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/*

 * 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/gfs2_ondisk.h>

#include <linux/crc32.h>

#include <linux/lm_interface.h>

#include <linux/delay.h>

#include "gfs2.h"

#include "incore.h"

#include "bmap.h"

#include "glock.h"

#include "log.h"

#include "lops.h"

#include "meta_io.h"

#include "util.h"

#include "dir.h"

#define PULL 1

/**

 * gfs2_struct2blk - compute stuff

 * @sdp: the filesystem

 * @nstruct: the number of structures

 * @ssize: the size of the structures

 *

 * Compute the number of log descriptor blocks needed to hold a certain number

 * of structures of a certain size.

 *

 * Returns: the number of blocks needed (minimum is always 1)

 */

unsigned int gfs2_struct2blk(struct gfs2_sbd *sdp, unsigned int nstruct,

                             unsigned int ssize)

{

        unsigned int blks;

        unsigned int first, second;

        blks = 1;

        first = (sdp->sd_sb.sb_bsize - sizeof(struct gfs2_log_descriptor)) / ssize;

        if (nstruct > first) {

                second = (sdp->sd_sb.sb_bsize -

                          sizeof(struct gfs2_meta_header)) / ssize;

                blks += DIV_ROUND_UP(nstruct - first, second);

        }

        return blks;

}

/**

 * gfs2_remove_from_ail - Remove an entry from the ail lists, updating counters

 * @mapping: The associated mapping (maybe NULL)

 * @bd: The gfs2_bufdata to remove

 *

 * The log lock _must_ be held when calling this function

 *

 */

void gfs2_remove_from_ail(struct address_space *mapping, struct gfs2_bufdata *bd)

{

        bd->bd_ail = NULL;

        list_del_init(&bd->bd_ail_st_list);

        list_del_init(&bd->bd_ail_gl_list);

        atomic_dec(&bd->bd_gl->gl_ail_count);

        if (mapping)

                gfs2_meta_cache_flush(GFS2_I(mapping->host));

        brelse(bd->bd_bh);

}

/**

 * gfs2_ail1_start_one - Start I/O on a part of the AIL

 * @sdp: the filesystem

 * @tr: the part of the AIL

 *

 */

static void gfs2_ail1_start_one(struct gfs2_sbd *sdp, struct gfs2_ail *ai)

{

        struct gfs2_bufdata *bd, *s;

        struct buffer_head *bh;

        int retry;

        BUG_ON(!spin_is_locked(&sdp->sd_log_lock));

        do {

                retry = 0;

                list_for_each_entry_safe_reverse(bd, s, &ai->ai_ail1_list,

                                                 bd_ail_st_list) {

                        bh = bd->bd_bh;

                        gfs2_assert(sdp, bd->bd_ail == ai);

                        if (!buffer_busy(bh)) {

                                if (!buffer_uptodate(bh))

                                        gfs2_io_error_bh(sdp, bh);

                                list_move(&bd->bd_ail_st_list, &ai->ai_ail2_list);

                                continue;

                        }

                        if (!buffer_dirty(bh))

                                continue;

                        list_move(&bd->bd_ail_st_list, &ai->ai_ail1_list);

                        get_bh(bh);

                        gfs2_log_unlock(sdp);

                        lock_buffer(bh);

                        if (test_clear_buffer_dirty(bh)) {

                                bh->b_end_io = end_buffer_write_sync;

                                submit_bh(WRITE, bh);

                        } else {

                                unlock_buffer(bh);

                                brelse(bh);

                        }

                        gfs2_log_lock(sdp);

                        retry = 1;

                        break;

                }

        } while (retry);

}

/**

 * gfs2_ail1_empty_one - Check whether or not a trans in the AIL has been synced

 * @sdp: the filesystem

 * @ai: the AIL entry

 *

 */

static int gfs2_ail1_empty_one(struct gfs2_sbd *sdp, struct gfs2_ail *ai, int flags)

{

        struct gfs2_bufdata *bd, *s;

        struct buffer_head *bh;

        list_for_each_entry_safe_reverse(bd, s, &ai->ai_ail1_list,

                                         bd_ail_st_list) {

                bh = bd->bd_bh;

                gfs2_assert(sdp, bd->bd_ail == ai);

                if (buffer_busy(bh)) {

                        if (flags & DIO_ALL)

                                continue;

                        else

                                break;

                }

                if (!buffer_uptodate(bh))

                        gfs2_io_error_bh(sdp, bh);

                list_move(&bd->bd_ail_st_list, &ai->ai_ail2_list);

        }

        return list_empty(&ai->ai_ail1_list);

