tcp/dccp: Consolidate common code for RFC 3390 conversion

[pohmelfs.git] / fs / affs / file.c

/*
 *  linux/fs/affs/file.c
 *
 *  (c) 1996  Hans-Joachim Widmaier - Rewritten
 *
 *  (C) 1993  Ray Burr - Modified for Amiga FFS filesystem.
 *
 *  (C) 1992  Eric Youngdale Modified for ISO 9660 filesystem.
 *
 *  (C) 1991  Linus Torvalds - minix filesystem
 *
 *  affs regular file handling primitives
 */

#include "affs.h"

#if PAGE_SIZE < 4096
#error PAGE_SIZE must be at least 4096
#endif

static int affs_grow_extcache(struct inode *inode, u32 lc_idx);
static struct buffer_head *affs_alloc_extblock(struct inode *inode, struct buffer_head *bh, u32 ext);
static inline struct buffer_head *affs_get_extblock(struct inode *inode, u32 ext);
static struct buffer_head *affs_get_extblock_slow(struct inode *inode, u32 ext);
static int affs_file_open(struct inode *inode, struct file *filp);
static int affs_file_release(struct inode *inode, struct file *filp);

const struct file_operations affs_file_operations = {
        .llseek         = generic_file_llseek,
        .read           = do_sync_read,
        .aio_read       = generic_file_aio_read,
        .write          = do_sync_write,
        .aio_write      = generic_file_aio_write,
        .mmap           = generic_file_mmap,
        .open           = affs_file_open,
        .release        = affs_file_release,
        .fsync          = affs_file_fsync,
        .splice_read    = generic_file_splice_read,
};

const struct inode_operations affs_file_inode_operations = {
        .truncate       = affs_truncate,
        .setattr        = affs_notify_change,
};

static int
affs_file_open(struct inode *inode, struct file *filp)
{
        pr_debug("AFFS: open(%lu,%d)\n",
                 inode->i_ino, atomic_read(&AFFS_I(inode)->i_opencnt));
        atomic_inc(&AFFS_I(inode)->i_opencnt);
        return 0;
}

static int
affs_file_release(struct inode *inode, struct file *filp)
{
        pr_debug("AFFS: release(%lu, %d)\n",
                 inode->i_ino, atomic_read(&AFFS_I(inode)->i_opencnt));

        if (atomic_dec_and_test(&AFFS_I(inode)->i_opencnt)) {
                mutex_lock(&inode->i_mutex);
                if (inode->i_size != AFFS_I(inode)->mmu_private)
                        affs_truncate(inode);
                affs_free_prealloc(inode);
                mutex_unlock(&inode->i_mutex);
        }

        return 0;
}

static int
affs_grow_extcache(struct inode *inode, u32 lc_idx)
{
        struct super_block      *sb = inode->i_sb;
        struct buffer_head      *bh;
        u32 lc_max;
        int i, j, key;

        if (!AFFS_I(inode)->i_lc) {
                char *ptr = (char *)get_zeroed_page(GFP_NOFS);
                if (!ptr)
                        return -ENOMEM;
                AFFS_I(inode)->i_lc = (u32 *)ptr;
                AFFS_I(inode)->i_ac = (struct affs_ext_key *)(ptr + AFFS_CACHE_SIZE / 2);
        }

        lc_max = AFFS_LC_SIZE << AFFS_I(inode)->i_lc_shift;

        if (AFFS_I(inode)->i_extcnt > lc_max) {
                u32 lc_shift, lc_mask, tmp, off;

                /* need to recalculate linear cache, start from old size */
                lc_shift = AFFS_I(inode)->i_lc_shift;
                tmp = (AFFS_I(inode)->i_extcnt / AFFS_LC_SIZE) >> lc_shift;
                for (; tmp; tmp >>= 1)
                        lc_shift++;
                lc_mask = (1 << lc_shift) - 1;

                /* fix idx and old size to new shift */
                lc_idx >>= (lc_shift - AFFS_I(inode)->i_lc_shift);
                AFFS_I(inode)->i_lc_size >>= (lc_shift - AFFS_I(inode)->i_lc_shift);

                /* first shrink old cache to make more space */
                off = 1 << (lc_shift - AFFS_I(inode)->i_lc_shift);
                for (i = 1, j = off; j < AFFS_LC_SIZE; i++, j += off)
                        AFFS_I(inode)->i_ac[i] = AFFS_I(inode)->i_ac[j];

