meta_io.c

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

#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/completion.h>
#include <linux/buffer_head.h>
#include <linux/mm.h>
#include <linux/pagemap.h>
#include <linux/writeback.h>
#include <linux/swap.h>
#include <linux/delay.h>
#include <linux/bio.h>
#include <linux/gfs2_ondisk.h>

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

static int gfs2_aspace_writepage(struct page *page, struct writeback_control *wbc)
{
    struct buffer_head *bh, *head;
    int nr_underway = 0;
    int write_op = REQ_META | REQ_PRIO |
        (wbc->sync_mode == WB_SYNC_ALL ? WRITE_SYNC : WRITE);

    BUG_ON(!PageLocked(page));
    BUG_ON(!page_has_buffers(page));

    head = page_buffers(page);
    bh = head;

    do {
        if (!buffer_mapped(bh))
            continue;
        /*
         * If it's a fully non-blocking write attempt and we cannot
         * lock the buffer then redirty the page.  Note that this can
         * potentially cause a busy-wait loop from flusher thread and kswapd
         * activity, but those code paths have their own higher-level
         * throttling.
         */
        if (wbc->sync_mode != WB_SYNC_NONE) {
            lock_buffer(bh);
        } else if (!trylock_buffer(bh)) {
            redirty_page_for_writepage(wbc, page);
            continue;
        }
        if (test_clear_buffer_dirty(bh)) {
            mark_buffer_async_write(bh);
        } else {
            unlock_buffer(bh);
        }
    } while ((bh = bh->b_this_page) != head);

    /*
     * The page and its buffers are protected by PageWriteback(), so we can
     * drop the bh refcounts early.
     */
    BUG_ON(PageWriteback(page));
    set_page_writeback(page);

    do {
        struct buffer_head *next = bh->b_this_page;
        if (buffer_async_write(bh)) {
            submit_bh(write_op, bh);
            nr_underway++;
        }
        bh = next;
    } while (bh != head);
    unlock_page(page);

    if (nr_underway == 0)
        end_page_writeback(page);

    return 0;
}

const struct address_space_operations gfs2_meta_aops = {
    .writepage = gfs2_aspace_writepage,
    .releasepage = gfs2_releasepage,
};

void gfs2_meta_sync(struct gfs2_glock *gl)
{
    struct address_space *mapping = gfs2_glock2aspace(gl);
    int error;

    filemap_fdatawrite(mapping);
    error = filemap_fdatawait(mapping);

    if (error)
        gfs2_io_error(gl->gl_sbd);
}

struct buffer_head *gfs2_getbuf(struct gfs2_glock *gl, u64 blkno, int create)
{
    struct address_space *mapping = gfs2_glock2aspace(gl);
    struct gfs2_sbd *sdp = gl->gl_sbd;
    struct page *page;
    struct buffer_head *bh;
    unsigned int shift;
    unsigned long index;
    unsigned int bufnum;

    shift = PAGE_CACHE_SHIFT - sdp->sd_sb.sb_bsize_shift;
    index = blkno >> shift;             /* convert block to page */
    bufnum = blkno - (index << shift);  /* block buf index within page */

    if (create) {
        for (;;) {
            page = grab_cache_page(mapping, index);
            if (page)
                break;
            yield();
        }
    } else {
        page = find_lock_page(mapping, index);
        if (!page)
            return NULL;
    }

    if (!page_has_buffers(page))
        create_empty_buffers(page, sdp->sd_sb.sb_bsize, 0);

    /* Locate header for our buffer within our page */
    for (bh = page_buffers(page); bufnum--; bh = bh->b_this_page)
        /* Do nothing */;
    get_bh(bh);

    if (!buffer_mapped(bh))
        map_bh(bh, sdp->sd_vfs, blkno);

    unlock_page(page);
    mark_page_accessed(page);
    page_cache_release(page);

    return bh;
}

static void meta_prep_new(struct buffer_head *bh)
{
    struct gfs2_meta_header *mh = (struct gfs2_meta_header *)bh->b_data;

    lock_buffer(bh);
    clear_buffer_dirty(bh);
    set_buffer_uptodate(bh);
    unlock_buffer(bh);

    mh->mh_magic = cpu_to_be32(GFS2_MAGIC);
}

struct buffer_head *gfs2_meta_new(struct gfs2_glock *gl, u64 blkno)
{
    struct buffer_head *bh;
    bh = gfs2_getbuf(gl, blkno, CREATE);
    meta_prep_new(bh);
    return bh;
}

int gfs2_meta_read(struct gfs2_glock *gl, u64 blkno, int flags,
           struct buffer_head **bhp)
{
    struct gfs2_sbd *sdp = gl->gl_sbd;
    struct buffer_head *bh;

    if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags))) {
        *bhp = NULL;
        return -EIO;
    }

