/*
 *  linux/fs/ext3/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@redhat.com), 1993
 *  Big-endian to little-endian byte-swapping/bitmaps by
 *        David S. Miller (davem@caip.rutgers.edu), 1995
 */

#include <linux/quotaops.h>
#include <linux/random.h>

#include "ext3.h"
#include "xattr.h"
#include "acl.h"

/*
 * ialloc.c contains the inodes allocation and deallocation routines
 */

/*
 * The free inodes are managed by bitmaps.  A file system contains several
 * blocks groups.  Each group contains 1 bitmap block for blocks, 1 bitmap
 * block for inodes, N blocks for the inode table and data blocks.
 *
 * The file system contains group descriptors which are located after the
 * super block.  Each descriptor contains the number of the bitmap block and
 * the free blocks count in the block.
 */


/*
 * Read the inode allocation bitmap for a given block_group, reading
 * into the specified slot in the superblock's bitmap cache.
 *
 * Return buffer_head of bitmap on success or NULL.
 */
static struct buffer_head *
read_inode_bitmap(struct super_block * sb, unsigned long block_group)
{
        struct ext3_group_desc *desc;
        struct buffer_head *bh = NULL;

        desc = ext3_get_group_desc(sb, block_group, NULL);
        if (!desc)
                goto error_out;

        bh = sb_bread(sb, le32_to_cpu(desc->bg_inode_bitmap));
        if (!bh)
                ext3_error(sb, "read_inode_bitmap",
                            "Cannot read inode bitmap - "
                            "block_group = %lu, inode_bitmap = %u",
                            block_group, le32_to_cpu(desc->bg_inode_bitmap));
error_out:
        return bh;
}

/*
 * 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 ext3_free_inode (handle_t *handle, struct inode * inode)
{
        struct super_block * sb = inode->i_sb;
        int is_directory;
        unsigned long ino;
        struct buffer_head *bitmap_bh = NULL;
        struct buffer_head *bh2;
        unsigned long block_group;
        unsigned long bit;
        struct ext3_group_desc * gdp;
        struct ext3_super_block * es;
        struct ext3_sb_info *sbi;
        int fatal = 0, err;

        if (atomic_read(&inode->i_count) > 1) {
                printk ("ext3_free_inode: inode has count=%d\n",
                                        atomic_read(&inode->i_count));
                return;
        }
        if (inode->i_nlink) {
                printk ("ext3_free_inode: inode has nlink=%d\n",
                        inode->i_nlink);
                return;
        }
        if (!sb) {
                printk("ext3_free_inode: inode on nonexistent device\n");
                return;
        }
        sbi = EXT3_SB(sb);

        ino = inode->i_ino;
        ext3_debug ("freeing inode %lu\n", ino);
        trace_ext3_free_inode(inode);

        is_directory = S_ISDIR(inode->i_mode);

        es = EXT3_SB(sb)->s_es;
        if (ino < EXT3_FIRST_INO(sb) || ino > le32_to_cpu(es->s_inodes_count)) {
                ext3_error (sb, "ext3_free_inode",
                            "reserved or nonexistent inode %lu", ino);
                goto error_return;
        }
        block_group = (ino - 1) / EXT3_INODES_PER_GROUP(sb);
        bit = (ino - 1) % EXT3_INODES_PER_GROUP(sb);
        bitmap_bh = read_inode_bitmap(sb, block_group);
        if (!bitmap_bh)
                goto error_return;

        BUFFER_TRACE(bitmap_bh, "get_write_access");
        fatal = ext3_journal_get_write_access(handle, bitmap_bh);
        if (fatal)
                goto error_return;

        /* Ok, now we can actually update the inode bitmaps.. */
        if (!ext3_clear_bit_atomic(sb_bgl_lock(sbi, block_group),
                                        bit, bitmap_bh->b_data))
                ext3_error (sb, "ext3_free_inode",
                              "bit already cleared for inode %lu", ino);
        else {
                gdp = ext3_get_group_desc (sb, block_group, &bh2);

