, &seg_start, &seg_end);
if (!nblocks) {
start = seg_start;
nblocks = seg_end - seg_start + 1;
} else if (start + nblocks == seg_start) {
nblocks += seg_end - seg_start + 1;
} else {
ret = blkdev_issue_discard(nilfs->ns_bdev,
start * sects_per_block,
nblocks * sects_per_block,
GFP_NOFS, 0);
if (ret < 0)
return ret;
nblocks = 0;
}
}
if (nblocks)
ret = blkdev_issue_discard(nilfs->ns_bdev,
start * sects_per_block,
nblocks * sects_per_block,
GFP_NOFS, 0);
return ret;
}
int nilfs_count_free_blocks(struct the_nilfs *nilfs, sector_t *nblocks)
{
unsigned long ncleansegs;
down_read(&NILFS_MDT(nilfs->ns_dat)->mi_sem);
ncleansegs = nilfs_sufile_get_ncleansegs(nilfs->ns_sufile);
up_read(&NILFS_MDT(nilfs->ns_dat)->mi_sem);
*nblocks = (sector_t)ncleansegs * nilfs->ns_blocks_per_segment;
return 0;
}
int nilfs_near_disk_full(struct the_nilfs *nilfs)
{
unsigned long ncleansegs, nincsegs;
ncleansegs = nilfs_sufile_get_ncleansegs(nilfs->ns_sufile);
nincsegs = atomic_read(&nilfs->ns_ndirtyblks) /
nilfs->ns_blocks_per_segment + 1;
return ncleansegs <= nilfs->ns_nrsvsegs + nincsegs;
}
struct nilfs_root *nilfs_lookup_root(struct the_nilfs *nilfs, __u64 cno)
{
struct rb_node *n;
struct nilfs_root *root;
spin_lock(&nilfs->ns_cptree_lock);
n = nilfs->ns_cptree.rb_node;
while (n) {
root = rb_entry(n, struct nilfs_root, rb_node);
if (cno < root->cno) {
n = n->rb_left;
} else if (cno > root->cno) {
n = n->rb_right;
} else {
atomic_inc(&root->count);
spin_unlock(&nilfs->ns_cptree_lock);
return root;
}
}
spin_unlock(&nilfs->ns_cptree_lock);
return NULL;
}
struct nilfs_root *
nilfs_find_or_create_root(struct the_nilfs *nilfs, __u64 cno)
{
struct rb_node **p, *parent;
struct nilfs_root *root, *new;
int err;
root = nilfs_lookup_root(nilfs, cno);
if (root)
return root;
new = kzalloc(sizeof(*root), GFP_KERNEL);
if (!new)
return NULL;
spin_lock(&nilfs->ns_cptree_lock);
p = &nilfs->ns_cptree.rb_node;
parent = NULL;
while (*p) {
parent = *p;
root = rb_entry(parent, struct nilfs_root, rb_node);
if (cno < root->cno) {
p = &(*p)->rb_left;
} else if (cno > root->cno) {
p = &(*p)->rb_right;
} else {
atomic_inc(&root->count);
spin_unlock(&nilfs->ns_cptree_lock);
kfree(new);
return root;
}
}
new->cno = cno;
new->ifile = NULL;
new->nilfs = nilfs;
atomic_set(&new->count, 1);
atomic64_set(&new->inodes_count, 0);
atomic64_set(&new->blocks_count, 0);
rb_link_node(&new->rb_node, parent, p);
rb_insert_color(&new->rb_node, &nilfs->ns_cptree);
spin_unlock(&nilfs->ns_cptree_lock);
err = nilfs_sysfs_create_snapshot_group(new);
if (err) {
kfree(new);
new = NULL;
}
return new;
}
void nilfs_put_root(struct nilfs_root *root)
{
if (atomic_dec_and_test(&root->count)) {
struct the_nilfs *nilfs = root->nilfs;
nilfs_sysfs_delete_snapshot_group(root);
spin_lock(&nilfs->ns_cptree_lock);
rb_erase(&root->rb_node, &nilfs->ns_cptree);
spin_unlock(&nilfs->ns_cptree_lock);
if (root->ifile)
iput(root->ifile);
kfree(root);
}
}
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