/*
 *  linux/fs/ufs/ialloc.c
 *
 * Copyright (c) 1998
 * Daniel Pirkl <daniel.pirkl@email.cz>
 * Charles University, Faculty of Mathematics and Physics
 *
 *  from
 *
 *  linux/fs/ext2/ialloc.c
 *
 * Copyright (C) 1992, 1993, 1994, 1995
 * Remy Card (card@masi.ibp.fr)
 * Laboratoire MASI - Institut Blaise Pascal
 * Universite Pierre et Marie Curie (Paris VI)
 *
 *  BSD ufs-inspired inode and directory allocation by 
 *  Stephen Tweedie (sct@dcs.ed.ac.uk), 1993
 *  Big-endian to little-endian byte-swapping/bitmaps by
 *        David S. Miller (davem@caip.rutgers.edu), 1995
 *
 * UFS2 write support added by
 * Evgeniy Dushistov <dushistov@mail.ru>, 2007
 */

#include <linux/fs.h>
#include <linux/time.h>
#include <linux/stat.h>
#include <linux/string.h>
#include <linux/buffer_head.h>
#include <linux/sched.h>
#include <linux/bitops.h>
#include <asm/byteorder.h>

#include "ufs_fs.h"
#include "ufs.h"
#include "swab.h"
#include "util.h"

/*
 * NOTE! When we get the inode, we're the only people
 * that have access to it, and as such there are no
 * race conditions we have to worry about. The inode
 * is not on the hash-lists, and it cannot be reached
 * through the filesystem because the directory entry
 * has been deleted earlier.
 *
 * HOWEVER: we must make sure that we get no aliases,
 * which means that we have to call "clear_inode()"
 * _before_ we mark the inode not in use in the inode
 * bitmaps. Otherwise a newly created file might use
 * the same inode number (not actually the same pointer
 * though), and then we'd have two inodes sharing the
 * same inode number and space on the harddisk.
 */
void ufs_free_inode (struct inode * inode)
{
        struct super_block * sb;
        struct ufs_sb_private_info * uspi;
        struct ufs_super_block_first * usb1;
        struct ufs_cg_private_info * ucpi;
        struct ufs_cylinder_group * ucg;
        int is_directory;
        unsigned ino, cg, bit;
        
        UFSD("ENTER, ino %lu\n", inode->i_ino);

        sb = inode->i_sb;
        uspi = UFS_SB(sb)->s_uspi;
        usb1 = ubh_get_usb_first(uspi);
        
        ino = inode->i_ino;

        lock_super (sb);

        if (!((ino > 1) && (ino < (uspi->s_ncg * uspi->s_ipg )))) {
                ufs_warning(sb, "ufs_free_inode", "reserved inode or nonexistent inode %u\n", ino);
                unlock_super (sb);
                return;
        }
        
        cg = ufs_inotocg (ino);
        bit = ufs_inotocgoff (ino);
        ucpi = ufs_load_cylinder (sb, cg);
        if (!ucpi) {
                unlock_super (sb);
                return;
        }
        ucg = ubh_get_ucg(UCPI_UBH(ucpi));
        if (!ufs_cg_chkmagic(sb, ucg))
                ufs_panic (sb, "ufs_free_fragments", "internal error, bad cg magic number");

        ucg->cg_time = cpu_to_fs32(sb, get_seconds());

        is_directory = S_ISDIR(inode->i_mode);

        if (ubh_isclr (UCPI_UBH(ucpi), ucpi->c_iusedoff, bit))
                ufs_error(sb, "ufs_free_inode", "bit already cleared for inode %u", ino);
        else {
                ubh_clrbit (UCPI_UBH(ucpi), ucpi->c_iusedoff, bit);
                if (ino < ucpi->c_irotor)
                        ucpi->c_irotor = ino;
                fs32_add(sb, &ucg->cg_cs.cs_nifree, 1);
                uspi->cs_total.cs_nifree++;
                fs32_add(sb, &UFS_SB(sb)->fs_cs(cg).cs_nifree, 1);

                if (is_directory) {
                        fs32_sub(sb, &ucg->cg_cs.cs_ndir, 1);
                        uspi->cs_total.cs_ndir--;
                        fs32_sub(sb, &UFS_SB(sb)->fs_cs(cg).cs_ndir, 1);
                }
        }

        ubh_mark_buffer_dirty (USPI_UBH(uspi));
        ubh_mark_buffer_dirty (UCPI_UBH(ucpi));
        if (sb->s_flags & MS_SYNCHRONOUS)
                ubh_sync_block(UCPI_UBH(ucpi));
        
