// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
 * Copyright (C) 2004-2006 Red Hat, Inc.  All rights reserved.
 */

#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 <linux/list_sort.h>
#include <linux/blkdev.h>

#include "bmap.h"
#include "dir.h"
#include "gfs2.h"
#include "incore.h"
#include "inode.h"
#include "glock.h"
#include "glops.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
 */
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_wd(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_tr)
                list_move(&bd->bd_ail_st_list, &bd->bd_tr->tr_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_name.ln_sbd;
        struct gfs2_rgrpd *rgd = gfs2_glock2rgrp(gl);
        unsigned int index = bd->bd_bh->b_blocknr - gl->gl_name.ln_number;
        struct gfs2_bitmap *bi = rgd->rd_bits + index;

        rgrp_lock_local(rgd);
        if (bi->bi_clone == NULL)
                goto out;
        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_bytes);
        clear_bit(GBF_FULL, &bi->bi_flags);
        rgd->rd_free_clone = rgd->rd_free;
        BUG_ON(rgd->rd_free_clone < rgd->rd_reserved);
        rgd->rd_extfail_pt = rgd->rd_free;

out:
        rgrp_unlock_local(rgd);
}

/**
 * gfs2_unpin - Unpin a buffer
 * @sdp: the filesystem the buffer belongs to
 * @bh: The buffer to unpin
 * @tr: The system transaction being flushed
 */

static void gfs2_unpin(struct gfs2_sbd *sdp, struct buffer_head *bh,
                       struct gfs2_trans *tr)
{
        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_tr) {
                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_tr = tr;
        list_add(&bd->bd_ail_st_list, &tr->tr_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);
}

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;
}

u64 gfs2_log_bmap(struct gfs2_jdesc *jd, unsigned int lblock)
{
        struct gfs2_journal_extent *je;

        list_for_each_entry(je, &jd->extent_list, list) {
                if (lblock >= je->lblock && lblock < je->lblock + je->blocks)
                        return je->dblock + lblock - je->lblock;
        }

        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 relevant buffers and unlocks them 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,
                                  blk_status_t 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)
                        mark_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
 *
 * 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)
{
        struct gfs2_sbd *sdp = bio->bi_private;
        struct bio_vec *bvec;
        struct page *page;
        struct bvec_iter_all iter_all;

        if (bio->bi_status) {
                if (!cmpxchg(&sdp->sd_log_error, 0, (int)bio->bi_status))
                        fs_err(sdp, "Error %d writing to journal, jid=%u\n",
                               bio->bi_status, sdp->sd_jdesc->jd_jid);
                gfs2_withdraw_delayed(sdp);
                /* prevent more writes to the journal */
                clear_bit(SDF_JOURNAL_LIVE, &sdp->sd_flags);
                wake_up(&sdp->sd_logd_waitq);
        }

        bio_for_each_segment_all(bvec, bio, iter_all) {
                page = bvec->bv_page;
                if (page_has_buffers(page))
                        gfs2_end_log_write_bh(sdp, bvec, bio->bi_status);
                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_submit_bio - Submit any pending log bio
 * @biop: Address of the bio pointer
 * @opf: REQ_OP | op_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_submit_bio(struct bio **biop, int opf)
{
        struct bio *bio = *biop;
        if (bio) {
                struct gfs2_sbd *sdp = bio->bi_private;
                atomic_inc(&sdp->sd_log_in_flight);
                bio->bi_opf = opf;
                submit_bio(bio);
                *biop = NULL;
        }
}

/**
 * gfs2_log_alloc_bio - Allocate a bio
 * @sdp: The super block
 * @blkno: The device block number we want to write to
 * @end_io: The bi_end_io callback
 *
 * Allocate a new bio, initialize it with the given parameters and return it.
 *
 * Returns: The newly allocated bio
 */

static struct bio *gfs2_log_alloc_bio(struct gfs2_sbd *sdp, u64 blkno,
                                      bio_end_io_t *end_io)
{
        struct super_block *sb = sdp->sd_vfs;
        struct bio *bio = bio_alloc(GFP_NOIO, BIO_MAX_VECS);

        bio->bi_iter.bi_sector = blkno << sdp->sd_fsb2bb_shift;
        bio_set_dev(bio, sb->s_bdev);
        bio->bi_end_io = end_io;
        bio->bi_private = sdp;

        return bio;
}

/**
 * gfs2_log_get_bio - Get cached log bio, or allocate a new one
 * @sdp: The super block
 * @blkno: The device block number we want to write to
 * @biop: The bio to get or allocate
 * @op: REQ_OP
 * @end_io: The bi_end_io callback
 * @flush: Always flush the current bio and allocate a new one?
 *
 * 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 no 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 **biop, int op,
                                    bio_end_io_t *end_io, bool flush)
{
        struct bio *bio = *biop;

        if (bio) {
                u64 nblk;

                nblk = bio_end_sector(bio);
                nblk >>= sdp->sd_fsb2bb_shift;
                if (blkno == nblk && !flush)
                        return bio;
                gfs2_log_submit_bio(biop, op);
        }