                AFFS_I(inode)->i_lc_shift = lc_shift;
                AFFS_I(inode)->i_lc_mask = lc_mask;
        }

        /* fill cache to the needed index */
        i = AFFS_I(inode)->i_lc_size;
        AFFS_I(inode)->i_lc_size = lc_idx + 1;
        for (; i <= lc_idx; i++) {
                if (!i) {
                        AFFS_I(inode)->i_lc[0] = inode->i_ino;
                        continue;
                }
                key = AFFS_I(inode)->i_lc[i - 1];
                j = AFFS_I(inode)->i_lc_mask + 1;
                // unlock cache
                for (; j > 0; j--) {
                        bh = affs_bread(sb, key);
                        if (!bh)
                                goto err;
                        key = be32_to_cpu(AFFS_TAIL(sb, bh)->extension);
                        affs_brelse(bh);
                }
                // lock cache
                AFFS_I(inode)->i_lc[i] = key;
        }

        return 0;

err:
        // lock cache
        return -EIO;
}

static struct buffer_head *
affs_alloc_extblock(struct inode *inode, struct buffer_head *bh, u32 ext)
{
        struct super_block *sb = inode->i_sb;
        struct buffer_head *new_bh;
        u32 blocknr, tmp;

        blocknr = affs_alloc_block(inode, bh->b_blocknr);
        if (!blocknr)
                return ERR_PTR(-ENOSPC);

        new_bh = affs_getzeroblk(sb, blocknr);
        if (!new_bh) {
                affs_free_block(sb, blocknr);
                return ERR_PTR(-EIO);
        }

        AFFS_HEAD(new_bh)->ptype = cpu_to_be32(T_LIST);
        AFFS_HEAD(new_bh)->key = cpu_to_be32(blocknr);
        AFFS_TAIL(sb, new_bh)->stype = cpu_to_be32(ST_FILE);
        AFFS_TAIL(sb, new_bh)->parent = cpu_to_be32(inode->i_ino);
        affs_fix_checksum(sb, new_bh);

        mark_buffer_dirty_inode(new_bh, inode);

        tmp = be32_to_cpu(AFFS_TAIL(sb, bh)->extension);
        if (tmp)
                affs_warning(sb, "alloc_ext", "previous extension set (%x)", tmp);
        AFFS_TAIL(sb, bh)->extension = cpu_to_be32(blocknr);
        affs_adjust_checksum(bh, blocknr - tmp);
        mark_buffer_dirty_inode(bh, inode);

        AFFS_I(inode)->i_extcnt++;
        mark_inode_dirty(inode);

        return new_bh;
}

static inline struct buffer_head *
affs_get_extblock(struct inode *inode, u32 ext)
{
        /* inline the simplest case: same extended block as last time */
        struct buffer_head *bh = AFFS_I(inode)->i_ext_bh;
        if (ext == AFFS_I(inode)->i_ext_last)
                get_bh(bh);
        else
                /* we have to do more (not inlined) */
                bh = affs_get_extblock_slow(inode, ext);

        return bh;
}

static struct buffer_head *
affs_get_extblock_slow(struct inode *inode, u32 ext)
{
        struct super_block *sb = inode->i_sb;
        struct buffer_head *bh;
        u32 ext_key;
        u32 lc_idx, lc_off, ac_idx;
        u32 tmp, idx;

        if (ext == AFFS_I(inode)->i_ext_last + 1) {
                /* read the next extended block from the current one */
                bh = AFFS_I(inode)->i_ext_bh;
                ext_key = be32_to_cpu(AFFS_TAIL(sb, bh)->extension);
                if (ext < AFFS_I(inode)->i_extcnt)
                        goto read_ext;
                if (ext > AFFS_I(inode)->i_extcnt)
                        BUG();
                bh = affs_alloc_extblock(inode, bh, ext);
                if (IS_ERR(bh))
                        return bh;
                goto store_ext;
        }

        if (ext == 0) {
                /* we seek back to the file header block */
                ext_key = inode->i_ino;
                goto read_ext;
        }

        if (ext >= AFFS_I(inode)->i_extcnt) {
                struct buffer_head *prev_bh;

                /* allocate a new extended block */
                if (ext > AFFS_I(inode)->i_extcnt)
                        BUG();