        sb->s_dirt = 1;
        unlock_super (sb);
        UFSD("EXIT\n");
}

/*
 * Nullify new chunk of inodes,
 * BSD people also set ui_gen field of inode
 * during nullification, but we not care about
 * that because of linux ufs do not support NFS
 */
static void ufs2_init_inodes_chunk(struct super_block *sb,
                                   struct ufs_cg_private_info *ucpi,
                                   struct ufs_cylinder_group *ucg)
{
        struct buffer_head *bh;
        struct ufs_sb_private_info *uspi = UFS_SB(sb)->s_uspi;
        sector_t beg = uspi->s_sbbase +
                ufs_inotofsba(ucpi->c_cgx * uspi->s_ipg +
                              fs32_to_cpu(sb, ucg->cg_u.cg_u2.cg_initediblk));
        sector_t end = beg + uspi->s_fpb;

        UFSD("ENTER cgno %d\n", ucpi->c_cgx);

        for (; beg < end; ++beg) {
                bh = sb_getblk(sb, beg);
                lock_buffer(bh);
                memset(bh->b_data, 0, sb->s_blocksize);
                set_buffer_uptodate(bh);
                mark_buffer_dirty(bh);
                unlock_buffer(bh);
                if (sb->s_flags & MS_SYNCHRONOUS)
                        sync_dirty_buffer(bh);
                brelse(bh);
        }

        fs32_add(sb, &ucg->cg_u.cg_u2.cg_initediblk, uspi->s_inopb);
        ubh_mark_buffer_dirty(UCPI_UBH(ucpi));
        if (sb->s_flags & MS_SYNCHRONOUS)
                ubh_sync_block(UCPI_UBH(ucpi));

        UFSD("EXIT\n");
}

/*
 * There are two policies for allocating an inode.  If the new inode is
 * a directory, then a forward search is made for a block group with both
 * free space and a low directory-to-inode ratio; if that fails, then of
 * the groups with above-average free space, that group with the fewest
 * directories already is chosen.
 *
 * For other inodes, search forward from the parent directory's block
 * group to find a free inode.
 */
struct inode * ufs_new_inode(struct inode * dir, int mode)
{
        struct super_block * sb;
        struct ufs_sb_info * sbi;
        struct ufs_sb_private_info * uspi;
        struct ufs_super_block_first * usb1;
        struct ufs_cg_private_info * ucpi;
        struct ufs_cylinder_group * ucg;
        struct inode * inode;
        unsigned cg, bit, i, j, start;
        struct ufs_inode_info *ufsi;
        int err = -ENOSPC;

        UFSD("ENTER\n");
        
        /* Cannot create files in a deleted directory */
        if (!dir || !dir->i_nlink)
                return ERR_PTR(-EPERM);
        sb = dir->i_sb;
        inode = new_inode(sb);
        if (!inode)
                return ERR_PTR(-ENOMEM);
        ufsi = UFS_I(inode);
        sbi = UFS_SB(sb);
        uspi = sbi->s_uspi;
        usb1 = ubh_get_usb_first(uspi);

        lock_super (sb);

        /*
         * Try to place the inode in its parent directory
         */
        i = ufs_inotocg(dir->i_ino);
        if (sbi->fs_cs(i).cs_nifree) {
                cg = i;
                goto cg_found;
        }

        /*
         * Use a quadratic hash to find a group with a free inode
         */
        for ( j = 1; j < uspi->s_ncg; j <<= 1 ) {
                i += j;
                if (i >= uspi->s_ncg)
                        i -= uspi->s_ncg;
                if (sbi->fs_cs(i).cs_nifree) {
                        cg = i;
                        goto cg_found;
                }
        }

        /*
         * That failed: try linear search for a free inode
         */
        i = ufs_inotocg(dir->i_ino) + 1;
        for (j = 2; j < uspi->s_ncg; j++) {
                i++;
                if (i >= uspi->s_ncg)
                        i = 0;
                if (sbi->fs_cs(i).cs_nifree) {
                        cg = i;
                        goto cg_found;
                }
        }

        goto failed;

cg_found:
        ucpi = ufs_load_cylinder (sb, cg);
        if (!ucpi) {
                err = -EIO;
                goto failed;
        }
        ucg = ubh_get_ucg(UCPI_UBH(ucpi));
        if (!ufs_cg_chkmagic(sb, ucg)) 
                ufs_panic (sb, "ufs_new_inode", "internal error, bad cg magic number");