}

static void gfs2_ail1_start(struct gfs2_sbd *sdp, int flags)

{

        struct list_head *head;

        u64 sync_gen;

        struct list_head *first;

        struct gfs2_ail *first_ai, *ai, *tmp;

        int done = 0;

        gfs2_log_lock(sdp);

        head = &sdp->sd_ail1_list;

        if (list_empty(head)) {

                gfs2_log_unlock(sdp);

                return;

        }

        sync_gen = sdp->sd_ail_sync_gen++;

        first = head->prev;

        first_ai = list_entry(first, struct gfs2_ail, ai_list);

        first_ai->ai_sync_gen = sync_gen;

        gfs2_ail1_start_one(sdp, first_ai); /* This may drop log lock */

        if (flags & DIO_ALL)

                first = NULL;

        while(!done) {

                if (first && (head->prev != first ||

                              gfs2_ail1_empty_one(sdp, first_ai, 0)))

                        break;

                done = 1;

                list_for_each_entry_safe_reverse(ai, tmp, head, ai_list) {

                        if (ai->ai_sync_gen >= sync_gen)

                                continue;

                        ai->ai_sync_gen = sync_gen;

                        gfs2_ail1_start_one(sdp, ai); /* This may drop log lock */

                        done = 0;

                        break;

                }

        }

        gfs2_log_unlock(sdp);

}

int gfs2_ail1_empty(struct gfs2_sbd *sdp, int flags)

{

        struct gfs2_ail *ai, *s;

        int ret;

        gfs2_log_lock(sdp);

        list_for_each_entry_safe_reverse(ai, s, &sdp->sd_ail1_list, ai_list) {

                if (gfs2_ail1_empty_one(sdp, ai, flags))

                        list_move(&ai->ai_list, &sdp->sd_ail2_list);

                else if (!(flags & DIO_ALL))

                        break;

        }

        ret = list_empty(&sdp->sd_ail1_list);

        gfs2_log_unlock(sdp);

        return ret;

}

/**

 * gfs2_ail2_empty_one - Check whether or not a trans in the AIL has been synced

 * @sdp: the filesystem

 * @ai: the AIL entry

 *

 */

static void gfs2_ail2_empty_one(struct gfs2_sbd *sdp, struct gfs2_ail *ai)

{

        struct list_head *head = &ai->ai_ail2_list;

        struct gfs2_bufdata *bd;

        while (!list_empty(head)) {

                bd = list_entry(head->prev, struct gfs2_bufdata,

                                bd_ail_st_list);

                gfs2_assert(sdp, bd->bd_ail == ai);

                gfs2_remove_from_ail(bd->bd_bh->b_page->mapping, bd);

        }

}

static void ail2_empty(struct gfs2_sbd *sdp, unsigned int new_tail)

{

        struct gfs2_ail *ai, *safe;

        unsigned int old_tail = sdp->sd_log_tail;

        int wrap = (new_tail < old_tail);

        int a, b, rm;

        gfs2_log_lock(sdp);

        list_for_each_entry_safe(ai, safe, &sdp->sd_ail2_list, ai_list) {

                a = (old_tail <= ai->ai_first);

                b = (ai->ai_first < new_tail);

                rm = (wrap) ? (a || b) : (a && b);

                if (!rm)

                        continue;

                gfs2_ail2_empty_one(sdp, ai);

                list_del(&ai->ai_list);

                gfs2_assert_warn(sdp, list_empty(&ai->ai_ail1_list));

                gfs2_assert_warn(sdp, list_empty(&ai->ai_ail2_list));

                kfree(ai);

        }

        gfs2_log_unlock(sdp);

}

/**

 * gfs2_log_reserve - Make a log reservation

 * @sdp: The GFS2 superblock

 * @blks: The number of blocks to reserve

 *

 * Note that we never give out the last few blocks of the journal. Thats

 * due to the fact that there is a small number of header blocks

 * associated with each log flush. The exact number can't be known until

 * flush time, so we ensure that we have just enough free blocks at all

 * times to avoid running out during a log flush.

