GFS2: Move quota bitmap operations under their own lock

[deliverable/linux.git] / fs / gfs2 / ops_fstype.c

/*
 * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
 * Copyright (C) 2004-2008 Red Hat, Inc.  All rights reserved.
 *
 * This copyrighted material is made available to anyone wishing to use,
 * modify, copy, or redistribute it subject to the terms and conditions
 * of the GNU General Public License version 2.
 */

#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/completion.h>
#include <linux/buffer_head.h>
#include <linux/blkdev.h>
#include <linux/kthread.h>
#include <linux/export.h>
#include <linux/namei.h>
#include <linux/mount.h>
#include <linux/gfs2_ondisk.h>
#include <linux/quotaops.h>
#include <linux/lockdep.h>
#include <linux/module.h>

#include "gfs2.h"
#include "incore.h"
#include "bmap.h"
#include "glock.h"
#include "glops.h"
#include "inode.h"
#include "recovery.h"
#include "rgrp.h"
#include "super.h"
#include "sys.h"
#include "util.h"
#include "log.h"
#include "quota.h"
#include "dir.h"
#include "meta_io.h"
#include "trace_gfs2.h"

#define DO 0
#define UNDO 1

/**
 * gfs2_tune_init - Fill a gfs2_tune structure with default values
 * @gt: tune
 *
 */

static void gfs2_tune_init(struct gfs2_tune *gt)
{
        spin_lock_init(&gt->gt_spin);

        gt->gt_quota_warn_period = 10;
        gt->gt_quota_scale_num = 1;
        gt->gt_quota_scale_den = 1;
        gt->gt_new_files_jdata = 0;
        gt->gt_max_readahead = 1 << 18;
        gt->gt_complain_secs = 10;
}

static struct gfs2_sbd *init_sbd(struct super_block *sb)
{
        struct gfs2_sbd *sdp;
        struct address_space *mapping;

        sdp = kzalloc(sizeof(struct gfs2_sbd), GFP_KERNEL);
        if (!sdp)
                return NULL;

        sb->s_fs_info = sdp;
        sdp->sd_vfs = sb;
        sdp->sd_lkstats = alloc_percpu(struct gfs2_pcpu_lkstats);
        if (!sdp->sd_lkstats) {
                kfree(sdp);
                return NULL;
        }

        set_bit(SDF_NOJOURNALID, &sdp->sd_flags);
        gfs2_tune_init(&sdp->sd_tune);

        init_waitqueue_head(&sdp->sd_glock_wait);
        atomic_set(&sdp->sd_glock_disposal, 0);
        init_completion(&sdp->sd_locking_init);
        init_completion(&sdp->sd_wdack);
        spin_lock_init(&sdp->sd_statfs_spin);

        spin_lock_init(&sdp->sd_rindex_spin);
        sdp->sd_rindex_tree.rb_node = NULL;

        INIT_LIST_HEAD(&sdp->sd_jindex_list);
        spin_lock_init(&sdp->sd_jindex_spin);
        mutex_init(&sdp->sd_jindex_mutex);

        INIT_LIST_HEAD(&sdp->sd_quota_list);
        mutex_init(&sdp->sd_quota_mutex);
        mutex_init(&sdp->sd_quota_sync_mutex);
        init_waitqueue_head(&sdp->sd_quota_wait);
        INIT_LIST_HEAD(&sdp->sd_trunc_list);
        spin_lock_init(&sdp->sd_trunc_lock);
        spin_lock_init(&sdp->sd_bitmap_lock);

        mapping = &sdp->sd_aspace;

        address_space_init_once(mapping);
        mapping->a_ops = &gfs2_meta_aops;
        mapping->host = sb->s_bdev->bd_inode;
        mapping->flags = 0;
        mapping_set_gfp_mask(mapping, GFP_NOFS);
        mapping->private_data = NULL;
        mapping->backing_dev_info = sb->s_bdi;
        mapping->writeback_index = 0;

        spin_lock_init(&sdp->sd_log_lock);
        atomic_set(&sdp->sd_log_pinned, 0);
        INIT_LIST_HEAD(&sdp->sd_log_le_buf);
        INIT_LIST_HEAD(&sdp->sd_log_le_revoke);
        INIT_LIST_HEAD(&sdp->sd_log_le_databuf);
        INIT_LIST_HEAD(&sdp->sd_log_le_ordered);
        spin_lock_init(&sdp->sd_ordered_lock);

        init_waitqueue_head(&sdp->sd_log_waitq);
        init_waitqueue_head(&sdp->sd_logd_waitq);
        spin_lock_init(&sdp->sd_ail_lock);
        INIT_LIST_HEAD(&sdp->sd_ail1_list);
        INIT_LIST_HEAD(&sdp->sd_ail2_list);

        init_rwsem(&sdp->sd_log_flush_lock);
        atomic_set(&sdp->sd_log_in_flight, 0);
        init_waitqueue_head(&sdp->sd_log_flush_wait);

        INIT_LIST_HEAD(&sdp->sd_revoke_list);

        return sdp;
}


/**
 * gfs2_check_sb - Check superblock
 * @sdp: the filesystem
 * @sb: The superblock
 * @silent: Don't print a message if the check fails
 *
 * Checks the version code of the FS is one that we understand how to
 * read and that the sizes of the various on-disk structures have not
 * changed.
 */

static int gfs2_check_sb(struct gfs2_sbd *sdp, int silent)
{
        struct gfs2_sb_host *sb = &sdp->sd_sb;

        if (sb->sb_magic != GFS2_MAGIC ||
            sb->sb_type != GFS2_METATYPE_SB) {
                if (!silent)
                        printk(KERN_WARNING "GFS2: not a GFS2 filesystem\n");
                return -EINVAL;
        }

