extents.c

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/*
 *  linux/fs/hfsplus/extents.c
 *
 * Copyright (C) 2001
 * Brad Boyer ([email protected])
 * (C) 2003 Ardis Technologies <[email protected]>
 *
 * Handling of Extents both in catalog and extents overflow trees
 */

#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/pagemap.h>

#include "hfsplus_fs.h"
#include "hfsplus_raw.h"

/* Compare two extents keys, returns 0 on same, pos/neg for difference */
int hfsplus_ext_cmp_key(const hfsplus_btree_key *k1,
            const hfsplus_btree_key *k2)
{
    __be32 k1id, k2id;
    __be32 k1s, k2s;

    k1id = k1->ext.cnid;
    k2id = k2->ext.cnid;
    if (k1id != k2id)
        return be32_to_cpu(k1id) < be32_to_cpu(k2id) ? -1 : 1;

    if (k1->ext.fork_type != k2->ext.fork_type)
        return k1->ext.fork_type < k2->ext.fork_type ? -1 : 1;

    k1s = k1->ext.start_block;
    k2s = k2->ext.start_block;
    if (k1s == k2s)
        return 0;
    return be32_to_cpu(k1s) < be32_to_cpu(k2s) ? -1 : 1;
}

static void hfsplus_ext_build_key(hfsplus_btree_key *key, u32 cnid,
                  u32 block, u8 type)
{
    key->key_len = cpu_to_be16(HFSPLUS_EXT_KEYLEN - 2);
    key->ext.cnid = cpu_to_be32(cnid);
    key->ext.start_block = cpu_to_be32(block);
    key->ext.fork_type = type;
    key->ext.pad = 0;
}

static u32 hfsplus_ext_find_block(struct hfsplus_extent *ext, u32 off)
{
    int i;
    u32 count;

    for (i = 0; i < 8; ext++, i++) {
        count = be32_to_cpu(ext->block_count);
        if (off < count)
            return be32_to_cpu(ext->start_block) + off;
        off -= count;
    }
    /* panic? */
    return 0;
}

static int hfsplus_ext_block_count(struct hfsplus_extent *ext)
{
    int i;
    u32 count = 0;

    for (i = 0; i < 8; ext++, i++)
        count += be32_to_cpu(ext->block_count);
    return count;
}

static u32 hfsplus_ext_lastblock(struct hfsplus_extent *ext)
{
    int i;

    ext += 7;
    for (i = 0; i < 7; ext--, i++)
        if (ext->block_count)
            break;
    return be32_to_cpu(ext->start_block) + be32_to_cpu(ext->block_count);
}

static void __hfsplus_ext_write_extent(struct inode *inode,
        struct hfs_find_data *fd)
{
    struct hfsplus_inode_info *hip = HFSPLUS_I(inode);
    int res;

    WARN_ON(!mutex_is_locked(&hip->extents_lock));

    hfsplus_ext_build_key(fd->search_key, inode->i_ino, hip->cached_start,
                  HFSPLUS_IS_RSRC(inode) ?
                HFSPLUS_TYPE_RSRC : HFSPLUS_TYPE_DATA);

    res = hfs_brec_find(fd);
    if (hip->extent_state & HFSPLUS_EXT_NEW) {
        if (res != -ENOENT)
            return;
        hfs_brec_insert(fd, hip->cached_extents,
                sizeof(hfsplus_extent_rec));
        hip->extent_state &= ~(HFSPLUS_EXT_DIRTY | HFSPLUS_EXT_NEW);
    } else {
        if (res)
            return;
        hfs_bnode_write(fd->bnode, hip->cached_extents,
                fd->entryoffset, fd->entrylength);
        hip->extent_state &= ~HFSPLUS_EXT_DIRTY;
    }

