Merge tag 'hwmon-for-v6.13-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git...

[linux.git] / fs / gfs2 / super.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
 * Copyright (C) 2004-2007 Red Hat, Inc.  All rights reserved.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/bio.h>
#include <linux/sched/signal.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/completion.h>
#include <linux/buffer_head.h>
#include <linux/statfs.h>
#include <linux/seq_file.h>
#include <linux/mount.h>
#include <linux/kthread.h>
#include <linux/delay.h>
#include <linux/gfs2_ondisk.h>
#include <linux/crc32.h>
#include <linux/time.h>
#include <linux/wait.h>
#include <linux/writeback.h>
#include <linux/backing-dev.h>
#include <linux/kernel.h>

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

enum evict_behavior {
        EVICT_SHOULD_DELETE,
        EVICT_SHOULD_SKIP_DELETE,
        EVICT_SHOULD_DEFER_DELETE,
};

/**
 * gfs2_jindex_free - Clear all the journal index information
 * @sdp: The GFS2 superblock
 *
 */

void gfs2_jindex_free(struct gfs2_sbd *sdp)
{
        struct list_head list;
        struct gfs2_jdesc *jd;

        spin_lock(&sdp->sd_jindex_spin);
        list_add(&list, &sdp->sd_jindex_list);
        list_del_init(&sdp->sd_jindex_list);
        sdp->sd_journals = 0;
        spin_unlock(&sdp->sd_jindex_spin);

        down_write(&sdp->sd_log_flush_lock);
        sdp->sd_jdesc = NULL;
        up_write(&sdp->sd_log_flush_lock);

        while (!list_empty(&list)) {
                jd = list_first_entry(&list, struct gfs2_jdesc, jd_list);
                BUG_ON(jd->jd_log_bio);
                gfs2_free_journal_extents(jd);
                list_del(&jd->jd_list);
                iput(jd->jd_inode);
                jd->jd_inode = NULL;
                kfree(jd);
        }
}

static struct gfs2_jdesc *jdesc_find_i(struct list_head *head, unsigned int jid)
{
        struct gfs2_jdesc *jd;

        list_for_each_entry(jd, head, jd_list) {
                if (jd->jd_jid == jid)
                        return jd;
        }
        return NULL;
}

struct gfs2_jdesc *gfs2_jdesc_find(struct gfs2_sbd *sdp, unsigned int jid)
{
        struct gfs2_jdesc *jd;

        spin_lock(&sdp->sd_jindex_spin);
        jd = jdesc_find_i(&sdp->sd_jindex_list, jid);
        spin_unlock(&sdp->sd_jindex_spin);

        return jd;
}

int gfs2_jdesc_check(struct gfs2_jdesc *jd)
{
        struct gfs2_inode *ip = GFS2_I(jd->jd_inode);
        struct gfs2_sbd *sdp = GFS2_SB(jd->jd_inode);
        u64 size = i_size_read(jd->jd_inode);

        if (gfs2_check_internal_file_size(jd->jd_inode, 8 << 20, BIT(30)))
                return -EIO;

        jd->jd_blocks = size >> sdp->sd_sb.sb_bsize_shift;

        if (gfs2_write_alloc_required(ip, 0, size)) {
                gfs2_consist_inode(ip);
                return -EIO;
        }

        return 0;
}

/**
 * gfs2_make_fs_rw - Turn a Read-Only FS into a Read-Write one
 * @sdp: the filesystem
 *
 * Returns: errno
 */

int gfs2_make_fs_rw(struct gfs2_sbd *sdp)
{
        struct gfs2_inode *ip = GFS2_I(sdp->sd_jdesc->jd_inode);
        struct gfs2_glock *j_gl = ip->i_gl;
        struct gfs2_log_header_host head;
        int error;

        j_gl->gl_ops->go_inval(j_gl, DIO_METADATA);
        if (gfs2_withdrawing_or_withdrawn(sdp))
                return -EIO;

        error = gfs2_find_jhead(sdp->sd_jdesc, &head, false);
        if (error) {
                gfs2_consist(sdp);
                return error;
        }

        if (!(head.lh_flags & GFS2_LOG_HEAD_UNMOUNT)) {
                gfs2_consist(sdp);
                return -EIO;
        }

        /*  Initialize some head of the log stuff  */
        sdp->sd_log_sequence = head.lh_sequence + 1;
        gfs2_log_pointers_init(sdp, head.lh_blkno);

        error = gfs2_quota_init(sdp);
        if (!error && gfs2_withdrawing_or_withdrawn(sdp))
                error = -EIO;
        if (!error)
                set_bit(SDF_JOURNAL_LIVE, &sdp->sd_flags);
        return error;
}

void gfs2_statfs_change_in(struct gfs2_statfs_change_host *sc, const void *buf)
{
        const struct gfs2_statfs_change *str = buf;

        sc->sc_total = be64_to_cpu(str->sc_total);
        sc->sc_free = be64_to_cpu(str->sc_free);
        sc->sc_dinodes = be64_to_cpu(str->sc_dinodes);
}

void gfs2_statfs_change_out(const struct gfs2_statfs_change_host *sc, void *buf)
{
        struct gfs2_statfs_change *str = buf;

        str->sc_total = cpu_to_be64(sc->sc_total);
        str->sc_free = cpu_to_be64(sc->sc_free);
        str->sc_dinodes = cpu_to_be64(sc->sc_dinodes);
}

int gfs2_statfs_init(struct gfs2_sbd *sdp)
{
        struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
        struct gfs2_statfs_change_host *m_sc = &sdp->sd_statfs_master;
        struct gfs2_statfs_change_host *l_sc = &sdp->sd_statfs_local;
        struct buffer_head *m_bh;
        struct gfs2_holder gh;
        int error;

        error = gfs2_glock_nq_init(m_ip->i_gl, LM_ST_EXCLUSIVE, GL_NOCACHE,
                                   &gh);
        if (error)
                return error;

        error = gfs2_meta_inode_buffer(m_ip, &m_bh);
        if (error)
                goto out;

        if (sdp->sd_args.ar_spectator) {
                spin_lock(&sdp->sd_statfs_spin);
                gfs2_statfs_change_in(m_sc, m_bh->b_data +
                                      sizeof(struct gfs2_dinode));
                spin_unlock(&sdp->sd_statfs_spin);
        } else {
                spin_lock(&sdp->sd_statfs_spin);
                gfs2_statfs_change_in(m_sc, m_bh->b_data +
                                      sizeof(struct gfs2_dinode));
                gfs2_statfs_change_in(l_sc, sdp->sd_sc_bh->b_data +
                                      sizeof(struct gfs2_dinode));
                spin_unlock(&sdp->sd_statfs_spin);

