Linux 4.8.3

[linux/fpc-iii.git] / fs / reiserfs / bitmap.c

/*
 * Copyright 2000 by Hans Reiser, licensing governed by reiserfs/README
 */
/* Reiserfs block (de)allocator, bitmap-based. */

#include <linux/time.h>
#include "reiserfs.h"
#include <linux/errno.h>
#include <linux/buffer_head.h>
#include <linux/kernel.h>
#include <linux/pagemap.h>
#include <linux/vmalloc.h>
#include <linux/quotaops.h>
#include <linux/seq_file.h>

#define PREALLOCATION_SIZE 9

/* different reiserfs block allocator options */

#define SB_ALLOC_OPTS(s) (REISERFS_SB(s)->s_alloc_options.bits)

#define  _ALLOC_concentrating_formatted_nodes 0
#define  _ALLOC_displacing_large_files 1
#define  _ALLOC_displacing_new_packing_localities 2
#define  _ALLOC_old_hashed_relocation 3
#define  _ALLOC_new_hashed_relocation 4
#define  _ALLOC_skip_busy 5
#define  _ALLOC_displace_based_on_dirid 6
#define  _ALLOC_hashed_formatted_nodes 7
#define  _ALLOC_old_way 8
#define  _ALLOC_hundredth_slices 9
#define  _ALLOC_dirid_groups 10
#define  _ALLOC_oid_groups 11
#define  _ALLOC_packing_groups 12

#define  concentrating_formatted_nodes(s)       test_bit(_ALLOC_concentrating_formatted_nodes, &SB_ALLOC_OPTS(s))
#define  displacing_large_files(s)              test_bit(_ALLOC_displacing_large_files, &SB_ALLOC_OPTS(s))
#define  displacing_new_packing_localities(s)   test_bit(_ALLOC_displacing_new_packing_localities, &SB_ALLOC_OPTS(s))

#define SET_OPTION(optname) \
   do { \
        reiserfs_info(s, "block allocator option \"%s\" is set", #optname); \
        set_bit(_ALLOC_ ## optname , &SB_ALLOC_OPTS(s)); \
    } while(0)
#define TEST_OPTION(optname, s) \
    test_bit(_ALLOC_ ## optname , &SB_ALLOC_OPTS(s))

static inline void get_bit_address(struct super_block *s,
                                   b_blocknr_t block,
                                   unsigned int *bmap_nr,
                                   unsigned int *offset)
{
        /*
         * It is in the bitmap block number equal to the block
         * number divided by the number of bits in a block.
         */
        *bmap_nr = block >> (s->s_blocksize_bits + 3);
        /* Within that bitmap block it is located at bit offset *offset. */
        *offset = block & ((s->s_blocksize << 3) - 1);
}

int is_reusable(struct super_block *s, b_blocknr_t block, int bit_value)
{
        unsigned int bmap, offset;
        unsigned int bmap_count = reiserfs_bmap_count(s);

        if (block == 0 || block >= SB_BLOCK_COUNT(s)) {
                reiserfs_error(s, "vs-4010",
                               "block number is out of range %lu (%u)",
                               block, SB_BLOCK_COUNT(s));
                return 0;
        }

        get_bit_address(s, block, &bmap, &offset);

        /*
         * Old format filesystem? Unlikely, but the bitmaps are all
         * up front so we need to account for it.
         */
        if (unlikely(test_bit(REISERFS_OLD_FORMAT,
                              &REISERFS_SB(s)->s_properties))) {
                b_blocknr_t bmap1 = REISERFS_SB(s)->s_sbh->b_blocknr + 1;
                if (block >= bmap1 &&
                    block <= bmap1 + bmap_count) {
                        reiserfs_error(s, "vs-4019", "bitmap block %lu(%u) "
                                       "can't be freed or reused",
                                       block, bmap_count);
                        return 0;
                }
        } else {
                if (offset == 0) {
                        reiserfs_error(s, "vs-4020", "bitmap block %lu(%u) "
                                       "can't be freed or reused",
                                       block, bmap_count);
                        return 0;
                }
        }

        if (bmap >= bmap_count) {
                reiserfs_error(s, "vs-4030", "bitmap for requested block "
                               "is out of range: block=%lu, bitmap_nr=%u",
                               block, bmap);
                return 0;
        }

        if (bit_value == 0 && block == SB_ROOT_BLOCK(s)) {
                reiserfs_error(s, "vs-4050", "this is root block (%u), "
                               "it must be busy", SB_ROOT_BLOCK(s));
                return 0;
        }

