jfs_metapage.c

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/*
 *   Copyright (C) International Business Machines Corp., 2000-2005
 *   Portions Copyright (C) Christoph Hellwig, 2001-2002
 *
 *   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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/bio.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/buffer_head.h>
#include <linux/mempool.h>
#include <linux/seq_file.h>
#include "jfs_incore.h"
#include "jfs_superblock.h"
#include "jfs_filsys.h"
#include "jfs_metapage.h"
#include "jfs_txnmgr.h"
#include "jfs_debug.h"

#ifdef CONFIG_JFS_STATISTICS
static struct {
    uint    pagealloc;  /* # of page allocations */
    uint    pagefree;   /* # of page frees */
    uint    lockwait;   /* # of sleeping lock_metapage() calls */
} mpStat;
#endif

#define metapage_locked(mp) test_bit(META_locked, &(mp)->flag)
#define trylock_metapage(mp) test_and_set_bit_lock(META_locked, &(mp)->flag)

static inline void unlock_metapage(struct metapage *mp)
{
    clear_bit_unlock(META_locked, &mp->flag);
    wake_up(&mp->wait);
}

static inline void __lock_metapage(struct metapage *mp)
{
    DECLARE_WAITQUEUE(wait, current);
    INCREMENT(mpStat.lockwait);
    add_wait_queue_exclusive(&mp->wait, &wait);
    do {
        set_current_state(TASK_UNINTERRUPTIBLE);
        if (metapage_locked(mp)) {
            unlock_page(mp->page);
            io_schedule();
            lock_page(mp->page);
        }
    } while (trylock_metapage(mp));
    __set_current_state(TASK_RUNNING);
    remove_wait_queue(&mp->wait, &wait);
}

/*
 * Must have mp->page locked
 */
static inline void lock_metapage(struct metapage *mp)
{
    if (trylock_metapage(mp))
        __lock_metapage(mp);
}

#define METAPOOL_MIN_PAGES 32
static struct kmem_cache *metapage_cache;
static mempool_t *metapage_mempool;

#define MPS_PER_PAGE (PAGE_CACHE_SIZE >> L2PSIZE)

#if MPS_PER_PAGE > 1

struct meta_anchor {
    int mp_count;
    atomic_t io_count;
    struct metapage *mp[MPS_PER_PAGE];
};
#define mp_anchor(page) ((struct meta_anchor *)page_private(page))

static inline struct metapage *page_to_mp(struct page *page, int offset)
{
    if (!PagePrivate(page))
        return NULL;
    return mp_anchor(page)->mp[offset >> L2PSIZE];
}

static inline int insert_metapage(struct page *page, struct metapage *mp)
{
    struct meta_anchor *a;
    int index;
    int l2mp_blocks;    /* log2 blocks per metapage */

    if (PagePrivate(page))
        a = mp_anchor(page);
    else {
        a = kzalloc(sizeof(struct meta_anchor), GFP_NOFS);
        if (!a)
            return -ENOMEM;
        set_page_private(page, (unsigned long)a);
        SetPagePrivate(page);
        kmap(page);
    }

    if (mp) {
        l2mp_blocks = L2PSIZE - page->mapping->host->i_blkbits;
        index = (mp->index >> l2mp_blocks) & (MPS_PER_PAGE - 1);
        a->mp_count++;
        a->mp[index] = mp;
    }

    return 0;
}

static inline void remove_metapage(struct page *page, struct metapage *mp)
{
    struct meta_anchor *a = mp_anchor(page);
    int l2mp_blocks = L2PSIZE - page->mapping->host->i_blkbits;
    int index;

    index = (mp->index >> l2mp_blocks) & (MPS_PER_PAGE - 1);

    BUG_ON(a->mp[index] != mp);

    a->mp[index] = NULL;
    if (--a->mp_count == 0) {
        kfree(a);
        set_page_private(page, 0);
        ClearPagePrivate(page);
        kunmap(page);
    }
}

static inline void inc_io(struct page *page)
{
    atomic_inc(&mp_anchor(page)->io_count);
}

static inline void dec_io(struct page *page, void (*handler) (struct page *))
{
    if (atomic_dec_and_test(&mp_anchor(page)->io_count))
        handler(page);
}