        }

        brelse(m_bh);
out:
        gfs2_glock_dq_uninit(&gh);
        return 0;
}

void gfs2_statfs_change(struct gfs2_sbd *sdp, s64 total, s64 free,
                        s64 dinodes)
{
        struct gfs2_inode *l_ip = GFS2_I(sdp->sd_sc_inode);
        struct gfs2_statfs_change_host *l_sc = &sdp->sd_statfs_local;
        struct gfs2_statfs_change_host *m_sc = &sdp->sd_statfs_master;
        s64 x, y;
        int need_sync = 0;

        gfs2_trans_add_meta(l_ip->i_gl, sdp->sd_sc_bh);

        spin_lock(&sdp->sd_statfs_spin);
        l_sc->sc_total += total;
        l_sc->sc_free += free;
        l_sc->sc_dinodes += dinodes;
        gfs2_statfs_change_out(l_sc, sdp->sd_sc_bh->b_data +
                               sizeof(struct gfs2_dinode));
        if (sdp->sd_args.ar_statfs_percent) {
                x = 100 * l_sc->sc_free;
                y = m_sc->sc_free * sdp->sd_args.ar_statfs_percent;
                if (x >= y || x <= -y)
                        need_sync = 1;
        }
        spin_unlock(&sdp->sd_statfs_spin);

        if (need_sync)
                gfs2_wake_up_statfs(sdp);
}

void update_statfs(struct gfs2_sbd *sdp, struct buffer_head *m_bh)
{
        struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
        struct gfs2_inode *l_ip = GFS2_I(sdp->sd_sc_inode);
        struct gfs2_statfs_change_host *m_sc = &sdp->sd_statfs_master;
        struct gfs2_statfs_change_host *l_sc = &sdp->sd_statfs_local;

        gfs2_trans_add_meta(l_ip->i_gl, sdp->sd_sc_bh);
        gfs2_trans_add_meta(m_ip->i_gl, m_bh);

        spin_lock(&sdp->sd_statfs_spin);
        m_sc->sc_total += l_sc->sc_total;
        m_sc->sc_free += l_sc->sc_free;
        m_sc->sc_dinodes += l_sc->sc_dinodes;
        memset(l_sc, 0, sizeof(struct gfs2_statfs_change));
        memset(sdp->sd_sc_bh->b_data + sizeof(struct gfs2_dinode),
               0, sizeof(struct gfs2_statfs_change));
        gfs2_statfs_change_out(m_sc, m_bh->b_data + sizeof(struct gfs2_dinode));
        spin_unlock(&sdp->sd_statfs_spin);
}

int gfs2_statfs_sync(struct super_block *sb, int type)
{
        struct gfs2_sbd *sdp = sb->s_fs_info;
        struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
        struct gfs2_statfs_change_host *m_sc = &sdp->sd_statfs_master;
        struct gfs2_statfs_change_host *l_sc = &sdp->sd_statfs_local;
        struct gfs2_holder gh;
        struct buffer_head *m_bh;
        int error;

        error = gfs2_glock_nq_init(m_ip->i_gl, LM_ST_EXCLUSIVE, GL_NOCACHE,
                                   &gh);
        if (error)
                goto out;

        error = gfs2_meta_inode_buffer(m_ip, &m_bh);
        if (error)
                goto out_unlock;

        spin_lock(&sdp->sd_statfs_spin);
        gfs2_statfs_change_in(m_sc, m_bh->b_data +
                              sizeof(struct gfs2_dinode));
        if (!l_sc->sc_total && !l_sc->sc_free && !l_sc->sc_dinodes) {
                spin_unlock(&sdp->sd_statfs_spin);
                goto out_bh;
        }
        spin_unlock(&sdp->sd_statfs_spin);

        error = gfs2_trans_begin(sdp, 2 * RES_DINODE, 0);
        if (error)
                goto out_bh;

        update_statfs(sdp, m_bh);
        sdp->sd_statfs_force_sync = 0;

        gfs2_trans_end(sdp);

out_bh:
        brelse(m_bh);
out_unlock:
        gfs2_glock_dq_uninit(&gh);
out:
        return error;
}

struct lfcc {
        struct list_head list;
        struct gfs2_holder gh;
};

/**
 * gfs2_lock_fs_check_clean - Stop all writes to the FS and check that all
 *                            journals are clean
 * @sdp: the file system
 *
 * Returns: errno
 */

static int gfs2_lock_fs_check_clean(struct gfs2_sbd *sdp)
{
        struct gfs2_inode *ip;
        struct gfs2_jdesc *jd;
        struct lfcc *lfcc;
        LIST_HEAD(list);
        struct gfs2_log_header_host lh;
        int error, error2;

        /*
         * Grab all the journal glocks in SH mode.  We are *probably* doing
         * that to prevent recovery.
         */

        list_for_each_entry(jd, &sdp->sd_jindex_list, jd_list) {
                lfcc = kmalloc(sizeof(struct lfcc), GFP_KERNEL);
                if (!lfcc) {
                        error = -ENOMEM;
                        goto out;
                }
                ip = GFS2_I(jd->jd_inode);
                error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, 0, &lfcc->gh);
                if (error) {
                        kfree(lfcc);
                        goto out;
                }
                list_add(&lfcc->list, &list);
        }

        gfs2_freeze_unlock(sdp);

        error = gfs2_glock_nq_init(sdp->sd_freeze_gl, LM_ST_EXCLUSIVE,
                                   LM_FLAG_NOEXP | GL_NOPID,
                                   &sdp->sd_freeze_gh);
        if (error)
                goto relock_shared;

        list_for_each_entry(jd, &sdp->sd_jindex_list, jd_list) {
                error = gfs2_jdesc_check(jd);
                if (error)
                        break;
                error = gfs2_find_jhead(jd, &lh, false);
                if (error)
                        break;
                if (!(lh.lh_flags & GFS2_LOG_HEAD_UNMOUNT)) {
                        error = -EBUSY;
                        break;
                }
        }

        if (!error)
                goto out;  /* success */

        gfs2_freeze_unlock(sdp);

relock_shared:
        error2 = gfs2_freeze_lock_shared(sdp);
        gfs2_assert_withdraw(sdp, !error2);

out:
        while (!list_empty(&list)) {
                lfcc = list_first_entry(&list, struct lfcc, list);
                list_del(&lfcc->list);
                gfs2_glock_dq_uninit(&lfcc->gh);
                kfree(lfcc);
        }
        return error;
}

void gfs2_dinode_out(const struct gfs2_inode *ip, void *buf)
{
        const struct inode *inode = &ip->i_inode;
        struct gfs2_dinode *str = buf;

        str->di_header.mh_magic = cpu_to_be32(GFS2_MAGIC);
        str->di_header.mh_type = cpu_to_be32(GFS2_METATYPE_DI);
        str->di_header.mh_format = cpu_to_be32(GFS2_FORMAT_DI);
        str->di_num.no_addr = cpu_to_be64(ip->i_no_addr);
        str->di_num.no_formal_ino = cpu_to_be64(ip->i_no_formal_ino);
        str->di_mode = cpu_to_be32(inode->i_mode);
        str->di_uid = cpu_to_be32(i_uid_read(inode));
        str->di_gid = cpu_to_be32(i_gid_read(inode));
        str->di_nlink = cpu_to_be32(inode->i_nlink);
        str->di_size = cpu_to_be64(i_size_read(inode));
        str->di_blocks = cpu_to_be64(gfs2_get_inode_blocks(inode));
        str->di_atime = cpu_to_be64(inode_get_atime_sec(inode));
        str->di_mtime = cpu_to_be64(inode_get_mtime_sec(inode));
        str->di_ctime = cpu_to_be64(inode_get_ctime_sec(inode));

