GFS2: Merge two nearly identical xattr functions

[mirror_ubuntu-artful-kernel.git] / fs / gfs2 / lops.c

/*
 * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
 * Copyright (C) 2004-2006 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/mempool.h>
#include <linux/gfs2_ondisk.h>
#include <linux/bio.h>
#include <linux/fs.h>

#include "gfs2.h"
#include "incore.h"
#include "inode.h"
#include "glock.h"
#include "log.h"
#include "lops.h"
#include "meta_io.h"
#include "recovery.h"
#include "rgrp.h"
#include "trans.h"
#include "util.h"
#include "trace_gfs2.h"

/**
 * gfs2_pin - Pin a buffer in memory
 * @sdp: The superblock
 * @bh: The buffer to be pinned
 *
 * The log lock must be held when calling this function
 */
static void gfs2_pin(struct gfs2_sbd *sdp, struct buffer_head *bh)
{
        struct gfs2_bufdata *bd;

        BUG_ON(!current->journal_info);

        clear_buffer_dirty(bh);
        if (test_set_buffer_pinned(bh))
                gfs2_assert_withdraw(sdp, 0);
        if (!buffer_uptodate(bh))
                gfs2_io_error_bh(sdp, bh);
        bd = bh->b_private;
        /* If this buffer is in the AIL and it has already been written
         * to in-place disk block, remove it from the AIL.
         */
        spin_lock(&sdp->sd_ail_lock);
        if (bd->bd_ail)
                list_move(&bd->bd_ail_st_list, &bd->bd_ail->ai_ail2_list);
        spin_unlock(&sdp->sd_ail_lock);
        get_bh(bh);
        atomic_inc(&sdp->sd_log_pinned);
        trace_gfs2_pin(bd, 1);
}

static bool buffer_is_rgrp(const struct gfs2_bufdata *bd)
{
        return bd->bd_gl->gl_name.ln_type == LM_TYPE_RGRP;
}

static void maybe_release_space(struct gfs2_bufdata *bd)
{
        struct gfs2_glock *gl = bd->bd_gl;
        struct gfs2_sbd *sdp = gl->gl_sbd;
        struct gfs2_rgrpd *rgd = gl->gl_object;
        unsigned int index = bd->bd_bh->b_blocknr - gl->gl_name.ln_number;
        struct gfs2_bitmap *bi = rgd->rd_bits + index;

        if (bi->bi_clone == 0)
                return;
        if (sdp->sd_args.ar_discard)
                gfs2_rgrp_send_discards(sdp, rgd->rd_data0, bd->bd_bh, bi, 1, NULL);
        memcpy(bi->bi_clone + bi->bi_offset,
               bd->bd_bh->b_data + bi->bi_offset, bi->bi_len);
        clear_bit(GBF_FULL, &bi->bi_flags);
        rgd->rd_free_clone = rgd->rd_free;
}

/**
 * gfs2_unpin - Unpin a buffer
 * @sdp: the filesystem the buffer belongs to
 * @bh: The buffer to unpin
 * @ai:
 * @flags: The inode dirty flags
 *
 */

static void gfs2_unpin(struct gfs2_sbd *sdp, struct buffer_head *bh,
                       struct gfs2_ail *ai)
{
        struct gfs2_bufdata *bd = bh->b_private;

        BUG_ON(!buffer_uptodate(bh));
        BUG_ON(!buffer_pinned(bh));

        lock_buffer(bh);
        mark_buffer_dirty(bh);
        clear_buffer_pinned(bh);

        if (buffer_is_rgrp(bd))
                maybe_release_space(bd);

        spin_lock(&sdp->sd_ail_lock);
        if (bd->bd_ail) {
                list_del(&bd->bd_ail_st_list);
                brelse(bh);
        } else {
                struct gfs2_glock *gl = bd->bd_gl;
                list_add(&bd->bd_ail_gl_list, &gl->gl_ail_list);
                atomic_inc(&gl->gl_ail_count);
        }
        bd->bd_ail = ai;
        list_add(&bd->bd_ail_st_list, &ai->ai_ail1_list);
        spin_unlock(&sdp->sd_ail_lock);