#else
static inline struct metapage *page_to_mp(struct page *page, int offset)
{
    return PagePrivate(page) ? (struct metapage *)page_private(page) : NULL;
}

static inline int insert_metapage(struct page *page, struct metapage *mp)
{
    if (mp) {
        set_page_private(page, (unsigned long)mp);
        SetPagePrivate(page);
        kmap(page);
    }
    return 0;
}

static inline void remove_metapage(struct page *page, struct metapage *mp)
{
    set_page_private(page, 0);
    ClearPagePrivate(page);
    kunmap(page);
}

#define inc_io(page) do {} while(0)
#define dec_io(page, handler) handler(page)

#endif

static void init_once(void *foo)
{
    struct metapage *mp = (struct metapage *)foo;

    mp->lid = 0;
    mp->lsn = 0;
    mp->flag = 0;
    mp->data = NULL;
    mp->clsn = 0;
    mp->log = NULL;
    set_bit(META_free, &mp->flag);
    init_waitqueue_head(&mp->wait);
}

static inline struct metapage *alloc_metapage(gfp_t gfp_mask)
{
    return mempool_alloc(metapage_mempool, gfp_mask);
}

static inline void free_metapage(struct metapage *mp)
{
    mp->flag = 0;
    set_bit(META_free, &mp->flag);

    mempool_free(mp, metapage_mempool);
}

int __init metapage_init(void)
{
    /*
     * Allocate the metapage structures
     */
    metapage_cache = kmem_cache_create("jfs_mp", sizeof(struct metapage),
                       0, 0, init_once);
    if (metapage_cache == NULL)
        return -ENOMEM;

    metapage_mempool = mempool_create_slab_pool(METAPOOL_MIN_PAGES,
                            metapage_cache);

    if (metapage_mempool == NULL) {
        kmem_cache_destroy(metapage_cache);
        return -ENOMEM;
    }

    return 0;
}

void metapage_exit(void)
{
    mempool_destroy(metapage_mempool);
    kmem_cache_destroy(metapage_cache);
}

static inline void drop_metapage(struct page *page, struct metapage *mp)
{
    if (mp->count || mp->nohomeok || test_bit(META_dirty, &mp->flag) ||
        test_bit(META_io, &mp->flag))
        return;
    remove_metapage(page, mp);
    INCREMENT(mpStat.pagefree);
    free_metapage(mp);
}

/*
 * Metapage address space operations
 */

static sector_t metapage_get_blocks(struct inode *inode, sector_t lblock,
                    int *len)
{
    int rc = 0;
    int xflag;
    s64 xaddr;
    sector_t file_blocks = (inode->i_size + inode->i_sb->s_blocksize - 1) >>
                   inode->i_blkbits;

    if (lblock >= file_blocks)
        return 0;
    if (lblock + *len > file_blocks)
        *len = file_blocks - lblock;

    if (inode->i_ino) {
        rc = xtLookup(inode, (s64)lblock, *len, &xflag, &xaddr, len, 0);
        if ((rc == 0) && *len)
            lblock = (sector_t)xaddr;
        else
            lblock = 0;
    } /* else no mapping */

    return lblock;
}

static void last_read_complete(struct page *page)
{
    if (!PageError(page))
        SetPageUptodate(page);
    unlock_page(page);
}

static void metapage_read_end_io(struct bio *bio, int err)
{
    struct page *page = bio->bi_private;

    if (!test_bit(BIO_UPTODATE, &bio->bi_flags)) {
        printk(KERN_ERR "metapage_read_end_io: I/O error\n");
        SetPageError(page);
    }

    dec_io(page, last_read_complete);
    bio_put(bio);
}

static void remove_from_logsync(struct metapage *mp)
{
    struct jfs_log *log = mp->log;
    unsigned long flags;
/*
 * This can race.  Recheck that log hasn't been set to null, and after
 * acquiring logsync lock, recheck lsn
 */
    if (!log)
        return;