                /* get previous extended block */
                prev_bh = affs_get_extblock(inode, ext - 1);
                if (IS_ERR(prev_bh))
                        return prev_bh;
                bh = affs_alloc_extblock(inode, prev_bh, ext);
                affs_brelse(prev_bh);
                if (IS_ERR(bh))
                        return bh;
                goto store_ext;
        }

again:
        /* check if there is an extended cache and whether it's large enough */
        lc_idx = ext >> AFFS_I(inode)->i_lc_shift;
        lc_off = ext & AFFS_I(inode)->i_lc_mask;

        if (lc_idx >= AFFS_I(inode)->i_lc_size) {
                int err;

                err = affs_grow_extcache(inode, lc_idx);
                if (err)
                        return ERR_PTR(err);
                goto again;
        }

        /* every n'th key we find in the linear cache */
        if (!lc_off) {
                ext_key = AFFS_I(inode)->i_lc[lc_idx];
                goto read_ext;
        }

        /* maybe it's still in the associative cache */
        ac_idx = (ext - lc_idx - 1) & AFFS_AC_MASK;
        if (AFFS_I(inode)->i_ac[ac_idx].ext == ext) {
                ext_key = AFFS_I(inode)->i_ac[ac_idx].key;
                goto read_ext;
        }

        /* try to find one of the previous extended blocks */
        tmp = ext;
        idx = ac_idx;
        while (--tmp, --lc_off > 0) {
                idx = (idx - 1) & AFFS_AC_MASK;
                if (AFFS_I(inode)->i_ac[idx].ext == tmp) {
                        ext_key = AFFS_I(inode)->i_ac[idx].key;
                        goto find_ext;
                }
        }

        /* fall back to the linear cache */
        ext_key = AFFS_I(inode)->i_lc[lc_idx];
find_ext:
        /* read all extended blocks until we find the one we need */
        //unlock cache
        do {
                bh = affs_bread(sb, ext_key);
                if (!bh)
                        goto err_bread;
                ext_key = be32_to_cpu(AFFS_TAIL(sb, bh)->extension);
                affs_brelse(bh);
                tmp++;
        } while (tmp < ext);
        //lock cache

        /* store it in the associative cache */
        // recalculate ac_idx?
        AFFS_I(inode)->i_ac[ac_idx].ext = ext;
        AFFS_I(inode)->i_ac[ac_idx].key = ext_key;

read_ext:
        /* finally read the right extended block */
        //unlock cache
        bh = affs_bread(sb, ext_key);
        if (!bh)
                goto err_bread;
        //lock cache

store_ext:
        /* release old cached extended block and store the new one */
        affs_brelse(AFFS_I(inode)->i_ext_bh);
        AFFS_I(inode)->i_ext_last = ext;
        AFFS_I(inode)->i_ext_bh = bh;
        get_bh(bh);

        return bh;

err_bread:
        affs_brelse(bh);
        return ERR_PTR(-EIO);
}

static int
affs_get_block(struct inode *inode, sector_t block, struct buffer_head *bh_result, int create)
{
        struct super_block      *sb = inode->i_sb;
        struct buffer_head      *ext_bh;
        u32                      ext;

        pr_debug("AFFS: get_block(%u, %lu)\n", (u32)inode->i_ino, (unsigned long)block);

        BUG_ON(block > (sector_t)0x7fffffffUL);

        if (block >= AFFS_I(inode)->i_blkcnt) {
                if (block > AFFS_I(inode)->i_blkcnt || !create)
                        goto err_big;
        } else
                create = 0;

        //lock cache
        affs_lock_ext(inode);

        ext = (u32)block / AFFS_SB(sb)->s_hashsize;
        block -= ext * AFFS_SB(sb)->s_hashsize;
        ext_bh = affs_get_extblock(inode, ext);
        if (IS_ERR(ext_bh))
                goto err_ext;
        map_bh(bh_result, sb, (sector_t)be32_to_cpu(AFFS_BLOCK(sb, ext_bh, block)));

        if (create) {
                u32 blocknr = affs_alloc_block(inode, ext_bh->b_blocknr);
                if (!blocknr)
                        goto err_alloc;
                set_buffer_new(bh_result);
                AFFS_I(inode)->mmu_private += AFFS_SB(sb)->s_data_blksize;
                AFFS_I(inode)->i_blkcnt++;