        str->di_goal_meta = cpu_to_be64(ip->i_goal);
        str->di_goal_data = cpu_to_be64(ip->i_goal);
        str->di_generation = cpu_to_be64(ip->i_generation);

        str->di_flags = cpu_to_be32(ip->i_diskflags);
        str->di_height = cpu_to_be16(ip->i_height);
        str->di_payload_format = cpu_to_be32(S_ISDIR(inode->i_mode) &&
                                             !(ip->i_diskflags & GFS2_DIF_EXHASH) ?
                                             GFS2_FORMAT_DE : 0);
        str->di_depth = cpu_to_be16(ip->i_depth);
        str->di_entries = cpu_to_be32(ip->i_entries);

        str->di_eattr = cpu_to_be64(ip->i_eattr);
        str->di_atime_nsec = cpu_to_be32(inode_get_atime_nsec(inode));
        str->di_mtime_nsec = cpu_to_be32(inode_get_mtime_nsec(inode));
        str->di_ctime_nsec = cpu_to_be32(inode_get_ctime_nsec(inode));
}

/**
 * gfs2_write_inode - Make sure the inode is stable on the disk
 * @inode: The inode
 * @wbc: The writeback control structure
 *
 * Returns: errno
 */

static int gfs2_write_inode(struct inode *inode, struct writeback_control *wbc)
{
        struct gfs2_inode *ip = GFS2_I(inode);
        struct gfs2_sbd *sdp = GFS2_SB(inode);
        struct address_space *metamapping = gfs2_glock2aspace(ip->i_gl);
        struct backing_dev_info *bdi = inode_to_bdi(metamapping->host);
        int ret = 0;
        bool flush_all = (wbc->sync_mode == WB_SYNC_ALL || gfs2_is_jdata(ip));

        if (flush_all)
                gfs2_log_flush(GFS2_SB(inode), ip->i_gl,
                               GFS2_LOG_HEAD_FLUSH_NORMAL |
                               GFS2_LFC_WRITE_INODE);
        if (bdi->wb.dirty_exceeded)
                gfs2_ail1_flush(sdp, wbc);
        else
                filemap_fdatawrite(metamapping);
        if (flush_all)
                ret = filemap_fdatawait(metamapping);
        if (ret)
                mark_inode_dirty_sync(inode);
        else {
                spin_lock(&inode->i_lock);
                if (!(inode->i_flags & I_DIRTY))
                        gfs2_ordered_del_inode(ip);
                spin_unlock(&inode->i_lock);
        }
        return ret;
}

/**
 * gfs2_dirty_inode - check for atime updates
 * @inode: The inode in question
 * @flags: The type of dirty
 *
 * Unfortunately it can be called under any combination of inode
 * glock and freeze glock, so we have to check carefully.
 *
 * At the moment this deals only with atime - it should be possible
 * to expand that role in future, once a review of the locking has
 * been carried out.
 */

static void gfs2_dirty_inode(struct inode *inode, int flags)
{
        struct gfs2_inode *ip = GFS2_I(inode);
        struct gfs2_sbd *sdp = GFS2_SB(inode);
        struct buffer_head *bh;
        struct gfs2_holder gh;
        int need_unlock = 0;
        int need_endtrans = 0;
        int ret;

        if (unlikely(!ip->i_gl)) {
                /* This can only happen during incomplete inode creation. */
                BUG_ON(!test_bit(GIF_ALLOC_FAILED, &ip->i_flags));
                return;
        }

        if (gfs2_withdrawing_or_withdrawn(sdp))
                return;
        if (!gfs2_glock_is_locked_by_me(ip->i_gl)) {
                ret = gfs2_glock_nq_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &gh);
                if (ret) {
                        fs_err(sdp, "dirty_inode: glock %d\n", ret);
                        gfs2_dump_glock(NULL, ip->i_gl, true);
                        return;
                }
                need_unlock = 1;
        } else if (WARN_ON_ONCE(ip->i_gl->gl_state != LM_ST_EXCLUSIVE))
                return;

        if (current->journal_info == NULL) {
                ret = gfs2_trans_begin(sdp, RES_DINODE, 0);
                if (ret) {
                        fs_err(sdp, "dirty_inode: gfs2_trans_begin %d\n", ret);
                        goto out;
                }
                need_endtrans = 1;
        }

        ret = gfs2_meta_inode_buffer(ip, &bh);
        if (ret == 0) {
                gfs2_trans_add_meta(ip->i_gl, bh);
                gfs2_dinode_out(ip, bh->b_data);
                brelse(bh);
        }

        if (need_endtrans)
                gfs2_trans_end(sdp);
out:
        if (need_unlock)
                gfs2_glock_dq_uninit(&gh);
}

/**
 * gfs2_make_fs_ro - Turn a Read-Write FS into a Read-Only one
 * @sdp: the filesystem
 *
 * Returns: errno
 */

void gfs2_make_fs_ro(struct gfs2_sbd *sdp)
{
        int log_write_allowed = test_bit(SDF_JOURNAL_LIVE, &sdp->sd_flags);

        if (!test_bit(SDF_KILL, &sdp->sd_flags))
                gfs2_flush_delete_work(sdp);

        gfs2_destroy_threads(sdp);

        if (log_write_allowed) {
                gfs2_quota_sync(sdp->sd_vfs, 0);
                gfs2_statfs_sync(sdp->sd_vfs, 0);

                /* We do two log flushes here. The first one commits dirty inodes
                 * and rgrps to the journal, but queues up revokes to the ail list.
                 * The second flush writes out and removes the revokes.
                 *
                 * The first must be done before the FLUSH_SHUTDOWN code
                 * clears the LIVE flag, otherwise it will not be able to start
                 * a transaction to write its revokes, and the error will cause
                 * a withdraw of the file system. */
                gfs2_log_flush(sdp, NULL, GFS2_LFC_MAKE_FS_RO);
                gfs2_log_flush(sdp, NULL, GFS2_LOG_HEAD_FLUSH_SHUTDOWN |
                               GFS2_LFC_MAKE_FS_RO);
                wait_event_timeout(sdp->sd_log_waitq,
                                   gfs2_log_is_empty(sdp),
                                   HZ * 5);
                gfs2_assert_warn(sdp, gfs2_log_is_empty(sdp));
        }
        gfs2_quota_cleanup(sdp);
}

/**
 * gfs2_put_super - Unmount the filesystem
 * @sb: The VFS superblock
 *
 */

static void gfs2_put_super(struct super_block *sb)
{
        struct gfs2_sbd *sdp = sb->s_fs_info;
        struct gfs2_jdesc *jd;

        /* No more recovery requests */
        set_bit(SDF_NORECOVERY, &sdp->sd_flags);
        smp_mb();

