btnode.c

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/*
 * btnode.c - NILFS B-tree node cache
 *
 * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * This file was originally written by Seiji Kihara <[email protected]>
 * and fully revised by Ryusuke Konishi <[email protected]> for
 * stabilization and simplification.
 *
 */

#include <linux/types.h>
#include <linux/buffer_head.h>
#include <linux/mm.h>
#include <linux/backing-dev.h>
#include <linux/gfp.h>
#include "nilfs.h"
#include "mdt.h"
#include "dat.h"
#include "page.h"
#include "btnode.h"

void nilfs_btnode_cache_clear(struct address_space *btnc)
{
    invalidate_mapping_pages(btnc, 0, -1);
    truncate_inode_pages(btnc, 0);
}

struct buffer_head *
nilfs_btnode_create_block(struct address_space *btnc, __u64 blocknr)
{
    struct inode *inode = NILFS_BTNC_I(btnc);
    struct buffer_head *bh;

    bh = nilfs_grab_buffer(inode, btnc, blocknr, 1 << BH_NILFS_Node);
    if (unlikely(!bh))
        return NULL;

    if (unlikely(buffer_mapped(bh) || buffer_uptodate(bh) ||
             buffer_dirty(bh))) {
        brelse(bh);
        BUG();
    }
    memset(bh->b_data, 0, 1 << inode->i_blkbits);
    bh->b_bdev = inode->i_sb->s_bdev;
    bh->b_blocknr = blocknr;
    set_buffer_mapped(bh);
    set_buffer_uptodate(bh);

    unlock_page(bh->b_page);
    page_cache_release(bh->b_page);
    return bh;
}

int nilfs_btnode_submit_block(struct address_space *btnc, __u64 blocknr,
                  sector_t pblocknr, int mode,
                  struct buffer_head **pbh, sector_t *submit_ptr)
{
    struct buffer_head *bh;
    struct inode *inode = NILFS_BTNC_I(btnc);
    struct page *page;
    int err;

    bh = nilfs_grab_buffer(inode, btnc, blocknr, 1 << BH_NILFS_Node);
    if (unlikely(!bh))
        return -ENOMEM;

    err = -EEXIST; /* internal code */
    page = bh->b_page;

    if (buffer_uptodate(bh) || buffer_dirty(bh))
        goto found;

    if (pblocknr == 0) {
        pblocknr = blocknr;
        if (inode->i_ino != NILFS_DAT_INO) {
            struct the_nilfs *nilfs = inode->i_sb->s_fs_info;

            /* blocknr is a virtual block number */
            err = nilfs_dat_translate(nilfs->ns_dat, blocknr,
                          &pblocknr);
            if (unlikely(err)) {
                brelse(bh);
                goto out_locked;
            }
        }
    }

    if (mode == READA) {
        if (pblocknr != *submit_ptr + 1 || !trylock_buffer(bh)) {
            err = -EBUSY; /* internal code */
            brelse(bh);
            goto out_locked;
        }
    } else { /* mode == READ */
        lock_buffer(bh);
    }
    if (buffer_uptodate(bh)) {
        unlock_buffer(bh);
        err = -EEXIST; /* internal code */
        goto found;
    }
    set_buffer_mapped(bh);
    bh->b_bdev = inode->i_sb->s_bdev;
    bh->b_blocknr = pblocknr; /* set block address for read */
    bh->b_end_io = end_buffer_read_sync;
    get_bh(bh);
    submit_bh(mode, bh);
    bh->b_blocknr = blocknr; /* set back to the given block address */
    *submit_ptr = pblocknr;
    err = 0;
found:
    *pbh = bh;

out_locked:
    unlock_page(page);
    page_cache_release(page);
    return err;
}

void nilfs_btnode_delete(struct buffer_head *bh)
{
    struct address_space *mapping;
    struct page *page = bh->b_page;
    pgoff_t index = page_index(page);
    int still_dirty;

    page_cache_get(page);
    lock_page(page);
    wait_on_page_writeback(page);

    nilfs_forget_buffer(bh);
    still_dirty = PageDirty(page);
    mapping = page->mapping;
    unlock_page(page);
    page_cache_release(page);

    if (!still_dirty && mapping)
        invalidate_inode_pages2_range(mapping, index, index);
}