        clear_bit(GLF_LFLUSH, &bd->bd_gl->gl_flags);
        trace_gfs2_pin(bd, 0);
        unlock_buffer(bh);
        atomic_dec(&sdp->sd_log_pinned);
}

static void gfs2_log_incr_head(struct gfs2_sbd *sdp)
{
        BUG_ON((sdp->sd_log_flush_head == sdp->sd_log_tail) &&
               (sdp->sd_log_flush_head != sdp->sd_log_head));

        if (++sdp->sd_log_flush_head == sdp->sd_jdesc->jd_blocks) {
                sdp->sd_log_flush_head = 0;
                sdp->sd_log_flush_wrapped = 1;
        }
}

static u64 gfs2_log_bmap(struct gfs2_sbd *sdp)
{
        unsigned int lbn = sdp->sd_log_flush_head;
        struct gfs2_journal_extent *je;
        u64 block;

        list_for_each_entry(je, &sdp->sd_jdesc->extent_list, extent_list) {
                if (lbn >= je->lblock && lbn < je->lblock + je->blocks) {
                        block = je->dblock + lbn - je->lblock;
                        gfs2_log_incr_head(sdp);
                        return block;
                }
        }

        return -1;
}

/**
 * gfs2_end_log_write_bh - end log write of pagecache data with buffers
 * @sdp: The superblock
 * @bvec: The bio_vec
 * @error: The i/o status
 *
 * This finds the relavent buffers and unlocks then and sets the
 * error flag according to the status of the i/o request. This is
 * used when the log is writing data which has an in-place version
 * that is pinned in the pagecache.
 */

static void gfs2_end_log_write_bh(struct gfs2_sbd *sdp, struct bio_vec *bvec,
                                  int error)
{
        struct buffer_head *bh, *next;
        struct page *page = bvec->bv_page;
        unsigned size;

        bh = page_buffers(page);
        size = bvec->bv_len;
        while (bh_offset(bh) < bvec->bv_offset)
                bh = bh->b_this_page;
        do {
                if (error)
                        set_buffer_write_io_error(bh);
                unlock_buffer(bh);
                next = bh->b_this_page;
                size -= bh->b_size;
                brelse(bh);
                bh = next;
        } while(bh && size);
}

/**
 * gfs2_end_log_write - end of i/o to the log
 * @bio: The bio
 * @error: Status of i/o request
 *
 * Each bio_vec contains either data from the pagecache or data
 * relating to the log itself. Here we iterate over the bio_vec
 * array, processing both kinds of data.
 *
 */

static void gfs2_end_log_write(struct bio *bio, int error)
{
        struct gfs2_sbd *sdp = bio->bi_private;
        struct bio_vec *bvec;
        struct page *page;
        int i;

        if (error) {
                sdp->sd_log_error = error;
                fs_err(sdp, "Error %d writing to log\n", error);
        }

        bio_for_each_segment(bvec, bio, i) {
                page = bvec->bv_page;
                if (page_has_buffers(page))
                        gfs2_end_log_write_bh(sdp, bvec, error);
                else
                        mempool_free(page, gfs2_page_pool);
        }

        bio_put(bio);
        if (atomic_dec_and_test(&sdp->sd_log_in_flight))
                wake_up(&sdp->sd_log_flush_wait);
}

/**
 * gfs2_log_flush_bio - Submit any pending log bio
 * @sdp: The superblock
 * @rw: The rw flags
 *
 * Submit any pending part-built or full bio to the block device. If
 * there is no pending bio, then this is a no-op.
 */

void gfs2_log_flush_bio(struct gfs2_sbd *sdp, int rw)
{
        if (sdp->sd_log_bio) {
                atomic_inc(&sdp->sd_log_in_flight);
                submit_bio(rw, sdp->sd_log_bio);
                sdp->sd_log_bio = NULL;
        }
}

