ARM: 7747/1: pcpu: ensure __my_cpu_offset cannot be re-ordered across barrier()

[linux/fpc-iii.git] / fs / jfs / super.c

/*
 *   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 many 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,
};
MODULE_ALIAS_FS("jfs");

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)