super.c

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/*
 *   Copyright (C) International Business Machines Corp., 2000-2004
 *   Portions Copyright (C) Christoph Hellwig, 2001-2002
 *
 *   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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

#include <linux/fs.h>
#include <linux/module.h>
#include <linux/parser.h>
#include <linux/completion.h>
#include <linux/vfs.h>
#include <linux/quotaops.h>
#include <linux/mount.h>
#include <linux/moduleparam.h>
#include <linux/kthread.h>
#include <linux/posix_acl.h>
#include <linux/buffer_head.h>
#include <linux/exportfs.h>
#include <linux/crc32.h>
#include <linux/slab.h>
#include <asm/uaccess.h>
#include <linux/seq_file.h>
#include <linux/blkdev.h>

#include "jfs_incore.h"
#include "jfs_filsys.h"
#include "jfs_inode.h"
#include "jfs_metapage.h"
#include "jfs_superblock.h"
#include "jfs_dmap.h"
#include "jfs_imap.h"
#include "jfs_acl.h"
#include "jfs_debug.h"

MODULE_DESCRIPTION("The Journaled Filesystem (JFS)");
MODULE_AUTHOR("Steve Best/Dave Kleikamp/Barry Arndt, IBM");
MODULE_LICENSE("GPL");

static struct kmem_cache * jfs_inode_cachep;

static const struct super_operations jfs_super_operations;
static const struct export_operations jfs_export_operations;
static struct file_system_type jfs_fs_type;

#define MAX_COMMIT_THREADS 64
static int commit_threads = 0;
module_param(commit_threads, int, 0);
MODULE_PARM_DESC(commit_threads, "Number of commit threads");

static struct task_struct *jfsCommitThread[MAX_COMMIT_THREADS];
struct task_struct *jfsIOthread;
struct task_struct *jfsSyncThread;

#ifdef CONFIG_JFS_DEBUG
int jfsloglevel = JFS_LOGLEVEL_WARN;
module_param(jfsloglevel, int, 0644);
MODULE_PARM_DESC(jfsloglevel, "Specify JFS loglevel (0, 1 or 2)");
#endif

static void jfs_handle_error(struct super_block *sb)
{
    struct jfs_sb_info *sbi = JFS_SBI(sb);

    if (sb->s_flags & MS_RDONLY)
        return;

    updateSuper(sb, FM_DIRTY);

    if (sbi->flag & JFS_ERR_PANIC)
        panic("JFS (device %s): panic forced after error\n",
            sb->s_id);
    else if (sbi->flag & JFS_ERR_REMOUNT_RO) {
        jfs_err("ERROR: (device %s): remounting filesystem "
            "as read-only\n",
            sb->s_id);
        sb->s_flags |= MS_RDONLY;
    }

    /* nothing is done for continue beyond marking the superblock dirty */
}

void jfs_error(struct super_block *sb, const char * function, ...)
{
    static char error_buf[256];
    va_list args;

    va_start(args, function);
    vsnprintf(error_buf, sizeof(error_buf), function, args);
    va_end(args);

    pr_err("ERROR: (device %s): %s\n", sb->s_id, error_buf);

    jfs_handle_error(sb);
}

static struct inode *jfs_alloc_inode(struct super_block *sb)
{
    struct jfs_inode_info *jfs_inode;

    jfs_inode = kmem_cache_alloc(jfs_inode_cachep, GFP_NOFS);
    if (!jfs_inode)
        return NULL;
    return &jfs_inode->vfs_inode;
}

static void jfs_i_callback(struct rcu_head *head)
{
    struct inode *inode = container_of(head, struct inode, i_rcu);
    struct jfs_inode_info *ji = JFS_IP(inode);
    kmem_cache_free(jfs_inode_cachep, ji);
}

static void jfs_destroy_inode(struct inode *inode)
{
    struct jfs_inode_info *ji = JFS_IP(inode);

