Linux-2.6.33.2/fs/nilfs2/the_nilfs.c
/*
* 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_destroy(nilfs->ns_sufile);
nilfs_mdt_destroy(nilfs->ns_cpfile);
nilfs_mdt_destroy(nilfs->ns_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)
{
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_dat_new(nilfs, dat_entry_size);
if (unlikely(!nilfs->ns_dat))
goto failed;
nilfs->ns_gc_dat = nilfs_dat_new(nilfs, dat_entry_size);
if (unlikely(!nilfs->ns_gc_dat))
goto failed_dat;
nilfs->ns_cpfile = nilfs_cpfile_new(nilfs, checkpoint_size);
if (unlikely(!nilfs->ns_cpfile))
goto failed_gc_dat;
nilfs->ns_sufile = nilfs_sufile_new(nilfs, segment_usage_size);
if (unlikely(!nilfs->ns_sufile))
goto failed_cpfile;
nilfs_mdt_set_shadow(nilfs->ns_dat, nilfs->ns_gc_dat);
err = nilfs_dat_read(nilfs->ns_dat, (void *)bh_sr->b_data +
NILFS_SR_DAT_OFFSET(inode_size));
if (unlikely(err))
goto failed_sufile;
err = nilfs_cpfile_read(nilfs->ns_cpfile, (void *)bh_sr->b_data +
NILFS_SR_CPFILE_OFFSET(inode_size));
if (unlikely(err))
goto failed_sufile;
err = nilfs_sufile_read(nilfs->ns_sufile, (void *)bh_sr->b_data +
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);
int valid_fs = nilfs_valid_fs(nilfs);
int err;
if (nilfs_loaded(nilfs)) {
if (valid_fs ||
((s_flags & MS_RDONLY) && nilfs_test_opt(sbi, NORECOVERY)))
return 0;
printk(KERN_ERR "NILFS: the filesystem is in an incomplete "
"recovery state.\n");
return -EINVAL;
}
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, 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)
goto skip_recovery;
if (s_flags & MS_RDONLY) {
if (nilfs_test_opt(sbi, NORECOVERY)) {
printk(KERN_INFO "NILFS: norecovery option specified. "
"skipping roll-forward recovery\n");
goto skip_recovery;
}
if (really_read_only) {
printk(KERN_ERR "NILFS: write access "
"unavailable, cannot proceed.\n");
err = -EROFS;
goto failed_unload;
}
sbi->s_super->s_flags &= ~MS_RDONLY;
} else if (nilfs_test_opt(sbi, 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_recover_logical_segments(nilfs, sbi, &ri);
if (err)
goto failed_unload;
down_write(&nilfs->ns_sem);
nilfs->ns_mount_state |= NILFS_VALID_FS;
nilfs->ns_sbp[0]->s_state = cpu_to_le16(nilfs->ns_mount_state);
err = nilfs_commit_super(sbi, 1);
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:
set_nilfs_loaded(nilfs);
nilfs_clear_recovery_info(&ri);
sbi->s_super->s_flags = s_flags;
return 0;
failed_unload:
nilfs_mdt_destroy(nilfs->ns_cpfile);
nilfs_mdt_destroy(nilfs->ns_sufile);
nilfs_mdt_destroy(nilfs->ns_dat);
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;
down_read(&NILFS_MDT(dat)->mi_sem); /* XXX */
ncleansegs = nilfs_sufile_get_ncleansegs(nilfs->ns_sufile);
up_read(&NILFS_MDT(dat)->mi_sem); /* XXX */
*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;
}
/**
* 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;
}