        /* Wait on outstanding recovery */
restart:
        spin_lock(&sdp->sd_jindex_spin);
        list_for_each_entry(jd, &sdp->sd_jindex_list, jd_list) {
                if (!test_bit(JDF_RECOVERY, &jd->jd_flags))
                        continue;
                spin_unlock(&sdp->sd_jindex_spin);
                wait_on_bit(&jd->jd_flags, JDF_RECOVERY,
                            TASK_UNINTERRUPTIBLE);
                goto restart;
        }
        spin_unlock(&sdp->sd_jindex_spin);

        if (!sb_rdonly(sb))
                gfs2_make_fs_ro(sdp);
        else {
                if (gfs2_withdrawing_or_withdrawn(sdp))
                        gfs2_destroy_threads(sdp);

                gfs2_quota_cleanup(sdp);
        }

        WARN_ON(gfs2_withdrawing(sdp));

        /*  At this point, we're through modifying the disk  */

        /*  Release stuff  */

        gfs2_freeze_unlock(sdp);

        iput(sdp->sd_jindex);
        iput(sdp->sd_statfs_inode);
        iput(sdp->sd_rindex);
        iput(sdp->sd_quota_inode);

        gfs2_glock_put(sdp->sd_rename_gl);
        gfs2_glock_put(sdp->sd_freeze_gl);

        if (!sdp->sd_args.ar_spectator) {
                if (gfs2_holder_initialized(&sdp->sd_journal_gh))
                        gfs2_glock_dq_uninit(&sdp->sd_journal_gh);
                if (gfs2_holder_initialized(&sdp->sd_jinode_gh))
                        gfs2_glock_dq_uninit(&sdp->sd_jinode_gh);
                brelse(sdp->sd_sc_bh);
                gfs2_glock_dq_uninit(&sdp->sd_sc_gh);
                gfs2_glock_dq_uninit(&sdp->sd_qc_gh);
                free_local_statfs_inodes(sdp);
                iput(sdp->sd_qc_inode);
        }

        gfs2_glock_dq_uninit(&sdp->sd_live_gh);
        gfs2_clear_rgrpd(sdp);
        gfs2_jindex_free(sdp);
        /*  Take apart glock structures and buffer lists  */
        gfs2_gl_hash_clear(sdp);
        truncate_inode_pages_final(&sdp->sd_aspace);
        gfs2_delete_debugfs_file(sdp);

        gfs2_sys_fs_del(sdp);
        free_sbd(sdp);
}

/**
 * gfs2_sync_fs - sync the filesystem
 * @sb: the superblock
 * @wait: true to wait for completion
 *
 * Flushes the log to disk.
 */

static int gfs2_sync_fs(struct super_block *sb, int wait)
{
        struct gfs2_sbd *sdp = sb->s_fs_info;

        gfs2_quota_sync(sb, -1);
        if (wait)
                gfs2_log_flush(sdp, NULL, GFS2_LOG_HEAD_FLUSH_NORMAL |
                               GFS2_LFC_SYNC_FS);
        return sdp->sd_log_error;
}

static int gfs2_do_thaw(struct gfs2_sbd *sdp)
{
        struct super_block *sb = sdp->sd_vfs;
        int error;

        error = gfs2_freeze_lock_shared(sdp);
        if (error)
                goto fail;
        error = thaw_super(sb, FREEZE_HOLDER_USERSPACE);
        if (!error)
                return 0;

fail:
        fs_info(sdp, "GFS2: couldn't thaw filesystem: %d\n", error);
        gfs2_assert_withdraw(sdp, 0);
        return error;
}

void gfs2_freeze_func(struct work_struct *work)
{
        struct gfs2_sbd *sdp = container_of(work, struct gfs2_sbd, sd_freeze_work);
        struct super_block *sb = sdp->sd_vfs;
        int error;

        mutex_lock(&sdp->sd_freeze_mutex);
        error = -EBUSY;
        if (test_bit(SDF_FROZEN, &sdp->sd_flags))
                goto freeze_failed;

        error = freeze_super(sb, FREEZE_HOLDER_USERSPACE);
        if (error)
                goto freeze_failed;

        gfs2_freeze_unlock(sdp);
        set_bit(SDF_FROZEN, &sdp->sd_flags);

        error = gfs2_do_thaw(sdp);
        if (error)
                goto out;

        clear_bit(SDF_FROZEN, &sdp->sd_flags);
        goto out;

freeze_failed:
        fs_info(sdp, "GFS2: couldn't freeze filesystem: %d\n", error);

out:
        mutex_unlock(&sdp->sd_freeze_mutex);
        deactivate_super(sb);
}

/**
 * gfs2_freeze_super - prevent further writes to the filesystem
 * @sb: the VFS structure for the filesystem
 *
 */

static int gfs2_freeze_super(struct super_block *sb, enum freeze_holder who)
{
        struct gfs2_sbd *sdp = sb->s_fs_info;
        int error;

        if (!mutex_trylock(&sdp->sd_freeze_mutex))
                return -EBUSY;
        if (test_bit(SDF_FROZEN, &sdp->sd_flags)) {
                mutex_unlock(&sdp->sd_freeze_mutex);
                return -EBUSY;
        }

        for (;;) {
                error = freeze_super(sb, FREEZE_HOLDER_USERSPACE);
                if (error) {
                        fs_info(sdp, "GFS2: couldn't freeze filesystem: %d\n",
                                error);
                        goto out;
                }

                error = gfs2_lock_fs_check_clean(sdp);
                if (!error) {
                        set_bit(SDF_FREEZE_INITIATOR, &sdp->sd_flags);
                        set_bit(SDF_FROZEN, &sdp->sd_flags);
                        break;
                }

                error = gfs2_do_thaw(sdp);
                if (error)
                        goto out;

                if (error == -EBUSY)
                        fs_err(sdp, "waiting for recovery before freeze\n");
                else if (error == -EIO) {
                        fs_err(sdp, "Fatal IO error: cannot freeze gfs2 due "
                               "to recovery error.\n");
                        goto out;
                } else {
                        fs_err(sdp, "error freezing FS: %d\n", error);
                }
                fs_err(sdp, "retrying...\n");
                msleep(1000);
        }

out:
        mutex_unlock(&sdp->sd_freeze_mutex);
        return error;
}

static int gfs2_freeze_fs(struct super_block *sb)
{
        struct gfs2_sbd *sdp = sb->s_fs_info;

        if (test_bit(SDF_JOURNAL_LIVE, &sdp->sd_flags)) {
                gfs2_log_flush(sdp, NULL, GFS2_LOG_HEAD_FLUSH_FREEZE |
                               GFS2_LFC_FREEZE_GO_SYNC);
                if (gfs2_withdrawing_or_withdrawn(sdp))
                        return -EIO;
        }
        return 0;
}