    BUG_ON(!list_empty(&ji->anon_inode_list));

    spin_lock_irq(&ji->ag_lock);
    if (ji->active_ag != -1) {
        struct bmap *bmap = JFS_SBI(inode->i_sb)->bmap;
        atomic_dec(&bmap->db_active[ji->active_ag]);
        ji->active_ag = -1;
    }
    spin_unlock_irq(&ji->ag_lock);
    call_rcu(&inode->i_rcu, jfs_i_callback);
}

static int jfs_statfs(struct dentry *dentry, struct kstatfs *buf)
{
    struct jfs_sb_info *sbi = JFS_SBI(dentry->d_sb);
    s64 maxinodes;
    struct inomap *imap = JFS_IP(sbi->ipimap)->i_imap;

    jfs_info("In jfs_statfs");
    buf->f_type = JFS_SUPER_MAGIC;
    buf->f_bsize = sbi->bsize;
    buf->f_blocks = sbi->bmap->db_mapsize;
    buf->f_bfree = sbi->bmap->db_nfree;
    buf->f_bavail = sbi->bmap->db_nfree;
    /*
     * If we really return the number of allocated & free inodes, some
     * applications will fail because they won't see enough free inodes.
     * We'll try to calculate some guess as to how may inodes we can
     * really allocate
     *
     * buf->f_files = atomic_read(&imap->im_numinos);
     * buf->f_ffree = atomic_read(&imap->im_numfree);
     */
    maxinodes = min((s64) atomic_read(&imap->im_numinos) +
            ((sbi->bmap->db_nfree >> imap->im_l2nbperiext)
             << L2INOSPEREXT), (s64) 0xffffffffLL);
    buf->f_files = maxinodes;
    buf->f_ffree = maxinodes - (atomic_read(&imap->im_numinos) -
                    atomic_read(&imap->im_numfree));
    buf->f_fsid.val[0] = (u32)crc32_le(0, sbi->uuid, sizeof(sbi->uuid)/2);
    buf->f_fsid.val[1] = (u32)crc32_le(0, sbi->uuid + sizeof(sbi->uuid)/2,
                    sizeof(sbi->uuid)/2);

    buf->f_namelen = JFS_NAME_MAX;
    return 0;
}

static void jfs_put_super(struct super_block *sb)
{
    struct jfs_sb_info *sbi = JFS_SBI(sb);
    int rc;

    jfs_info("In jfs_put_super");

    dquot_disable(sb, -1, DQUOT_USAGE_ENABLED | DQUOT_LIMITS_ENABLED);

    rc = jfs_umount(sb);
    if (rc)
        jfs_err("jfs_umount failed with return code %d", rc);

    unload_nls(sbi->nls_tab);

    truncate_inode_pages(sbi->direct_inode->i_mapping, 0);
    iput(sbi->direct_inode);

    kfree(sbi);
}

enum {
    Opt_integrity, Opt_nointegrity, Opt_iocharset, Opt_resize,
    Opt_resize_nosize, Opt_errors, Opt_ignore, Opt_err, Opt_quota,
    Opt_usrquota, Opt_grpquota, Opt_uid, Opt_gid, Opt_umask,
    Opt_discard, Opt_nodiscard, Opt_discard_minblk
};

static const match_table_t tokens = {
    {Opt_integrity, "integrity"},
    {Opt_nointegrity, "nointegrity"},
    {Opt_iocharset, "iocharset=%s"},
    {Opt_resize, "resize=%u"},
    {Opt_resize_nosize, "resize"},
    {Opt_errors, "errors=%s"},
    {Opt_ignore, "noquota"},
    {Opt_ignore, "quota"},
    {Opt_usrquota, "usrquota"},
    {Opt_grpquota, "grpquota"},
    {Opt_uid, "uid=%u"},
    {Opt_gid, "gid=%u"},
    {Opt_umask, "umask=%u"},
    {Opt_discard, "discard"},
    {Opt_nodiscard, "nodiscard"},
    {Opt_discard_minblk, "discard=%u"},
    {Opt_err, NULL}
};

static int parse_options(char *options, struct super_block *sb, s64 *newLVSize,
             int *flag)
{
    void *nls_map = (void *)-1; /* -1: no change;  NULL: none */
    char *p;
    struct jfs_sb_info *sbi = JFS_SBI(sb);