/**
 * gfs2_log_alloc_bio - Allocate a new bio for log writing
 * @sdp: The superblock
 * @blkno: The next device block number we want to write to
 *
 * This should never be called when there is a cached bio in the
 * super block. When it returns, there will be a cached bio in the
 * super block which will have as many bio_vecs as the device is
 * happy to handle.
 *
 * Returns: Newly allocated bio
 */

static struct bio *gfs2_log_alloc_bio(struct gfs2_sbd *sdp, u64 blkno)
{
        struct super_block *sb = sdp->sd_vfs;
        unsigned nrvecs = bio_get_nr_vecs(sb->s_bdev);
        struct bio *bio;

        BUG_ON(sdp->sd_log_bio);

        while (1) {
                bio = bio_alloc(GFP_NOIO, nrvecs);
                if (likely(bio))
                        break;
                nrvecs = max(nrvecs/2, 1U);
        }

        bio->bi_sector = blkno * (sb->s_blocksize >> 9);
        bio->bi_bdev = sb->s_bdev;
        bio->bi_end_io = gfs2_end_log_write;
        bio->bi_private = sdp;

        sdp->sd_log_bio = bio;

        return bio;
}

/**
 * gfs2_log_get_bio - Get cached log bio, or allocate a new one
 * @sdp: The superblock
 * @blkno: The device block number we want to write to
 *
 * If there is a cached bio, then if the next block number is sequential
 * with the previous one, return it, otherwise flush the bio to the
 * device. If there is not a cached bio, or we just flushed it, then
 * allocate a new one.
 *
 * Returns: The bio to use for log writes
 */

static struct bio *gfs2_log_get_bio(struct gfs2_sbd *sdp, u64 blkno)
{
        struct bio *bio = sdp->sd_log_bio;
        u64 nblk;

        if (bio) {
                nblk = bio->bi_sector + bio_sectors(bio);
                nblk >>= sdp->sd_fsb2bb_shift;
                if (blkno == nblk)
                        return bio;
                gfs2_log_flush_bio(sdp, WRITE);
        }

        return gfs2_log_alloc_bio(sdp, blkno);
}


/**
 * gfs2_log_write - write to log
 * @sdp: the filesystem
 * @page: the page to write
 * @size: the size of the data to write
 * @offset: the offset within the page 
 *
 * Try and add the page segment to the current bio. If that fails,
 * submit the current bio to the device and create a new one, and
 * then add the page segment to that.
 */

static void gfs2_log_write(struct gfs2_sbd *sdp, struct page *page,
                           unsigned size, unsigned offset)
{
        u64 blkno = gfs2_log_bmap(sdp);
        struct bio *bio;
        int ret;

        bio = gfs2_log_get_bio(sdp, blkno);
        ret = bio_add_page(bio, page, size, offset);
        if (ret == 0) {
                gfs2_log_flush_bio(sdp, WRITE);
                bio = gfs2_log_alloc_bio(sdp, blkno);
                ret = bio_add_page(bio, page, size, offset);
                WARN_ON(ret == 0);
        }
}

/**
 * gfs2_log_write_bh - write a buffer's content to the log
 * @sdp: The super block
 * @bh: The buffer pointing to the in-place location
 * 
 * This writes the content of the buffer to the next available location
 * in the log. The buffer will be unlocked once the i/o to the log has
 * completed.
 */

static void gfs2_log_write_bh(struct gfs2_sbd *sdp, struct buffer_head *bh)
{
        gfs2_log_write(sdp, bh->b_page, bh->b_size, bh_offset(bh));
}

/**
 * gfs2_log_write_page - write one block stored in a page, into the log
 * @sdp: The superblock
 * @page: The struct page
 *
 * This writes the first block-sized part of the page into the log. Note
 * that the page must have been allocated from the gfs2_page_pool mempool
 * and that after this has been called, ownership has been transferred and
 * the page may be freed at any time.
 */

void gfs2_log_write_page(struct gfs2_sbd *sdp, struct page *page)
{
        struct super_block *sb = sdp->sd_vfs;
        gfs2_log_write(sdp, page, sb->s_blocksize, 0);
}