    LOGSYNC_LOCK(log, flags);
    if (mp->lsn) {
        mp->log = NULL;
        mp->lsn = 0;
        mp->clsn = 0;
        log->count--;
        list_del(&mp->synclist);
    }
    LOGSYNC_UNLOCK(log, flags);
}

static void last_write_complete(struct page *page)
{
    struct metapage *mp;
    unsigned int offset;

    for (offset = 0; offset < PAGE_CACHE_SIZE; offset += PSIZE) {
        mp = page_to_mp(page, offset);
        if (mp && test_bit(META_io, &mp->flag)) {
            if (mp->lsn)
                remove_from_logsync(mp);
            clear_bit(META_io, &mp->flag);
        }
        /*
         * I'd like to call drop_metapage here, but I don't think it's
         * safe unless I have the page locked
         */
    }
    end_page_writeback(page);
}

static void metapage_write_end_io(struct bio *bio, int err)
{
    struct page *page = bio->bi_private;

    BUG_ON(!PagePrivate(page));

    if (! test_bit(BIO_UPTODATE, &bio->bi_flags)) {
        printk(KERN_ERR "metapage_write_end_io: I/O error\n");
        SetPageError(page);
    }
    dec_io(page, last_write_complete);
    bio_put(bio);
}

static int metapage_writepage(struct page *page, struct writeback_control *wbc)
{
    struct bio *bio = NULL;
    int block_offset;   /* block offset of mp within page */
    struct inode *inode = page->mapping->host;
    int blocks_per_mp = JFS_SBI(inode->i_sb)->nbperpage;
    int len;
    int xlen;
    struct metapage *mp;
    int redirty = 0;
    sector_t lblock;
    int nr_underway = 0;
    sector_t pblock;
    sector_t next_block = 0;
    sector_t page_start;
    unsigned long bio_bytes = 0;
    unsigned long bio_offset = 0;
    int offset;
    int bad_blocks = 0;

    page_start = (sector_t)page->index <<
             (PAGE_CACHE_SHIFT - inode->i_blkbits);
    BUG_ON(!PageLocked(page));
    BUG_ON(PageWriteback(page));
    set_page_writeback(page);

    for (offset = 0; offset < PAGE_CACHE_SIZE; offset += PSIZE) {
        mp = page_to_mp(page, offset);

        if (!mp || !test_bit(META_dirty, &mp->flag))
            continue;

        if (mp->nohomeok && !test_bit(META_forcewrite, &mp->flag)) {
            redirty = 1;
            /*
             * Make sure this page isn't blocked indefinitely.
             * If the journal isn't undergoing I/O, push it
             */
            if (mp->log && !(mp->log->cflag & logGC_PAGEOUT))
                jfs_flush_journal(mp->log, 0);
            continue;
        }

        clear_bit(META_dirty, &mp->flag);
        set_bit(META_io, &mp->flag);
        block_offset = offset >> inode->i_blkbits;
        lblock = page_start + block_offset;
        if (bio) {
            if (xlen && lblock == next_block) {
                /* Contiguous, in memory & on disk */
                len = min(xlen, blocks_per_mp);
                xlen -= len;
                bio_bytes += len << inode->i_blkbits;
                continue;
            }
            /* Not contiguous */
            if (bio_add_page(bio, page, bio_bytes, bio_offset) <
                bio_bytes)
                goto add_failed;
            /*
             * Increment counter before submitting i/o to keep
             * count from hitting zero before we're through
             */
            inc_io(page);
            if (!bio->bi_size)
                goto dump_bio;
            submit_bio(WRITE, bio);
            nr_underway++;
            bio = NULL;
        } else
            inc_io(page);
        xlen = (PAGE_CACHE_SIZE - offset) >> inode->i_blkbits;
        pblock = metapage_get_blocks(inode, lblock, &xlen);
        if (!pblock) {
            printk(KERN_ERR "JFS: metapage_get_blocks failed\n");
            /*
             * We already called inc_io(), but can't cancel it
             * with dec_io() until we're done with the page
             */
            bad_blocks++;
            continue;
        }
        len = min(xlen, (int)JFS_SBI(inode->i_sb)->nbperpage);

        bio = bio_alloc(GFP_NOFS, 1);
        bio->bi_bdev = inode->i_sb->s_bdev;
        bio->bi_sector = pblock << (inode->i_blkbits - 9);
        bio->bi_end_io = metapage_write_end_io;
        bio->bi_private = page;