    *newLVSize = 0;

    if (!options)
        return 1;

    while ((p = strsep(&options, ",")) != NULL) {
        substring_t args[MAX_OPT_ARGS];
        int token;
        if (!*p)
            continue;

        token = match_token(p, tokens, args);
        switch (token) {
        case Opt_integrity:
            *flag &= ~JFS_NOINTEGRITY;
            break;
        case Opt_nointegrity:
            *flag |= JFS_NOINTEGRITY;
            break;
        case Opt_ignore:
            /* Silently ignore the quota options */
            /* Don't do anything ;-) */
            break;
        case Opt_iocharset:
            if (nls_map && nls_map != (void *) -1)
                unload_nls(nls_map);
            if (!strcmp(args[0].from, "none"))
                nls_map = NULL;
            else {
                nls_map = load_nls(args[0].from);
                if (!nls_map) {
                    pr_err("JFS: charset not found\n");
                    goto cleanup;
                }
            }
            break;
        case Opt_resize:
        {
            char *resize = args[0].from;
            *newLVSize = simple_strtoull(resize, &resize, 0);
            break;
        }
        case Opt_resize_nosize:
        {
            *newLVSize = sb->s_bdev->bd_inode->i_size >>
                sb->s_blocksize_bits;
            if (*newLVSize == 0)
                pr_err("JFS: Cannot determine volume size\n");
            break;
        }
        case Opt_errors:
        {
            char *errors = args[0].from;
            if (!errors || !*errors)
                goto cleanup;
            if (!strcmp(errors, "continue")) {
                *flag &= ~JFS_ERR_REMOUNT_RO;
                *flag &= ~JFS_ERR_PANIC;
                *flag |= JFS_ERR_CONTINUE;
            } else if (!strcmp(errors, "remount-ro")) {
                *flag &= ~JFS_ERR_CONTINUE;
                *flag &= ~JFS_ERR_PANIC;
                *flag |= JFS_ERR_REMOUNT_RO;
            } else if (!strcmp(errors, "panic")) {
                *flag &= ~JFS_ERR_CONTINUE;
                *flag &= ~JFS_ERR_REMOUNT_RO;
                *flag |= JFS_ERR_PANIC;
            } else {
                pr_err("JFS: %s is an invalid error handler\n",
                       errors);
                goto cleanup;
            }
            break;
        }

#ifdef CONFIG_QUOTA
        case Opt_quota:
        case Opt_usrquota:
            *flag |= JFS_USRQUOTA;
            break;
        case Opt_grpquota:
            *flag |= JFS_GRPQUOTA;
            break;
#else
        case Opt_usrquota:
        case Opt_grpquota:
        case Opt_quota:
            pr_err("JFS: quota operations not supported\n");
            break;
#endif
        case Opt_uid:
        {
            char *uid = args[0].from;
            uid_t val = simple_strtoul(uid, &uid, 0);
            sbi->uid = make_kuid(current_user_ns(), val);
            if (!uid_valid(sbi->uid))
                goto cleanup;
            break;
        }

        case Opt_gid:
        {
            char *gid = args[0].from;
            gid_t val = simple_strtoul(gid, &gid, 0);
            sbi->gid = make_kgid(current_user_ns(), val);
            if (!gid_valid(sbi->gid))
                goto cleanup;
            break;
        }

        case Opt_umask:
        {
            char *umask = args[0].from;
            sbi->umask = simple_strtoul(umask, &umask, 8);
            if (sbi->umask & ~0777) {
                pr_err("JFS: Invalid value of umask\n");
                goto cleanup;
            }
            break;
        }