        return 1;
}

/*
 * Searches in journal structures for a given block number (bmap, off).
 * If block is found in reiserfs journal it suggests next free block
 * candidate to test.
 */
static inline int is_block_in_journal(struct super_block *s, unsigned int bmap,
                                      int off, int *next)
{
        b_blocknr_t tmp;

        if (reiserfs_in_journal(s, bmap, off, 1, &tmp)) {
                if (tmp) {      /* hint supplied */
                        *next = tmp;
                        PROC_INFO_INC(s, scan_bitmap.in_journal_hint);
                } else {
                        (*next) = off + 1;  /* inc offset to avoid looping. */
                        PROC_INFO_INC(s, scan_bitmap.in_journal_nohint);
                }
                PROC_INFO_INC(s, scan_bitmap.retry);
                return 1;
        }
        return 0;
}

/*
 * Searches for a window of zero bits with given minimum and maximum
 * lengths in one bitmap block
 */
static int scan_bitmap_block(struct reiserfs_transaction_handle *th,
                             unsigned int bmap_n, int *beg, int boundary,
                             int min, int max, int unfm)
{
        struct super_block *s = th->t_super;
        struct reiserfs_bitmap_info *bi = &SB_AP_BITMAP(s)[bmap_n];
        struct buffer_head *bh;
        int end, next;
        int org = *beg;

        BUG_ON(!th->t_trans_id);
        RFALSE(bmap_n >= reiserfs_bmap_count(s), "Bitmap %u is out of "
               "range (0..%u)", bmap_n, reiserfs_bmap_count(s) - 1);
        PROC_INFO_INC(s, scan_bitmap.bmap);

        if (!bi) {
                reiserfs_error(s, "jdm-4055", "NULL bitmap info pointer "
                               "for bitmap %d", bmap_n);
                return 0;
        }

        bh = reiserfs_read_bitmap_block(s, bmap_n);
        if (bh == NULL)
                return 0;

        while (1) {
cont:
                if (bi->free_count < min) {
                        brelse(bh);
                        return 0;       /* No free blocks in this bitmap */
                }

                /* search for a first zero bit -- beginning of a window */
                *beg = reiserfs_find_next_zero_le_bit
                    ((unsigned long *)(bh->b_data), boundary, *beg);

                /*
                 * search for a zero bit fails or the rest of bitmap block
                 * cannot contain a zero window of minimum size
                 */
                if (*beg + min > boundary) {
                        brelse(bh);
                        return 0;
                }

                if (unfm && is_block_in_journal(s, bmap_n, *beg, beg))
                        continue;
                /* first zero bit found; we check next bits */
                for (end = *beg + 1;; end++) {
                        if (end >= *beg + max || end >= boundary
                            || reiserfs_test_le_bit(end, bh->b_data)) {
                                next = end;
                                break;
                        }

                        /*
                         * finding the other end of zero bit window requires
                         * looking into journal structures (in case of
                         * searching for free blocks for unformatted nodes)
                         */
                        if (unfm && is_block_in_journal(s, bmap_n, end, &next))
                                break;
                }

                /*
                 * now (*beg) points to beginning of zero bits window,
                 * (end) points to one bit after the window end
                 */

                /* found window of proper size */
                if (end - *beg >= min) {
                        int i;
                        reiserfs_prepare_for_journal(s, bh, 1);
                        /*
                         * try to set all blocks used checking are
                         * they still free
                         */
                        for (i = *beg; i < end; i++) {
                                /* Don't check in journal again. */
                                if (reiserfs_test_and_set_le_bit
                                    (i, bh->b_data)) {
                                        /*
                                         * bit was set by another process while
                                         * we slept in prepare_for_journal()
                                         */
                                        PROC_INFO_INC(s, scan_bitmap.stolen);

                                        /*
                                         * we can continue with smaller set
                                         * of allocated blocks, if length of
                                         * this set is more or equal to `min'
                                         */
                                        if (i >= *beg + min) {
                                                end = i;
                                                break;
                                        }

                                        /*
                                         * otherwise we clear all bit
                                         * were set ...
                                         */
                                        while (--i >= *beg)
                                                reiserfs_clear_le_bit
                                                    (i, bh->b_data);
                                        reiserfs_restore_prepared_buffer(s, bh);
                                        *beg = org;

                                        /*
                                         * Search again in current block
                                         * from beginning
                                         */
                                        goto cont;
                                }
                        }
                        bi->free_count -= (end - *beg);
                        journal_mark_dirty(th, bh);
                        brelse(bh);