/**
 * gfs2_thaw_super - reallow writes to the filesystem
 * @sb: the VFS structure for the filesystem
 *
 */

static int gfs2_thaw_super(struct super_block *sb, enum freeze_holder who)
{
        struct gfs2_sbd *sdp = sb->s_fs_info;
        int error;

        if (!mutex_trylock(&sdp->sd_freeze_mutex))
                return -EBUSY;
        if (!test_bit(SDF_FREEZE_INITIATOR, &sdp->sd_flags)) {
                mutex_unlock(&sdp->sd_freeze_mutex);
                return -EINVAL;
        }

        atomic_inc(&sb->s_active);
        gfs2_freeze_unlock(sdp);

        error = gfs2_do_thaw(sdp);

        if (!error) {
                clear_bit(SDF_FREEZE_INITIATOR, &sdp->sd_flags);
                clear_bit(SDF_FROZEN, &sdp->sd_flags);
        }
        mutex_unlock(&sdp->sd_freeze_mutex);
        deactivate_super(sb);
        return error;
}

void gfs2_thaw_freeze_initiator(struct super_block *sb)
{
        struct gfs2_sbd *sdp = sb->s_fs_info;

        mutex_lock(&sdp->sd_freeze_mutex);
        if (!test_bit(SDF_FREEZE_INITIATOR, &sdp->sd_flags))
                goto out;

        gfs2_freeze_unlock(sdp);

out:
        mutex_unlock(&sdp->sd_freeze_mutex);
}

/**
 * statfs_slow_fill - fill in the sg for a given RG
 * @rgd: the RG
 * @sc: the sc structure
 *
 * Returns: 0 on success, -ESTALE if the LVB is invalid
 */

static int statfs_slow_fill(struct gfs2_rgrpd *rgd,
                            struct gfs2_statfs_change_host *sc)
{
        gfs2_rgrp_verify(rgd);
        sc->sc_total += rgd->rd_data;
        sc->sc_free += rgd->rd_free;
        sc->sc_dinodes += rgd->rd_dinodes;
        return 0;
}

/**
 * gfs2_statfs_slow - Stat a filesystem using asynchronous locking
 * @sdp: the filesystem
 * @sc: the sc info that will be returned
 *
 * Any error (other than a signal) will cause this routine to fall back
 * to the synchronous version.
 *
 * FIXME: This really shouldn't busy wait like this.
 *
 * Returns: errno
 */

static int gfs2_statfs_slow(struct gfs2_sbd *sdp, struct gfs2_statfs_change_host *sc)
{
        struct gfs2_rgrpd *rgd_next;
        struct gfs2_holder *gha, *gh;
        unsigned int slots = 64;
        unsigned int x;
        int done;
        int error = 0, err;

        memset(sc, 0, sizeof(struct gfs2_statfs_change_host));
        gha = kmalloc_array(slots, sizeof(struct gfs2_holder), GFP_KERNEL);
        if (!gha)
                return -ENOMEM;
        for (x = 0; x < slots; x++)
                gfs2_holder_mark_uninitialized(gha + x);

        rgd_next = gfs2_rgrpd_get_first(sdp);

        for (;;) {
                done = 1;

                for (x = 0; x < slots; x++) {
                        gh = gha + x;

                        if (gfs2_holder_initialized(gh) && gfs2_glock_poll(gh)) {
                                err = gfs2_glock_wait(gh);
                                if (err) {
                                        gfs2_holder_uninit(gh);
                                        error = err;
                                } else {
                                        if (!error) {
                                                struct gfs2_rgrpd *rgd =
                                                        gfs2_glock2rgrp(gh->gh_gl);

                                                error = statfs_slow_fill(rgd, sc);
                                        }
                                        gfs2_glock_dq_uninit(gh);
                                }
                        }

                        if (gfs2_holder_initialized(gh))
                                done = 0;
                        else if (rgd_next && !error) {
                                error = gfs2_glock_nq_init(rgd_next->rd_gl,
                                                           LM_ST_SHARED,
                                                           GL_ASYNC,
                                                           gh);
                                rgd_next = gfs2_rgrpd_get_next(rgd_next);
                                done = 0;
                        }

                        if (signal_pending(current))
                                error = -ERESTARTSYS;
                }

                if (done)
                        break;

                yield();
        }

        kfree(gha);
        return error;
}

/**
 * gfs2_statfs_i - Do a statfs
 * @sdp: the filesystem
 * @sc: the sc structure
 *
 * Returns: errno
 */

static int gfs2_statfs_i(struct gfs2_sbd *sdp, struct gfs2_statfs_change_host *sc)
{
        struct gfs2_statfs_change_host *m_sc = &sdp->sd_statfs_master;
        struct gfs2_statfs_change_host *l_sc = &sdp->sd_statfs_local;

        spin_lock(&sdp->sd_statfs_spin);

        *sc = *m_sc;
        sc->sc_total += l_sc->sc_total;
        sc->sc_free += l_sc->sc_free;
        sc->sc_dinodes += l_sc->sc_dinodes;

        spin_unlock(&sdp->sd_statfs_spin);

        if (sc->sc_free < 0)
                sc->sc_free = 0;
        if (sc->sc_free > sc->sc_total)
                sc->sc_free = sc->sc_total;
        if (sc->sc_dinodes < 0)
                sc->sc_dinodes = 0;

        return 0;
}

/**
 * gfs2_statfs - Gather and return stats about the filesystem
 * @dentry: The name of the link
 * @buf: The buffer
 *
 * Returns: 0 on success or error code
 */

static int gfs2_statfs(struct dentry *dentry, struct kstatfs *buf)
{
        struct super_block *sb = dentry->d_sb;
        struct gfs2_sbd *sdp = sb->s_fs_info;
        struct gfs2_statfs_change_host sc;
        int error;

        error = gfs2_rindex_update(sdp);
        if (error)
                return error;

        if (gfs2_tune_get(sdp, gt_statfs_slow))
                error = gfs2_statfs_slow(sdp, &sc);
        else
                error = gfs2_statfs_i(sdp, &sc);

        if (error)
                return error;

        buf->f_type = GFS2_MAGIC;
        buf->f_bsize = sdp->sd_sb.sb_bsize;
        buf->f_blocks = sc.sc_total;
        buf->f_bfree = sc.sc_free;
        buf->f_bavail = sc.sc_free;
        buf->f_files = sc.sc_dinodes + sc.sc_free;
        buf->f_ffree = sc.sc_free;
        buf->f_namelen = GFS2_FNAMESIZE;
        buf->f_fsid = uuid_to_fsid(sb->s_uuid.b);

        return 0;
}

/**
 * gfs2_drop_inode - Drop an inode (test for remote unlink)
 * @inode: The inode to drop
 *
 * If we've received a callback on an iopen lock then it's because a
 * remote node tried to deallocate the inode but failed due to this node
 * still having the inode open. Here we mark the link count zero
 * since we know that it must have reached zero if the GLF_DEMOTE flag
 * is set on the iopen glock. If we didn't do a disk read since the
 * remote node removed the final link then we might otherwise miss
 * this event. This check ensures that this node will deallocate the
 * inode's blocks, or alternatively pass the baton on to another
 * node for later deallocation.
 */

static int gfs2_drop_inode(struct inode *inode)
{
        struct gfs2_inode *ip = GFS2_I(inode);
        struct gfs2_sbd *sdp = GFS2_SB(inode);

        if (inode->i_nlink &&
            gfs2_holder_initialized(&ip->i_iopen_gh)) {
                struct gfs2_glock *gl = ip->i_iopen_gh.gh_gl;
                if (glock_needs_demote(gl))
                        clear_nlink(inode);
        }