        *biop = gfs2_log_alloc_bio(sdp, blkno, end_io);
        return *biop;
}

/**
 * gfs2_log_write - write to log
 * @sdp: the filesystem
 * @jd: The journal descriptor
 * @page: the page to write
 * @size: the size of the data to write
 * @offset: the offset within the page 
 * @blkno: block number of the log entry
 *
 * 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.
 */

void gfs2_log_write(struct gfs2_sbd *sdp, struct gfs2_jdesc *jd,
                    struct page *page, unsigned size, unsigned offset,
                    u64 blkno)
{
        struct bio *bio;
        int ret;

        bio = gfs2_log_get_bio(sdp, blkno, &jd->jd_log_bio, REQ_OP_WRITE,
                               gfs2_end_log_write, false);
        ret = bio_add_page(bio, page, size, offset);
        if (ret == 0) {
                bio = gfs2_log_get_bio(sdp, blkno, &jd->jd_log_bio,
                                       REQ_OP_WRITE, gfs2_end_log_write, true);
                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)
{
        u64 dblock;

        dblock = gfs2_log_bmap(sdp->sd_jdesc, sdp->sd_log_flush_head);
        gfs2_log_incr_head(sdp);
        gfs2_log_write(sdp, sdp->sd_jdesc, bh->b_page, bh->b_size,
                       bh_offset(bh), dblock);
}

/**
 * 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.
 */

static void gfs2_log_write_page(struct gfs2_sbd *sdp, struct page *page)
{
        struct super_block *sb = sdp->sd_vfs;
        u64 dblock;

        dblock = gfs2_log_bmap(sdp->sd_jdesc, sdp->sd_log_flush_head);
        gfs2_log_incr_head(sdp);
        gfs2_log_write(sdp, sdp->sd_jdesc, page, sb->s_blocksize, 0, dblock);
}

/**
 * gfs2_end_log_read - end I/O callback for reads from the log
 * @bio: The bio
 *
 * Simply unlock the pages in the bio. The main thread will wait on them and
 * process them in order as necessary.
 */

static void gfs2_end_log_read(struct bio *bio)
{
        struct page *page;
        struct bio_vec *bvec;
        struct bvec_iter_all iter_all;

        bio_for_each_segment_all(bvec, bio, iter_all) {
                page = bvec->bv_page;
                if (bio->bi_status) {
                        int err = blk_status_to_errno(bio->bi_status);

                        SetPageError(page);
                        mapping_set_error(page->mapping, err);
                }
                unlock_page(page);
        }

        bio_put(bio);
}

/**
 * gfs2_jhead_pg_srch - Look for the journal head in a given page.
 * @jd: The journal descriptor
 * @head: The journal head to start from
 * @page: The page to look in
 *
 * Returns: 1 if found, 0 otherwise.
 */

static bool gfs2_jhead_pg_srch(struct gfs2_jdesc *jd,
                              struct gfs2_log_header_host *head,
                              struct page *page)
{
        struct gfs2_sbd *sdp = GFS2_SB(jd->jd_inode);
        struct gfs2_log_header_host lh;
        void *kaddr = kmap_atomic(page);
        unsigned int offset;
        bool ret = false;

        for (offset = 0; offset < PAGE_SIZE; offset += sdp->sd_sb.sb_bsize) {
                if (!__get_log_header(sdp, kaddr + offset, 0, &lh)) {
                        if (lh.lh_sequence >= head->lh_sequence)
                                *head = lh;
                        else {
                                ret = true;
                                break;
                        }
                }
        }
        kunmap_atomic(kaddr);
        return ret;
}