    /*
     * We can't just use hfsplus_mark_inode_dirty here, because we
     * also get called from hfsplus_write_inode, which should not
     * redirty the inode.  Instead the callers have to be careful
     * to explicily mark the inode dirty, too.
     */
    set_bit(HFSPLUS_I_EXT_DIRTY, &hip->flags);
}

static int hfsplus_ext_write_extent_locked(struct inode *inode)
{
    int res;

    if (HFSPLUS_I(inode)->extent_state & HFSPLUS_EXT_DIRTY) {
        struct hfs_find_data fd;

        res = hfs_find_init(HFSPLUS_SB(inode->i_sb)->ext_tree, &fd);
        if (res)
            return res;
        __hfsplus_ext_write_extent(inode, &fd);
        hfs_find_exit(&fd);
    }
    return 0;
}

int hfsplus_ext_write_extent(struct inode *inode)
{
    int res;

    mutex_lock(&HFSPLUS_I(inode)->extents_lock);
    res = hfsplus_ext_write_extent_locked(inode);
    mutex_unlock(&HFSPLUS_I(inode)->extents_lock);

    return res;
}

static inline int __hfsplus_ext_read_extent(struct hfs_find_data *fd,
                        struct hfsplus_extent *extent,
                        u32 cnid, u32 block, u8 type)
{
    int res;

    hfsplus_ext_build_key(fd->search_key, cnid, block, type);
    fd->key->ext.cnid = 0;
    res = hfs_brec_find(fd);
    if (res && res != -ENOENT)
        return res;
    if (fd->key->ext.cnid != fd->search_key->ext.cnid ||
        fd->key->ext.fork_type != fd->search_key->ext.fork_type)
        return -ENOENT;
    if (fd->entrylength != sizeof(hfsplus_extent_rec))
        return -EIO;
    hfs_bnode_read(fd->bnode, extent, fd->entryoffset,
        sizeof(hfsplus_extent_rec));
    return 0;
}

static inline int __hfsplus_ext_cache_extent(struct hfs_find_data *fd,
        struct inode *inode, u32 block)
{
    struct hfsplus_inode_info *hip = HFSPLUS_I(inode);
    int res;

    WARN_ON(!mutex_is_locked(&hip->extents_lock));

    if (hip->extent_state & HFSPLUS_EXT_DIRTY)
        __hfsplus_ext_write_extent(inode, fd);

    res = __hfsplus_ext_read_extent(fd, hip->cached_extents, inode->i_ino,
                    block, HFSPLUS_IS_RSRC(inode) ?
                        HFSPLUS_TYPE_RSRC :
                        HFSPLUS_TYPE_DATA);
    if (!res) {
        hip->cached_start = be32_to_cpu(fd->key->ext.start_block);
        hip->cached_blocks =
            hfsplus_ext_block_count(hip->cached_extents);
    } else {
        hip->cached_start = hip->cached_blocks = 0;
        hip->extent_state &= ~(HFSPLUS_EXT_DIRTY | HFSPLUS_EXT_NEW);
    }
    return res;
}

static int hfsplus_ext_read_extent(struct inode *inode, u32 block)
{
    struct hfsplus_inode_info *hip = HFSPLUS_I(inode);
    struct hfs_find_data fd;
    int res;

    if (block >= hip->cached_start &&
        block < hip->cached_start + hip->cached_blocks)
        return 0;

    res = hfs_find_init(HFSPLUS_SB(inode->i_sb)->ext_tree, &fd);
    if (!res) {
        res = __hfsplus_ext_cache_extent(&fd, inode, block);
        hfs_find_exit(&fd);
    }
    return res;
}

/* Get a block at iblock for inode, possibly allocating if create */
int hfsplus_get_block(struct inode *inode, sector_t iblock,
              struct buffer_head *bh_result, int create)
{
    struct super_block *sb = inode->i_sb;
    struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb);
    struct hfsplus_inode_info *hip = HFSPLUS_I(inode);
    int res = -EIO;
    u32 ablock, dblock, mask;
    sector_t sector;
    int was_dirty = 0;
    int shift;