                BUFFER_TRACE(bh2, "get_write_access");
                fatal = ext3_journal_get_write_access(handle, bh2);
                if (fatal) goto error_return;

                if (gdp) {
                        spin_lock(sb_bgl_lock(sbi, block_group));
                        le16_add_cpu(&gdp->bg_free_inodes_count, 1);
                        if (is_directory)
                                le16_add_cpu(&gdp->bg_used_dirs_count, -1);
                        spin_unlock(sb_bgl_lock(sbi, block_group));
                        percpu_counter_inc(&sbi->s_freeinodes_counter);
                        if (is_directory)
                                percpu_counter_dec(&sbi->s_dirs_counter);

                }
                BUFFER_TRACE(bh2, "call ext3_journal_dirty_metadata");
                err = ext3_journal_dirty_metadata(handle, bh2);
                if (!fatal) fatal = err;
        }
        BUFFER_TRACE(bitmap_bh, "call ext3_journal_dirty_metadata");
        err = ext3_journal_dirty_metadata(handle, bitmap_bh);
        if (!fatal)
                fatal = err;

error_return:
        brelse(bitmap_bh);
        ext3_std_error(sb, fatal);
}

/*
 * Orlov's allocator for directories.
 *
 * We always try to spread first-level directories.
 *
 * If there are blockgroups with both free inodes and free blocks counts
 * not worse than average we return one with smallest directory count.
 * Otherwise we simply return a random group.
 *
 * For the rest rules look so:
 *
 * It's OK to put directory into a group unless
 * it has too many directories already (max_dirs) or
 * it has too few free inodes left (min_inodes) or
 * it has too few free blocks left (min_blocks).
 * Parent's group is preferred, if it doesn't satisfy these
 * conditions we search cyclically through the rest. If none
 * of the groups look good we just look for a group with more
 * free inodes than average (starting at parent's group).
 *
 * Debt is incremented each time we allocate a directory and decremented
 * when we allocate an inode, within 0--255.
 */

static int find_group_orlov(struct super_block *sb, struct inode *parent)
{
        int parent_group = EXT3_I(parent)->i_block_group;
        struct ext3_sb_info *sbi = EXT3_SB(sb);
        int ngroups = sbi->s_groups_count;
        int inodes_per_group = EXT3_INODES_PER_GROUP(sb);
        unsigned int freei, avefreei;
        ext3_fsblk_t freeb, avefreeb;
        unsigned int ndirs;
        int max_dirs, min_inodes;
        ext3_grpblk_t min_blocks;
        int group = -1, i;
        struct ext3_group_desc *desc;

        freei = percpu_counter_read_positive(&sbi->s_freeinodes_counter);
        avefreei = freei / ngroups;
        freeb = percpu_counter_read_positive(&sbi->s_freeblocks_counter);
        avefreeb = freeb / ngroups;
        ndirs = percpu_counter_read_positive(&sbi->s_dirs_counter);

        if ((parent == sb->s_root->d_inode) ||
            (EXT3_I(parent)->i_flags & EXT3_TOPDIR_FL)) {
                int best_ndir = inodes_per_group;
                int best_group = -1;

                get_random_bytes(&group, sizeof(group));
                parent_group = (unsigned)group % ngroups;
                for (i = 0; i < ngroups; i++) {
                        group = (parent_group + i) % ngroups;
                        desc = ext3_get_group_desc (sb, group, NULL);
                        if (!desc || !desc->bg_free_inodes_count)
                                continue;
                        if (le16_to_cpu(desc->bg_used_dirs_count) >= best_ndir)
                                continue;
                        if (le16_to_cpu(desc->bg_free_inodes_count) < avefreei)
                                continue;
                        if (le16_to_cpu(desc->bg_free_blocks_count) < avefreeb)
                                continue;
                        best_group = group;
                        best_ndir = le16_to_cpu(desc->bg_used_dirs_count);
                }
                if (best_group >= 0)
                        return best_group;
                goto fallback;
        }