                /* store new block */
                if (bh_result->b_blocknr)
                        affs_warning(sb, "get_block", "block already set (%x)", bh_result->b_blocknr);
                AFFS_BLOCK(sb, ext_bh, block) = cpu_to_be32(blocknr);
                AFFS_HEAD(ext_bh)->block_count = cpu_to_be32(block + 1);
                affs_adjust_checksum(ext_bh, blocknr - bh_result->b_blocknr + 1);
                bh_result->b_blocknr = blocknr;

                if (!block) {
                        /* insert first block into header block */
                        u32 tmp = be32_to_cpu(AFFS_HEAD(ext_bh)->first_data);
                        if (tmp)
                                affs_warning(sb, "get_block", "first block already set (%d)", tmp);
                        AFFS_HEAD(ext_bh)->first_data = cpu_to_be32(blocknr);
                        affs_adjust_checksum(ext_bh, blocknr - tmp);
                }
        }

        affs_brelse(ext_bh);
        //unlock cache
        affs_unlock_ext(inode);
        return 0;

err_big:
        affs_error(inode->i_sb,"get_block","strange block request %d", block);
        return -EIO;
err_ext:
        // unlock cache
        affs_unlock_ext(inode);
        return PTR_ERR(ext_bh);
err_alloc:
        brelse(ext_bh);
        clear_buffer_mapped(bh_result);
        bh_result->b_bdev = NULL;
        // unlock cache
        affs_unlock_ext(inode);
        return -ENOSPC;
}

static int affs_writepage(struct page *page, struct writeback_control *wbc)
{
        return block_write_full_page(page, affs_get_block, wbc);
}

static int affs_readpage(struct file *file, struct page *page)
{
        return block_read_full_page(page, affs_get_block);
}

static int affs_write_begin(struct file *file, struct address_space *mapping,
                        loff_t pos, unsigned len, unsigned flags,
                        struct page **pagep, void **fsdata)
{
        int ret;

        *pagep = NULL;
        ret = cont_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
                                affs_get_block,
                                &AFFS_I(mapping->host)->mmu_private);
        if (unlikely(ret)) {
                loff_t isize = mapping->host->i_size;
                if (pos + len > isize)
                        vmtruncate(mapping->host, isize);
        }

        return ret;
}

static sector_t _affs_bmap(struct address_space *mapping, sector_t block)
{
        return generic_block_bmap(mapping,block,affs_get_block);
}

const struct address_space_operations affs_aops = {
        .readpage = affs_readpage,
        .writepage = affs_writepage,
        .sync_page = block_sync_page,
        .write_begin = affs_write_begin,
        .write_end = generic_write_end,
        .bmap = _affs_bmap
};

static inline struct buffer_head *
affs_bread_ino(struct inode *inode, int block, int create)
{
        struct buffer_head *bh, tmp_bh;
        int err;

        tmp_bh.b_state = 0;
        err = affs_get_block(inode, block, &tmp_bh, create);
        if (!err) {
                bh = affs_bread(inode->i_sb, tmp_bh.b_blocknr);
                if (bh) {
                        bh->b_state |= tmp_bh.b_state;
                        return bh;
                }
                err = -EIO;
        }
        return ERR_PTR(err);
}

static inline struct buffer_head *
affs_getzeroblk_ino(struct inode *inode, int block)
{
        struct buffer_head *bh, tmp_bh;
        int err;

        tmp_bh.b_state = 0;
        err = affs_get_block(inode, block, &tmp_bh, 1);
        if (!err) {
                bh = affs_getzeroblk(inode->i_sb, tmp_bh.b_blocknr);
                if (bh) {
                        bh->b_state |= tmp_bh.b_state;
                        return bh;
                }
                err = -EIO;
        }
        return ERR_PTR(err);
}

static inline struct buffer_head *
affs_getemptyblk_ino(struct inode *inode, int block)
{
        struct buffer_head *bh, tmp_bh;
        int err;

        tmp_bh.b_state = 0;
        err = affs_get_block(inode, block, &tmp_bh, 1);
        if (!err) {
                bh = affs_getemptyblk(inode->i_sb, tmp_bh.b_blocknr);
                if (bh) {
                        bh->b_state |= tmp_bh.b_state;
                        return bh;
                }
                err = -EIO;
        }
        return ERR_PTR(err);
}

static int
affs_do_readpage_ofs(struct file *file, struct page *page, unsigned from, unsigned to)
{
        struct inode *inode = page->mapping->host;
        struct super_block *sb = inode->i_sb;
        struct buffer_head *bh;
        char *data;
        u32 bidx, boff, bsize;
        u32 tmp;