        case Opt_discard:
        {
            struct request_queue *q = bdev_get_queue(sb->s_bdev);
            /* if set to 1, even copying files will cause
             * trimming :O
             * -> user has more control over the online trimming
             */
            sbi->minblks_trim = 64;
            if (blk_queue_discard(q)) {
                *flag |= JFS_DISCARD;
            } else {
                pr_err("JFS: discard option " \
                    "not supported on device\n");
            }
            break;
        }

        case Opt_nodiscard:
            *flag &= ~JFS_DISCARD;
            break;

        case Opt_discard_minblk:
        {
            struct request_queue *q = bdev_get_queue(sb->s_bdev);
            char *minblks_trim = args[0].from;
            if (blk_queue_discard(q)) {
                *flag |= JFS_DISCARD;
                sbi->minblks_trim = simple_strtoull(
                    minblks_trim, &minblks_trim, 0);
            } else {
                pr_err("JFS: discard option " \
                    "not supported on device\n");
            }
            break;
        }

        default:
            printk("jfs: Unrecognized mount option \"%s\" "
                    " or missing value\n", p);
            goto cleanup;
        }
    }

    if (nls_map != (void *) -1) {
        /* Discard old (if remount) */
        unload_nls(sbi->nls_tab);
        sbi->nls_tab = nls_map;
    }
    return 1;

cleanup:
    if (nls_map && nls_map != (void *) -1)
        unload_nls(nls_map);
    return 0;
}

static int jfs_remount(struct super_block *sb, int *flags, char *data)
{
    s64 newLVSize = 0;
    int rc = 0;
    int flag = JFS_SBI(sb)->flag;
    int ret;

    if (!parse_options(data, sb, &newLVSize, &flag)) {
        return -EINVAL;
    }

    if (newLVSize) {
        if (sb->s_flags & MS_RDONLY) {
            pr_err("JFS: resize requires volume" \
                " to be mounted read-write\n");
            return -EROFS;
        }
        rc = jfs_extendfs(sb, newLVSize, 0);
        if (rc)
            return rc;
    }

    if ((sb->s_flags & MS_RDONLY) && !(*flags & MS_RDONLY)) {
        /*
         * Invalidate any previously read metadata.  fsck may have
         * changed the on-disk data since we mounted r/o
         */
        truncate_inode_pages(JFS_SBI(sb)->direct_inode->i_mapping, 0);

        JFS_SBI(sb)->flag = flag;
        ret = jfs_mount_rw(sb, 1);

        /* mark the fs r/w for quota activity */
        sb->s_flags &= ~MS_RDONLY;

        dquot_resume(sb, -1);
        return ret;
    }
    if ((!(sb->s_flags & MS_RDONLY)) && (*flags & MS_RDONLY)) {
        rc = dquot_suspend(sb, -1);
        if (rc < 0) {
            return rc;
        }
        rc = jfs_umount_rw(sb);
        JFS_SBI(sb)->flag = flag;
        return rc;
    }
    if ((JFS_SBI(sb)->flag & JFS_NOINTEGRITY) != (flag & JFS_NOINTEGRITY))
        if (!(sb->s_flags & MS_RDONLY)) {
            rc = jfs_umount_rw(sb);
            if (rc)
                return rc;

            JFS_SBI(sb)->flag = flag;
            ret = jfs_mount_rw(sb, 1);
            return ret;
        }
    JFS_SBI(sb)->flag = flag;

    return 0;
}

static int jfs_fill_super(struct super_block *sb, void *data, int silent)
{
    struct jfs_sb_info *sbi;
    struct inode *inode;
    int rc;
    s64 newLVSize = 0;
    int flag, ret = -EINVAL;

    jfs_info("In jfs_read_super: s_flags=0x%lx", sb->s_flags);

    if (!new_valid_dev(sb->s_bdev->bd_dev))
        return -EOVERFLOW;

    sbi = kzalloc(sizeof (struct jfs_sb_info), GFP_KERNEL);
    if (!sbi)
        return -ENOMEM;

    sb->s_fs_info = sbi;
    sb->s_max_links = JFS_LINK_MAX;
    sbi->sb = sb;
    sbi->uid = INVALID_UID;
    sbi->gid = INVALID_GID;
    sbi->umask = -1;