                        /* free block count calculation */
                        reiserfs_prepare_for_journal(s, SB_BUFFER_WITH_SB(s),
                                                     1);
                        PUT_SB_FREE_BLOCKS(s, SB_FREE_BLOCKS(s) - (end - *beg));
                        journal_mark_dirty(th, SB_BUFFER_WITH_SB(s));

                        return end - (*beg);
                } else {
                        *beg = next;
                }
        }
}

static int bmap_hash_id(struct super_block *s, u32 id)
{
        char *hash_in = NULL;
        unsigned long hash;
        unsigned bm;

        if (id <= 2) {
                bm = 1;
        } else {
                hash_in = (char *)(&id);
                hash = keyed_hash(hash_in, 4);
                bm = hash % reiserfs_bmap_count(s);
                if (!bm)
                        bm = 1;
        }
        /* this can only be true when SB_BMAP_NR = 1 */
        if (bm >= reiserfs_bmap_count(s))
                bm = 0;
        return bm;
}

/*
 * hashes the id and then returns > 0 if the block group for the
 * corresponding hash is full
 */
static inline int block_group_used(struct super_block *s, u32 id)
{
        int bm = bmap_hash_id(s, id);
        struct reiserfs_bitmap_info *info = &SB_AP_BITMAP(s)[bm];

        /*
         * If we don't have cached information on this bitmap block, we're
         * going to have to load it later anyway. Loading it here allows us
         * to make a better decision. This favors long-term performance gain
         * with a better on-disk layout vs. a short term gain of skipping the
         * read and potentially having a bad placement.
         */
        if (info->free_count == UINT_MAX) {
                struct buffer_head *bh = reiserfs_read_bitmap_block(s, bm);
                brelse(bh);
        }

        if (info->free_count > ((s->s_blocksize << 3) * 60 / 100)) {
                return 0;
        }
        return 1;
}

/*
 * the packing is returned in disk byte order
 */
__le32 reiserfs_choose_packing(struct inode * dir)
{
        __le32 packing;
        if (TEST_OPTION(packing_groups, dir->i_sb)) {
                u32 parent_dir = le32_to_cpu(INODE_PKEY(dir)->k_dir_id);
                /*
                 * some versions of reiserfsck expect packing locality 1 to be
                 * special
                 */
                if (parent_dir == 1 || block_group_used(dir->i_sb, parent_dir))
                        packing = INODE_PKEY(dir)->k_objectid;
                else
                        packing = INODE_PKEY(dir)->k_dir_id;
        } else
                packing = INODE_PKEY(dir)->k_objectid;
        return packing;
}

/*
 * Tries to find contiguous zero bit window (given size) in given region of
 * bitmap and place new blocks there. Returns number of allocated blocks.
 */
static int scan_bitmap(struct reiserfs_transaction_handle *th,
                       b_blocknr_t * start, b_blocknr_t finish,
                       int min, int max, int unfm, sector_t file_block)
{
        int nr_allocated = 0;
        struct super_block *s = th->t_super;
        unsigned int bm, off;
        unsigned int end_bm, end_off;
        unsigned int off_max = s->s_blocksize << 3;

        BUG_ON(!th->t_trans_id);
        PROC_INFO_INC(s, scan_bitmap.call);

        /* No point in looking for more free blocks */
        if (SB_FREE_BLOCKS(s) <= 0)
                return 0;

        get_bit_address(s, *start, &bm, &off);
        get_bit_address(s, finish, &end_bm, &end_off);
        if (bm > reiserfs_bmap_count(s))
                return 0;
        if (end_bm > reiserfs_bmap_count(s))
                end_bm = reiserfs_bmap_count(s);

        /*
         * When the bitmap is more than 10% free, anyone can allocate.
         * When it's less than 10% free, only files that already use the
         * bitmap are allowed. Once we pass 80% full, this restriction
         * is lifted.
         *
         * We do this so that files that grow later still have space close to
         * their original allocation. This improves locality, and presumably
         * performance as a result.
         *
         * This is only an allocation policy and does not make up for getting a
         * bad hint. Decent hinting must be implemented for this to work well.
         */
        if (TEST_OPTION(skip_busy, s)
            && SB_FREE_BLOCKS(s) > SB_BLOCK_COUNT(s) / 20) {
                for (; bm < end_bm; bm++, off = 0) {
                        if ((off && (!unfm || (file_block != 0)))
                            || SB_AP_BITMAP(s)[bm].free_count >
                            (s->s_blocksize << 3) / 10)
                                nr_allocated =
                                    scan_bitmap_block(th, bm, &off, off_max,
                                                      min, max, unfm);
                        if (nr_allocated)
                                goto ret;
                }
                /* we know from above that start is a reasonable number */
                get_bit_address(s, *start, &bm, &off);
        }

        for (; bm < end_bm; bm++, off = 0) {
                nr_allocated =
                    scan_bitmap_block(th, bm, &off, off_max, min, max, unfm);
                if (nr_allocated)
                        goto ret;
        }

        nr_allocated =
            scan_bitmap_block(th, bm, &off, end_off + 1, min, max, unfm);

ret:
        *start = bm * off_max + off;
        return nr_allocated;