        pr_debug("AFFS: read_page(%u, %ld, %d, %d)\n", (u32)inode->i_ino, page->index, from, to);
        BUG_ON(from > to || to > PAGE_CACHE_SIZE);
        kmap(page);
        data = page_address(page);
        bsize = AFFS_SB(sb)->s_data_blksize;
        tmp = (page->index << PAGE_CACHE_SHIFT) + from;
        bidx = tmp / bsize;
        boff = tmp % bsize;

        while (from < to) {
                bh = affs_bread_ino(inode, bidx, 0);
                if (IS_ERR(bh))
                        return PTR_ERR(bh);
                tmp = min(bsize - boff, to - from);
                BUG_ON(from + tmp > to || tmp > bsize);
                memcpy(data + from, AFFS_DATA(bh) + boff, tmp);
                affs_brelse(bh);
                bidx++;
                from += tmp;
                boff = 0;
        }
        flush_dcache_page(page);
        kunmap(page);
        return 0;
}

static int
affs_extent_file_ofs(struct inode *inode, u32 newsize)
{
        struct super_block *sb = inode->i_sb;
        struct buffer_head *bh, *prev_bh;
        u32 bidx, boff;
        u32 size, bsize;
        u32 tmp;

        pr_debug("AFFS: extent_file(%u, %d)\n", (u32)inode->i_ino, newsize);
        bsize = AFFS_SB(sb)->s_data_blksize;
        bh = NULL;
        size = AFFS_I(inode)->mmu_private;
        bidx = size / bsize;
        boff = size % bsize;
        if (boff) {
                bh = affs_bread_ino(inode, bidx, 0);
                if (IS_ERR(bh))
                        return PTR_ERR(bh);
                tmp = min(bsize - boff, newsize - size);
                BUG_ON(boff + tmp > bsize || tmp > bsize);
                memset(AFFS_DATA(bh) + boff, 0, tmp);
                be32_add_cpu(&AFFS_DATA_HEAD(bh)->size, tmp);
                affs_fix_checksum(sb, bh);
                mark_buffer_dirty_inode(bh, inode);
                size += tmp;
                bidx++;
        } else if (bidx) {
                bh = affs_bread_ino(inode, bidx - 1, 0);
                if (IS_ERR(bh))
                        return PTR_ERR(bh);
        }

        while (size < newsize) {
                prev_bh = bh;
                bh = affs_getzeroblk_ino(inode, bidx);
                if (IS_ERR(bh))
                        goto out;
                tmp = min(bsize, newsize - size);
                BUG_ON(tmp > bsize);
                AFFS_DATA_HEAD(bh)->ptype = cpu_to_be32(T_DATA);
                AFFS_DATA_HEAD(bh)->key = cpu_to_be32(inode->i_ino);
                AFFS_DATA_HEAD(bh)->sequence = cpu_to_be32(bidx);
                AFFS_DATA_HEAD(bh)->size = cpu_to_be32(tmp);
                affs_fix_checksum(sb, bh);
                bh->b_state &= ~(1UL << BH_New);
                mark_buffer_dirty_inode(bh, inode);
                if (prev_bh) {
                        u32 tmp = be32_to_cpu(AFFS_DATA_HEAD(prev_bh)->next);
                        if (tmp)
                                affs_warning(sb, "extent_file_ofs", "next block already set for %d (%d)", bidx, tmp);
                        AFFS_DATA_HEAD(prev_bh)->next = cpu_to_be32(bh->b_blocknr);
                        affs_adjust_checksum(prev_bh, bh->b_blocknr - tmp);
                        mark_buffer_dirty_inode(prev_bh, inode);
                        affs_brelse(prev_bh);
                }
                size += bsize;
                bidx++;
        }
        affs_brelse(bh);
        inode->i_size = AFFS_I(inode)->mmu_private = newsize;
        return 0;

out:
        inode->i_size = AFFS_I(inode)->mmu_private = newsize;
        return PTR_ERR(bh);
}

static int
affs_readpage_ofs(struct file *file, struct page *page)
{
        struct inode *inode = page->mapping->host;
        u32 to;
        int err;

        pr_debug("AFFS: read_page(%u, %ld)\n", (u32)inode->i_ino, page->index);
        to = PAGE_CACHE_SIZE;
        if (((page->index + 1) << PAGE_CACHE_SHIFT) > inode->i_size) {
                to = inode->i_size & ~PAGE_CACHE_MASK;
                memset(page_address(page) + to, 0, PAGE_CACHE_SIZE - to);
        }