    /* initialize the mount flag and determine the default error handler */
    flag = JFS_ERR_REMOUNT_RO;

    if (!parse_options((char *) data, sb, &newLVSize, &flag))
        goto out_kfree;
    sbi->flag = flag;

#ifdef CONFIG_JFS_POSIX_ACL
    sb->s_flags |= MS_POSIXACL;
#endif

    if (newLVSize) {
        pr_err("resize option for remount only\n");
        goto out_kfree;
    }

    /*
     * Initialize blocksize to 4K.
     */
    sb_set_blocksize(sb, PSIZE);

    /*
     * Set method vectors.
     */
    sb->s_op = &jfs_super_operations;
    sb->s_export_op = &jfs_export_operations;
#ifdef CONFIG_QUOTA
    sb->dq_op = &dquot_operations;
    sb->s_qcop = &dquot_quotactl_ops;
#endif

    /*
     * Initialize direct-mapping inode/address-space
     */
    inode = new_inode(sb);
    if (inode == NULL) {
        ret = -ENOMEM;
        goto out_unload;
    }
    inode->i_ino = 0;
    inode->i_size = sb->s_bdev->bd_inode->i_size;
    inode->i_mapping->a_ops = &jfs_metapage_aops;
    insert_inode_hash(inode);
    mapping_set_gfp_mask(inode->i_mapping, GFP_NOFS);

    sbi->direct_inode = inode;

    rc = jfs_mount(sb);
    if (rc) {
        if (!silent) {
            jfs_err("jfs_mount failed w/return code = %d", rc);
        }
        goto out_mount_failed;
    }
    if (sb->s_flags & MS_RDONLY)
        sbi->log = NULL;
    else {
        rc = jfs_mount_rw(sb, 0);
        if (rc) {
            if (!silent) {
                jfs_err("jfs_mount_rw failed, return code = %d",
                    rc);
            }
            goto out_no_rw;
        }
    }

    sb->s_magic = JFS_SUPER_MAGIC;

    if (sbi->mntflag & JFS_OS2)
        sb->s_d_op = &jfs_ci_dentry_operations;

    inode = jfs_iget(sb, ROOT_I);
    if (IS_ERR(inode)) {
        ret = PTR_ERR(inode);
        goto out_no_rw;
    }
    sb->s_root = d_make_root(inode);
    if (!sb->s_root)
        goto out_no_root;

    /* logical blocks are represented by 40 bits in pxd_t, etc. */
    sb->s_maxbytes = ((u64) sb->s_blocksize) << 40;
#if BITS_PER_LONG == 32
    /*
     * Page cache is indexed by long.
     * I would use MAX_LFS_FILESIZE, but it's only half as big
     */
    sb->s_maxbytes = min(((u64) PAGE_CACHE_SIZE << 32) - 1, (u64)sb->s_maxbytes);
#endif
    sb->s_time_gran = 1;
    return 0;

out_no_root:
    jfs_err("jfs_read_super: get root dentry failed");

out_no_rw:
    rc = jfs_umount(sb);
    if (rc) {
        jfs_err("jfs_umount failed with return code %d", rc);
    }
out_mount_failed:
    filemap_write_and_wait(sbi->direct_inode->i_mapping);
    truncate_inode_pages(sbi->direct_inode->i_mapping, 0);
    make_bad_inode(sbi->direct_inode);
    iput(sbi->direct_inode);
    sbi->direct_inode = NULL;
out_unload:
    if (sbi->nls_tab)
        unload_nls(sbi->nls_tab);
out_kfree:
    kfree(sbi);
    return ret;
}

