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/*

 *  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          = 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)

{

        if (atomic_read(&filp->f_count) != 1)

                return 0;

        pr_debug("AFFS: open(%d)\n", AFFS_I(inode)->i_opencnt);

        AFFS_I(inode)->i_opencnt++;

        return 0;

}

static int

affs_file_release(struct inode *inode, struct file *filp)

{

        if (atomic_read(&filp->f_count) != 0)

                return 0;

        pr_debug("AFFS: release(%d)\n", AFFS_I(inode)->i_opencnt);

        AFFS_I(inode)->i_opencnt--;

        if (!AFFS_I(inode)->i_opencnt)

                affs_free_prealloc(inode);

        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)

                atomic_inc(&bh->b_count);

        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;

        atomic_inc(&bh->b_count);

        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);

        if (block > (sector_t)0x7fffffffUL)

                BUG();

        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)

{

        *pagep = NULL;

        return cont_write_begin(file, mapping, pos, len, flags, pagep, fsdata,

                                affs_get_block,

                                &AFFS_I(mapping->host)->mmu_private);

}

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);

        if (from > to || to > PAGE_CACHE_SIZE)

                BUG();

        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);

                if (from + tmp > to || tmp > bsize)

                        BUG();

                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);

                if (boff + tmp > bsize || tmp > bsize)

                        BUG();

                memset(AFFS_DATA(bh) + boff, 0, tmp);

                AFFS_DATA_HEAD(bh)->size = cpu_to_be32(be32_to_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);

                if (tmp > bsize)

                        BUG();

                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);