        max_dirs = ndirs / ngroups + inodes_per_group / 16;
        min_inodes = avefreei - inodes_per_group / 4;
        min_blocks = avefreeb - EXT3_BLOCKS_PER_GROUP(sb) / 4;

        for (i = 0; i < ngroups; i++) {
                group = (parent_group + i) % ngroups;
                desc = ext3_get_group_desc (sb, group, NULL);
                if (!desc || !desc->bg_free_inodes_count)
                        continue;
                if (le16_to_cpu(desc->bg_used_dirs_count) >= max_dirs)
                        continue;
                if (le16_to_cpu(desc->bg_free_inodes_count) < min_inodes)
                        continue;
                if (le16_to_cpu(desc->bg_free_blocks_count) < min_blocks)
                        continue;
                return group;
        }

fallback:
        for (i = 0; i < ngroups; i++) {
                group = (parent_group + i) % ngroups;
                desc = ext3_get_group_desc (sb, group, NULL);
                if (!desc || !desc->bg_free_inodes_count)
                        continue;
                if (le16_to_cpu(desc->bg_free_inodes_count) >= avefreei)
                        return group;
        }

        if (avefreei) {
                /*
                 * The free-inodes counter is approximate, and for really small
                 * filesystems the above test can fail to find any blockgroups
                 */
                avefreei = 0;
                goto fallback;
        }

        return -1;
}

static int find_group_other(struct super_block *sb, struct inode *parent)
{
        int parent_group = EXT3_I(parent)->i_block_group;
        int ngroups = EXT3_SB(sb)->s_groups_count;
        struct ext3_group_desc *desc;
        int group, i;

        /*
         * Try to place the inode in its parent directory
         */
        group = parent_group;
        desc = ext3_get_group_desc (sb, group, NULL);
        if (desc && le16_to_cpu(desc->bg_free_inodes_count) &&
                        le16_to_cpu(desc->bg_free_blocks_count))
                return group;

        /*
         * We're going to place this inode in a different blockgroup from its
         * parent.  We want to cause files in a common directory to all land in
         * the same blockgroup.  But we want files which are in a different
         * directory which shares a blockgroup with our parent to land in a
         * different blockgroup.
         *
         * So add our directory's i_ino into the starting point for the hash.
         */
        group = (group + parent->i_ino) % ngroups;

        /*
         * Use a quadratic hash to find a group with a free inode and some free
         * blocks.
         */
        for (i = 1; i < ngroups; i <<= 1) {
                group += i;
                if (group >= ngroups)
                        group -= ngroups;
                desc = ext3_get_group_desc (sb, group, NULL);
                if (desc && le16_to_cpu(desc->bg_free_inodes_count) &&
                                le16_to_cpu(desc->bg_free_blocks_count))
                        return group;
        }

        /*
         * That failed: try linear search for a free inode, even if that group
         * has no free blocks.
         */
        group = parent_group;
        for (i = 0; i < ngroups; i++) {
                if (++group >= ngroups)
                        group = 0;
                desc = ext3_get_group_desc (sb, group, NULL);
                if (desc && le16_to_cpu(desc->bg_free_inodes_count))
                        return group;
        }

        return -1;
}

/*
 * 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 *ext3_new_inode(handle_t *handle, struct inode * dir,
                             const struct qstr *qstr, umode_t mode)
{
        struct super_block *sb;
        struct buffer_head *bitmap_bh = NULL;
        struct buffer_head *bh2;
        int group;
        unsigned long ino = 0;
        struct inode * inode;
        struct ext3_group_desc * gdp = NULL;
        struct ext3_super_block * es;
        struct ext3_inode_info *ei;
        struct ext3_sb_info *sbi;
        int err = 0;
        struct inode *ret;
        int i;