static int jfs_freeze(struct super_block *sb)
{
    struct jfs_sb_info *sbi = JFS_SBI(sb);
    struct jfs_log *log = sbi->log;

    if (!(sb->s_flags & MS_RDONLY)) {
        txQuiesce(sb);
        lmLogShutdown(log);
        updateSuper(sb, FM_CLEAN);
    }
    return 0;
}

static int jfs_unfreeze(struct super_block *sb)
{
    struct jfs_sb_info *sbi = JFS_SBI(sb);
    struct jfs_log *log = sbi->log;
    int rc = 0;

    if (!(sb->s_flags & MS_RDONLY)) {
        updateSuper(sb, FM_MOUNT);
        if ((rc = lmLogInit(log)))
            jfs_err("jfs_unlock failed with return code %d", rc);
        else
            txResume(sb);
    }
    return 0;
}

static struct dentry *jfs_do_mount(struct file_system_type *fs_type,
    int flags, const char *dev_name, void *data)
{
    return mount_bdev(fs_type, flags, dev_name, data, jfs_fill_super);
}

static int jfs_sync_fs(struct super_block *sb, int wait)
{
    struct jfs_log *log = JFS_SBI(sb)->log;

    /* log == NULL indicates read-only mount */
    if (log) {
        /*
         * Write quota structures to quota file, sync_blockdev() will
         * write them to disk later
         */
        dquot_writeback_dquots(sb, -1);
        jfs_flush_journal(log, wait);
        jfs_syncpt(log, 0);
    }

    return 0;
}

static int jfs_show_options(struct seq_file *seq, struct dentry *root)
{
    struct jfs_sb_info *sbi = JFS_SBI(root->d_sb);

    if (uid_valid(sbi->uid))
        seq_printf(seq, ",uid=%d", from_kuid(&init_user_ns, sbi->uid));
    if (gid_valid(sbi->gid))
        seq_printf(seq, ",gid=%d", from_kgid(&init_user_ns, sbi->gid));
    if (sbi->umask != -1)
        seq_printf(seq, ",umask=%03o", sbi->umask);
    if (sbi->flag & JFS_NOINTEGRITY)
        seq_puts(seq, ",nointegrity");
    if (sbi->flag & JFS_DISCARD)
        seq_printf(seq, ",discard=%u", sbi->minblks_trim);
    if (sbi->nls_tab)
        seq_printf(seq, ",iocharset=%s", sbi->nls_tab->charset);
    if (sbi->flag & JFS_ERR_CONTINUE)
        seq_printf(seq, ",errors=continue");
    if (sbi->flag & JFS_ERR_PANIC)
        seq_printf(seq, ",errors=panic");

#ifdef CONFIG_QUOTA
    if (sbi->flag & JFS_USRQUOTA)
        seq_puts(seq, ",usrquota");

    if (sbi->flag & JFS_GRPQUOTA)
        seq_puts(seq, ",grpquota");
#endif

    return 0;
}

#ifdef CONFIG_QUOTA

/* Read data from quotafile - avoid pagecache and such because we cannot afford
 * acquiring the locks... As quota files are never truncated and quota code
 * itself serializes the operations (and no one else should touch the files)
 * we don't have to be afraid of races */
static ssize_t jfs_quota_read(struct super_block *sb, int type, char *data,
                  size_t len, loff_t off)
{
    struct inode *inode = sb_dqopt(sb)->files[type];
    sector_t blk = off >> sb->s_blocksize_bits;
    int err = 0;
    int offset = off & (sb->s_blocksize - 1);
    int tocopy;
    size_t toread;
    struct buffer_head tmp_bh;
    struct buffer_head *bh;
    loff_t i_size = i_size_read(inode);

    if (off > i_size)
        return 0;
    if (off+len > i_size)
        len = i_size-off;
    toread = len;
    while (toread > 0) {
        tocopy = sb->s_blocksize - offset < toread ?
                sb->s_blocksize - offset : toread;