        err = affs_do_readpage_ofs(file, page, 0, to);
        if (!err)
                SetPageUptodate(page);
        unlock_page(page);
        return err;
}

static int affs_write_begin_ofs(struct file *file, struct address_space *mapping,
                                loff_t pos, unsigned len, unsigned flags,
                                struct page **pagep, void **fsdata)
{
        struct inode *inode = mapping->host;
        struct page *page;
        pgoff_t index;
        int err = 0;

        pr_debug("AFFS: write_begin(%u, %llu, %llu)\n", (u32)inode->i_ino, (unsigned long long)pos, (unsigned long long)pos + len);
        if (pos > AFFS_I(inode)->mmu_private) {
                /* XXX: this probably leaves a too-big i_size in case of
                 * failure. Should really be updating i_size at write_end time
                 */
                err = affs_extent_file_ofs(inode, pos);
                if (err)
                        return err;
        }

        index = pos >> PAGE_CACHE_SHIFT;
        page = grab_cache_page_write_begin(mapping, index, flags);
        if (!page)
                return -ENOMEM;
        *pagep = page;

        if (PageUptodate(page))
                return 0;

        /* XXX: inefficient but safe in the face of short writes */
        err = affs_do_readpage_ofs(file, page, 0, PAGE_CACHE_SIZE);
        if (err) {
                unlock_page(page);
                page_cache_release(page);
        }
        return err;
}

static int affs_write_end_ofs(struct file *file, struct address_space *mapping,
                                loff_t pos, unsigned len, unsigned copied,
                                struct page *page, void *fsdata)
{
        struct inode *inode = mapping->host;
        struct super_block *sb = inode->i_sb;
        struct buffer_head *bh, *prev_bh;
        char *data;
        u32 bidx, boff, bsize;
        unsigned from, to;
        u32 tmp;
        int written;

        from = pos & (PAGE_CACHE_SIZE - 1);
        to = pos + len;
        /*
         * XXX: not sure if this can handle short copies (len < copied), but
         * we don't have to, because the page should always be uptodate here,
         * due to write_begin.
         */

        pr_debug("AFFS: write_begin(%u, %llu, %llu)\n", (u32)inode->i_ino, (unsigned long long)pos, (unsigned long long)pos + len);
        bsize = AFFS_SB(sb)->s_data_blksize;
        data = page_address(page);