        /*  If format numbers match exactly, we're done.  */

        if (sb->sb_fs_format == GFS2_FORMAT_FS &&
            sb->sb_multihost_format == GFS2_FORMAT_MULTI)
                return 0;

        fs_warn(sdp, "Unknown on-disk format, unable to mount\n");

        return -EINVAL;
}

static void end_bio_io_page(struct bio *bio, int error)
{
        struct page *page = bio->bi_private;

        if (!error)
                SetPageUptodate(page);
        else
                printk(KERN_WARNING "gfs2: error %d reading superblock\n", error);
        unlock_page(page);
}

static void gfs2_sb_in(struct gfs2_sbd *sdp, const void *buf)
{
        struct gfs2_sb_host *sb = &sdp->sd_sb;
        struct super_block *s = sdp->sd_vfs;
        const struct gfs2_sb *str = buf;

        sb->sb_magic = be32_to_cpu(str->sb_header.mh_magic);
        sb->sb_type = be32_to_cpu(str->sb_header.mh_type);
        sb->sb_format = be32_to_cpu(str->sb_header.mh_format);
        sb->sb_fs_format = be32_to_cpu(str->sb_fs_format);
        sb->sb_multihost_format = be32_to_cpu(str->sb_multihost_format);
        sb->sb_bsize = be32_to_cpu(str->sb_bsize);
        sb->sb_bsize_shift = be32_to_cpu(str->sb_bsize_shift);
        sb->sb_master_dir.no_addr = be64_to_cpu(str->sb_master_dir.no_addr);
        sb->sb_master_dir.no_formal_ino = be64_to_cpu(str->sb_master_dir.no_formal_ino);
        sb->sb_root_dir.no_addr = be64_to_cpu(str->sb_root_dir.no_addr);
        sb->sb_root_dir.no_formal_ino = be64_to_cpu(str->sb_root_dir.no_formal_ino);

        memcpy(sb->sb_lockproto, str->sb_lockproto, GFS2_LOCKNAME_LEN);
        memcpy(sb->sb_locktable, str->sb_locktable, GFS2_LOCKNAME_LEN);
        memcpy(s->s_uuid, str->sb_uuid, 16);
}

/**
 * gfs2_read_super - Read the gfs2 super block from disk
 * @sdp: The GFS2 super block
 * @sector: The location of the super block
 * @error: The error code to return
 *
 * This uses the bio functions to read the super block from disk
 * because we want to be 100% sure that we never read cached data.
 * A super block is read twice only during each GFS2 mount and is
 * never written to by the filesystem. The first time its read no
 * locks are held, and the only details which are looked at are those
 * relating to the locking protocol. Once locking is up and working,
 * the sb is read again under the lock to establish the location of
 * the master directory (contains pointers to journals etc) and the
 * root directory.
 *
 * Returns: 0 on success or error
 */

static int gfs2_read_super(struct gfs2_sbd *sdp, sector_t sector, int silent)
{
        struct super_block *sb = sdp->sd_vfs;
        struct gfs2_sb *p;
        struct page *page;
        struct bio *bio;

        page = alloc_page(GFP_NOFS);
        if (unlikely(!page))
                return -ENOBUFS;

        ClearPageUptodate(page);
        ClearPageDirty(page);
        lock_page(page);

        bio = bio_alloc(GFP_NOFS, 1);
        bio->bi_sector = sector * (sb->s_blocksize >> 9);
        bio->bi_bdev = sb->s_bdev;
        bio_add_page(bio, page, PAGE_SIZE, 0);

        bio->bi_end_io = end_bio_io_page;
        bio->bi_private = page;
        submit_bio(READ_SYNC | REQ_META, bio);
        wait_on_page_locked(page);
        bio_put(bio);
        if (!PageUptodate(page)) {
                __free_page(page);
                return -EIO;
        }
        p = kmap(page);
        gfs2_sb_in(sdp, p);
        kunmap(page);
        __free_page(page);
        return gfs2_check_sb(sdp, silent);
}

/**
 * gfs2_read_sb - Read super block
 * @sdp: The GFS2 superblock
 * @silent: Don't print message if mount fails
 *
 */

static int gfs2_read_sb(struct gfs2_sbd *sdp, int silent)
{
        u32 hash_blocks, ind_blocks, leaf_blocks;
        u32 tmp_blocks;
        unsigned int x;
        int error;

        error = gfs2_read_super(sdp, GFS2_SB_ADDR >> sdp->sd_fsb2bb_shift, silent);
        if (error) {
                if (!silent)
                        fs_err(sdp, "can't read superblock\n");
                return error;
        }

        sdp->sd_fsb2bb_shift = sdp->sd_sb.sb_bsize_shift -
                               GFS2_BASIC_BLOCK_SHIFT;
        sdp->sd_fsb2bb = 1 << sdp->sd_fsb2bb_shift;
        sdp->sd_diptrs = (sdp->sd_sb.sb_bsize -
                          sizeof(struct gfs2_dinode)) / sizeof(u64);
        sdp->sd_inptrs = (sdp->sd_sb.sb_bsize -
                          sizeof(struct gfs2_meta_header)) / sizeof(u64);
        sdp->sd_jbsize = sdp->sd_sb.sb_bsize - sizeof(struct gfs2_meta_header);
        sdp->sd_hash_bsize = sdp->sd_sb.sb_bsize / 2;
        sdp->sd_hash_bsize_shift = sdp->sd_sb.sb_bsize_shift - 1;
        sdp->sd_hash_ptrs = sdp->sd_hash_bsize / sizeof(u64);
        sdp->sd_qc_per_block = (sdp->sd_sb.sb_bsize -
                                sizeof(struct gfs2_meta_header)) /
                                sizeof(struct gfs2_quota_change);
        sdp->sd_blocks_per_bitmap = (sdp->sd_sb.sb_bsize -
                                     sizeof(struct gfs2_meta_header))
                * GFS2_NBBY; /* not the rgrp bitmap, subsequent bitmaps only */

        /* Compute maximum reservation required to add a entry to a directory */

        hash_blocks = DIV_ROUND_UP(sizeof(u64) * (1 << GFS2_DIR_MAX_DEPTH),
                             sdp->sd_jbsize);

        ind_blocks = 0;
        for (tmp_blocks = hash_blocks; tmp_blocks > sdp->sd_diptrs;) {
                tmp_blocks = DIV_ROUND_UP(tmp_blocks, sdp->sd_inptrs);
                ind_blocks += tmp_blocks;
        }

        leaf_blocks = 2 + GFS2_DIR_MAX_DEPTH;

        sdp->sd_max_dirres = hash_blocks + ind_blocks + leaf_blocks;

        sdp->sd_heightsize[0] = sdp->sd_sb.sb_bsize -
                                sizeof(struct gfs2_dinode);
        sdp->sd_heightsize[1] = sdp->sd_sb.sb_bsize * sdp->sd_diptrs;
        for (x = 2;; x++) {
                u64 space, d;
                u32 m;

                space = sdp->sd_heightsize[x - 1] * sdp->sd_inptrs;
                d = space;
                m = do_div(d, sdp->sd_inptrs);

                if (d != sdp->sd_heightsize[x - 1] || m)
                        break;
                sdp->sd_heightsize[x] = space;
        }
        sdp->sd_max_height = x;
        sdp->sd_heightsize[x] = ~0;
        gfs2_assert(sdp, sdp->sd_max_height <= GFS2_MAX_META_HEIGHT);

        sdp->sd_jheightsize[0] = sdp->sd_sb.sb_bsize -
                                 sizeof(struct gfs2_dinode);
        sdp->sd_jheightsize[1] = sdp->sd_jbsize * sdp->sd_diptrs;
        for (x = 2;; x++) {
                u64 space, d;
                u32 m;

                space = sdp->sd_jheightsize[x - 1] * sdp->sd_inptrs;
                d = space;
                m = do_div(d, sdp->sd_inptrs);

                if (d != sdp->sd_jheightsize[x - 1] || m)
                        break;
                sdp->sd_jheightsize[x] = space;
        }
        sdp->sd_max_jheight = x;
        sdp->sd_jheightsize[x] = ~0;
        gfs2_assert(sdp, sdp->sd_max_jheight <= GFS2_MAX_META_HEIGHT);

        return 0;
}

static int init_names(struct gfs2_sbd *sdp, int silent)
{
        char *proto, *table;
        int error = 0;

        proto = sdp->sd_args.ar_lockproto;
        table = sdp->sd_args.ar_locktable;