        tmp_bh.b_state = 0;
        tmp_bh.b_size = 1 << inode->i_blkbits;
        err = jfs_get_block(inode, blk, &tmp_bh, 0);
        if (err)
            return err;
        if (!buffer_mapped(&tmp_bh))    /* A hole? */
            memset(data, 0, tocopy);
        else {
            bh = sb_bread(sb, tmp_bh.b_blocknr);
            if (!bh)
                return -EIO;
            memcpy(data, bh->b_data+offset, tocopy);
            brelse(bh);
        }
        offset = 0;
        toread -= tocopy;
        data += tocopy;
        blk++;
    }
    return len;
}

/* Write to quotafile */
static ssize_t jfs_quota_write(struct super_block *sb, int type,
                   const char *data, size_t len, loff_t off)
{
    struct inode *inode = sb_dqopt(sb)->files[type];
    sector_t blk = off >> sb->s_blocksize_bits;
    int err = 0;
    int offset = off & (sb->s_blocksize - 1);
    int tocopy;
    size_t towrite = len;
    struct buffer_head tmp_bh;
    struct buffer_head *bh;

    mutex_lock(&inode->i_mutex);
    while (towrite > 0) {
        tocopy = sb->s_blocksize - offset < towrite ?
                sb->s_blocksize - offset : towrite;

        tmp_bh.b_state = 0;
        tmp_bh.b_size = 1 << inode->i_blkbits;
        err = jfs_get_block(inode, blk, &tmp_bh, 1);
        if (err)
            goto out;
        if (offset || tocopy != sb->s_blocksize)
            bh = sb_bread(sb, tmp_bh.b_blocknr);
        else
            bh = sb_getblk(sb, tmp_bh.b_blocknr);
        if (!bh) {
            err = -EIO;
            goto out;
        }
        lock_buffer(bh);
        memcpy(bh->b_data+offset, data, tocopy);
        flush_dcache_page(bh->b_page);
        set_buffer_uptodate(bh);
        mark_buffer_dirty(bh);
        unlock_buffer(bh);
        brelse(bh);
        offset = 0;
        towrite -= tocopy;
        data += tocopy;
        blk++;
    }
out:
    if (len == towrite) {
        mutex_unlock(&inode->i_mutex);
        return err;
    }
    if (inode->i_size < off+len-towrite)
        i_size_write(inode, off+len-towrite);
    inode->i_version++;
    inode->i_mtime = inode->i_ctime = CURRENT_TIME;
    mark_inode_dirty(inode);
    mutex_unlock(&inode->i_mutex);
    return len - towrite;
}

#endif

static const struct super_operations jfs_super_operations = {
    .alloc_inode    = jfs_alloc_inode,
    .destroy_inode  = jfs_destroy_inode,
    .dirty_inode    = jfs_dirty_inode,
    .write_inode    = jfs_write_inode,
    .evict_inode    = jfs_evict_inode,
    .put_super  = jfs_put_super,
    .sync_fs    = jfs_sync_fs,
    .freeze_fs  = jfs_freeze,
    .unfreeze_fs    = jfs_unfreeze,
    .statfs     = jfs_statfs,
    .remount_fs = jfs_remount,
    .show_options   = jfs_show_options,
#ifdef CONFIG_QUOTA
    .quota_read = jfs_quota_read,
    .quota_write    = jfs_quota_write,
#endif
};

static const struct export_operations jfs_export_operations = {
    .fh_to_dentry   = jfs_fh_to_dentry,
    .fh_to_parent   = jfs_fh_to_parent,
    .get_parent = jfs_get_parent,
};

static struct file_system_type jfs_fs_type = {
    .owner      = THIS_MODULE,
    .name       = "jfs",
    .mount      = jfs_do_mount,
    .kill_sb    = kill_block_super,
    .fs_flags   = FS_REQUIRES_DEV,
};