    *bhp = bh = gfs2_getbuf(gl, blkno, CREATE);

    lock_buffer(bh);
    if (buffer_uptodate(bh)) {
        unlock_buffer(bh);
        return 0;
    }
    bh->b_end_io = end_buffer_read_sync;
    get_bh(bh);
    submit_bh(READ_SYNC | REQ_META | REQ_PRIO, bh);
    if (!(flags & DIO_WAIT))
        return 0;

    wait_on_buffer(bh);
    if (unlikely(!buffer_uptodate(bh))) {
        struct gfs2_trans *tr = current->journal_info;
        if (tr && tr->tr_touched)
            gfs2_io_error_bh(sdp, bh);
        brelse(bh);
        *bhp = NULL;
        return -EIO;
    }

    return 0;
}

int gfs2_meta_wait(struct gfs2_sbd *sdp, struct buffer_head *bh)
{
    if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
        return -EIO;

    wait_on_buffer(bh);

    if (!buffer_uptodate(bh)) {
        struct gfs2_trans *tr = current->journal_info;
        if (tr && tr->tr_touched)
            gfs2_io_error_bh(sdp, bh);
        return -EIO;
    }
    if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
        return -EIO;

    return 0;
}

void gfs2_attach_bufdata(struct gfs2_glock *gl, struct buffer_head *bh,
             int meta)
{
    struct gfs2_bufdata *bd;

    if (meta)
        lock_page(bh->b_page);

    if (bh->b_private) {
        if (meta)
            unlock_page(bh->b_page);
        return;
    }

    bd = kmem_cache_zalloc(gfs2_bufdata_cachep, GFP_NOFS | __GFP_NOFAIL);
    bd->bd_bh = bh;
    bd->bd_gl = gl;

    if (meta)
        lops_init_le(bd, &gfs2_buf_lops);
    else
        lops_init_le(bd, &gfs2_databuf_lops);
    bh->b_private = bd;

    if (meta)
        unlock_page(bh->b_page);
}

void gfs2_remove_from_journal(struct buffer_head *bh, struct gfs2_trans *tr, int meta)
{
    struct address_space *mapping = bh->b_page->mapping;
    struct gfs2_sbd *sdp = gfs2_mapping2sbd(mapping);
    struct gfs2_bufdata *bd = bh->b_private;

    if (test_clear_buffer_pinned(bh)) {
        trace_gfs2_pin(bd, 0);
        atomic_dec(&sdp->sd_log_pinned);
        list_del_init(&bd->bd_list);
        if (meta) {
            gfs2_assert_warn(sdp, sdp->sd_log_num_buf);
            sdp->sd_log_num_buf--;
            tr->tr_num_buf_rm++;
        } else {
            gfs2_assert_warn(sdp, sdp->sd_log_num_databuf);
            sdp->sd_log_num_databuf--;
            tr->tr_num_databuf_rm++;
        }
        tr->tr_touched = 1;
        brelse(bh);
    }
    if (bd) {
        spin_lock(&sdp->sd_ail_lock);
        if (bd->bd_ail) {
            gfs2_remove_from_ail(bd);
            bh->b_private = NULL;
            bd->bd_bh = NULL;
            bd->bd_blkno = bh->b_blocknr;
            gfs2_trans_add_revoke(sdp, bd);
        }
        spin_unlock(&sdp->sd_ail_lock);
    }
    clear_buffer_dirty(bh);
    clear_buffer_uptodate(bh);
}

void gfs2_meta_wipe(struct gfs2_inode *ip, u64 bstart, u32 blen)
{
    struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
    struct buffer_head *bh;

    while (blen) {
        bh = gfs2_getbuf(ip->i_gl, bstart, NO_CREATE);
        if (bh) {
            lock_buffer(bh);
            gfs2_log_lock(sdp);
            gfs2_remove_from_journal(bh, current->journal_info, 1);
            gfs2_log_unlock(sdp);
            unlock_buffer(bh);
            brelse(bh);
        }

        bstart++;
        blen--;
    }
}

int gfs2_meta_indirect_buffer(struct gfs2_inode *ip, int height, u64 num,
                  struct buffer_head **bhp)
{
    struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
    struct gfs2_glock *gl = ip->i_gl;
    struct buffer_head *bh;
    int ret = 0;
    u32 mtype = height ? GFS2_METATYPE_IN : GFS2_METATYPE_DI;

    ret = gfs2_meta_read(gl, num, DIO_WAIT, &bh);
    if (ret == 0 && gfs2_metatype_check(sdp, bh, mtype)) {
        brelse(bh);
        ret = -EIO;
    }
    *bhp = bh;
    return ret;
}

struct buffer_head *gfs2_meta_ra(struct gfs2_glock *gl, u64 dblock, u32 extlen)
{
    struct gfs2_sbd *sdp = gl->gl_sbd;
    struct buffer_head *first_bh, *bh;
    u32 max_ra = gfs2_tune_get(sdp, gt_max_readahead) >>
              sdp->sd_sb.sb_bsize_shift;

    BUG_ON(!extlen);

    if (max_ra < 1)
        max_ra = 1;
    if (extlen > max_ra)
        extlen = max_ra;

    first_bh = gfs2_getbuf(gl, dblock, CREATE);

    if (buffer_uptodate(first_bh))
        goto out;
    if (!buffer_locked(first_bh))
        ll_rw_block(READ_SYNC | REQ_META, 1, &first_bh);

    dblock++;
    extlen--;

    while (extlen) {
        bh = gfs2_getbuf(gl, dblock, CREATE);

        if (!buffer_uptodate(bh) && !buffer_locked(bh))
            ll_rw_block(READA | REQ_META, 1, &bh);
        brelse(bh);
        dblock++;
        extlen--;
        if (!buffer_locked(first_bh) && buffer_uptodate(first_bh))
            goto out;
    }

    wait_on_buffer(first_bh);
out:
    return first_bh;
}