        /*  Try to autodetect  */

        if (!proto[0] || !table[0]) {
                error = gfs2_read_super(sdp, GFS2_SB_ADDR >> sdp->sd_fsb2bb_shift, silent);
                if (error)
                        return error;

                if (!proto[0])
                        proto = sdp->sd_sb.sb_lockproto;
                if (!table[0])
                        table = sdp->sd_sb.sb_locktable;
        }

        if (!table[0])
                table = sdp->sd_vfs->s_id;

        strlcpy(sdp->sd_proto_name, proto, GFS2_FSNAME_LEN);
        strlcpy(sdp->sd_table_name, table, GFS2_FSNAME_LEN);

        table = sdp->sd_table_name;
        while ((table = strchr(table, '/')))
                *table = '_';

        return error;
}

static int init_locking(struct gfs2_sbd *sdp, struct gfs2_holder *mount_gh,
                        int undo)
{
        int error = 0;

        if (undo)
                goto fail_trans;

        error = gfs2_glock_nq_num(sdp,
                                  GFS2_MOUNT_LOCK, &gfs2_nondisk_glops,
                                  LM_ST_EXCLUSIVE, LM_FLAG_NOEXP | GL_NOCACHE,
                                  mount_gh);
        if (error) {
                fs_err(sdp, "can't acquire mount glock: %d\n", error);
                goto fail;
        }

        error = gfs2_glock_nq_num(sdp,
                                  GFS2_LIVE_LOCK, &gfs2_nondisk_glops,
                                  LM_ST_SHARED,
                                  LM_FLAG_NOEXP | GL_EXACT,
                                  &sdp->sd_live_gh);
        if (error) {
                fs_err(sdp, "can't acquire live glock: %d\n", error);
                goto fail_mount;
        }

        error = gfs2_glock_get(sdp, GFS2_RENAME_LOCK, &gfs2_nondisk_glops,
                               CREATE, &sdp->sd_rename_gl);
        if (error) {
                fs_err(sdp, "can't create rename glock: %d\n", error);
                goto fail_live;
        }

        error = gfs2_glock_get(sdp, GFS2_TRANS_LOCK, &gfs2_trans_glops,
                               CREATE, &sdp->sd_trans_gl);
        if (error) {
                fs_err(sdp, "can't create transaction glock: %d\n", error);
                goto fail_rename;
        }

        return 0;

fail_trans:
        gfs2_glock_put(sdp->sd_trans_gl);
fail_rename:
        gfs2_glock_put(sdp->sd_rename_gl);
fail_live:
        gfs2_glock_dq_uninit(&sdp->sd_live_gh);
fail_mount:
        gfs2_glock_dq_uninit(mount_gh);
fail:
        return error;
}

static int gfs2_lookup_root(struct super_block *sb, struct dentry **dptr,
                            u64 no_addr, const char *name)
{
        struct gfs2_sbd *sdp = sb->s_fs_info;
        struct dentry *dentry;
        struct inode *inode;

        inode = gfs2_inode_lookup(sb, DT_DIR, no_addr, 0, 0);
        if (IS_ERR(inode)) {
                fs_err(sdp, "can't read in %s inode: %ld\n", name, PTR_ERR(inode));
                return PTR_ERR(inode);
        }
        dentry = d_make_root(inode);
        if (!dentry) {
                fs_err(sdp, "can't alloc %s dentry\n", name);
                return -ENOMEM;
        }
        *dptr = dentry;
        return 0;
}

static int init_sb(struct gfs2_sbd *sdp, int silent)
{
        struct super_block *sb = sdp->sd_vfs;
        struct gfs2_holder sb_gh;
        u64 no_addr;
        int ret;

        ret = gfs2_glock_nq_num(sdp, GFS2_SB_LOCK, &gfs2_meta_glops,
                                LM_ST_SHARED, 0, &sb_gh);
        if (ret) {
                fs_err(sdp, "can't acquire superblock glock: %d\n", ret);
                return ret;
        }

        ret = gfs2_read_sb(sdp, silent);
        if (ret) {
                fs_err(sdp, "can't read superblock: %d\n", ret);
                goto out;
        }

        /* Set up the buffer cache and SB for real */
        if (sdp->sd_sb.sb_bsize < bdev_logical_block_size(sb->s_bdev)) {
                ret = -EINVAL;
                fs_err(sdp, "FS block size (%u) is too small for device "
                       "block size (%u)\n",
                       sdp->sd_sb.sb_bsize, bdev_logical_block_size(sb->s_bdev));
                goto out;
        }
        if (sdp->sd_sb.sb_bsize > PAGE_SIZE) {
                ret = -EINVAL;
                fs_err(sdp, "FS block size (%u) is too big for machine "
                       "page size (%u)\n",
                       sdp->sd_sb.sb_bsize, (unsigned int)PAGE_SIZE);
                goto out;
        }
        sb_set_blocksize(sb, sdp->sd_sb.sb_bsize);

        /* Get the root inode */
        no_addr = sdp->sd_sb.sb_root_dir.no_addr;
        ret = gfs2_lookup_root(sb, &sdp->sd_root_dir, no_addr, "root");
        if (ret)
                goto out;

        /* Get the master inode */
        no_addr = sdp->sd_sb.sb_master_dir.no_addr;
        ret = gfs2_lookup_root(sb, &sdp->sd_master_dir, no_addr, "master");
        if (ret) {
                dput(sdp->sd_root_dir);
                goto out;
        }
        sb->s_root = dget(sdp->sd_args.ar_meta ? sdp->sd_master_dir : sdp->sd_root_dir);
out:
        gfs2_glock_dq_uninit(&sb_gh);
        return ret;
}