        /* Don't call bio_add_page yet, we may add to this vec */
        bio_offset = offset;
        bio_bytes = len << inode->i_blkbits;

        xlen -= len;
        next_block = lblock + len;
    }
    if (bio) {
        if (bio_add_page(bio, page, bio_bytes, bio_offset) < bio_bytes)
                goto add_failed;
        if (!bio->bi_size)
            goto dump_bio;

        submit_bio(WRITE, bio);
        nr_underway++;
    }
    if (redirty)
        redirty_page_for_writepage(wbc, page);

    unlock_page(page);

    if (bad_blocks)
        goto err_out;

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

    return 0;
add_failed:
    /* We should never reach here, since we're only adding one vec */
    printk(KERN_ERR "JFS: bio_add_page failed unexpectedly\n");
    goto skip;
dump_bio:
    print_hex_dump(KERN_ERR, "JFS: dump of bio: ", DUMP_PREFIX_ADDRESS, 16,
               4, bio, sizeof(*bio), 0);
skip:
    bio_put(bio);
    unlock_page(page);
    dec_io(page, last_write_complete);
err_out:
    while (bad_blocks--)
        dec_io(page, last_write_complete);
    return -EIO;
}

static int metapage_readpage(struct file *fp, struct page *page)
{
    struct inode *inode = page->mapping->host;
    struct bio *bio = NULL;
    int block_offset;
    int blocks_per_page = PAGE_CACHE_SIZE >> inode->i_blkbits;
    sector_t page_start;    /* address of page in fs blocks */
    sector_t pblock;
    int xlen;
    unsigned int len;
    int offset;

    BUG_ON(!PageLocked(page));
    page_start = (sector_t)page->index <<
             (PAGE_CACHE_SHIFT - inode->i_blkbits);

    block_offset = 0;
    while (block_offset < blocks_per_page) {
        xlen = blocks_per_page - block_offset;
        pblock = metapage_get_blocks(inode, page_start + block_offset,
                         &xlen);
        if (pblock) {
            if (!PagePrivate(page))
                insert_metapage(page, NULL);
            inc_io(page);
            if (bio)
                submit_bio(READ, bio);

            bio = bio_alloc(GFP_NOFS, 1);
            bio->bi_bdev = inode->i_sb->s_bdev;
            bio->bi_sector = pblock << (inode->i_blkbits - 9);
            bio->bi_end_io = metapage_read_end_io;
            bio->bi_private = page;
            len = xlen << inode->i_blkbits;
            offset = block_offset << inode->i_blkbits;
            if (bio_add_page(bio, page, len, offset) < len)
                goto add_failed;
            block_offset += xlen;
        } else
            block_offset++;
    }
    if (bio)
        submit_bio(READ, bio);
    else
        unlock_page(page);

    return 0;

add_failed:
    printk(KERN_ERR "JFS: bio_add_page failed unexpectedly\n");
    bio_put(bio);
    dec_io(page, last_read_complete);
    return -EIO;
}

static int metapage_releasepage(struct page *page, gfp_t gfp_mask)
{
    struct metapage *mp;
    int ret = 1;
    int offset;

    for (offset = 0; offset < PAGE_CACHE_SIZE; offset += PSIZE) {
        mp = page_to_mp(page, offset);

        if (!mp)
            continue;

        jfs_info("metapage_releasepage: mp = 0x%p", mp);
        if (mp->count || mp->nohomeok ||
            test_bit(META_dirty, &mp->flag)) {
            jfs_info("count = %ld, nohomeok = %d", mp->count,
                 mp->nohomeok);
            ret = 0;
            continue;
        }
        if (mp->lsn)
            remove_from_logsync(mp);
        remove_metapage(page, mp);
        INCREMENT(mpStat.pagefree);
        free_metapage(mp);
    }
    return ret;
}

static void metapage_invalidatepage(struct page *page, unsigned long offset)
{
    BUG_ON(offset);