static struct page *gfs2_get_log_desc(struct gfs2_sbd *sdp, u32 ld_type,
                                      u32 ld_length, u32 ld_data1)
{
        struct page *page = mempool_alloc(gfs2_page_pool, GFP_NOIO);
        struct gfs2_log_descriptor *ld = page_address(page);
        clear_page(ld);
        ld->ld_header.mh_magic = cpu_to_be32(GFS2_MAGIC);
        ld->ld_header.mh_type = cpu_to_be32(GFS2_METATYPE_LD);
        ld->ld_header.mh_format = cpu_to_be32(GFS2_FORMAT_LD);
        ld->ld_type = cpu_to_be32(ld_type);
        ld->ld_length = cpu_to_be32(ld_length);
        ld->ld_data1 = cpu_to_be32(ld_data1);
        ld->ld_data2 = 0;
        return page;
}

static void buf_lo_add(struct gfs2_sbd *sdp, struct gfs2_bufdata *bd)
{
        struct gfs2_meta_header *mh;
        struct gfs2_trans *tr;

        lock_buffer(bd->bd_bh);
        gfs2_log_lock(sdp);
        tr = current->journal_info;
        tr->tr_touched = 1;
        if (!list_empty(&bd->bd_list))
                goto out;
        set_bit(GLF_LFLUSH, &bd->bd_gl->gl_flags);
        set_bit(GLF_DIRTY, &bd->bd_gl->gl_flags);
        mh = (struct gfs2_meta_header *)bd->bd_bh->b_data;
        if (unlikely(mh->mh_magic != cpu_to_be32(GFS2_MAGIC))) {
                printk(KERN_ERR
                       "Attempting to add uninitialised block to journal (inplace block=%lld)\n",
                       (unsigned long long)bd->bd_bh->b_blocknr);
                BUG();
        }
        gfs2_pin(sdp, bd->bd_bh);
        mh->__pad0 = cpu_to_be64(0);
        mh->mh_jid = cpu_to_be32(sdp->sd_jdesc->jd_jid);
        sdp->sd_log_num_buf++;
        list_add(&bd->bd_list, &sdp->sd_log_le_buf);
        tr->tr_num_buf_new++;
out:
        gfs2_log_unlock(sdp);
        unlock_buffer(bd->bd_bh);
}

static void gfs2_check_magic(struct buffer_head *bh)
{
        void *kaddr;
        __be32 *ptr;

        clear_buffer_escaped(bh);
        kaddr = kmap_atomic(bh->b_page);
        ptr = kaddr + bh_offset(bh);
        if (*ptr == cpu_to_be32(GFS2_MAGIC))
                set_buffer_escaped(bh);
        kunmap_atomic(kaddr);
}

static void gfs2_before_commit(struct gfs2_sbd *sdp, unsigned int limit,
                                unsigned int total, struct list_head *blist,
                                bool is_databuf)
{
        struct gfs2_log_descriptor *ld;
        struct gfs2_bufdata *bd1 = NULL, *bd2;
        struct page *page;
        unsigned int num;
        unsigned n;
        __be64 *ptr;

        gfs2_log_lock(sdp);
        bd1 = bd2 = list_prepare_entry(bd1, blist, bd_list);
        while(total) {
                num = total;
                if (total > limit)
                        num = limit;
                gfs2_log_unlock(sdp);
                page = gfs2_get_log_desc(sdp, GFS2_LOG_DESC_METADATA, num + 1, num);
                ld = page_address(page);
                gfs2_log_lock(sdp);
                ptr = (__be64 *)(ld + 1);

                n = 0;
                list_for_each_entry_continue(bd1, blist, bd_list) {
                        *ptr++ = cpu_to_be64(bd1->bd_bh->b_blocknr);
                        if (is_databuf) {
                                gfs2_check_magic(bd1->bd_bh);
                                *ptr++ = cpu_to_be64(buffer_escaped(bd1->bd_bh) ? 1 : 0);
                        }
                        if (++n >= num)
                                break;
                }

                gfs2_log_unlock(sdp);
                gfs2_log_write_page(sdp, page);
                gfs2_log_lock(sdp);

                n = 0;
                list_for_each_entry_continue(bd2, blist, bd_list) {
                        get_bh(bd2->bd_bh);
                        gfs2_log_unlock(sdp);
                        lock_buffer(bd2->bd_bh);