/**
 * map_journal_extents - create a reusable "extent" mapping from all logical
 * blocks to all physical blocks for the given journal.  This will save
 * us time when writing journal blocks.  Most journals will have only one
 * extent that maps all their logical blocks.  That's because gfs2.mkfs
 * arranges the journal blocks sequentially to maximize performance.
 * So the extent would map the first block for the entire file length.
 * However, gfs2_jadd can happen while file activity is happening, so
 * those journals may not be sequential.  Less likely is the case where
 * the users created their own journals by mounting the metafs and
 * laying it out.  But it's still possible.  These journals might have
 * several extents.
 *
 * TODO: This should be done in bigger chunks rather than one block at a time,
 *       but since it's only done at mount time, I'm not worried about the
 *       time it takes.
 */
static int map_journal_extents(struct gfs2_sbd *sdp)
{
        struct gfs2_jdesc *jd = sdp->sd_jdesc;
        unsigned int lb;
        u64 db, prev_db; /* logical block, disk block, prev disk block */
        struct gfs2_inode *ip = GFS2_I(jd->jd_inode);
        struct gfs2_journal_extent *jext = NULL;
        struct buffer_head bh;
        int rc = 0;

        prev_db = 0;

        for (lb = 0; lb < i_size_read(jd->jd_inode) >> sdp->sd_sb.sb_bsize_shift; lb++) {
                bh.b_state = 0;
                bh.b_blocknr = 0;
                bh.b_size = 1 << ip->i_inode.i_blkbits;
                rc = gfs2_block_map(jd->jd_inode, lb, &bh, 0);
                db = bh.b_blocknr;
                if (rc || !db) {
                        printk(KERN_INFO "GFS2 journal mapping error %d: lb="
                               "%u db=%llu\n", rc, lb, (unsigned long long)db);
                        break;
                }
                if (!prev_db || db != prev_db + 1) {
                        jext = kzalloc(sizeof(struct gfs2_journal_extent),
                                       GFP_KERNEL);
                        if (!jext) {
                                printk(KERN_INFO "GFS2 error: out of memory "
                                       "mapping journal extents.\n");
                                rc = -ENOMEM;
                                break;
                        }
                        jext->dblock = db;
                        jext->lblock = lb;
                        jext->blocks = 1;
                        list_add_tail(&jext->extent_list, &jd->extent_list);
                } else {
                        jext->blocks++;
                }
                prev_db = db;
        }
        return rc;
}

static void gfs2_others_may_mount(struct gfs2_sbd *sdp)
{
        char *message = "FIRSTMOUNT=Done";
        char *envp[] = { message, NULL };

        fs_info(sdp, "first mount done, others may mount\n");

        if (sdp->sd_lockstruct.ls_ops->lm_first_done)
                sdp->sd_lockstruct.ls_ops->lm_first_done(sdp);

        kobject_uevent_env(&sdp->sd_kobj, KOBJ_CHANGE, envp);
}

/**
 * gfs2_jindex_hold - Grab a lock on the jindex
 * @sdp: The GFS2 superblock
 * @ji_gh: the holder for the jindex glock
 *
 * Returns: errno
 */

static int gfs2_jindex_hold(struct gfs2_sbd *sdp, struct gfs2_holder *ji_gh)
{
        struct gfs2_inode *dip = GFS2_I(sdp->sd_jindex);
        struct qstr name;
        char buf[20];
        struct gfs2_jdesc *jd;
        int error;

        name.name = buf;

        mutex_lock(&sdp->sd_jindex_mutex);

        for (;;) {
                error = gfs2_glock_nq_init(dip->i_gl, LM_ST_SHARED, 0, ji_gh);
                if (error)
                        break;

                name.len = sprintf(buf, "journal%u", sdp->sd_journals);
                name.hash = gfs2_disk_hash(name.name, name.len);

                error = gfs2_dir_check(sdp->sd_jindex, &name, NULL);
                if (error == -ENOENT) {
                        error = 0;
                        break;
                }

                gfs2_glock_dq_uninit(ji_gh);

                if (error)
                        break;

                error = -ENOMEM;
                jd = kzalloc(sizeof(struct gfs2_jdesc), GFP_KERNEL);
                if (!jd)
                        break;

                INIT_LIST_HEAD(&jd->extent_list);
                INIT_WORK(&jd->jd_work, gfs2_recover_func);
                jd->jd_inode = gfs2_lookupi(sdp->sd_jindex, &name, 1);
                if (!jd->jd_inode || IS_ERR(jd->jd_inode)) {
                        if (!jd->jd_inode)
                                error = -ENOENT;
                        else
                                error = PTR_ERR(jd->jd_inode);
                        kfree(jd);
                        break;
                }

                spin_lock(&sdp->sd_jindex_spin);
                jd->jd_jid = sdp->sd_journals++;
                list_add_tail(&jd->jd_list, &sdp->sd_jindex_list);
                spin_unlock(&sdp->sd_jindex_spin);
        }

        mutex_unlock(&sdp->sd_jindex_mutex);

        return error;
}

/**
 * check_journal_clean - Make sure a journal is clean for a spectator mount
 * @sdp: The GFS2 superblock
 * @jd: The journal descriptor
 *
 * Returns: 0 if the journal is clean or locked, else an error
 */
static int check_journal_clean(struct gfs2_sbd *sdp, struct gfs2_jdesc *jd)
{
        int error;
        struct gfs2_holder j_gh;
        struct gfs2_log_header_host head;
        struct gfs2_inode *ip;

        ip = GFS2_I(jd->jd_inode);
        error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_NOEXP |
                                   GL_EXACT | GL_NOCACHE, &j_gh);
        if (error) {
                fs_err(sdp, "Error locking journal for spectator mount.\n");
                return -EPERM;
        }
        error = gfs2_jdesc_check(jd);
        if (error) {
                fs_err(sdp, "Error checking journal for spectator mount.\n");
                goto out_unlock;
        }
        error = gfs2_find_jhead(jd, &head);
        if (error) {
                fs_err(sdp, "Error parsing journal for spectator mount.\n");
                goto out_unlock;
        }
        if (!(head.lh_flags & GFS2_LOG_HEAD_UNMOUNT)) {
                error = -EPERM;
                fs_err(sdp, "jid=%u: Journal is dirty, so the first mounter "
                       "must not be a spectator.\n", jd->jd_jid);
        }

out_unlock:
        gfs2_glock_dq_uninit(&j_gh);
        return error;
}

static int init_journal(struct gfs2_sbd *sdp, int undo)
{
        struct inode *master = sdp->sd_master_dir->d_inode;
        struct gfs2_holder ji_gh;
        struct gfs2_inode *ip;
        int jindex = 1;
        int error = 0;

        if (undo) {
                jindex = 0;
                goto fail_jinode_gh;
        }

        sdp->sd_jindex = gfs2_lookup_simple(master, "jindex");
        if (IS_ERR(sdp->sd_jindex)) {
                fs_err(sdp, "can't lookup journal index: %d\n", error);
                return PTR_ERR(sdp->sd_jindex);
        }