        /*
         * When under memory pressure when an inode's link count has dropped to
         * zero, defer deleting the inode to the delete workqueue.  This avoids
         * calling into DLM under memory pressure, which can deadlock.
         */
        if (!inode->i_nlink &&
            unlikely(current->flags & PF_MEMALLOC) &&
            gfs2_holder_initialized(&ip->i_iopen_gh)) {
                struct gfs2_glock *gl = ip->i_iopen_gh.gh_gl;

                gfs2_glock_hold(gl);
                if (!gfs2_queue_verify_delete(gl, true))
                        gfs2_glock_put_async(gl);
                return 0;
        }

        /*
         * No longer cache inodes when trying to evict them all.
         */
        if (test_bit(SDF_EVICTING, &sdp->sd_flags))
                return 1;

        return generic_drop_inode(inode);
}

/**
 * gfs2_show_options - Show mount options for /proc/mounts
 * @s: seq_file structure
 * @root: root of this (sub)tree
 *
 * Returns: 0 on success or error code
 */

static int gfs2_show_options(struct seq_file *s, struct dentry *root)
{
        struct gfs2_sbd *sdp = root->d_sb->s_fs_info;
        struct gfs2_args *args = &sdp->sd_args;
        unsigned int logd_secs, statfs_slow, statfs_quantum, quota_quantum;

        spin_lock(&sdp->sd_tune.gt_spin);
        logd_secs = sdp->sd_tune.gt_logd_secs;
        quota_quantum = sdp->sd_tune.gt_quota_quantum;
        statfs_quantum = sdp->sd_tune.gt_statfs_quantum;
        statfs_slow = sdp->sd_tune.gt_statfs_slow;
        spin_unlock(&sdp->sd_tune.gt_spin);

        if (is_subdir(root, sdp->sd_master_dir))
                seq_puts(s, ",meta");
        if (args->ar_lockproto[0])
                seq_show_option(s, "lockproto", args->ar_lockproto);
        if (args->ar_locktable[0])
                seq_show_option(s, "locktable", args->ar_locktable);
        if (args->ar_hostdata[0])
                seq_show_option(s, "hostdata", args->ar_hostdata);
        if (args->ar_spectator)
                seq_puts(s, ",spectator");
        if (args->ar_localflocks)
                seq_puts(s, ",localflocks");
        if (args->ar_debug)
                seq_puts(s, ",debug");
        if (args->ar_posix_acl)
                seq_puts(s, ",acl");
        if (args->ar_quota != GFS2_QUOTA_DEFAULT) {
                char *state;
                switch (args->ar_quota) {
                case GFS2_QUOTA_OFF:
                        state = "off";
                        break;
                case GFS2_QUOTA_ACCOUNT:
                        state = "account";
                        break;
                case GFS2_QUOTA_ON:
                        state = "on";
                        break;
                case GFS2_QUOTA_QUIET:
                        state = "quiet";
                        break;
                default:
                        state = "unknown";
                        break;
                }
                seq_printf(s, ",quota=%s", state);
        }
        if (args->ar_suiddir)
                seq_puts(s, ",suiddir");
        if (args->ar_data != GFS2_DATA_DEFAULT) {
                char *state;
                switch (args->ar_data) {
                case GFS2_DATA_WRITEBACK:
                        state = "writeback";
                        break;
                case GFS2_DATA_ORDERED:
                        state = "ordered";
                        break;
                default:
                        state = "unknown";
                        break;
                }
                seq_printf(s, ",data=%s", state);
        }
        if (args->ar_discard)
                seq_puts(s, ",discard");
        if (logd_secs != 30)
                seq_printf(s, ",commit=%d", logd_secs);
        if (statfs_quantum != 30)
                seq_printf(s, ",statfs_quantum=%d", statfs_quantum);
        else if (statfs_slow)
                seq_puts(s, ",statfs_quantum=0");
        if (quota_quantum != 60)
                seq_printf(s, ",quota_quantum=%d", quota_quantum);
        if (args->ar_statfs_percent)
                seq_printf(s, ",statfs_percent=%d", args->ar_statfs_percent);
        if (args->ar_errors != GFS2_ERRORS_DEFAULT) {
                const char *state;

                switch (args->ar_errors) {
                case GFS2_ERRORS_WITHDRAW:
                        state = "withdraw";
                        break;
                case GFS2_ERRORS_PANIC:
                        state = "panic";
                        break;
                default:
                        state = "unknown";
                        break;
                }
                seq_printf(s, ",errors=%s", state);
        }
        if (test_bit(SDF_NOBARRIERS, &sdp->sd_flags))
                seq_puts(s, ",nobarrier");
        if (test_bit(SDF_DEMOTE, &sdp->sd_flags))
                seq_puts(s, ",demote_interface_used");
        if (args->ar_rgrplvb)
                seq_puts(s, ",rgrplvb");
        if (args->ar_loccookie)
                seq_puts(s, ",loccookie");
        return 0;
}

static void gfs2_final_release_pages(struct gfs2_inode *ip)
{
        struct inode *inode = &ip->i_inode;
        struct gfs2_glock *gl = ip->i_gl;

        if (unlikely(!gl)) {
                /* This can only happen during incomplete inode creation. */
                BUG_ON(!test_bit(GIF_ALLOC_FAILED, &ip->i_flags));
                return;
        }

        truncate_inode_pages(gfs2_glock2aspace(gl), 0);
        truncate_inode_pages(&inode->i_data, 0);

        if (atomic_read(&gl->gl_revokes) == 0) {
                clear_bit(GLF_LFLUSH, &gl->gl_flags);
                clear_bit(GLF_DIRTY, &gl->gl_flags);
        }
}

static int gfs2_dinode_dealloc(struct gfs2_inode *ip)
{
        struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
        struct gfs2_rgrpd *rgd;
        struct gfs2_holder gh;
        int error;

        if (gfs2_get_inode_blocks(&ip->i_inode) != 1) {
                gfs2_consist_inode(ip);
                return -EIO;
        }

        gfs2_rindex_update(sdp);

        error = gfs2_quota_hold(ip, NO_UID_QUOTA_CHANGE, NO_GID_QUOTA_CHANGE);
        if (error)
                return error;

        rgd = gfs2_blk2rgrpd(sdp, ip->i_no_addr, 1);
        if (!rgd) {
                gfs2_consist_inode(ip);
                error = -EIO;
                goto out_qs;
        }

        error = gfs2_glock_nq_init(rgd->rd_gl, LM_ST_EXCLUSIVE,
                                   LM_FLAG_NODE_SCOPE, &gh);
        if (error)
                goto out_qs;

        error = gfs2_trans_begin(sdp, RES_RG_BIT + RES_STATFS + RES_QUOTA,
                                 sdp->sd_jdesc->jd_blocks);
        if (error)
                goto out_rg_gunlock;

        gfs2_free_di(rgd, ip);

        gfs2_final_release_pages(ip);

        gfs2_trans_end(sdp);

out_rg_gunlock:
        gfs2_glock_dq_uninit(&gh);
out_qs:
        gfs2_quota_unhold(ip);
        return error;
}