/**
 * gfs2_jhead_process_page - Search/cleanup a page
 * @jd: The journal descriptor
 * @index: Index of the page to look into
 * @head: The journal head to start from
 * @done: If set, perform only cleanup, else search and set if found.
 *
 * Find the page with 'index' in the journal's mapping. Search the page for
 * the journal head if requested (cleanup == false). Release refs on the
 * page so the page cache can reclaim it (put_page() twice). We grabbed a
 * reference on this page two times, first when we did a find_or_create_page()
 * to obtain the page to add it to the bio and second when we do a
 * find_get_page() here to get the page to wait on while I/O on it is being
 * completed.
 * This function is also used to free up a page we might've grabbed but not
 * used. Maybe we added it to a bio, but not submitted it for I/O. Or we
 * submitted the I/O, but we already found the jhead so we only need to drop
 * our references to the page.
 */

static void gfs2_jhead_process_page(struct gfs2_jdesc *jd, unsigned long index,
                                    struct gfs2_log_header_host *head,
                                    bool *done)
{
        struct page *page;

        page = find_get_page(jd->jd_inode->i_mapping, index);
        wait_on_page_locked(page);

        if (PageError(page))
                *done = true;

        if (!*done)
                *done = gfs2_jhead_pg_srch(jd, head, page);

        put_page(page); /* Once for find_get_page */
        put_page(page); /* Once more for find_or_create_page */
}

static struct bio *gfs2_chain_bio(struct bio *prev, unsigned int nr_iovecs)
{
        struct bio *new;

        new = bio_alloc(GFP_NOIO, nr_iovecs);
        bio_copy_dev(new, prev);
        new->bi_iter.bi_sector = bio_end_sector(prev);
        new->bi_opf = prev->bi_opf;
        new->bi_write_hint = prev->bi_write_hint;
        bio_chain(new, prev);
        submit_bio(prev);
        return new;
}

/**
 * gfs2_find_jhead - find the head of a log
 * @jd: The journal descriptor
 * @head: The log descriptor for the head of the log is returned here
 * @keep_cache: If set inode pages will not be truncated
 *
 * Do a search of a journal by reading it in large chunks using bios and find
 * the valid log entry with the highest sequence number.  (i.e. the log head)
 *
 * Returns: 0 on success, errno otherwise
 */
int gfs2_find_jhead(struct gfs2_jdesc *jd, struct gfs2_log_header_host *head,
                    bool keep_cache)
{
        struct gfs2_sbd *sdp = GFS2_SB(jd->jd_inode);
        struct address_space *mapping = jd->jd_inode->i_mapping;
        unsigned int block = 0, blocks_submitted = 0, blocks_read = 0;
        unsigned int bsize = sdp->sd_sb.sb_bsize, off;
        unsigned int bsize_shift = sdp->sd_sb.sb_bsize_shift;
        unsigned int shift = PAGE_SHIFT - bsize_shift;
        unsigned int max_blocks = 2 * 1024 * 1024 >> bsize_shift;
        struct gfs2_journal_extent *je;
        int sz, ret = 0;
        struct bio *bio = NULL;
        struct page *page = NULL;
        bool done = false;
        errseq_t since;

        memset(head, 0, sizeof(*head));
        if (list_empty(&jd->extent_list))
                gfs2_map_journal_extents(sdp, jd);

        since = filemap_sample_wb_err(mapping);
        list_for_each_entry(je, &jd->extent_list, list) {
                u64 dblock = je->dblock;

                for (; block < je->lblock + je->blocks; block++, dblock++) {
                        if (!page) {
                                page = find_or_create_page(mapping,
                                                block >> shift, GFP_NOFS);
                                if (!page) {
                                        ret = -ENOMEM;
                                        done = true;
                                        goto out;
                                }
                                off = 0;
                        }

                        if (bio && (off || block < blocks_submitted + max_blocks)) {
                                sector_t sector = dblock << sdp->sd_fsb2bb_shift;

                                if (bio_end_sector(bio) == sector) {
                                        sz = bio_add_page(bio, page, bsize, off);
                                        if (sz == bsize)
                                                goto block_added;
                                }
                                if (off) {
                                        unsigned int blocks =
                                                (PAGE_SIZE - off) >> bsize_shift;

                                        bio = gfs2_chain_bio(bio, blocks);
                                        goto add_block_to_new_bio;
                                }
                        }

                        if (bio) {
                                blocks_submitted = block;
                                submit_bio(bio);
                        }

                        bio = gfs2_log_alloc_bio(sdp, dblock, gfs2_end_log_read);
                        bio->bi_opf = REQ_OP_READ;
add_block_to_new_bio:
                        sz = bio_add_page(bio, page, bsize, off);
                        BUG_ON(sz != bsize);
block_added:
                        off += bsize;
                        if (off == PAGE_SIZE)
                                page = NULL;
                        if (blocks_submitted <= blocks_read + max_blocks) {
                                /* Keep at least one bio in flight */
                                continue;
                        }