                        if (buffer_escaped(bd2->bd_bh)) {
                                void *kaddr;
                                page = mempool_alloc(gfs2_page_pool, GFP_NOIO);
                                ptr = page_address(page);
                                kaddr = kmap_atomic(bd2->bd_bh->b_page);
                                memcpy(ptr, kaddr + bh_offset(bd2->bd_bh),
                                       bd2->bd_bh->b_size);
                                kunmap_atomic(kaddr);
                                *(__be32 *)ptr = 0;
                                clear_buffer_escaped(bd2->bd_bh);
                                unlock_buffer(bd2->bd_bh);
                                brelse(bd2->bd_bh);
                                gfs2_log_write_page(sdp, page);
                        } else {
                                gfs2_log_write_bh(sdp, bd2->bd_bh);
                        }
                        gfs2_log_lock(sdp);
                        if (++n >= num)
                                break;
                }

                BUG_ON(total < num);
                total -= num;
        }
        gfs2_log_unlock(sdp);
}

static void buf_lo_before_commit(struct gfs2_sbd *sdp)
{
        unsigned int limit = buf_limit(sdp); /* 503 for 4k blocks */

        gfs2_before_commit(sdp, limit, sdp->sd_log_num_buf,
                           &sdp->sd_log_le_buf, 0);
}

static void buf_lo_after_commit(struct gfs2_sbd *sdp, struct gfs2_ail *ai)
{
        struct list_head *head = &sdp->sd_log_le_buf;
        struct gfs2_bufdata *bd;

        while (!list_empty(head)) {
                bd = list_entry(head->next, struct gfs2_bufdata, bd_list);
                list_del_init(&bd->bd_list);
                sdp->sd_log_num_buf--;

                gfs2_unpin(sdp, bd->bd_bh, ai);
        }
        gfs2_assert_warn(sdp, !sdp->sd_log_num_buf);
}

static void buf_lo_before_scan(struct gfs2_jdesc *jd,
                               struct gfs2_log_header_host *head, int pass)
{
        struct gfs2_sbd *sdp = GFS2_SB(jd->jd_inode);

        if (pass != 0)
                return;

        sdp->sd_found_blocks = 0;
        sdp->sd_replayed_blocks = 0;
}

static int buf_lo_scan_elements(struct gfs2_jdesc *jd, unsigned int start,
                                struct gfs2_log_descriptor *ld, __be64 *ptr,
                                int pass)
{
        struct gfs2_inode *ip = GFS2_I(jd->jd_inode);
        struct gfs2_sbd *sdp = GFS2_SB(jd->jd_inode);
        struct gfs2_glock *gl = ip->i_gl;
        unsigned int blks = be32_to_cpu(ld->ld_data1);
        struct buffer_head *bh_log, *bh_ip;
        u64 blkno;
        int error = 0;

        if (pass != 1 || be32_to_cpu(ld->ld_type) != GFS2_LOG_DESC_METADATA)
                return 0;

        gfs2_replay_incr_blk(sdp, &start);

        for (; blks; gfs2_replay_incr_blk(sdp, &start), blks--) {
                blkno = be64_to_cpu(*ptr++);

                sdp->sd_found_blocks++;

                if (gfs2_revoke_check(sdp, blkno, start))
                        continue;

                error = gfs2_replay_read_block(jd, start, &bh_log);
                if (error)
                        return error;

                bh_ip = gfs2_meta_new(gl, blkno);
                memcpy(bh_ip->b_data, bh_log->b_data, bh_log->b_size);

                if (gfs2_meta_check(sdp, bh_ip))
                        error = -EIO;
                else
                        mark_buffer_dirty(bh_ip);

                brelse(bh_log);
                brelse(bh_ip);

                if (error)
                        break;

                sdp->sd_replayed_blocks++;
        }

        return error;
}

static void buf_lo_after_scan(struct gfs2_jdesc *jd, int error, int pass)
{
        struct gfs2_inode *ip = GFS2_I(jd->jd_inode);
        struct gfs2_sbd *sdp = GFS2_SB(jd->jd_inode);

        if (error) {
                gfs2_meta_sync(ip->i_gl);
                return;
        }
        if (pass != 1)
                return;