        bh = NULL;
        written = 0;
        tmp = (page->index << PAGE_CACHE_SHIFT) + from;
        bidx = tmp / bsize;
        boff = tmp % bsize;
        if (boff) {
                bh = affs_bread_ino(inode, bidx, 0);
                if (IS_ERR(bh))
                        return PTR_ERR(bh);
                tmp = min(bsize - boff, to - from);
                BUG_ON(boff + tmp > bsize || tmp > bsize);
                memcpy(AFFS_DATA(bh) + boff, data + from, tmp);
                be32_add_cpu(&AFFS_DATA_HEAD(bh)->size, tmp);
                affs_fix_checksum(sb, bh);
                mark_buffer_dirty_inode(bh, inode);
                written += tmp;
                from += tmp;
                bidx++;
        } else if (bidx) {
                bh = affs_bread_ino(inode, bidx - 1, 0);
                if (IS_ERR(bh))
                        return PTR_ERR(bh);
        }
        while (from + bsize <= to) {
                prev_bh = bh;
                bh = affs_getemptyblk_ino(inode, bidx);
                if (IS_ERR(bh))
                        goto out;
                memcpy(AFFS_DATA(bh), data + from, bsize);
                if (buffer_new(bh)) {
                        AFFS_DATA_HEAD(bh)->ptype = cpu_to_be32(T_DATA);
                        AFFS_DATA_HEAD(bh)->key = cpu_to_be32(inode->i_ino);
                        AFFS_DATA_HEAD(bh)->sequence = cpu_to_be32(bidx);
                        AFFS_DATA_HEAD(bh)->size = cpu_to_be32(bsize);
                        AFFS_DATA_HEAD(bh)->next = 0;
                        bh->b_state &= ~(1UL << BH_New);
                        if (prev_bh) {
                                u32 tmp = be32_to_cpu(AFFS_DATA_HEAD(prev_bh)->next);
                                if (tmp)
                                        affs_warning(sb, "commit_write_ofs", "next block already set for %d (%d)", bidx, tmp);
                                AFFS_DATA_HEAD(prev_bh)->next = cpu_to_be32(bh->b_blocknr);
                                affs_adjust_checksum(prev_bh, bh->b_blocknr - tmp);
                                mark_buffer_dirty_inode(prev_bh, inode);
                        }
                }
                affs_brelse(prev_bh);
                affs_fix_checksum(sb, bh);
                mark_buffer_dirty_inode(bh, inode);
                written += bsize;
                from += bsize;
                bidx++;
        }
        if (from < to) {
                prev_bh = bh;
                bh = affs_bread_ino(inode, bidx, 1);
                if (IS_ERR(bh))
                        goto out;
                tmp = min(bsize, to - from);
                BUG_ON(tmp > bsize);
                memcpy(AFFS_DATA(bh), data + from, tmp);
                if (buffer_new(bh)) {
                        AFFS_DATA_HEAD(bh)->ptype = cpu_to_be32(T_DATA);
                        AFFS_DATA_HEAD(bh)->key = cpu_to_be32(inode->i_ino);
                        AFFS_DATA_HEAD(bh)->sequence = cpu_to_be32(bidx);
                        AFFS_DATA_HEAD(bh)->size = cpu_to_be32(tmp);
                        AFFS_DATA_HEAD(bh)->next = 0;
                        bh->b_state &= ~(1UL << BH_New);
                        if (prev_bh) {
                                u32 tmp = be32_to_cpu(AFFS_DATA_HEAD(prev_bh)->next);
                                if (tmp)
                                        affs_warning(sb, "commit_write_ofs", "next block already set for %d (%d)", bidx, tmp);
                                AFFS_DATA_HEAD(prev_bh)->next = cpu_to_be32(bh->b_blocknr);
                                affs_adjust_checksum(prev_bh, bh->b_blocknr - tmp);
                                mark_buffer_dirty_inode(prev_bh, inode);
                        }
                } else if (be32_to_cpu(AFFS_DATA_HEAD(bh)->size) < tmp)
                        AFFS_DATA_HEAD(bh)->size = cpu_to_be32(tmp);
                affs_brelse(prev_bh);
                affs_fix_checksum(sb, bh);
                mark_buffer_dirty_inode(bh, inode);
                written += tmp;
                from += tmp;
                bidx++;
        }
        SetPageUptodate(page);

done:
        affs_brelse(bh);
        tmp = (page->index << PAGE_CACHE_SHIFT) + from;
        if (tmp > inode->i_size)
                inode->i_size = AFFS_I(inode)->mmu_private = tmp;

        unlock_page(page);
        page_cache_release(page);

        return written;

out:
        bh = prev_bh;
        if (!written)
                written = PTR_ERR(bh);
        goto done;
}

const struct address_space_operations affs_aops_ofs = {
        .readpage = affs_readpage_ofs,
        //.writepage = affs_writepage_ofs,
        //.sync_page = affs_sync_page_ofs,
        .write_begin = affs_write_begin_ofs,
        .write_end = affs_write_end_ofs
};

/* Free any preallocated blocks. */

void
affs_free_prealloc(struct inode *inode)
{
        struct super_block *sb = inode->i_sb;

        pr_debug("AFFS: free_prealloc(ino=%lu)\n", inode->i_ino);

        while (AFFS_I(inode)->i_pa_cnt) {
                AFFS_I(inode)->i_pa_cnt--;
                affs_free_block(sb, ++AFFS_I(inode)->i_lastalloc);
        }
}

/* Truncate (or enlarge) a file to the requested size. */

void
affs_truncate(struct inode *inode)
{
        struct super_block *sb = inode->i_sb;
        u32 ext, ext_key;
        u32 last_blk, blkcnt, blk;
        u32 size;
        struct buffer_head *ext_bh;
        int i;

        pr_debug("AFFS: truncate(inode=%d, oldsize=%u, newsize=%u)\n",
                 (u32)inode->i_ino, (u32)AFFS_I(inode)->mmu_private, (u32)inode->i_size);

        last_blk = 0;
        ext = 0;
        if (inode->i_size) {
                last_blk = ((u32)inode->i_size - 1) / AFFS_SB(sb)->s_data_blksize;
                ext = last_blk / AFFS_SB(sb)->s_hashsize;
        }

        if (inode->i_size > AFFS_I(inode)->mmu_private) {
                struct address_space *mapping = inode->i_mapping;
                struct page *page;
                void *fsdata;
                u32 size = inode->i_size;
                int res;

                res = mapping->a_ops->write_begin(NULL, mapping, size, 0, 0, &page, &fsdata);
                if (!res)
                        res = mapping->a_ops->write_end(NULL, mapping, size, 0, 0, page, fsdata);
                else
                        inode->i_size = AFFS_I(inode)->mmu_private;
                mark_inode_dirty(inode);
                return;
        } else if (inode->i_size == AFFS_I(inode)->mmu_private)
                return;