        /* Cannot create files in a deleted directory */
        if (!dir || !dir->i_nlink)
                return ERR_PTR(-EPERM);

        sb = dir->i_sb;
        trace_ext3_request_inode(dir, mode);
        inode = new_inode(sb);
        if (!inode)
                return ERR_PTR(-ENOMEM);
        ei = EXT3_I(inode);

        sbi = EXT3_SB(sb);
        es = sbi->s_es;
        if (S_ISDIR(mode))
                group = find_group_orlov(sb, dir);
        else
                group = find_group_other(sb, dir);

        err = -ENOSPC;
        if (group == -1)
                goto out;

        for (i = 0; i < sbi->s_groups_count; i++) {
                err = -EIO;

                gdp = ext3_get_group_desc(sb, group, &bh2);
                if (!gdp)
                        goto fail;

                brelse(bitmap_bh);
                bitmap_bh = read_inode_bitmap(sb, group);
                if (!bitmap_bh)
                        goto fail;

                ino = 0;

repeat_in_this_group:
                ino = ext3_find_next_zero_bit((unsigned long *)
                                bitmap_bh->b_data, EXT3_INODES_PER_GROUP(sb), ino);
                if (ino < EXT3_INODES_PER_GROUP(sb)) {

                        BUFFER_TRACE(bitmap_bh, "get_write_access");
                        err = ext3_journal_get_write_access(handle, bitmap_bh);
                        if (err)
                                goto fail;

                        if (!ext3_set_bit_atomic(sb_bgl_lock(sbi, group),
                                                ino, bitmap_bh->b_data)) {
                                /* we won it */
                                BUFFER_TRACE(bitmap_bh,
                                        "call ext3_journal_dirty_metadata");
                                err = ext3_journal_dirty_metadata(handle,
                                                                bitmap_bh);
                                if (err)
                                        goto fail;
                                goto got;
                        }
                        /* we lost it */
                        journal_release_buffer(handle, bitmap_bh);

                        if (++ino < EXT3_INODES_PER_GROUP(sb))
                                goto repeat_in_this_group;
                }

                /*
                 * This case is possible in concurrent environment.  It is very
                 * rare.  We cannot repeat the find_group_xxx() call because
                 * that will simply return the same blockgroup, because the
                 * group descriptor metadata has not yet been updated.
                 * So we just go onto the next blockgroup.
                 */
                if (++group == sbi->s_groups_count)
                        group = 0;
        }
        err = -ENOSPC;
        goto out;

got:
        ino += group * EXT3_INODES_PER_GROUP(sb) + 1;
        if (ino < EXT3_FIRST_INO(sb) || ino > le32_to_cpu(es->s_inodes_count)) {
                ext3_error (sb, "ext3_new_inode",
                            "reserved inode or inode > inodes count - "
                            "block_group = %d, inode=%lu", group, ino);
                err = -EIO;
                goto fail;
        }

        BUFFER_TRACE(bh2, "get_write_access");
        err = ext3_journal_get_write_access(handle, bh2);
        if (err) goto fail;
        spin_lock(sb_bgl_lock(sbi, group));
        le16_add_cpu(&gdp->bg_free_inodes_count, -1);
        if (S_ISDIR(mode)) {
                le16_add_cpu(&gdp->bg_used_dirs_count, 1);
        }
        spin_unlock(sb_bgl_lock(sbi, group));
        BUFFER_TRACE(bh2, "call ext3_journal_dirty_metadata");
        err = ext3_journal_dirty_metadata(handle, bh2);
        if (err) goto fail;

        percpu_counter_dec(&sbi->s_freeinodes_counter);
        if (S_ISDIR(mode))
                percpu_counter_inc(&sbi->s_dirs_counter);


        if (test_opt(sb, GRPID)) {
                inode->i_mode = mode;
                inode->i_uid = current_fsuid();
                inode->i_gid = dir->i_gid;
        } else
                inode_init_owner(inode, dir, mode);

        inode->i_ino = ino;
        /* This is the optimal IO size (for stat), not the fs block size */
        inode->i_blocks = 0;
        inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME_SEC;

        memset(ei->i_data, 0, sizeof(ei->i_data));
        ei->i_dir_start_lookup = 0;
        ei->i_disksize = 0;