        /* Load in the journal index special file */

        error = gfs2_jindex_hold(sdp, &ji_gh);
        if (error) {
                fs_err(sdp, "can't read journal index: %d\n", error);
                goto fail;
        }

        error = -EUSERS;
        if (!gfs2_jindex_size(sdp)) {
                fs_err(sdp, "no journals!\n");
                goto fail_jindex;
        }

        if (sdp->sd_args.ar_spectator) {
                sdp->sd_jdesc = gfs2_jdesc_find(sdp, 0);
                atomic_set(&sdp->sd_log_blks_free, sdp->sd_jdesc->jd_blocks);
                atomic_set(&sdp->sd_log_thresh1, 2*sdp->sd_jdesc->jd_blocks/5);
                atomic_set(&sdp->sd_log_thresh2, 4*sdp->sd_jdesc->jd_blocks/5);
        } else {
                if (sdp->sd_lockstruct.ls_jid >= gfs2_jindex_size(sdp)) {
                        fs_err(sdp, "can't mount journal #%u\n",
                               sdp->sd_lockstruct.ls_jid);
                        fs_err(sdp, "there are only %u journals (0 - %u)\n",
                               gfs2_jindex_size(sdp),
                               gfs2_jindex_size(sdp) - 1);
                        goto fail_jindex;
                }
                sdp->sd_jdesc = gfs2_jdesc_find(sdp, sdp->sd_lockstruct.ls_jid);

                error = gfs2_glock_nq_num(sdp, sdp->sd_lockstruct.ls_jid,
                                          &gfs2_journal_glops,
                                          LM_ST_EXCLUSIVE, LM_FLAG_NOEXP,
                                          &sdp->sd_journal_gh);
                if (error) {
                        fs_err(sdp, "can't acquire journal glock: %d\n", error);
                        goto fail_jindex;
                }

                ip = GFS2_I(sdp->sd_jdesc->jd_inode);
                error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED,
                                           LM_FLAG_NOEXP | GL_EXACT | GL_NOCACHE,
                                           &sdp->sd_jinode_gh);
                if (error) {
                        fs_err(sdp, "can't acquire journal inode glock: %d\n",
                               error);
                        goto fail_journal_gh;
                }

                error = gfs2_jdesc_check(sdp->sd_jdesc);
                if (error) {
                        fs_err(sdp, "my journal (%u) is bad: %d\n",
                               sdp->sd_jdesc->jd_jid, error);
                        goto fail_jinode_gh;
                }
                atomic_set(&sdp->sd_log_blks_free, sdp->sd_jdesc->jd_blocks);
                atomic_set(&sdp->sd_log_thresh1, 2*sdp->sd_jdesc->jd_blocks/5);
                atomic_set(&sdp->sd_log_thresh2, 4*sdp->sd_jdesc->jd_blocks/5);

                /* Map the extents for this journal's blocks */
                map_journal_extents(sdp);
        }
        trace_gfs2_log_blocks(sdp, atomic_read(&sdp->sd_log_blks_free));

        if (sdp->sd_lockstruct.ls_first) {
                unsigned int x;
                for (x = 0; x < sdp->sd_journals; x++) {
                        struct gfs2_jdesc *jd = gfs2_jdesc_find(sdp, x);

                        if (sdp->sd_args.ar_spectator) {
                                error = check_journal_clean(sdp, jd);
                                if (error)
                                        goto fail_jinode_gh;
                                continue;
                        }
                        error = gfs2_recover_journal(jd, true);
                        if (error) {
                                fs_err(sdp, "error recovering journal %u: %d\n",
                                       x, error);
                                goto fail_jinode_gh;
                        }
                }

                gfs2_others_may_mount(sdp);
        } else if (!sdp->sd_args.ar_spectator) {
                error = gfs2_recover_journal(sdp->sd_jdesc, true);
                if (error) {
                        fs_err(sdp, "error recovering my journal: %d\n", error);
                        goto fail_jinode_gh;
                }
        }

        set_bit(SDF_JOURNAL_CHECKED, &sdp->sd_flags);
        gfs2_glock_dq_uninit(&ji_gh);
        jindex = 0;

        return 0;

fail_jinode_gh:
        if (!sdp->sd_args.ar_spectator)
                gfs2_glock_dq_uninit(&sdp->sd_jinode_gh);
fail_journal_gh:
        if (!sdp->sd_args.ar_spectator)
                gfs2_glock_dq_uninit(&sdp->sd_journal_gh);
fail_jindex:
        gfs2_jindex_free(sdp);
        if (jindex)
                gfs2_glock_dq_uninit(&ji_gh);
fail:
        iput(sdp->sd_jindex);
        return error;
}

static struct lock_class_key gfs2_quota_imutex_key;

static int init_inodes(struct gfs2_sbd *sdp, int undo)
{
        int error = 0;
        struct inode *master = sdp->sd_master_dir->d_inode;

        if (undo)
                goto fail_qinode;

        error = init_journal(sdp, undo);
        if (error)
                goto fail;

        /* Read in the master statfs inode */
        sdp->sd_statfs_inode = gfs2_lookup_simple(master, "statfs");
        if (IS_ERR(sdp->sd_statfs_inode)) {
                error = PTR_ERR(sdp->sd_statfs_inode);
                fs_err(sdp, "can't read in statfs inode: %d\n", error);
                goto fail_journal;
        }

        /* Read in the resource index inode */
        sdp->sd_rindex = gfs2_lookup_simple(master, "rindex");
        if (IS_ERR(sdp->sd_rindex)) {
                error = PTR_ERR(sdp->sd_rindex);
                fs_err(sdp, "can't get resource index inode: %d\n", error);
                goto fail_statfs;
        }
        sdp->sd_rindex_uptodate = 0;