 *

 * Returns: errno

 */

int gfs2_log_reserve(struct gfs2_sbd *sdp, unsigned int blks)

{

        unsigned int try = 0;

        unsigned reserved_blks = 6 * (4096 / sdp->sd_vfs->s_blocksize);

        if (gfs2_assert_warn(sdp, blks) ||

            gfs2_assert_warn(sdp, blks <= sdp->sd_jdesc->jd_blocks))

                return -EINVAL;

        mutex_lock(&sdp->sd_log_reserve_mutex);

        gfs2_log_lock(sdp);

        while(sdp->sd_log_blks_free <= (blks + reserved_blks)) {

                gfs2_log_unlock(sdp);

                gfs2_ail1_empty(sdp, 0);

                gfs2_log_flush(sdp, NULL);

                if (try++)

                        gfs2_ail1_start(sdp, 0);

                gfs2_log_lock(sdp);

        }

        sdp->sd_log_blks_free -= blks;

        gfs2_log_unlock(sdp);

        mutex_unlock(&sdp->sd_log_reserve_mutex);

        down_read(&sdp->sd_log_flush_lock);

        return 0;

}

/**

 * gfs2_log_release - Release a given number of log blocks

 * @sdp: The GFS2 superblock

 * @blks: The number of blocks

 *

 */

void gfs2_log_release(struct gfs2_sbd *sdp, unsigned int blks)

{

        gfs2_log_lock(sdp);

        sdp->sd_log_blks_free += blks;

        gfs2_assert_withdraw(sdp,

                             sdp->sd_log_blks_free <= sdp->sd_jdesc->jd_blocks);

        gfs2_log_unlock(sdp);

        up_read(&sdp->sd_log_flush_lock);

}

static u64 log_bmap(struct gfs2_sbd *sdp, unsigned int lbn)

{

        struct inode *inode = sdp->sd_jdesc->jd_inode;

        int error;

        struct buffer_head bh_map = { .b_state = 0, .b_blocknr = 0 };

        bh_map.b_size = 1 << inode->i_blkbits;

        error = gfs2_block_map(inode, lbn, 0, &bh_map);

        if (error || !bh_map.b_blocknr)

                printk(KERN_INFO "error=%d, dbn=%llu lbn=%u", error,

                       (unsigned long long)bh_map.b_blocknr, lbn);

        gfs2_assert_withdraw(sdp, !error && bh_map.b_blocknr);

        return bh_map.b_blocknr;

}

/**

 * log_distance - Compute distance between two journal blocks

 * @sdp: The GFS2 superblock

 * @newer: The most recent journal block of the pair

 * @older: The older journal block of the pair

 *

 *   Compute the distance (in the journal direction) between two

 *   blocks in the journal

 *

 * Returns: the distance in blocks

 */

static inline unsigned int log_distance(struct gfs2_sbd *sdp, unsigned int newer,

                                        unsigned int older)

{

        int dist;

        dist = newer - older;

        if (dist < 0)

                dist += sdp->sd_jdesc->jd_blocks;

        return dist;

}

/**

 * calc_reserved - Calculate the number of blocks to reserve when

 *                 refunding a transaction's unused buffers.

 * @sdp: The GFS2 superblock

 *

 * This is complex.  We need to reserve room for all our currently used

 * metadata buffers (e.g. normal file I/O rewriting file time stamps) and

 * all our journaled data buffers for journaled files (e.g. files in the

 * meta_fs like rindex, or files for which chattr +j was done.)

 * If we don't reserve enough space, gfs2_log_refund and gfs2_log_flush

 * will count it as free space (sd_log_blks_free) and corruption will follow.

 *

 * We can have metadata bufs and jdata bufs in the same journal.  So each

 * type gets its own log header, for which we need to reserve a block.

 * In fact, each type has the potential for needing more than one header

 * in cases where we have more buffers than will fit on a journal page.

 * Metadata journal entries take up half the space of journaled buffer entries.

 * Thus, metadata entries have buf_limit (502) and journaled buffers have

 * databuf_limit (251) before they cause a wrap around.

 *

 * Also, we need to reserve blocks for revoke journal entries and one for an

 * overall header for the lot.

 *

 * Returns: the number of blocks reserved

 */

static unsigned int calc_reserved(struct gfs2_sbd *sdp)

{

        unsigned int reserved = 0;

        unsigned int mbuf_limit, metabufhdrs_needed;

        unsigned int dbuf_limit, databufhdrs_needed;

        unsigned int revokes = 0;

        mbuf_limit = buf_limit(sdp);

        metabufhdrs_needed = (sdp->sd_log_commited_buf +

                              (mbuf_limit - 1)) / mbuf_limit;

        dbuf_limit = databuf_limit(sdp);

        databufhdrs_needed = (sdp->sd_log_commited_databuf +

                              (dbuf_limit - 1)) / dbuf_limit;

        if (sdp->sd_log_commited_revoke)

                revokes = gfs2_struct2blk(sdp, sdp->sd_log_commited_revoke,

                                          sizeof(u64));

        reserved = sdp->sd_log_commited_buf + metabufhdrs_needed +

                sdp->sd_log_commited_databuf + databufhdrs_needed +

                revokes;