    BUG_ON(PageWriteback(page));

    metapage_releasepage(page, 0);
}

const struct address_space_operations jfs_metapage_aops = {
    .readpage   = metapage_readpage,
    .writepage  = metapage_writepage,
    .releasepage    = metapage_releasepage,
    .invalidatepage = metapage_invalidatepage,
    .set_page_dirty = __set_page_dirty_nobuffers,
};

struct metapage *__get_metapage(struct inode *inode, unsigned long lblock,
                unsigned int size, int absolute,
                unsigned long new)
{
    int l2BlocksPerPage;
    int l2bsize;
    struct address_space *mapping;
    struct metapage *mp = NULL;
    struct page *page;
    unsigned long page_index;
    unsigned long page_offset;

    jfs_info("__get_metapage: ino = %ld, lblock = 0x%lx, abs=%d",
         inode->i_ino, lblock, absolute);

    l2bsize = inode->i_blkbits;
    l2BlocksPerPage = PAGE_CACHE_SHIFT - l2bsize;
    page_index = lblock >> l2BlocksPerPage;
    page_offset = (lblock - (page_index << l2BlocksPerPage)) << l2bsize;
    if ((page_offset + size) > PAGE_CACHE_SIZE) {
        jfs_err("MetaData crosses page boundary!!");
        jfs_err("lblock = %lx, size  = %d", lblock, size);
        dump_stack();
        return NULL;
    }
    if (absolute)
        mapping = JFS_SBI(inode->i_sb)->direct_inode->i_mapping;
    else {
        /*
         * If an nfs client tries to read an inode that is larger
         * than any existing inodes, we may try to read past the
         * end of the inode map
         */
        if ((lblock << inode->i_blkbits) >= inode->i_size)
            return NULL;
        mapping = inode->i_mapping;
    }

    if (new && (PSIZE == PAGE_CACHE_SIZE)) {
        page = grab_cache_page(mapping, page_index);
        if (!page) {
            jfs_err("grab_cache_page failed!");
            return NULL;
        }
        SetPageUptodate(page);
    } else {
        page = read_mapping_page(mapping, page_index, NULL);
        if (IS_ERR(page) || !PageUptodate(page)) {
            jfs_err("read_mapping_page failed!");
            return NULL;
        }
        lock_page(page);
    }

    mp = page_to_mp(page, page_offset);
    if (mp) {
        if (mp->logical_size != size) {
            jfs_error(inode->i_sb,
                  "__get_metapage: mp->logical_size != size");
            jfs_err("logical_size = %d, size = %d",
                mp->logical_size, size);
            dump_stack();
            goto unlock;
        }
        mp->count++;
        lock_metapage(mp);
        if (test_bit(META_discard, &mp->flag)) {
            if (!new) {
                jfs_error(inode->i_sb,
                      "__get_metapage: using a "
                      "discarded metapage");
                discard_metapage(mp);
                goto unlock;
            }
            clear_bit(META_discard, &mp->flag);
        }
    } else {
        INCREMENT(mpStat.pagealloc);
        mp = alloc_metapage(GFP_NOFS);
        mp->page = page;
        mp->flag = 0;
        mp->xflag = COMMIT_PAGE;
        mp->count = 1;
        mp->nohomeok = 0;
        mp->logical_size = size;
        mp->data = page_address(page) + page_offset;
        mp->index = lblock;
        if (unlikely(insert_metapage(page, mp))) {
            free_metapage(mp);
            goto unlock;
        }
        lock_metapage(mp);
    }

    if (new) {
        jfs_info("zeroing mp = 0x%p", mp);
        memset(mp->data, 0, PSIZE);
    }

    unlock_page(page);
    jfs_info("__get_metapage: returning = 0x%p data = 0x%p", mp, mp->data);
    return mp;

unlock:
    unlock_page(page);
    return NULL;
}

void grab_metapage(struct metapage * mp)
{
    jfs_info("grab_metapage: mp = 0x%p", mp);
    page_cache_get(mp->page);
    lock_page(mp->page);
    mp->count++;
    lock_metapage(mp);
    unlock_page(mp->page);
}