        gfs2_meta_sync(ip->i_gl);

        fs_info(sdp, "jid=%u: Replayed %u of %u blocks\n",
                jd->jd_jid, sdp->sd_replayed_blocks, sdp->sd_found_blocks);
}

static void revoke_lo_add(struct gfs2_sbd *sdp, struct gfs2_bufdata *bd)
{
        struct gfs2_glock *gl = bd->bd_gl;
        struct gfs2_trans *tr;

        tr = current->journal_info;
        tr->tr_touched = 1;
        tr->tr_num_revoke++;
        sdp->sd_log_num_revoke++;
        atomic_inc(&gl->gl_revokes);
        set_bit(GLF_LFLUSH, &gl->gl_flags);
        list_add(&bd->bd_list, &sdp->sd_log_le_revoke);
}

static void revoke_lo_before_commit(struct gfs2_sbd *sdp)
{
        struct gfs2_log_descriptor *ld;
        struct gfs2_meta_header *mh;
        unsigned int offset;
        struct list_head *head = &sdp->sd_log_le_revoke;
        struct gfs2_bufdata *bd;
        struct page *page;
        unsigned int length;

        if (!sdp->sd_log_num_revoke)
                return;

        length = gfs2_struct2blk(sdp, sdp->sd_log_num_revoke, sizeof(u64));
        page = gfs2_get_log_desc(sdp, GFS2_LOG_DESC_REVOKE, length, sdp->sd_log_num_revoke);
        ld = page_address(page);
        offset = sizeof(struct gfs2_log_descriptor);

        list_for_each_entry(bd, head, bd_list) {
                sdp->sd_log_num_revoke--;

                if (offset + sizeof(u64) > sdp->sd_sb.sb_bsize) {

                        gfs2_log_write_page(sdp, page);
                        page = mempool_alloc(gfs2_page_pool, GFP_NOIO);
                        mh = page_address(page);
                        clear_page(mh);
                        mh->mh_magic = cpu_to_be32(GFS2_MAGIC);
                        mh->mh_type = cpu_to_be32(GFS2_METATYPE_LB);
                        mh->mh_format = cpu_to_be32(GFS2_FORMAT_LB);
                        offset = sizeof(struct gfs2_meta_header);
                }

                *(__be64 *)(page_address(page) + offset) = cpu_to_be64(bd->bd_blkno);
                offset += sizeof(u64);
        }
        gfs2_assert_withdraw(sdp, !sdp->sd_log_num_revoke);

        gfs2_log_write_page(sdp, page);
}

static void revoke_lo_after_commit(struct gfs2_sbd *sdp, struct gfs2_ail *ai)
{
        struct list_head *head = &sdp->sd_log_le_revoke;
        struct gfs2_bufdata *bd;
        struct gfs2_glock *gl;

        while (!list_empty(head)) {
                bd = list_entry(head->next, struct gfs2_bufdata, bd_list);
                list_del_init(&bd->bd_list);
                gl = bd->bd_gl;
                atomic_dec(&gl->gl_revokes);
                clear_bit(GLF_LFLUSH, &gl->gl_flags);
                kmem_cache_free(gfs2_bufdata_cachep, bd);
        }
}

static void revoke_lo_before_scan(struct gfs2_jdesc *jd,
                                  struct gfs2_log_header_host *head, int pass)
{
        struct gfs2_sbd *sdp = GFS2_SB(jd->jd_inode);

        if (pass != 0)
                return;

        sdp->sd_found_revokes = 0;
        sdp->sd_replay_tail = head->lh_tail;
}

static int revoke_lo_scan_elements(struct gfs2_jdesc *jd, unsigned int start,
                                   struct gfs2_log_descriptor *ld, __be64 *ptr,
                                   int pass)
{
        struct gfs2_sbd *sdp = GFS2_SB(jd->jd_inode);
        unsigned int blks = be32_to_cpu(ld->ld_length);
        unsigned int revokes = be32_to_cpu(ld->ld_data1);
        struct buffer_head *bh;
        unsigned int offset;
        u64 blkno;
        int first = 1;
        int error;

        if (pass != 0 || be32_to_cpu(ld->ld_type) != GFS2_LOG_DESC_REVOKE)
                return 0;

        offset = sizeof(struct gfs2_log_descriptor);

        for (; blks; gfs2_replay_incr_blk(sdp, &start), blks--) {
                error = gfs2_replay_read_block(jd, start, &bh);
                if (error)
                        return error;

                if (!first)
                        gfs2_metatype_check(sdp, bh, GFS2_METATYPE_LB);

                while (offset + sizeof(u64) <= sdp->sd_sb.sb_bsize) {
                        blkno = be64_to_cpu(*(__be64 *)(bh->b_data + offset));