/**
 * gfs2_glock_put_eventually
 * @gl: The glock to put
 *
 * When under memory pressure, trigger a deferred glock put to make sure we
 * won't call into DLM and deadlock.  Otherwise, put the glock directly.
 */

static void gfs2_glock_put_eventually(struct gfs2_glock *gl)
{
        if (current->flags & PF_MEMALLOC)
                gfs2_glock_put_async(gl);
        else
                gfs2_glock_put(gl);
}

static enum evict_behavior gfs2_upgrade_iopen_glock(struct inode *inode)
{
        struct gfs2_inode *ip = GFS2_I(inode);
        struct gfs2_sbd *sdp = GFS2_SB(inode);
        struct gfs2_holder *gh = &ip->i_iopen_gh;
        int error;

        gh->gh_flags |= GL_NOCACHE;
        gfs2_glock_dq_wait(gh);

        /*
         * If there are no other lock holders, we will immediately get
         * exclusive access to the iopen glock here.
         *
         * Otherwise, the other nodes holding the lock will be notified about
         * our locking request (see iopen_go_callback()).  If they do not have
         * the inode open, they are expected to evict the cached inode and
         * release the lock, allowing us to proceed.
         *
         * Otherwise, if they cannot evict the inode, they are expected to poke
         * the inode glock (note: not the iopen glock).  We will notice that
         * and stop waiting for the iopen glock immediately.  The other node(s)
         * are then expected to take care of deleting the inode when they no
         * longer use it.
         *
         * As a last resort, if another node keeps holding the iopen glock
         * without showing any activity on the inode glock, we will eventually
         * time out and fail the iopen glock upgrade.
         */

        gfs2_holder_reinit(LM_ST_EXCLUSIVE, GL_ASYNC | GL_NOCACHE, gh);
        error = gfs2_glock_nq(gh);
        if (error)
                return EVICT_SHOULD_SKIP_DELETE;

        wait_event_interruptible_timeout(sdp->sd_async_glock_wait,
                !test_bit(HIF_WAIT, &gh->gh_iflags) ||
                glock_needs_demote(ip->i_gl),
                5 * HZ);
        if (!test_bit(HIF_HOLDER, &gh->gh_iflags)) {
                gfs2_glock_dq(gh);
                if (glock_needs_demote(ip->i_gl))
                        return EVICT_SHOULD_SKIP_DELETE;
                return EVICT_SHOULD_DEFER_DELETE;
        }
        error = gfs2_glock_holder_ready(gh);
        if (error)
                return EVICT_SHOULD_SKIP_DELETE;
        return EVICT_SHOULD_DELETE;
}

/**
 * evict_should_delete - determine whether the inode is eligible for deletion
 * @inode: The inode to evict
 * @gh: The glock holder structure
 *
 * This function determines whether the evicted inode is eligible to be deleted
 * and locks the inode glock.
 *
 * Returns: the fate of the dinode
 */
static enum evict_behavior evict_should_delete(struct inode *inode,
                                               struct gfs2_holder *gh)
{
        struct gfs2_inode *ip = GFS2_I(inode);
        struct super_block *sb = inode->i_sb;
        struct gfs2_sbd *sdp = sb->s_fs_info;
        int ret;

        if (unlikely(test_bit(GIF_ALLOC_FAILED, &ip->i_flags)))
                goto should_delete;

        if (test_bit(GIF_DEFER_DELETE, &ip->i_flags))
                return EVICT_SHOULD_DEFER_DELETE;

        /* Deletes should never happen under memory pressure anymore.  */
        if (WARN_ON_ONCE(current->flags & PF_MEMALLOC))
                return EVICT_SHOULD_DEFER_DELETE;

        /* Must not read inode block until block type has been verified */
        ret = gfs2_glock_nq_init(ip->i_gl, LM_ST_EXCLUSIVE, GL_SKIP, gh);
        if (unlikely(ret)) {
                glock_clear_object(ip->i_iopen_gh.gh_gl, ip);
                ip->i_iopen_gh.gh_flags |= GL_NOCACHE;
                gfs2_glock_dq_uninit(&ip->i_iopen_gh);
                return EVICT_SHOULD_DEFER_DELETE;
        }

        if (gfs2_inode_already_deleted(ip->i_gl, ip->i_no_formal_ino))
                return EVICT_SHOULD_SKIP_DELETE;
        ret = gfs2_check_blk_type(sdp, ip->i_no_addr, GFS2_BLKST_UNLINKED);
        if (ret)
                return EVICT_SHOULD_SKIP_DELETE;

        ret = gfs2_instantiate(gh);
        if (ret)
                return EVICT_SHOULD_SKIP_DELETE;

        /*
         * The inode may have been recreated in the meantime.
         */
        if (inode->i_nlink)
                return EVICT_SHOULD_SKIP_DELETE;

should_delete:
        if (gfs2_holder_initialized(&ip->i_iopen_gh) &&
            test_bit(HIF_HOLDER, &ip->i_iopen_gh.gh_iflags)) {
                enum evict_behavior behavior =
                        gfs2_upgrade_iopen_glock(inode);

                if (behavior != EVICT_SHOULD_DELETE) {
                        gfs2_holder_uninit(&ip->i_iopen_gh);
                        return behavior;
                }
        }
        return EVICT_SHOULD_DELETE;
}

/**
 * evict_unlinked_inode - delete the pieces of an unlinked evicted inode
 * @inode: The inode to evict
 */
static int evict_unlinked_inode(struct inode *inode)
{
        struct gfs2_inode *ip = GFS2_I(inode);
        int ret;

        if (S_ISDIR(inode->i_mode) &&
            (ip->i_diskflags & GFS2_DIF_EXHASH)) {
                ret = gfs2_dir_exhash_dealloc(ip);
                if (ret)
                        goto out;
        }

        if (ip->i_eattr) {
                ret = gfs2_ea_dealloc(ip);
                if (ret)
                        goto out;
        }

        if (!gfs2_is_stuffed(ip)) {
                ret = gfs2_file_dealloc(ip);
                if (ret)
                        goto out;
        }

        /*
         * As soon as we clear the bitmap for the dinode, gfs2_create_inode()
         * can get called to recreate it, or even gfs2_inode_lookup() if the
         * inode was recreated on another node in the meantime.
         *
         * However, inserting the new inode into the inode hash table will not
         * succeed until the old inode is removed, and that only happens after
         * ->evict_inode() returns.  The new inode is attached to its inode and
         *  iopen glocks after inserting it into the inode hash table, so at
         *  that point we can be sure that both glocks are unused.
         */

        ret = gfs2_dinode_dealloc(ip);
        if (!ret && ip->i_gl)
                gfs2_inode_remember_delete(ip->i_gl, ip->i_no_formal_ino);

out:
        return ret;
}

/*
 * evict_linked_inode - evict an inode whose dinode has not been unlinked
 * @inode: The inode to evict
 */
static int evict_linked_inode(struct inode *inode)
{
        struct super_block *sb = inode->i_sb;
        struct gfs2_sbd *sdp = sb->s_fs_info;
        struct gfs2_inode *ip = GFS2_I(inode);
        struct address_space *metamapping;
        int ret;

        gfs2_log_flush(sdp, ip->i_gl, GFS2_LOG_HEAD_FLUSH_NORMAL |
                       GFS2_LFC_EVICT_INODE);
        metamapping = gfs2_glock2aspace(ip->i_gl);
        if (test_bit(GLF_DIRTY, &ip->i_gl->gl_flags)) {
                filemap_fdatawrite(metamapping);
                filemap_fdatawait(metamapping);
        }
        write_inode_now(inode, 1);
        gfs2_ail_flush(ip->i_gl, 0);

        ret = gfs2_trans_begin(sdp, 0, sdp->sd_jdesc->jd_blocks);
        if (ret)
                return ret;