        start = ucpi->c_irotor;
        bit = ubh_find_next_zero_bit (UCPI_UBH(ucpi), ucpi->c_iusedoff, uspi->s_ipg, start);
        if (!(bit < uspi->s_ipg)) {
                bit = ubh_find_first_zero_bit (UCPI_UBH(ucpi), ucpi->c_iusedoff, start);
                if (!(bit < start)) {
                        ufs_error (sb, "ufs_new_inode",
                            "cylinder group %u corrupted - error in inode bitmap\n", cg);
                        err = -EIO;
                        goto failed;
                }
        }
        UFSD("start = %u, bit = %u, ipg = %u\n", start, bit, uspi->s_ipg);
        if (ubh_isclr (UCPI_UBH(ucpi), ucpi->c_iusedoff, bit))
                ubh_setbit (UCPI_UBH(ucpi), ucpi->c_iusedoff, bit);
        else {
                ufs_panic (sb, "ufs_new_inode", "internal error");
                err = -EIO;
                goto failed;
        }

        if (uspi->fs_magic == UFS2_MAGIC) {
                u32 initediblk = fs32_to_cpu(sb, ucg->cg_u.cg_u2.cg_initediblk);

                if (bit + uspi->s_inopb > initediblk &&
                    initediblk < fs32_to_cpu(sb, ucg->cg_u.cg_u2.cg_niblk))
                        ufs2_init_inodes_chunk(sb, ucpi, ucg);
        }

        fs32_sub(sb, &ucg->cg_cs.cs_nifree, 1);
        uspi->cs_total.cs_nifree--;
        fs32_sub(sb, &sbi->fs_cs(cg).cs_nifree, 1);
        
        if (S_ISDIR(mode)) {
                fs32_add(sb, &ucg->cg_cs.cs_ndir, 1);
                uspi->cs_total.cs_ndir++;
                fs32_add(sb, &sbi->fs_cs(cg).cs_ndir, 1);
        }
        ubh_mark_buffer_dirty (USPI_UBH(uspi));
        ubh_mark_buffer_dirty (UCPI_UBH(ucpi));
        if (sb->s_flags & MS_SYNCHRONOUS)
                ubh_sync_block(UCPI_UBH(ucpi));
        sb->s_dirt = 1;

        inode->i_ino = cg * uspi->s_ipg + bit;
        inode_init_owner(inode, dir, mode);
        inode->i_blocks = 0;
        inode->i_generation = 0;
        inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME_SEC;
        ufsi->i_flags = UFS_I(dir)->i_flags;
        ufsi->i_lastfrag = 0;
        ufsi->i_shadow = 0;
        ufsi->i_osync = 0;
        ufsi->i_oeftflag = 0;
        ufsi->i_dir_start_lookup = 0;
        memset(&ufsi->i_u1, 0, sizeof(ufsi->i_u1));
        insert_inode_hash(inode);
        mark_inode_dirty(inode);

        if (uspi->fs_magic == UFS2_MAGIC) {
                struct buffer_head *bh;
                struct ufs2_inode *ufs2_inode;

                /*
                 * setup birth date, we do it here because of there is no sense
                 * to hold it in struct ufs_inode_info, and lose 64 bit
                 */
                bh = sb_bread(sb, uspi->s_sbbase + ufs_inotofsba(inode->i_ino));
                if (!bh) {
                        ufs_warning(sb, "ufs_read_inode",
                                    "unable to read inode %lu\n",
                                    inode->i_ino);
                        err = -EIO;
                        goto fail_remove_inode;
                }
                lock_buffer(bh);
                ufs2_inode = (struct ufs2_inode *)bh->b_data;
                ufs2_inode += ufs_inotofsbo(inode->i_ino);
                ufs2_inode->ui_birthtime = cpu_to_fs64(sb, CURRENT_TIME.tv_sec);
                ufs2_inode->ui_birthnsec = cpu_to_fs32(sb, CURRENT_TIME.tv_nsec);
                mark_buffer_dirty(bh);
                unlock_buffer(bh);
                if (sb->s_flags & MS_SYNCHRONOUS)
                        sync_dirty_buffer(bh);
                brelse(bh);
        }

        unlock_super (sb);

        UFSD("allocating inode %lu\n", inode->i_ino);
        UFSD("EXIT\n");
        return inode;

fail_remove_inode:
        unlock_super(sb);
        inode->i_nlink = 0;
        iput(inode);
        UFSD("EXIT (FAILED): err %d\n", err);
        return ERR_PTR(err);
failed:
        unlock_super (sb);
        make_bad_inode(inode);
        iput (inode);
        UFSD("EXIT (FAILED): err %d\n", err);
        return ERR_PTR(err);
}