static void init_once(void *foo)
{
    struct jfs_inode_info *jfs_ip = (struct jfs_inode_info *) foo;

    memset(jfs_ip, 0, sizeof(struct jfs_inode_info));
    INIT_LIST_HEAD(&jfs_ip->anon_inode_list);
    init_rwsem(&jfs_ip->rdwrlock);
    mutex_init(&jfs_ip->commit_mutex);
    init_rwsem(&jfs_ip->xattr_sem);
    spin_lock_init(&jfs_ip->ag_lock);
    jfs_ip->active_ag = -1;
    inode_init_once(&jfs_ip->vfs_inode);
}

static int __init init_jfs_fs(void)
{
    int i;
    int rc;

    jfs_inode_cachep =
        kmem_cache_create("jfs_ip", sizeof(struct jfs_inode_info), 0,
                SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD,
                init_once);
    if (jfs_inode_cachep == NULL)
        return -ENOMEM;

    /*
     * Metapage initialization
     */
    rc = metapage_init();
    if (rc) {
        jfs_err("metapage_init failed w/rc = %d", rc);
        goto free_slab;
    }

    /*
     * Transaction Manager initialization
     */
    rc = txInit();
    if (rc) {
        jfs_err("txInit failed w/rc = %d", rc);
        goto free_metapage;
    }

    /*
     * I/O completion thread (endio)
     */
    jfsIOthread = kthread_run(jfsIOWait, NULL, "jfsIO");
    if (IS_ERR(jfsIOthread)) {
        rc = PTR_ERR(jfsIOthread);
        jfs_err("init_jfs_fs: fork failed w/rc = %d", rc);
        goto end_txmngr;
    }

    if (commit_threads < 1)
        commit_threads = num_online_cpus();
    if (commit_threads > MAX_COMMIT_THREADS)
        commit_threads = MAX_COMMIT_THREADS;

    for (i = 0; i < commit_threads; i++) {
        jfsCommitThread[i] = kthread_run(jfs_lazycommit, NULL, "jfsCommit");
        if (IS_ERR(jfsCommitThread[i])) {
            rc = PTR_ERR(jfsCommitThread[i]);
            jfs_err("init_jfs_fs: fork failed w/rc = %d", rc);
            commit_threads = i;
            goto kill_committask;
        }
    }

    jfsSyncThread = kthread_run(jfs_sync, NULL, "jfsSync");
    if (IS_ERR(jfsSyncThread)) {
        rc = PTR_ERR(jfsSyncThread);
        jfs_err("init_jfs_fs: fork failed w/rc = %d", rc);
        goto kill_committask;
    }

#ifdef PROC_FS_JFS
    jfs_proc_init();
#endif

    rc = register_filesystem(&jfs_fs_type);
    if (!rc)
        return 0;

#ifdef PROC_FS_JFS
    jfs_proc_clean();
#endif
    kthread_stop(jfsSyncThread);
kill_committask:
    for (i = 0; i < commit_threads; i++)
        kthread_stop(jfsCommitThread[i]);
    kthread_stop(jfsIOthread);
end_txmngr:
    txExit();
free_metapage:
    metapage_exit();
free_slab:
    kmem_cache_destroy(jfs_inode_cachep);
    return rc;
}

static void __exit exit_jfs_fs(void)
{
    int i;

    jfs_info("exit_jfs_fs called");

    txExit();
    metapage_exit();

    kthread_stop(jfsIOthread);
    for (i = 0; i < commit_threads; i++)
        kthread_stop(jfsCommitThread[i]);
    kthread_stop(jfsSyncThread);
#ifdef PROC_FS_JFS
    jfs_proc_clean();
#endif
    unregister_filesystem(&jfs_fs_type);

    /*
     * Make sure all delayed rcu free inodes are flushed before we
     * destroy cache.
     */
    rcu_barrier();
    kmem_cache_destroy(jfs_inode_cachep);
}

module_init(init_jfs_fs)
module_exit(exit_jfs_fs)