        /* Needs to be done before glock release & also in a transaction */
        truncate_inode_pages(&inode->i_data, 0);
        truncate_inode_pages(metamapping, 0);
        gfs2_trans_end(sdp);
        return 0;
}

/**
 * gfs2_evict_inode - Remove an inode from cache
 * @inode: The inode to evict
 *
 * There are three cases to consider:
 * 1. i_nlink == 0, we are final opener (and must deallocate)
 * 2. i_nlink == 0, we are not the final opener (and cannot deallocate)
 * 3. i_nlink > 0
 *
 * If the fs is read only, then we have to treat all cases as per #3
 * since we are unable to do any deallocation. The inode will be
 * deallocated by the next read/write node to attempt an allocation
 * in the same resource group
 *
 * We have to (at the moment) hold the inodes main lock to cover
 * the gap between unlocking the shared lock on the iopen lock and
 * taking the exclusive lock. I'd rather do a shared -> exclusive
 * conversion on the iopen lock, but we can change that later. This
 * is safe, just less efficient.
 */

static void gfs2_evict_inode(struct inode *inode)
{
        struct super_block *sb = inode->i_sb;
        struct gfs2_sbd *sdp = sb->s_fs_info;
        struct gfs2_inode *ip = GFS2_I(inode);
        struct gfs2_holder gh;
        enum evict_behavior behavior;
        int ret;

        gfs2_holder_mark_uninitialized(&gh);
        if (inode->i_nlink || sb_rdonly(sb) || !ip->i_no_addr)
                goto out;

        /*
         * In case of an incomplete mount, gfs2_evict_inode() may be called for
         * system files without having an active journal to write to.  In that
         * case, skip the filesystem evict.
         */
        if (!sdp->sd_jdesc)
                goto out;

        behavior = evict_should_delete(inode, &gh);
        if (behavior == EVICT_SHOULD_DEFER_DELETE &&
            !test_bit(SDF_KILL, &sdp->sd_flags)) {
                struct gfs2_glock *io_gl = ip->i_iopen_gh.gh_gl;

                if (io_gl) {
                        gfs2_glock_hold(io_gl);
                        if (!gfs2_queue_verify_delete(io_gl, true))
                                gfs2_glock_put(io_gl);
                        goto out;
                }
                behavior = EVICT_SHOULD_DELETE;
        }
        if (behavior == EVICT_SHOULD_DELETE)
                ret = evict_unlinked_inode(inode);
        else
                ret = evict_linked_inode(inode);

        if (gfs2_rs_active(&ip->i_res))
                gfs2_rs_deltree(&ip->i_res);

        if (ret && ret != GLR_TRYFAILED && ret != -EROFS)
                fs_warn(sdp, "gfs2_evict_inode: %d\n", ret);
out:
        if (gfs2_holder_initialized(&gh))
                gfs2_glock_dq_uninit(&gh);
        truncate_inode_pages_final(&inode->i_data);
        if (ip->i_qadata)
                gfs2_assert_warn(sdp, ip->i_qadata->qa_ref == 0);
        gfs2_rs_deltree(&ip->i_res);
        gfs2_ordered_del_inode(ip);
        clear_inode(inode);
        gfs2_dir_hash_inval(ip);
        if (gfs2_holder_initialized(&ip->i_iopen_gh)) {
                struct gfs2_glock *gl = ip->i_iopen_gh.gh_gl;

                glock_clear_object(gl, ip);
                gfs2_glock_hold(gl);
                ip->i_iopen_gh.gh_flags |= GL_NOCACHE;
                gfs2_glock_dq_uninit(&ip->i_iopen_gh);
                gfs2_glock_put_eventually(gl);
        }
        if (ip->i_gl) {
                glock_clear_object(ip->i_gl, ip);
                wait_on_bit_io(&ip->i_flags, GIF_GLOP_PENDING, TASK_UNINTERRUPTIBLE);
                gfs2_glock_put_eventually(ip->i_gl);
                rcu_assign_pointer(ip->i_gl, NULL);
        }
}

static struct inode *gfs2_alloc_inode(struct super_block *sb)
{
        struct gfs2_inode *ip;

        ip = alloc_inode_sb(sb, gfs2_inode_cachep, GFP_KERNEL);
        if (!ip)
                return NULL;
        ip->i_no_addr = 0;
        ip->i_no_formal_ino = 0;
        ip->i_flags = 0;
        ip->i_gl = NULL;
        gfs2_holder_mark_uninitialized(&ip->i_iopen_gh);
        memset(&ip->i_res, 0, sizeof(ip->i_res));
        RB_CLEAR_NODE(&ip->i_res.rs_node);
        ip->i_diskflags = 0;
        ip->i_rahead = 0;
        return &ip->i_inode;
}

static void gfs2_free_inode(struct inode *inode)
{
        kmem_cache_free(gfs2_inode_cachep, GFS2_I(inode));
}

void free_local_statfs_inodes(struct gfs2_sbd *sdp)
{
        struct local_statfs_inode *lsi, *safe;

        /* Run through the statfs inodes list to iput and free memory */
        list_for_each_entry_safe(lsi, safe, &sdp->sd_sc_inodes_list, si_list) {
                if (lsi->si_jid == sdp->sd_jdesc->jd_jid)
                        sdp->sd_sc_inode = NULL; /* belongs to this node */
                if (lsi->si_sc_inode)
                        iput(lsi->si_sc_inode);
                list_del(&lsi->si_list);
                kfree(lsi);
        }
}

struct inode *find_local_statfs_inode(struct gfs2_sbd *sdp,
                                      unsigned int index)
{
        struct local_statfs_inode *lsi;

        /* Return the local (per node) statfs inode in the
         * sdp->sd_sc_inodes_list corresponding to the 'index'. */
        list_for_each_entry(lsi, &sdp->sd_sc_inodes_list, si_list) {
                if (lsi->si_jid == index)
                        return lsi->si_sc_inode;
        }
        return NULL;
}

const struct super_operations gfs2_super_ops = {
        .alloc_inode            = gfs2_alloc_inode,
        .free_inode             = gfs2_free_inode,
        .write_inode            = gfs2_write_inode,
        .dirty_inode            = gfs2_dirty_inode,
        .evict_inode            = gfs2_evict_inode,
        .put_super              = gfs2_put_super,
        .sync_fs                = gfs2_sync_fs,
        .freeze_super           = gfs2_freeze_super,
        .freeze_fs              = gfs2_freeze_fs,
        .thaw_super             = gfs2_thaw_super,
        .statfs                 = gfs2_statfs,
        .drop_inode             = gfs2_drop_inode,
        .show_options           = gfs2_show_options,
};