}

static void _reiserfs_free_block(struct reiserfs_transaction_handle *th,
                                 struct inode *inode, b_blocknr_t block,
                                 int for_unformatted)
{
        struct super_block *s = th->t_super;
        struct reiserfs_super_block *rs;
        struct buffer_head *sbh, *bmbh;
        struct reiserfs_bitmap_info *apbi;
        unsigned int nr, offset;

        BUG_ON(!th->t_trans_id);
        PROC_INFO_INC(s, free_block);
        rs = SB_DISK_SUPER_BLOCK(s);
        sbh = SB_BUFFER_WITH_SB(s);
        apbi = SB_AP_BITMAP(s);

        get_bit_address(s, block, &nr, &offset);

        if (nr >= reiserfs_bmap_count(s)) {
                reiserfs_error(s, "vs-4075", "block %lu is out of range",
                               block);
                return;
        }

        bmbh = reiserfs_read_bitmap_block(s, nr);
        if (!bmbh)
                return;

        reiserfs_prepare_for_journal(s, bmbh, 1);

        /* clear bit for the given block in bit map */
        if (!reiserfs_test_and_clear_le_bit(offset, bmbh->b_data)) {
                reiserfs_error(s, "vs-4080",
                               "block %lu: bit already cleared", block);
        }
        apbi[nr].free_count++;
        journal_mark_dirty(th, bmbh);
        brelse(bmbh);

        reiserfs_prepare_for_journal(s, sbh, 1);
        /* update super block */
        set_sb_free_blocks(rs, sb_free_blocks(rs) + 1);

        journal_mark_dirty(th, sbh);
        if (for_unformatted) {
                int depth = reiserfs_write_unlock_nested(s);
                dquot_free_block_nodirty(inode, 1);
                reiserfs_write_lock_nested(s, depth);
        }
}

void reiserfs_free_block(struct reiserfs_transaction_handle *th,
                         struct inode *inode, b_blocknr_t block,
                         int for_unformatted)
{
        struct super_block *s = th->t_super;

        BUG_ON(!th->t_trans_id);
        RFALSE(!s, "vs-4061: trying to free block on nonexistent device");
        if (!is_reusable(s, block, 1))
                return;

        if (block > sb_block_count(REISERFS_SB(s)->s_rs)) {
                reiserfs_error(th->t_super, "bitmap-4072",
                               "Trying to free block outside file system "
                               "boundaries (%lu > %lu)",
                               block, sb_block_count(REISERFS_SB(s)->s_rs));
                return;
        }
        /* mark it before we clear it, just in case */
        journal_mark_freed(th, s, block);
        _reiserfs_free_block(th, inode, block, for_unformatted);
}

/* preallocated blocks don't need to be run through journal_mark_freed */
static void reiserfs_free_prealloc_block(struct reiserfs_transaction_handle *th,
                                         struct inode *inode, b_blocknr_t block)
{
        BUG_ON(!th->t_trans_id);
        RFALSE(!th->t_super,
               "vs-4060: trying to free block on nonexistent device");
        if (!is_reusable(th->t_super, block, 1))
                return;
        _reiserfs_free_block(th, inode, block, 1);
}

static void __discard_prealloc(struct reiserfs_transaction_handle *th,
                               struct reiserfs_inode_info *ei)
{
        unsigned long save = ei->i_prealloc_block;
        int dirty = 0;
        struct inode *inode = &ei->vfs_inode;

        BUG_ON(!th->t_trans_id);
#ifdef CONFIG_REISERFS_CHECK
        if (ei->i_prealloc_count < 0)
                reiserfs_error(th->t_super, "zam-4001",
                               "inode has negative prealloc blocks count.");
#endif
        while (ei->i_prealloc_count > 0) {
                reiserfs_free_prealloc_block(th, inode, ei->i_prealloc_block);
                ei->i_prealloc_block++;
                ei->i_prealloc_count--;
                dirty = 1;
        }
        if (dirty)
                reiserfs_update_sd(th, inode);
        ei->i_prealloc_block = save;
        list_del_init(&ei->i_prealloc_list);
}