        /* Read in the quota inode */
        sdp->sd_quota_inode = gfs2_lookup_simple(master, "quota");
        if (IS_ERR(sdp->sd_quota_inode)) {
                error = PTR_ERR(sdp->sd_quota_inode);
                fs_err(sdp, "can't get quota file inode: %d\n", error);
                goto fail_rindex;
        }
        /*
         * i_mutex on quota files is special. Since this inode is hidden system
         * file, we are safe to define locking ourselves.
         */
        lockdep_set_class(&sdp->sd_quota_inode->i_mutex,
                          &gfs2_quota_imutex_key);

        error = gfs2_rindex_update(sdp);
        if (error)
                goto fail_qinode;

        return 0;

fail_qinode:
        iput(sdp->sd_quota_inode);
fail_rindex:
        gfs2_clear_rgrpd(sdp);
        iput(sdp->sd_rindex);
fail_statfs:
        iput(sdp->sd_statfs_inode);
fail_journal:
        init_journal(sdp, UNDO);
fail:
        return error;
}

static int init_per_node(struct gfs2_sbd *sdp, int undo)
{
        struct inode *pn = NULL;
        char buf[30];
        int error = 0;
        struct gfs2_inode *ip;
        struct inode *master = sdp->sd_master_dir->d_inode;

        if (sdp->sd_args.ar_spectator)
                return 0;

        if (undo)
                goto fail_qc_gh;

        pn = gfs2_lookup_simple(master, "per_node");
        if (IS_ERR(pn)) {
                error = PTR_ERR(pn);
                fs_err(sdp, "can't find per_node directory: %d\n", error);
                return error;
        }

        sprintf(buf, "statfs_change%u", sdp->sd_jdesc->jd_jid);
        sdp->sd_sc_inode = gfs2_lookup_simple(pn, buf);
        if (IS_ERR(sdp->sd_sc_inode)) {
                error = PTR_ERR(sdp->sd_sc_inode);
                fs_err(sdp, "can't find local \"sc\" file: %d\n", error);
                goto fail;
        }

        sprintf(buf, "quota_change%u", sdp->sd_jdesc->jd_jid);
        sdp->sd_qc_inode = gfs2_lookup_simple(pn, buf);
        if (IS_ERR(sdp->sd_qc_inode)) {
                error = PTR_ERR(sdp->sd_qc_inode);
                fs_err(sdp, "can't find local \"qc\" file: %d\n", error);
                goto fail_ut_i;
        }

        iput(pn);
        pn = NULL;

        ip = GFS2_I(sdp->sd_sc_inode);
        error = gfs2_glock_nq_init(ip->i_gl, LM_ST_EXCLUSIVE, 0,
                                   &sdp->sd_sc_gh);
        if (error) {
                fs_err(sdp, "can't lock local \"sc\" file: %d\n", error);
                goto fail_qc_i;
        }

        ip = GFS2_I(sdp->sd_qc_inode);
        error = gfs2_glock_nq_init(ip->i_gl, LM_ST_EXCLUSIVE, 0,
                                   &sdp->sd_qc_gh);
        if (error) {
                fs_err(sdp, "can't lock local \"qc\" file: %d\n", error);
                goto fail_ut_gh;
        }

        return 0;

fail_qc_gh:
        gfs2_glock_dq_uninit(&sdp->sd_qc_gh);
fail_ut_gh:
        gfs2_glock_dq_uninit(&sdp->sd_sc_gh);
fail_qc_i:
        iput(sdp->sd_qc_inode);
fail_ut_i:
        iput(sdp->sd_sc_inode);
fail:
        if (pn)
                iput(pn);
        return error;
}

static const match_table_t nolock_tokens = {
        { Opt_jid, "jid=%d\n", },
        { Opt_err, NULL },
};

static const struct lm_lockops nolock_ops = {
        .lm_proto_name = "lock_nolock",
        .lm_put_lock = gfs2_glock_free,
        .lm_tokens = &nolock_tokens,
};

/**
 * gfs2_lm_mount - mount a locking protocol
 * @sdp: the filesystem
 * @args: mount arguments
 * @silent: if 1, don't complain if the FS isn't a GFS2 fs
 *
 * Returns: errno
 */

static int gfs2_lm_mount(struct gfs2_sbd *sdp, int silent)
{
        const struct lm_lockops *lm;
        struct lm_lockstruct *ls = &sdp->sd_lockstruct;
        struct gfs2_args *args = &sdp->sd_args;
        const char *proto = sdp->sd_proto_name;
        const char *table = sdp->sd_table_name;
        char *o, *options;
        int ret;

        if (!strcmp("lock_nolock", proto)) {
                lm = &nolock_ops;
                sdp->sd_args.ar_localflocks = 1;
#ifdef CONFIG_GFS2_FS_LOCKING_DLM
        } else if (!strcmp("lock_dlm", proto)) {
                lm = &gfs2_dlm_ops;
#endif
        } else {
                printk(KERN_INFO "GFS2: can't find protocol %s\n", proto);
                return -ENOENT;
        }

        fs_info(sdp, "Trying to join cluster \"%s\", \"%s\"\n", proto, table);

        ls->ls_ops = lm;
        ls->ls_first = 1;

        for (options = args->ar_hostdata; (o = strsep(&options, ":")); ) {
                substring_t tmp[MAX_OPT_ARGS];
                int token, option;

                if (!o || !*o)
                        continue;

                token = match_token(o, *lm->lm_tokens, tmp);
                switch (token) {
                case Opt_jid:
                        ret = match_int(&tmp[0], &option);
                        if (ret || option < 0) 
                                goto hostdata_error;
                        if (test_and_clear_bit(SDF_NOJOURNALID, &sdp->sd_flags))
                                ls->ls_jid = option;
                        break;
                case Opt_id:
                case Opt_nodir:
                        /* Obsolete, but left for backward compat purposes */
                        break;
                case Opt_first:
                        ret = match_int(&tmp[0], &option);
                        if (ret || (option != 0 && option != 1))
                                goto hostdata_error;
                        ls->ls_first = option;
                        break;
                case Opt_err:
                default:
hostdata_error:
                        fs_info(sdp, "unknown hostdata (%s)\n", o);
                        return -EINVAL;
                }
        }

        if (lm->lm_mount == NULL) {
                fs_info(sdp, "Now mounting FS...\n");
                complete_all(&sdp->sd_locking_init);
                return 0;
        }
        ret = lm->lm_mount(sdp, table);
        if (ret == 0)
                fs_info(sdp, "Joined cluster. Now mounting FS...\n");
        complete_all(&sdp->sd_locking_init);
        return ret;
}

void gfs2_lm_unmount(struct gfs2_sbd *sdp)
{
        const struct lm_lockops *lm = sdp->sd_lockstruct.ls_ops;
        if (likely(!test_bit(SDF_SHUTDOWN, &sdp->sd_flags)) &&
            lm->lm_unmount)
                lm->lm_unmount(sdp);
}

static int gfs2_journalid_wait(void *word)
{
        if (signal_pending(current))
                return -EINTR;
        schedule();
        return 0;
}

static int wait_on_journal(struct gfs2_sbd *sdp)
{
        if (sdp->sd_lockstruct.ls_ops->lm_mount == NULL)
                return 0;

        return wait_on_bit(&sdp->sd_flags, SDF_NOJOURNALID, gfs2_journalid_wait, TASK_INTERRUPTIBLE);
}

void gfs2_online_uevent(struct gfs2_sbd *sdp)
{
        struct super_block *sb = sdp->sd_vfs;
        char ro[20];
        char spectator[20];
        char *envp[] = { ro, spectator, NULL };
        sprintf(ro, "RDONLY=%d", (sb->s_flags & MS_RDONLY) ? 1 : 0);
        sprintf(spectator, "SPECTATOR=%d", sdp->sd_args.ar_spectator ? 1 : 0);
        kobject_uevent_env(&sdp->sd_kobj, KOBJ_ONLINE, envp);
}