                        gfs2_jhead_process_page(jd, blocks_read >> shift, head, &done);
                        blocks_read += PAGE_SIZE >> bsize_shift;
                        if (done)
                                goto out;  /* found */
                }
        }

out:
        if (bio)
                submit_bio(bio);
        while (blocks_read < block) {
                gfs2_jhead_process_page(jd, blocks_read >> shift, head, &done);
                blocks_read += PAGE_SIZE >> bsize_shift;
        }

        if (!ret)
                ret = filemap_check_wb_err(mapping, since);

        if (!keep_cache)
                truncate_inode_pages(mapping, 0);

        return ret;
}

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 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 int blocknr_cmp(void *priv, const struct list_head *a,
                       const struct list_head *b)
{
        struct gfs2_bufdata *bda, *bdb;

        bda = list_entry(a, struct gfs2_bufdata, bd_list);
        bdb = list_entry(b, struct gfs2_bufdata, bd_list);

        if (bda->bd_bh->b_blocknr < bdb->bd_bh->b_blocknr)
                return -1;
        if (bda->bd_bh->b_blocknr > bdb->bd_bh->b_blocknr)
                return 1;
        return 0;
}

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);
        list_sort(NULL, blist, blocknr_cmp);
        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,
                                         is_databuf ? GFS2_LOG_DESC_JDATA :
                                         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, struct gfs2_trans *tr)
{
        unsigned int limit = buf_limit(sdp); /* 503 for 4k blocks */
        unsigned int nbuf;
        if (tr == NULL)
                return;
        nbuf = tr->tr_num_buf_new - tr->tr_num_buf_rm;
        gfs2_before_commit(sdp, limit, nbuf, &tr->tr_buf, 0);
}

static void buf_lo_after_commit(struct gfs2_sbd *sdp, struct gfs2_trans *tr)
{
        struct list_head *head;
        struct gfs2_bufdata *bd;

        if (tr == NULL)
                return;

        head = &tr->tr_buf;
        while (!list_empty(head)) {
                bd = list_first_entry(head, struct gfs2_bufdata, bd_list);
                list_del_init(&bd->bd_list);
                gfs2_unpin(sdp, bd->bd_bh, tr);
        }
}

static void buf_lo_before_scan(struct gfs2_jdesc *jd,
                               struct gfs2_log_header_host *head, int pass)
{
        if (pass != 0)
                return;

        jd->jd_found_blocks = 0;
        jd->jd_replayed_blocks = 0;
}

#define obsolete_rgrp_replay \
"Replaying 0x%llx from jid=%d/0x%llx but we already have a bh!\n"
#define obsolete_rgrp_replay2 \
"busy:%d, pinned:%d rg_gen:0x%llx, j_gen:0x%llx\n"

static void obsolete_rgrp(struct gfs2_jdesc *jd, struct buffer_head *bh_log,
                          u64 blkno)
{
        struct gfs2_sbd *sdp = GFS2_SB(jd->jd_inode);
        struct gfs2_rgrpd *rgd;
        struct gfs2_rgrp *jrgd = (struct gfs2_rgrp *)bh_log->b_data;

        rgd = gfs2_blk2rgrpd(sdp, blkno, false);
        if (rgd && rgd->rd_addr == blkno &&
            rgd->rd_bits && rgd->rd_bits->bi_bh) {
                fs_info(sdp, obsolete_rgrp_replay, (unsigned long long)blkno,
                        jd->jd_jid, bh_log->b_blocknr);
                fs_info(sdp, obsolete_rgrp_replay2,
                        buffer_busy(rgd->rd_bits->bi_bh) ? 1 : 0,
                        buffer_pinned(rgd->rd_bits->bi_bh),
                        rgd->rd_igeneration,
                        be64_to_cpu(jrgd->rg_igeneration));
                gfs2_dump_glock(NULL, rgd->rd_gl, true);
        }
}

static int buf_lo_scan_elements(struct gfs2_jdesc *jd, u32 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(jd, &start);

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

                jd->jd_found_blocks++;

                if (gfs2_revoke_check(jd, 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 {
                        struct gfs2_meta_header *mh =
                                (struct gfs2_meta_header *)bh_ip->b_data;