        ei->i_flags =
                ext3_mask_flags(mode, EXT3_I(dir)->i_flags & EXT3_FL_INHERITED);
#ifdef EXT3_FRAGMENTS
        ei->i_faddr = 0;
        ei->i_frag_no = 0;
        ei->i_frag_size = 0;
#endif
        ei->i_file_acl = 0;
        ei->i_dir_acl = 0;
        ei->i_dtime = 0;
        ei->i_block_alloc_info = NULL;
        ei->i_block_group = group;

        ext3_set_inode_flags(inode);
        if (IS_DIRSYNC(inode))
                handle->h_sync = 1;
        if (insert_inode_locked(inode) < 0) {
                /*
                 * Likely a bitmap corruption causing inode to be allocated
                 * twice.
                 */
                err = -EIO;
                goto fail;
        }
        spin_lock(&sbi->s_next_gen_lock);
        inode->i_generation = sbi->s_next_generation++;
        spin_unlock(&sbi->s_next_gen_lock);

        ei->i_state_flags = 0;
        ext3_set_inode_state(inode, EXT3_STATE_NEW);

        /* See comment in ext3_iget for explanation */
        if (ino >= EXT3_FIRST_INO(sb) + 1 &&
            EXT3_INODE_SIZE(sb) > EXT3_GOOD_OLD_INODE_SIZE) {
                ei->i_extra_isize =
                        sizeof(struct ext3_inode) - EXT3_GOOD_OLD_INODE_SIZE;
        } else {
                ei->i_extra_isize = 0;
        }

        ret = inode;
        dquot_initialize(inode);
        err = dquot_alloc_inode(inode);
        if (err)
                goto fail_drop;

        err = ext3_init_acl(handle, inode, dir);
        if (err)
                goto fail_free_drop;

        err = ext3_init_security(handle, inode, dir, qstr);
        if (err)
                goto fail_free_drop;

        err = ext3_mark_inode_dirty(handle, inode);
        if (err) {
                ext3_std_error(sb, err);
                goto fail_free_drop;
        }

        ext3_debug("allocating inode %lu\n", inode->i_ino);
        trace_ext3_allocate_inode(inode, dir, mode);
        goto really_out;
fail:
        ext3_std_error(sb, err);
out:
        iput(inode);
        ret = ERR_PTR(err);
really_out:
        brelse(bitmap_bh);
        return ret;

fail_free_drop:
        dquot_free_inode(inode);

fail_drop:
        dquot_drop(inode);
        inode->i_flags |= S_NOQUOTA;
        clear_nlink(inode);
        unlock_new_inode(inode);
        iput(inode);
        brelse(bitmap_bh);
        return ERR_PTR(err);
}

/* Verify that we are loading a valid orphan from disk */
struct inode *ext3_orphan_get(struct super_block *sb, unsigned long ino)
{
        unsigned long max_ino = le32_to_cpu(EXT3_SB(sb)->s_es->s_inodes_count);
        unsigned long block_group;
        int bit;
        struct buffer_head *bitmap_bh;
        struct inode *inode = NULL;
        long err = -EIO;

        /* Error cases - e2fsck has already cleaned up for us */
        if (ino > max_ino) {
                ext3_warning(sb, __func__,
                             "bad orphan ino %lu!  e2fsck was run?", ino);
                goto error;
        }

        block_group = (ino - 1) / EXT3_INODES_PER_GROUP(sb);
        bit = (ino - 1) % EXT3_INODES_PER_GROUP(sb);
        bitmap_bh = read_inode_bitmap(sb, block_group);
        if (!bitmap_bh) {
                ext3_warning(sb, __func__,
                             "inode bitmap error for orphan %lu", ino);
                goto error;
        }

        /* Having the inode bit set should be a 100% indicator that this
         * is a valid orphan (no e2fsck run on fs).  Orphans also include
         * inodes that were being truncated, so we can't check i_nlink==0.
         */
        if (!ext3_test_bit(bit, bitmap_bh->b_data))
                goto bad_orphan;

        inode = ext3_iget(sb, ino);
        if (IS_ERR(inode))
                goto iget_failed;