        // lock cache
        ext_bh = affs_get_extblock(inode, ext);
        if (IS_ERR(ext_bh)) {
                affs_warning(sb, "truncate", "unexpected read error for ext block %u (%d)",
                             ext, PTR_ERR(ext_bh));
                return;
        }
        if (AFFS_I(inode)->i_lc) {
                /* clear linear cache */
                i = (ext + 1) >> AFFS_I(inode)->i_lc_shift;
                if (AFFS_I(inode)->i_lc_size > i) {
                        AFFS_I(inode)->i_lc_size = i;
                        for (; i < AFFS_LC_SIZE; i++)
                                AFFS_I(inode)->i_lc[i] = 0;
                }
                /* clear associative cache */
                for (i = 0; i < AFFS_AC_SIZE; i++)
                        if (AFFS_I(inode)->i_ac[i].ext >= ext)
                                AFFS_I(inode)->i_ac[i].ext = 0;
        }
        ext_key = be32_to_cpu(AFFS_TAIL(sb, ext_bh)->extension);

        blkcnt = AFFS_I(inode)->i_blkcnt;
        i = 0;
        blk = last_blk;
        if (inode->i_size) {
                i = last_blk % AFFS_SB(sb)->s_hashsize + 1;
                blk++;
        } else
                AFFS_HEAD(ext_bh)->first_data = 0;
        AFFS_HEAD(ext_bh)->block_count = cpu_to_be32(i);
        size = AFFS_SB(sb)->s_hashsize;
        if (size > blkcnt - blk + i)
                size = blkcnt - blk + i;
        for (; i < size; i++, blk++) {
                affs_free_block(sb, be32_to_cpu(AFFS_BLOCK(sb, ext_bh, i)));
                AFFS_BLOCK(sb, ext_bh, i) = 0;
        }
        AFFS_TAIL(sb, ext_bh)->extension = 0;
        affs_fix_checksum(sb, ext_bh);
        mark_buffer_dirty_inode(ext_bh, inode);
        affs_brelse(ext_bh);

        if (inode->i_size) {
                AFFS_I(inode)->i_blkcnt = last_blk + 1;
                AFFS_I(inode)->i_extcnt = ext + 1;
                if (AFFS_SB(sb)->s_flags & SF_OFS) {
                        struct buffer_head *bh = affs_bread_ino(inode, last_blk, 0);
                        u32 tmp;
                        if (IS_ERR(ext_bh)) {
                                affs_warning(sb, "truncate", "unexpected read error for last block %u (%d)",
                                             ext, PTR_ERR(ext_bh));
                                return;
                        }
                        tmp = be32_to_cpu(AFFS_DATA_HEAD(bh)->next);
                        AFFS_DATA_HEAD(bh)->next = 0;
                        affs_adjust_checksum(bh, -tmp);
                        affs_brelse(bh);
                }
        } else {
                AFFS_I(inode)->i_blkcnt = 0;
                AFFS_I(inode)->i_extcnt = 1;
        }
        AFFS_I(inode)->mmu_private = inode->i_size;
        // unlock cache

        while (ext_key) {
                ext_bh = affs_bread(sb, ext_key);
                size = AFFS_SB(sb)->s_hashsize;
                if (size > blkcnt - blk)
                        size = blkcnt - blk;
                for (i = 0; i < size; i++, blk++)
                        affs_free_block(sb, be32_to_cpu(AFFS_BLOCK(sb, ext_bh, i)));
                affs_free_block(sb, ext_key);
                ext_key = be32_to_cpu(AFFS_TAIL(sb, ext_bh)->extension);
                affs_brelse(ext_bh);
        }
        affs_free_prealloc(inode);
}

int affs_file_fsync(struct file *filp, int datasync)
{
        struct inode *inode = filp->f_mapping->host;
        int ret, err;

        ret = write_inode_now(inode, 0);
        err = sync_blockdev(inode->i_sb->s_bdev);
        if (!ret)
                ret = err;
        return ret;
}