/**
 * fill_super - Read in superblock
 * @sb: The VFS superblock
 * @data: Mount options
 * @silent: Don't complain if it's not a GFS2 filesystem
 *
 * Returns: errno
 */

static int fill_super(struct super_block *sb, struct gfs2_args *args, int silent)
{
        struct gfs2_sbd *sdp;
        struct gfs2_holder mount_gh;
        int error;

        sdp = init_sbd(sb);
        if (!sdp) {
                printk(KERN_WARNING "GFS2: can't alloc struct gfs2_sbd\n");
                return -ENOMEM;
        }
        sdp->sd_args = *args;

        if (sdp->sd_args.ar_spectator) {
                sb->s_flags |= MS_RDONLY;
                set_bit(SDF_RORECOVERY, &sdp->sd_flags);
        }
        if (sdp->sd_args.ar_posix_acl)
                sb->s_flags |= MS_POSIXACL;
        if (sdp->sd_args.ar_nobarrier)
                set_bit(SDF_NOBARRIERS, &sdp->sd_flags);

        sb->s_flags |= MS_NOSEC;
        sb->s_magic = GFS2_MAGIC;
        sb->s_op = &gfs2_super_ops;
        sb->s_d_op = &gfs2_dops;
        sb->s_export_op = &gfs2_export_ops;
        sb->s_xattr = gfs2_xattr_handlers;
        sb->s_qcop = &gfs2_quotactl_ops;
        sb_dqopt(sb)->flags |= DQUOT_QUOTA_SYS_FILE;
        sb->s_time_gran = 1;
        sb->s_maxbytes = MAX_LFS_FILESIZE;

        /* Set up the buffer cache and fill in some fake block size values
           to allow us to read-in the on-disk superblock. */
        sdp->sd_sb.sb_bsize = sb_min_blocksize(sb, GFS2_BASIC_BLOCK);
        sdp->sd_sb.sb_bsize_shift = sb->s_blocksize_bits;
        sdp->sd_fsb2bb_shift = sdp->sd_sb.sb_bsize_shift -
                               GFS2_BASIC_BLOCK_SHIFT;
        sdp->sd_fsb2bb = 1 << sdp->sd_fsb2bb_shift;

        sdp->sd_tune.gt_logd_secs = sdp->sd_args.ar_commit;
        sdp->sd_tune.gt_quota_quantum = sdp->sd_args.ar_quota_quantum;
        if (sdp->sd_args.ar_statfs_quantum) {
                sdp->sd_tune.gt_statfs_slow = 0;
                sdp->sd_tune.gt_statfs_quantum = sdp->sd_args.ar_statfs_quantum;
        } else {
                sdp->sd_tune.gt_statfs_slow = 1;
                sdp->sd_tune.gt_statfs_quantum = 30;
        }

        error = init_names(sdp, silent);
        if (error) {
                /* In this case, we haven't initialized sysfs, so we have to
                   manually free the sdp. */
                free_percpu(sdp->sd_lkstats);
                kfree(sdp);
                sb->s_fs_info = NULL;
                return error;
        }

        snprintf(sdp->sd_fsname, GFS2_FSNAME_LEN, "%s", sdp->sd_table_name);

        error = gfs2_sys_fs_add(sdp);
        /*
         * If we hit an error here, gfs2_sys_fs_add will have called function
         * kobject_put which causes the sysfs usage count to go to zero, which
         * causes sysfs to call function gfs2_sbd_release, which frees sdp.
         * Subsequent error paths here will call gfs2_sys_fs_del, which also
         * kobject_put to free sdp.
         */
        if (error)
                return error;

        gfs2_create_debugfs_file(sdp);

        error = gfs2_lm_mount(sdp, silent);
        if (error)
                goto fail_debug;

        error = init_locking(sdp, &mount_gh, DO);
        if (error)
                goto fail_lm;

        error = init_sb(sdp, silent);
        if (error)
                goto fail_locking;

        error = wait_on_journal(sdp);
        if (error)
                goto fail_sb;

        /*
         * If user space has failed to join the cluster or some similar
         * failure has occurred, then the journal id will contain a
         * negative (error) number. This will then be returned to the
         * caller (of the mount syscall). We do this even for spectator
         * mounts (which just write a jid of 0 to indicate "ok" even though
         * the jid is unused in the spectator case)
         */
        if (sdp->sd_lockstruct.ls_jid < 0) {
                error = sdp->sd_lockstruct.ls_jid;
                sdp->sd_lockstruct.ls_jid = 0;
                goto fail_sb;
        }

        if (sdp->sd_args.ar_spectator)
                snprintf(sdp->sd_fsname, GFS2_FSNAME_LEN, "%s.s",
                         sdp->sd_table_name);
        else
                snprintf(sdp->sd_fsname, GFS2_FSNAME_LEN, "%s.%u",
                         sdp->sd_table_name, sdp->sd_lockstruct.ls_jid);

        error = init_inodes(sdp, DO);
        if (error)
                goto fail_sb;

        error = init_per_node(sdp, DO);
        if (error)
                goto fail_inodes;

        error = gfs2_statfs_init(sdp);
        if (error) {
                fs_err(sdp, "can't initialize statfs subsystem: %d\n", error);
                goto fail_per_node;
        }

        if (!(sb->s_flags & MS_RDONLY)) {
                error = gfs2_make_fs_rw(sdp);
                if (error) {
                        fs_err(sdp, "can't make FS RW: %d\n", error);
                        goto fail_per_node;
                }
        }

        gfs2_glock_dq_uninit(&mount_gh);
        gfs2_online_uevent(sdp);
        return 0;

fail_per_node:
        init_per_node(sdp, UNDO);
fail_inodes:
        init_inodes(sdp, UNDO);
fail_sb:
        if (sdp->sd_root_dir)
                dput(sdp->sd_root_dir);
        if (sdp->sd_master_dir)
                dput(sdp->sd_master_dir);
        if (sb->s_root)
                dput(sb->s_root);
        sb->s_root = NULL;
fail_locking:
        init_locking(sdp, &mount_gh, UNDO);
fail_lm:
        gfs2_gl_hash_clear(sdp);
        gfs2_lm_unmount(sdp);
fail_debug:
        gfs2_delete_debugfs_file(sdp);
        free_percpu(sdp->sd_lkstats);
        /* gfs2_sys_fs_del must be the last thing we do, since it causes
         * sysfs to call function gfs2_sbd_release, which frees sdp. */
        gfs2_sys_fs_del(sdp);
        sb->s_fs_info = NULL;
        return error;
}

static int set_gfs2_super(struct super_block *s, void *data)
{
        s->s_bdev = data;
        s->s_dev = s->s_bdev->bd_dev;