        /*
         * If the orphans has i_nlinks > 0 then it should be able to be
         * truncated, otherwise it won't be removed from the orphan list
         * during processing and an infinite loop will result.
         */
        if (inode->i_nlink && !ext3_can_truncate(inode))
                goto bad_orphan;

        if (NEXT_ORPHAN(inode) > max_ino)
                goto bad_orphan;
        brelse(bitmap_bh);
        return inode;

iget_failed:
        err = PTR_ERR(inode);
        inode = NULL;
bad_orphan:
        ext3_warning(sb, __func__,
                     "bad orphan inode %lu!  e2fsck was run?", ino);
        printk(KERN_NOTICE "ext3_test_bit(bit=%d, block=%llu) = %d\n",
               bit, (unsigned long long)bitmap_bh->b_blocknr,
               ext3_test_bit(bit, bitmap_bh->b_data));
        printk(KERN_NOTICE "inode=%p\n", inode);
        if (inode) {
                printk(KERN_NOTICE "is_bad_inode(inode)=%d\n",
                       is_bad_inode(inode));
                printk(KERN_NOTICE "NEXT_ORPHAN(inode)=%u\n",
                       NEXT_ORPHAN(inode));
                printk(KERN_NOTICE "max_ino=%lu\n", max_ino);
                printk(KERN_NOTICE "i_nlink=%u\n", inode->i_nlink);
                /* Avoid freeing blocks if we got a bad deleted inode */
                if (inode->i_nlink == 0)
                        inode->i_blocks = 0;
                iput(inode);
        }
        brelse(bitmap_bh);
error:
        return ERR_PTR(err);
}

unsigned long ext3_count_free_inodes (struct super_block * sb)
{
        unsigned long desc_count;
        struct ext3_group_desc *gdp;
        int i;
#ifdef EXT3FS_DEBUG
        struct ext3_super_block *es;
        unsigned long bitmap_count, x;
        struct buffer_head *bitmap_bh = NULL;

        es = EXT3_SB(sb)->s_es;
        desc_count = 0;
        bitmap_count = 0;
        gdp = NULL;
        for (i = 0; i < EXT3_SB(sb)->s_groups_count; i++) {
                gdp = ext3_get_group_desc (sb, i, NULL);
                if (!gdp)
                        continue;
                desc_count += le16_to_cpu(gdp->bg_free_inodes_count);
                brelse(bitmap_bh);
                bitmap_bh = read_inode_bitmap(sb, i);
                if (!bitmap_bh)
                        continue;

                x = ext3_count_free(bitmap_bh, EXT3_INODES_PER_GROUP(sb) / 8);
                printk("group %d: stored = %d, counted = %lu\n",
                        i, le16_to_cpu(gdp->bg_free_inodes_count), x);
                bitmap_count += x;
        }
        brelse(bitmap_bh);
        printk("ext3_count_free_inodes: stored = %u, computed = %lu, %lu\n",
                le32_to_cpu(es->s_free_inodes_count), desc_count, bitmap_count);
        return desc_count;
#else
        desc_count = 0;
        for (i = 0; i < EXT3_SB(sb)->s_groups_count; i++) {
                gdp = ext3_get_group_desc (sb, i, NULL);
                if (!gdp)
                        continue;
                desc_count += le16_to_cpu(gdp->bg_free_inodes_count);
                cond_resched();
        }
        return desc_count;
#endif
}

/* Called at mount-time, super-block is locked */
unsigned long ext3_count_dirs (struct super_block * sb)
{
        unsigned long count = 0;
        int i;

        for (i = 0; i < EXT3_SB(sb)->s_groups_count; i++) {
                struct ext3_group_desc *gdp = ext3_get_group_desc (sb, i, NULL);
                if (!gdp)
                        continue;
                count += le16_to_cpu(gdp->bg_used_dirs_count);
        }
        return count;
}