                        error = gfs2_revoke_add(sdp, blkno, start);
                        if (error < 0) {
                                brelse(bh);
                                return error;
                        }
                        else if (error)
                                sdp->sd_found_revokes++;

                        if (!--revokes)
                                break;
                        offset += sizeof(u64);
                }

                brelse(bh);
                offset = sizeof(struct gfs2_meta_header);
                first = 0;
        }

        return 0;
}

static void revoke_lo_after_scan(struct gfs2_jdesc *jd, int error, int pass)
{
        struct gfs2_sbd *sdp = GFS2_SB(jd->jd_inode);

        if (error) {
                gfs2_revoke_clean(sdp);
                return;
        }
        if (pass != 1)
                return;

        fs_info(sdp, "jid=%u: Found %u revoke tags\n",
                jd->jd_jid, sdp->sd_found_revokes);

        gfs2_revoke_clean(sdp);
}

/**
 * databuf_lo_add - Add a databuf to the transaction.
 *
 * This is used in two distinct cases:
 * i) In ordered write mode
 *    We put the data buffer on a list so that we can ensure that its
 *    synced to disk at the right time
 * ii) In journaled data mode
 *    We need to journal the data block in the same way as metadata in
 *    the functions above. The difference is that here we have a tag
 *    which is two __be64's being the block number (as per meta data)
 *    and a flag which says whether the data block needs escaping or
 *    not. This means we need a new log entry for each 251 or so data
 *    blocks, which isn't an enormous overhead but twice as much as
 *    for normal metadata blocks.
 */
static void databuf_lo_add(struct gfs2_sbd *sdp, struct gfs2_bufdata *bd)
{
        struct gfs2_trans *tr = current->journal_info;
        struct address_space *mapping = bd->bd_bh->b_page->mapping;
        struct gfs2_inode *ip = GFS2_I(mapping->host);

        lock_buffer(bd->bd_bh);
        gfs2_log_lock(sdp);
        if (tr)
                tr->tr_touched = 1;
        if (!list_empty(&bd->bd_list))
                goto out;
        set_bit(GLF_LFLUSH, &bd->bd_gl->gl_flags);
        set_bit(GLF_DIRTY, &bd->bd_gl->gl_flags);
        if (gfs2_is_jdata(ip)) {
                gfs2_pin(sdp, bd->bd_bh);
                tr->tr_num_databuf_new++;
                sdp->sd_log_num_databuf++;
                list_add_tail(&bd->bd_list, &sdp->sd_log_le_databuf);
        } else {
                list_add_tail(&bd->bd_list, &sdp->sd_log_le_ordered);
        }
out:
        gfs2_log_unlock(sdp);
        unlock_buffer(bd->bd_bh);
}

/**
 * databuf_lo_before_commit - Scan the data buffers, writing as we go
 *
 */

static void databuf_lo_before_commit(struct gfs2_sbd *sdp)
{
        unsigned int limit = buf_limit(sdp) / 2;

        gfs2_before_commit(sdp, limit, sdp->sd_log_num_databuf,
                           &sdp->sd_log_le_databuf, 1);
}

static int databuf_lo_scan_elements(struct gfs2_jdesc *jd, unsigned int start,
                                    struct gfs2_log_descriptor *ld,
                                    __be64 *ptr, int pass)
{
        struct gfs2_inode *ip = GFS2_I(jd->jd_inode);
        struct gfs2_sbd *sdp = GFS2_SB(jd->jd_inode);
        struct gfs2_glock *gl = ip->i_gl;
        unsigned int blks = be32_to_cpu(ld->ld_data1);
        struct buffer_head *bh_log, *bh_ip;
        u64 blkno;
        u64 esc;
        int error = 0;