        /* One for the overall header */

        if (reserved)

                reserved++;

        return reserved;

}

static unsigned int current_tail(struct gfs2_sbd *sdp)

{

        struct gfs2_ail *ai;

        unsigned int tail;

        gfs2_log_lock(sdp);

        if (list_empty(&sdp->sd_ail1_list)) {

                tail = sdp->sd_log_head;

        } else {

                ai = list_entry(sdp->sd_ail1_list.prev, struct gfs2_ail, ai_list);

                tail = ai->ai_first;

        }

        gfs2_log_unlock(sdp);

        return tail;

}

void gfs2_log_incr_head(struct gfs2_sbd *sdp)

{

        if (sdp->sd_log_flush_head == sdp->sd_log_tail)

                BUG_ON(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;

        }

}

/**

 * gfs2_log_write_endio - End of I/O for a log buffer

 * @bh: The buffer head

 * @uptodate: I/O Status

 *

 */

static void gfs2_log_write_endio(struct buffer_head *bh, int uptodate)

{

        struct gfs2_sbd *sdp = bh->b_private;

        bh->b_private = NULL;

        end_buffer_write_sync(bh, uptodate);

        if (atomic_dec_and_test(&sdp->sd_log_in_flight))

                wake_up(&sdp->sd_log_flush_wait);

}

/**

 * gfs2_log_get_buf - Get and initialize a buffer to use for log control data

 * @sdp: The GFS2 superblock

 *

 * Returns: the buffer_head

 */

struct buffer_head *gfs2_log_get_buf(struct gfs2_sbd *sdp)

{

        u64 blkno = log_bmap(sdp, sdp->sd_log_flush_head);

        struct buffer_head *bh;

        bh = sb_getblk(sdp->sd_vfs, blkno);

        lock_buffer(bh);

        memset(bh->b_data, 0, bh->b_size);

        set_buffer_uptodate(bh);

        clear_buffer_dirty(bh);

        gfs2_log_incr_head(sdp);

        atomic_inc(&sdp->sd_log_in_flight);

        bh->b_private = sdp;

        bh->b_end_io = gfs2_log_write_endio;

        return bh;

}

/**

 * gfs2_fake_write_endio -

 * @bh: The buffer head

 * @uptodate: The I/O Status

 *

 */

static void gfs2_fake_write_endio(struct buffer_head *bh, int uptodate)

{

        struct buffer_head *real_bh = bh->b_private;

        struct gfs2_bufdata *bd = real_bh->b_private;

        struct gfs2_sbd *sdp = bd->bd_gl->gl_sbd;

        end_buffer_write_sync(bh, uptodate);

        free_buffer_head(bh);

        unlock_buffer(real_bh);

        brelse(real_bh);

        if (atomic_dec_and_test(&sdp->sd_log_in_flight))

                wake_up(&sdp->sd_log_flush_wait);

}

/**

 * gfs2_log_fake_buf - Build a fake buffer head to write metadata buffer to log

 * @sdp: the filesystem

 * @data: the data the buffer_head should point to

 *

 * Returns: the log buffer descriptor

 */

struct buffer_head *gfs2_log_fake_buf(struct gfs2_sbd *sdp,

                                      struct buffer_head *real)

{

        u64 blkno = log_bmap(sdp, sdp->sd_log_flush_head);

        struct buffer_head *bh;

        bh = alloc_buffer_head(GFP_NOFS | __GFP_NOFAIL);

        atomic_set(&bh->b_count, 1);

        bh->b_state = (1 << BH_Mapped) | (1 << BH_Uptodate) | (1 << BH_Lock);

        set_bh_page(bh, real->b_page, bh_offset(real));

        bh->b_blocknr = blkno;

        bh->b_size = sdp->sd_sb.sb_bsize;

        bh->b_bdev = sdp->sd_vfs->s_bdev;

        bh->b_private = real;

        bh->b_end_io = gfs2_fake_write_endio;

        gfs2_log_incr_head(sdp);

        atomic_inc(&sdp->sd_log_in_flight);

        return bh;

}

static void log_pull_tail(struct gfs2_sbd *sdp, unsigned int new_tail)

{

        unsigned int dist = log_distance(sdp, new_tail, sdp->sd_log_tail);

        ail2_empty(sdp, new_tail);

        gfs2_log_lock(sdp);

        sdp->sd_log_blks_free += dist;

        gfs2_assert_withdraw(sdp, sdp->sd_log_blks_free <= sdp->sd_jdesc->jd_blocks);

        gfs2_log_unlock(sdp);

        sdp->sd_log_tail = new_tail;