int nilfs_btnode_prepare_change_key(struct address_space *btnc,
                    struct nilfs_btnode_chkey_ctxt *ctxt)
{
    struct buffer_head *obh, *nbh;
    struct inode *inode = NILFS_BTNC_I(btnc);
    __u64 oldkey = ctxt->oldkey, newkey = ctxt->newkey;
    int err;

    if (oldkey == newkey)
        return 0;

    obh = ctxt->bh;
    ctxt->newbh = NULL;

    if (inode->i_blkbits == PAGE_CACHE_SHIFT) {
        lock_page(obh->b_page);
        /*
         * We cannot call radix_tree_preload for the kernels older
         * than 2.6.23, because it is not exported for modules.
         */
retry:
        err = radix_tree_preload(GFP_NOFS & ~__GFP_HIGHMEM);
        if (err)
            goto failed_unlock;
        /* BUG_ON(oldkey != obh->b_page->index); */
        if (unlikely(oldkey != obh->b_page->index))
            NILFS_PAGE_BUG(obh->b_page,
                       "invalid oldkey %lld (newkey=%lld)",
                       (unsigned long long)oldkey,
                       (unsigned long long)newkey);

        spin_lock_irq(&btnc->tree_lock);
        err = radix_tree_insert(&btnc->page_tree, newkey, obh->b_page);
        spin_unlock_irq(&btnc->tree_lock);
        /*
         * Note: page->index will not change to newkey until
         * nilfs_btnode_commit_change_key() will be called.
         * To protect the page in intermediate state, the page lock
         * is held.
         */
        radix_tree_preload_end();
        if (!err)
            return 0;
        else if (err != -EEXIST)
            goto failed_unlock;

        err = invalidate_inode_pages2_range(btnc, newkey, newkey);
        if (!err)
            goto retry;
        /* fallback to copy mode */
        unlock_page(obh->b_page);
    }

    nbh = nilfs_btnode_create_block(btnc, newkey);
    if (!nbh)
        return -ENOMEM;

    BUG_ON(nbh == obh);
    ctxt->newbh = nbh;
    return 0;

 failed_unlock:
    unlock_page(obh->b_page);
    return err;
}

void nilfs_btnode_commit_change_key(struct address_space *btnc,
                    struct nilfs_btnode_chkey_ctxt *ctxt)
{
    struct buffer_head *obh = ctxt->bh, *nbh = ctxt->newbh;
    __u64 oldkey = ctxt->oldkey, newkey = ctxt->newkey;
    struct page *opage;

    if (oldkey == newkey)
        return;

    if (nbh == NULL) {  /* blocksize == pagesize */
        opage = obh->b_page;
        if (unlikely(oldkey != opage->index))
            NILFS_PAGE_BUG(opage,
                       "invalid oldkey %lld (newkey=%lld)",
                       (unsigned long long)oldkey,
                       (unsigned long long)newkey);
        mark_buffer_dirty(obh);

        spin_lock_irq(&btnc->tree_lock);
        radix_tree_delete(&btnc->page_tree, oldkey);
        radix_tree_tag_set(&btnc->page_tree, newkey,
                   PAGECACHE_TAG_DIRTY);
        spin_unlock_irq(&btnc->tree_lock);

        opage->index = obh->b_blocknr = newkey;
        unlock_page(opage);
    } else {
        nilfs_copy_buffer(nbh, obh);
        mark_buffer_dirty(nbh);

        nbh->b_blocknr = newkey;
        ctxt->bh = nbh;
        nilfs_btnode_delete(obh); /* will decrement bh->b_count */
    }
}

void nilfs_btnode_abort_change_key(struct address_space *btnc,
                   struct nilfs_btnode_chkey_ctxt *ctxt)
{
    struct buffer_head *nbh = ctxt->newbh;
    __u64 oldkey = ctxt->oldkey, newkey = ctxt->newkey;

    if (oldkey == newkey)
        return;

    if (nbh == NULL) {  /* blocksize == pagesize */
        spin_lock_irq(&btnc->tree_lock);
        radix_tree_delete(&btnc->page_tree, newkey);
        spin_unlock_irq(&btnc->tree_lock);
        unlock_page(ctxt->bh->b_page);
    } else
        brelse(nbh);
}