void force_metapage(struct metapage *mp)
{
    struct page *page = mp->page;
    jfs_info("force_metapage: mp = 0x%p", mp);
    set_bit(META_forcewrite, &mp->flag);
    clear_bit(META_sync, &mp->flag);
    page_cache_get(page);
    lock_page(page);
    set_page_dirty(page);
    write_one_page(page, 1);
    clear_bit(META_forcewrite, &mp->flag);
    page_cache_release(page);
}

void hold_metapage(struct metapage *mp)
{
    lock_page(mp->page);
}

void put_metapage(struct metapage *mp)
{
    if (mp->count || mp->nohomeok) {
        /* Someone else will release this */
        unlock_page(mp->page);
        return;
    }
    page_cache_get(mp->page);
    mp->count++;
    lock_metapage(mp);
    unlock_page(mp->page);
    release_metapage(mp);
}

void release_metapage(struct metapage * mp)
{
    struct page *page = mp->page;
    jfs_info("release_metapage: mp = 0x%p, flag = 0x%lx", mp, mp->flag);

    BUG_ON(!page);

    lock_page(page);
    unlock_metapage(mp);

    assert(mp->count);
    if (--mp->count || mp->nohomeok) {
        unlock_page(page);
        page_cache_release(page);
        return;
    }

    if (test_bit(META_dirty, &mp->flag)) {
        set_page_dirty(page);
        if (test_bit(META_sync, &mp->flag)) {
            clear_bit(META_sync, &mp->flag);
            write_one_page(page, 1);
            lock_page(page); /* write_one_page unlocks the page */
        }
    } else if (mp->lsn) /* discard_metapage doesn't remove it */
        remove_from_logsync(mp);

    /* Try to keep metapages from using up too much memory */
    drop_metapage(page, mp);

    unlock_page(page);
    page_cache_release(page);
}

void __invalidate_metapages(struct inode *ip, s64 addr, int len)
{
    sector_t lblock;
    int l2BlocksPerPage = PAGE_CACHE_SHIFT - ip->i_blkbits;
    int BlocksPerPage = 1 << l2BlocksPerPage;
    /* All callers are interested in block device's mapping */
    struct address_space *mapping =
        JFS_SBI(ip->i_sb)->direct_inode->i_mapping;
    struct metapage *mp;
    struct page *page;
    unsigned int offset;

    /*
     * Mark metapages to discard.  They will eventually be
     * released, but should not be written.
     */
    for (lblock = addr & ~(BlocksPerPage - 1); lblock < addr + len;
         lblock += BlocksPerPage) {
        page = find_lock_page(mapping, lblock >> l2BlocksPerPage);
        if (!page)
            continue;
        for (offset = 0; offset < PAGE_CACHE_SIZE; offset += PSIZE) {
            mp = page_to_mp(page, offset);
            if (!mp)
                continue;
            if (mp->index < addr)
                continue;
            if (mp->index >= addr + len)
                break;

            clear_bit(META_dirty, &mp->flag);
            set_bit(META_discard, &mp->flag);
            if (mp->lsn)
                remove_from_logsync(mp);
        }
        unlock_page(page);
        page_cache_release(page);
    }
}

#ifdef CONFIG_JFS_STATISTICS
static int jfs_mpstat_proc_show(struct seq_file *m, void *v)
{
    seq_printf(m,
               "JFS Metapage statistics\n"
               "=======================\n"
               "page allocations = %d\n"
               "page frees = %d\n"
               "lock waits = %d\n",
               mpStat.pagealloc,
               mpStat.pagefree,
               mpStat.lockwait);
    return 0;
}

static int jfs_mpstat_proc_open(struct inode *inode, struct file *file)
{
    return single_open(file, jfs_mpstat_proc_show, NULL);
}

const struct file_operations jfs_mpstat_proc_fops = {
    .owner      = THIS_MODULE,
    .open       = jfs_mpstat_proc_open,
    .read       = seq_read,
    .llseek     = seq_lseek,
    .release    = single_release,
};
#endif