    /* Convert inode block to disk allocation block */
    shift = sbi->alloc_blksz_shift - sb->s_blocksize_bits;
    ablock = iblock >> sbi->fs_shift;

    if (iblock >= hip->fs_blocks) {
        if (iblock > hip->fs_blocks || !create)
            return -EIO;
        if (ablock >= hip->alloc_blocks) {
            res = hfsplus_file_extend(inode);
            if (res)
                return res;
        }
    } else
        create = 0;

    if (ablock < hip->first_blocks) {
        dblock = hfsplus_ext_find_block(hip->first_extents, ablock);
        goto done;
    }

    if (inode->i_ino == HFSPLUS_EXT_CNID)
        return -EIO;

    mutex_lock(&hip->extents_lock);

    /*
     * hfsplus_ext_read_extent will write out a cached extent into
     * the extents btree.  In that case we may have to mark the inode
     * dirty even for a pure read of an extent here.
     */
    was_dirty = (hip->extent_state & HFSPLUS_EXT_DIRTY);
    res = hfsplus_ext_read_extent(inode, ablock);
    if (res) {
        mutex_unlock(&hip->extents_lock);
        return -EIO;
    }
    dblock = hfsplus_ext_find_block(hip->cached_extents,
                    ablock - hip->cached_start);
    mutex_unlock(&hip->extents_lock);

done:
    dprint(DBG_EXTENT, "get_block(%lu): %llu - %u\n",
        inode->i_ino, (long long)iblock, dblock);

    mask = (1 << sbi->fs_shift) - 1;
    sector = ((sector_t)dblock << sbi->fs_shift) +
          sbi->blockoffset + (iblock & mask);
    map_bh(bh_result, sb, sector);

    if (create) {
        set_buffer_new(bh_result);
        hip->phys_size += sb->s_blocksize;
        hip->fs_blocks++;
        inode_add_bytes(inode, sb->s_blocksize);
    }
    if (create || was_dirty)
        mark_inode_dirty(inode);
    return 0;
}

static void hfsplus_dump_extent(struct hfsplus_extent *extent)
{
    int i;

    dprint(DBG_EXTENT, "   ");
    for (i = 0; i < 8; i++)
        dprint(DBG_EXTENT, " %u:%u", be32_to_cpu(extent[i].start_block),
                 be32_to_cpu(extent[i].block_count));
    dprint(DBG_EXTENT, "\n");
}

static int hfsplus_add_extent(struct hfsplus_extent *extent, u32 offset,
                  u32 alloc_block, u32 block_count)
{
    u32 count, start;
    int i;

    hfsplus_dump_extent(extent);
    for (i = 0; i < 8; extent++, i++) {
        count = be32_to_cpu(extent->block_count);
        if (offset == count) {
            start = be32_to_cpu(extent->start_block);
            if (alloc_block != start + count) {
                if (++i >= 8)
                    return -ENOSPC;
                extent++;
                extent->start_block = cpu_to_be32(alloc_block);
            } else
                block_count += count;
            extent->block_count = cpu_to_be32(block_count);
            return 0;
        } else if (offset < count)
            break;
        offset -= count;
    }
    /* panic? */
    return -EIO;
}

static int hfsplus_free_extents(struct super_block *sb,
                struct hfsplus_extent *extent,
                u32 offset, u32 block_nr)
{
    u32 count, start;
    int i;

    hfsplus_dump_extent(extent);
    for (i = 0; i < 8; extent++, i++) {
        count = be32_to_cpu(extent->block_count);
        if (offset == count)
            goto found;
        else if (offset < count)
            break;
        offset -= count;
    }
    /* panic? */
    return -EIO;
found:
    for (;;) {
        start = be32_to_cpu(extent->start_block);
        if (count <= block_nr) {
            hfsplus_block_free(sb, start, count);
            extent->block_count = 0;
            extent->start_block = 0;
            block_nr -= count;
        } else {
            count -= block_nr;
            hfsplus_block_free(sb, start + count, block_nr);
            extent->block_count = cpu_to_be32(count);
            block_nr = 0;
        }
        if (!block_nr || !i)
            return 0;
        i--;
        extent--;
        count = be32_to_cpu(extent->block_count);
    }
}