                        if (mh->mh_type == cpu_to_be32(GFS2_METATYPE_RG))
                                obsolete_rgrp(jd, bh_log, blkno);

                        mark_buffer_dirty(bh_ip);
                }
                brelse(bh_log);
                brelse(bh_ip);

                if (error)
                        break;

                jd->jd_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_inode_metasync(ip->i_gl);
                return;
        }
        if (pass != 1)
                return;

        gfs2_inode_metasync(ip->i_gl);

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

static void revoke_lo_before_commit(struct gfs2_sbd *sdp, struct gfs2_trans *tr)
{
        struct gfs2_meta_header *mh;
        unsigned int offset;
        struct list_head *head = &sdp->sd_log_revokes;
        struct gfs2_bufdata *bd;
        struct page *page;
        unsigned int length;

        gfs2_flush_revokes(sdp);
        if (!sdp->sd_log_num_revoke)
                return;

        length = gfs2_struct2blk(sdp, sdp->sd_log_num_revoke);
        page = gfs2_get_log_desc(sdp, GFS2_LOG_DESC_REVOKE, length, sdp->sd_log_num_revoke);
        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);
}

void gfs2_drain_revokes(struct gfs2_sbd *sdp)
{
        struct list_head *head = &sdp->sd_log_revokes;
        struct gfs2_bufdata *bd;
        struct gfs2_glock *gl;

        while (!list_empty(head)) {
                bd = list_first_entry(head, struct gfs2_bufdata, bd_list);
                list_del_init(&bd->bd_list);
                gl = bd->bd_gl;
                gfs2_glock_remove_revoke(gl);
                kmem_cache_free(gfs2_bufdata_cachep, bd);
        }
}

static void revoke_lo_after_commit(struct gfs2_sbd *sdp, struct gfs2_trans *tr)
{
        gfs2_drain_revokes(sdp);
}

static void revoke_lo_before_scan(struct gfs2_jdesc *jd,
                                  struct gfs2_log_header_host *head, int pass)
{
        if (pass != 0)
                return;

        jd->jd_found_revokes = 0;
        jd->jd_replay_tail = head->lh_tail;
}

static int revoke_lo_scan_elements(struct gfs2_jdesc *jd, u32 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(jd, &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(jd, blkno, start);
                        if (error < 0) {
                                brelse(bh);
                                return error;
                        }
                        else if (error)
                                jd->jd_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(jd);
                return;
        }
        if (pass != 1)
                return;

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

        gfs2_revoke_clean(jd);
}

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

 * @sdp: The filesystem
 * @tr: The system transaction being flushed
 */

static void databuf_lo_before_commit(struct gfs2_sbd *sdp, struct gfs2_trans *tr)
{
        unsigned int limit = databuf_limit(sdp);
        unsigned int nbuf;
        if (tr == NULL)
                return;
        nbuf = tr->tr_num_databuf_new - tr->tr_num_databuf_rm;
        gfs2_before_commit(sdp, limit, nbuf, &tr->tr_databuf, 1);
}

static int databuf_lo_scan_elements(struct gfs2_jdesc *jd, u32 start,
                                    struct gfs2_log_descriptor *ld,
                                    __be64 *ptr, int pass)
{
        struct gfs2_inode *ip = GFS2_I(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(jd, &start);
        for (; blks; gfs2_replay_incr_blk(jd, &start), blks--) {
                blkno = be64_to_cpu(*ptr++);
                esc = be64_to_cpu(*ptr++);

                jd->jd_found_blocks++;

                if (gfs2_revoke_check(jd, 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);

                jd->jd_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_inode_metasync(ip->i_gl);
                return;
        }
        if (pass != 1)
                return;

        /* data sync? */
        gfs2_inode_metasync(ip->i_gl);

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

static void databuf_lo_after_commit(struct gfs2_sbd *sdp, struct gfs2_trans *tr)
{
        struct list_head *head;
        struct gfs2_bufdata *bd;

        if (tr == NULL)
                return;

        head = &tr->tr_databuf;
        while (!list_empty(head)) {
                bd = list_first_entry(head, struct gfs2_bufdata, bd_list);
                list_del_init(&bd->bd_list);
                gfs2_unpin(sdp, bd->bd_bh, tr);
        }
}


static const struct gfs2_log_operations gfs2_buf_lops = {
        .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",
};

static const struct gfs2_log_operations gfs2_revoke_lops = {
        .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",
};

static const struct gfs2_log_operations gfs2_databuf_lops = {
        .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_revoke_lops,
        NULL,
};