        /*
         * We set the bdi here to the queue backing, file systems can
         * overwrite this in ->fill_super()
         */
        s->s_bdi = &bdev_get_queue(s->s_bdev)->backing_dev_info;
        return 0;
}

static int test_gfs2_super(struct super_block *s, void *ptr)
{
        struct block_device *bdev = ptr;
        return (bdev == s->s_bdev);
}

/**
 * gfs2_mount - Get the GFS2 superblock
 * @fs_type: The GFS2 filesystem type
 * @flags: Mount flags
 * @dev_name: The name of the device
 * @data: The mount arguments
 *
 * Q. Why not use get_sb_bdev() ?
 * A. We need to select one of two root directories to mount, independent
 *    of whether this is the initial, or subsequent, mount of this sb
 *
 * Returns: 0 or -ve on error
 */

static struct dentry *gfs2_mount(struct file_system_type *fs_type, int flags,
                       const char *dev_name, void *data)
{
        struct block_device *bdev;
        struct super_block *s;
        fmode_t mode = FMODE_READ | FMODE_EXCL;
        int error;
        struct gfs2_args args;
        struct gfs2_sbd *sdp;

        if (!(flags & MS_RDONLY))
                mode |= FMODE_WRITE;

        bdev = blkdev_get_by_path(dev_name, mode, fs_type);
        if (IS_ERR(bdev))
                return ERR_CAST(bdev);

        /*
         * once the super is inserted into the list by sget, s_umount
         * will protect the lockfs code from trying to start a snapshot
         * while we are mounting
         */
        mutex_lock(&bdev->bd_fsfreeze_mutex);
        if (bdev->bd_fsfreeze_count > 0) {
                mutex_unlock(&bdev->bd_fsfreeze_mutex);
                error = -EBUSY;
                goto error_bdev;
        }
        s = sget(fs_type, test_gfs2_super, set_gfs2_super, flags, bdev);
        mutex_unlock(&bdev->bd_fsfreeze_mutex);
        error = PTR_ERR(s);
        if (IS_ERR(s))
                goto error_bdev;

        if (s->s_root) {
                /*
                 * s_umount nests inside bd_mutex during
                 * __invalidate_device().  blkdev_put() acquires
                 * bd_mutex and can't be called under s_umount.  Drop
                 * s_umount temporarily.  This is safe as we're
                 * holding an active reference.
                 */
                up_write(&s->s_umount);
                blkdev_put(bdev, mode);
                down_write(&s->s_umount);
        }

        memset(&args, 0, sizeof(args));
        args.ar_quota = GFS2_QUOTA_DEFAULT;
        args.ar_data = GFS2_DATA_DEFAULT;
        args.ar_commit = 30;
        args.ar_statfs_quantum = 30;
        args.ar_quota_quantum = 60;
        args.ar_errors = GFS2_ERRORS_DEFAULT;

        error = gfs2_mount_args(&args, data);
        if (error) {
                printk(KERN_WARNING "GFS2: can't parse mount arguments\n");
                goto error_super;
        }

        if (s->s_root) {
                error = -EBUSY;
                if ((flags ^ s->s_flags) & MS_RDONLY)
                        goto error_super;
        } else {
                char b[BDEVNAME_SIZE];

                s->s_mode = mode;
                strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
                sb_set_blocksize(s, block_size(bdev));
                error = fill_super(s, &args, flags & MS_SILENT ? 1 : 0);
                if (error)
                        goto error_super;
                s->s_flags |= MS_ACTIVE;
                bdev->bd_super = s;
        }

        sdp = s->s_fs_info;
        if (args.ar_meta)
                return dget(sdp->sd_master_dir);
        else
                return dget(sdp->sd_root_dir);

error_super:
        deactivate_locked_super(s);
        return ERR_PTR(error);
error_bdev:
        blkdev_put(bdev, mode);
        return ERR_PTR(error);
}

static int set_meta_super(struct super_block *s, void *ptr)
{
        return -EINVAL;
}

static struct dentry *gfs2_mount_meta(struct file_system_type *fs_type,
                        int flags, const char *dev_name, void *data)
{
        struct super_block *s;
        struct gfs2_sbd *sdp;
        struct path path;
        int error;

        error = kern_path(dev_name, LOOKUP_FOLLOW, &path);
        if (error) {
                printk(KERN_WARNING "GFS2: path_lookup on %s returned error %d\n",
                       dev_name, error);
                return ERR_PTR(error);
        }
        s = sget(&gfs2_fs_type, test_gfs2_super, set_meta_super, flags,
                 path.dentry->d_inode->i_sb->s_bdev);
        path_put(&path);
        if (IS_ERR(s)) {
                printk(KERN_WARNING "GFS2: gfs2 mount does not exist\n");
                return ERR_CAST(s);
        }
        if ((flags ^ s->s_flags) & MS_RDONLY) {
                deactivate_locked_super(s);
                return ERR_PTR(-EBUSY);
        }
        sdp = s->s_fs_info;
        return dget(sdp->sd_master_dir);
}

static void gfs2_kill_sb(struct super_block *sb)
{
        struct gfs2_sbd *sdp = sb->s_fs_info;

        if (sdp == NULL) {
                kill_block_super(sb);
                return;
        }

        gfs2_meta_syncfs(sdp);
        dput(sdp->sd_root_dir);
        dput(sdp->sd_master_dir);
        sdp->sd_root_dir = NULL;
        sdp->sd_master_dir = NULL;
        shrink_dcache_sb(sb);
        gfs2_delete_debugfs_file(sdp);
        free_percpu(sdp->sd_lkstats);
        kill_block_super(sb);
}

struct file_system_type gfs2_fs_type = {
        .name = "gfs2",
        .fs_flags = FS_REQUIRES_DEV,
        .mount = gfs2_mount,
        .kill_sb = gfs2_kill_sb,
        .owner = THIS_MODULE,
};
MODULE_ALIAS_FS("gfs2");

struct file_system_type gfs2meta_fs_type = {
        .name = "gfs2meta",
        .fs_flags = FS_REQUIRES_DEV,
        .mount = gfs2_mount_meta,
        .owner = THIS_MODULE,
};
MODULE_ALIAS_FS("gfs2meta");