int hfsplus_free_fork(struct super_block *sb, u32 cnid,
        struct hfsplus_fork_raw *fork, int type)
{
    struct hfs_find_data fd;
    hfsplus_extent_rec ext_entry;
    u32 total_blocks, blocks, start;
    int res, i;

    total_blocks = be32_to_cpu(fork->total_blocks);
    if (!total_blocks)
        return 0;

    blocks = 0;
    for (i = 0; i < 8; i++)
        blocks += be32_to_cpu(fork->extents[i].block_count);

    res = hfsplus_free_extents(sb, fork->extents, blocks, blocks);
    if (res)
        return res;
    if (total_blocks == blocks)
        return 0;

    res = hfs_find_init(HFSPLUS_SB(sb)->ext_tree, &fd);
    if (res)
        return res;
    do {
        res = __hfsplus_ext_read_extent(&fd, ext_entry, cnid,
                        total_blocks, type);
        if (res)
            break;
        start = be32_to_cpu(fd.key->ext.start_block);
        hfsplus_free_extents(sb, ext_entry,
                     total_blocks - start,
                     total_blocks);
        hfs_brec_remove(&fd);
        total_blocks = start;
    } while (total_blocks > blocks);
    hfs_find_exit(&fd);

    return res;
}

int hfsplus_file_extend(struct inode *inode)
{
    struct super_block *sb = inode->i_sb;
    struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb);
    struct hfsplus_inode_info *hip = HFSPLUS_I(inode);
    u32 start, len, goal;
    int res;

    if (sbi->alloc_file->i_size * 8 <
        sbi->total_blocks - sbi->free_blocks + 8) {
        /* extend alloc file */
        printk(KERN_ERR "hfs: extend alloc file! "
                "(%llu,%u,%u)\n",
            sbi->alloc_file->i_size * 8,
            sbi->total_blocks, sbi->free_blocks);
        return -ENOSPC;
    }

    mutex_lock(&hip->extents_lock);
    if (hip->alloc_blocks == hip->first_blocks)
        goal = hfsplus_ext_lastblock(hip->first_extents);
    else {
        res = hfsplus_ext_read_extent(inode, hip->alloc_blocks);
        if (res)
            goto out;
        goal = hfsplus_ext_lastblock(hip->cached_extents);
    }

    len = hip->clump_blocks;
    start = hfsplus_block_allocate(sb, sbi->total_blocks, goal, &len);
    if (start >= sbi->total_blocks) {
        start = hfsplus_block_allocate(sb, goal, 0, &len);
        if (start >= goal) {
            res = -ENOSPC;
            goto out;
        }
    }

    dprint(DBG_EXTENT, "extend %lu: %u,%u\n", inode->i_ino, start, len);

    if (hip->alloc_blocks <= hip->first_blocks) {
        if (!hip->first_blocks) {
            dprint(DBG_EXTENT, "first extents\n");
            /* no extents yet */
            hip->first_extents[0].start_block = cpu_to_be32(start);
            hip->first_extents[0].block_count = cpu_to_be32(len);
            res = 0;
        } else {
            /* try to append to extents in inode */
            res = hfsplus_add_extent(hip->first_extents,
                         hip->alloc_blocks,
                         start, len);
            if (res == -ENOSPC)
                goto insert_extent;
        }
        if (!res) {
            hfsplus_dump_extent(hip->first_extents);
            hip->first_blocks += len;
        }
    } else {
        res = hfsplus_add_extent(hip->cached_extents,
                     hip->alloc_blocks - hip->cached_start,
                     start, len);
        if (!res) {
            hfsplus_dump_extent(hip->cached_extents);
            hip->extent_state |= HFSPLUS_EXT_DIRTY;
            hip->cached_blocks += len;
        } else if (res == -ENOSPC)
            goto insert_extent;
    }
out:
    mutex_unlock(&hip->extents_lock);
    if (!res) {
        hip->alloc_blocks += len;
        hfsplus_mark_inode_dirty(inode, HFSPLUS_I_ALLOC_DIRTY);
    }
    return res;