        if (pass != 1 || be32_to_cpu(ld->ld_type) != GFS2_LOG_DESC_JDATA)
                return 0;

        gfs2_replay_incr_blk(sdp, &start);
        for (; blks; gfs2_replay_incr_blk(sdp, &start), blks--) {
                blkno = be64_to_cpu(*ptr++);
                esc = be64_to_cpu(*ptr++);

                sdp->sd_found_blocks++;

                if (gfs2_revoke_check(sdp, blkno, start))
                        continue;

                error = gfs2_replay_read_block(jd, start, &bh_log);
                if (error)
                        return error;

                bh_ip = gfs2_meta_new(gl, blkno);
                memcpy(bh_ip->b_data, bh_log->b_data, bh_log->b_size);

                /* Unescape */
                if (esc) {
                        __be32 *eptr = (__be32 *)bh_ip->b_data;
                        *eptr = cpu_to_be32(GFS2_MAGIC);
                }
                mark_buffer_dirty(bh_ip);

                brelse(bh_log);
                brelse(bh_ip);

                sdp->sd_replayed_blocks++;
        }

        return error;
}

/* FIXME: sort out accounting for log blocks etc. */

static void databuf_lo_after_scan(struct gfs2_jdesc *jd, int error, int pass)
{
        struct gfs2_inode *ip = GFS2_I(jd->jd_inode);
        struct gfs2_sbd *sdp = GFS2_SB(jd->jd_inode);

        if (error) {
                gfs2_meta_sync(ip->i_gl);
                return;
        }
        if (pass != 1)
                return;

        /* data sync? */
        gfs2_meta_sync(ip->i_gl);

        fs_info(sdp, "jid=%u: Replayed %u of %u data blocks\n",
                jd->jd_jid, sdp->sd_replayed_blocks, sdp->sd_found_blocks);
}

static void databuf_lo_after_commit(struct gfs2_sbd *sdp, struct gfs2_ail *ai)
{
        struct list_head *head = &sdp->sd_log_le_databuf;
        struct gfs2_bufdata *bd;

        while (!list_empty(head)) {
                bd = list_entry(head->next, struct gfs2_bufdata, bd_list);
                list_del_init(&bd->bd_list);
                sdp->sd_log_num_databuf--;
                gfs2_unpin(sdp, bd->bd_bh, ai);
        }
        gfs2_assert_warn(sdp, !sdp->sd_log_num_databuf);
}


const struct gfs2_log_operations gfs2_buf_lops = {
        .lo_add = buf_lo_add,
        .lo_before_commit = buf_lo_before_commit,
        .lo_after_commit = buf_lo_after_commit,
        .lo_before_scan = buf_lo_before_scan,
        .lo_scan_elements = buf_lo_scan_elements,
        .lo_after_scan = buf_lo_after_scan,
        .lo_name = "buf",
};

const struct gfs2_log_operations gfs2_revoke_lops = {
        .lo_add = revoke_lo_add,
        .lo_before_commit = revoke_lo_before_commit,
        .lo_after_commit = revoke_lo_after_commit,
        .lo_before_scan = revoke_lo_before_scan,
        .lo_scan_elements = revoke_lo_scan_elements,
        .lo_after_scan = revoke_lo_after_scan,
        .lo_name = "revoke",
};

const struct gfs2_log_operations gfs2_rg_lops = {
        .lo_name = "rg",
};

const struct gfs2_log_operations gfs2_databuf_lops = {
        .lo_add = databuf_lo_add,
        .lo_before_commit = databuf_lo_before_commit,
        .lo_after_commit = databuf_lo_after_commit,
        .lo_scan_elements = databuf_lo_scan_elements,
        .lo_after_scan = databuf_lo_after_scan,
        .lo_name = "databuf",
};

const struct gfs2_log_operations *gfs2_log_ops[] = {
        &gfs2_databuf_lops,
        &gfs2_buf_lops,
        &gfs2_rg_lops,
        &gfs2_revoke_lops,
        NULL,
};