}

/**

 * log_write_header - Get and initialize a journal header buffer

 * @sdp: The GFS2 superblock

 *

 * Returns: the initialized log buffer descriptor

 */

static void log_write_header(struct gfs2_sbd *sdp, u32 flags, int pull)

{

        u64 blkno = log_bmap(sdp, sdp->sd_log_flush_head);

        struct buffer_head *bh;

        struct gfs2_log_header *lh;

        unsigned int tail;

        u32 hash;

        bh = sb_getblk(sdp->sd_vfs, blkno);

        lock_buffer(bh);

        memset(bh->b_data, 0, bh->b_size);

        set_buffer_uptodate(bh);

        clear_buffer_dirty(bh);

        unlock_buffer(bh);

        gfs2_ail1_empty(sdp, 0);

        tail = current_tail(sdp);

        lh = (struct gfs2_log_header *)bh->b_data;

        memset(lh, 0, sizeof(struct gfs2_log_header));

        lh->lh_header.mh_magic = cpu_to_be32(GFS2_MAGIC);

        lh->lh_header.mh_type = cpu_to_be32(GFS2_METATYPE_LH);

        lh->lh_header.mh_format = cpu_to_be32(GFS2_FORMAT_LH);

        lh->lh_sequence = cpu_to_be64(sdp->sd_log_sequence++);

        lh->lh_flags = cpu_to_be32(flags);

        lh->lh_tail = cpu_to_be32(tail);

        lh->lh_blkno = cpu_to_be32(sdp->sd_log_flush_head);

        hash = gfs2_disk_hash(bh->b_data, sizeof(struct gfs2_log_header));

        lh->lh_hash = cpu_to_be32(hash);

        set_buffer_dirty(bh);

        if (sync_dirty_buffer(bh))

                gfs2_io_error_bh(sdp, bh);

        brelse(bh);

        if (sdp->sd_log_tail != tail)

                log_pull_tail(sdp, tail);

        else

                gfs2_assert_withdraw(sdp, !pull);

        sdp->sd_log_idle = (tail == sdp->sd_log_flush_head);

        gfs2_log_incr_head(sdp);

}

static void log_flush_commit(struct gfs2_sbd *sdp)

{

        DEFINE_WAIT(wait);

        if (atomic_read(&sdp->sd_log_in_flight)) {

                do {

                        prepare_to_wait(&sdp->sd_log_flush_wait, &wait,

                                        TASK_UNINTERRUPTIBLE);

                        if (atomic_read(&sdp->sd_log_in_flight))

                                io_schedule();

                } while(atomic_read(&sdp->sd_log_in_flight));

                finish_wait(&sdp->sd_log_flush_wait, &wait);

        }

        log_write_header(sdp, 0, 0);

}

static void gfs2_ordered_write(struct gfs2_sbd *sdp)

{

        struct gfs2_bufdata *bd;

        struct buffer_head *bh;

        LIST_HEAD(written);

        gfs2_log_lock(sdp);

        while (!list_empty(&sdp->sd_log_le_ordered)) {

                bd = list_entry(sdp->sd_log_le_ordered.next, struct gfs2_bufdata, bd_le.le_list);

                list_move(&bd->bd_le.le_list, &written);

                bh = bd->bd_bh;

                if (!buffer_dirty(bh))

                        continue;

                get_bh(bh);

                gfs2_log_unlock(sdp);

                lock_buffer(bh);

                if (test_clear_buffer_dirty(bh)) {

                        bh->b_end_io = end_buffer_write_sync;

                        submit_bh(WRITE, bh);

                } else {

                        unlock_buffer(bh);

                        brelse(bh);

                }

                gfs2_log_lock(sdp);

        }

        list_splice(&written, &sdp->sd_log_le_ordered);

        gfs2_log_unlock(sdp);

}

static void gfs2_ordered_wait(struct gfs2_sbd *sdp)

{

        struct gfs2_bufdata *bd;

        struct buffer_head *bh;

        gfs2_log_lock(sdp);

        while (!list_empty(&sdp->sd_log_le_ordered)) {

                bd = list_entry(sdp->sd_log_le_ordered.prev, struct gfs2_bufdata, bd_le.le_list);

                bh = bd->bd_bh;

                if (buffer_locked(bh)) {

                        get_bh(bh);

                        gfs2_log_unlock(sdp);

                        wait_on_buffer(bh);

                        brelse(bh);

                        gfs2_log_lock(sdp);