insert_extent:
    dprint(DBG_EXTENT, "insert new extent\n");
    res = hfsplus_ext_write_extent_locked(inode);
    if (res)
        goto out;

    memset(hip->cached_extents, 0, sizeof(hfsplus_extent_rec));
    hip->cached_extents[0].start_block = cpu_to_be32(start);
    hip->cached_extents[0].block_count = cpu_to_be32(len);
    hfsplus_dump_extent(hip->cached_extents);
    hip->extent_state |= HFSPLUS_EXT_DIRTY | HFSPLUS_EXT_NEW;
    hip->cached_start = hip->alloc_blocks;
    hip->cached_blocks = len;

    res = 0;
    goto out;
}

void hfsplus_file_truncate(struct inode *inode)
{
    struct super_block *sb = inode->i_sb;
    struct hfsplus_inode_info *hip = HFSPLUS_I(inode);
    struct hfs_find_data fd;
    u32 alloc_cnt, blk_cnt, start;
    int res;

    dprint(DBG_INODE, "truncate: %lu, %llu -> %llu\n",
        inode->i_ino, (long long)hip->phys_size,
        inode->i_size);

    if (inode->i_size > hip->phys_size) {
        struct address_space *mapping = inode->i_mapping;
        struct page *page;
        void *fsdata;
        u32 size = inode->i_size;

        res = pagecache_write_begin(NULL, mapping, size, 0,
                        AOP_FLAG_UNINTERRUPTIBLE,
                        &page, &fsdata);
        if (res)
            return;
        res = pagecache_write_end(NULL, mapping, size,
            0, 0, page, fsdata);
        if (res < 0)
            return;
        mark_inode_dirty(inode);
        return;
    } else if (inode->i_size == hip->phys_size)
        return;

    blk_cnt = (inode->i_size + HFSPLUS_SB(sb)->alloc_blksz - 1) >>
            HFSPLUS_SB(sb)->alloc_blksz_shift;
    alloc_cnt = hip->alloc_blocks;
    if (blk_cnt == alloc_cnt)
        goto out;

    mutex_lock(&hip->extents_lock);
    res = hfs_find_init(HFSPLUS_SB(sb)->ext_tree, &fd);
    if (res) {
        mutex_unlock(&hip->extents_lock);
        /* XXX: We lack error handling of hfsplus_file_truncate() */
        return;
    }
    while (1) {
        if (alloc_cnt == hip->first_blocks) {
            hfsplus_free_extents(sb, hip->first_extents,
                         alloc_cnt, alloc_cnt - blk_cnt);
            hfsplus_dump_extent(hip->first_extents);
            hip->first_blocks = blk_cnt;
            break;
        }
        res = __hfsplus_ext_cache_extent(&fd, inode, alloc_cnt);
        if (res)
            break;
        start = hip->cached_start;
        hfsplus_free_extents(sb, hip->cached_extents,
                     alloc_cnt - start, alloc_cnt - blk_cnt);
        hfsplus_dump_extent(hip->cached_extents);
        if (blk_cnt > start) {
            hip->extent_state |= HFSPLUS_EXT_DIRTY;
            break;
        }
        alloc_cnt = start;
        hip->cached_start = hip->cached_blocks = 0;
        hip->extent_state &= ~(HFSPLUS_EXT_DIRTY | HFSPLUS_EXT_NEW);
        hfs_brec_remove(&fd);
    }
    hfs_find_exit(&fd);
    mutex_unlock(&hip->extents_lock);

    hip->alloc_blocks = blk_cnt;
out:
    hip->phys_size = inode->i_size;
    hip->fs_blocks = (inode->i_size + sb->s_blocksize - 1) >>
        sb->s_blocksize_bits;
    inode_set_bytes(inode, hip->fs_blocks << sb->s_blocksize_bits);
    hfsplus_mark_inode_dirty(inode, HFSPLUS_I_ALLOC_DIRTY);
}