/* FIXME: It should be inline function */
void reiserfs_discard_prealloc(struct reiserfs_transaction_handle *th,
                               struct inode *inode)
{
        struct reiserfs_inode_info *ei = REISERFS_I(inode);

        BUG_ON(!th->t_trans_id);
        if (ei->i_prealloc_count)
                __discard_prealloc(th, ei);
}

void reiserfs_discard_all_prealloc(struct reiserfs_transaction_handle *th)
{
        struct list_head *plist = &SB_JOURNAL(th->t_super)->j_prealloc_list;

        BUG_ON(!th->t_trans_id);
        while (!list_empty(plist)) {
                struct reiserfs_inode_info *ei;
                ei = list_entry(plist->next, struct reiserfs_inode_info,
                                i_prealloc_list);
#ifdef CONFIG_REISERFS_CHECK
                if (!ei->i_prealloc_count) {
                        reiserfs_error(th->t_super, "zam-4001",
                                       "inode is in prealloc list but has "
                                       "no preallocated blocks.");
                }
#endif
                __discard_prealloc(th, ei);
        }
}

void reiserfs_init_alloc_options(struct super_block *s)
{
        set_bit(_ALLOC_skip_busy, &SB_ALLOC_OPTS(s));
        set_bit(_ALLOC_dirid_groups, &SB_ALLOC_OPTS(s));
        set_bit(_ALLOC_packing_groups, &SB_ALLOC_OPTS(s));
}

/* block allocator related options are parsed here */
int reiserfs_parse_alloc_options(struct super_block *s, char *options)
{
        char *this_char, *value;

        /* clear default settings */
        REISERFS_SB(s)->s_alloc_options.bits = 0;

        while ((this_char = strsep(&options, ":")) != NULL) {
                if ((value = strchr(this_char, '=')) != NULL)
                        *value++ = 0;

                if (!strcmp(this_char, "concentrating_formatted_nodes")) {
                        int temp;
                        SET_OPTION(concentrating_formatted_nodes);
                        temp = (value
                                && *value) ? simple_strtoul(value, &value,
                                                            0) : 10;
                        if (temp <= 0 || temp > 100) {
                                REISERFS_SB(s)->s_alloc_options.border = 10;
                        } else {
                                REISERFS_SB(s)->s_alloc_options.border =
                                    100 / temp;
                        }
                        continue;
                }
                if (!strcmp(this_char, "displacing_large_files")) {
                        SET_OPTION(displacing_large_files);
                        REISERFS_SB(s)->s_alloc_options.large_file_size =
                            (value
                             && *value) ? simple_strtoul(value, &value, 0) : 16;
                        continue;
                }
                if (!strcmp(this_char, "displacing_new_packing_localities")) {
                        SET_OPTION(displacing_new_packing_localities);
                        continue;
                }

                if (!strcmp(this_char, "old_hashed_relocation")) {
                        SET_OPTION(old_hashed_relocation);
                        continue;
                }

                if (!strcmp(this_char, "new_hashed_relocation")) {
                        SET_OPTION(new_hashed_relocation);
                        continue;
                }

                if (!strcmp(this_char, "dirid_groups")) {
                        SET_OPTION(dirid_groups);
                        continue;
                }
                if (!strcmp(this_char, "oid_groups")) {
                        SET_OPTION(oid_groups);
                        continue;
                }
                if (!strcmp(this_char, "packing_groups")) {
                        SET_OPTION(packing_groups);
                        continue;
                }
                if (!strcmp(this_char, "hashed_formatted_nodes")) {
                        SET_OPTION(hashed_formatted_nodes);
                        continue;
                }

                if (!strcmp(this_char, "skip_busy")) {
                        SET_OPTION(skip_busy);
                        continue;
                }

                if (!strcmp(this_char, "hundredth_slices")) {
                        SET_OPTION(hundredth_slices);
                        continue;
                }

                if (!strcmp(this_char, "old_way")) {
                        SET_OPTION(old_way);
                        continue;
                }

                if (!strcmp(this_char, "displace_based_on_dirid")) {
                        SET_OPTION(displace_based_on_dirid);
                        continue;
                }

                if (!strcmp(this_char, "preallocmin")) {
                        REISERFS_SB(s)->s_alloc_options.preallocmin =
                            (value
                             && *value) ? simple_strtoul(value, &value, 0) : 4;
                        continue;
                }

                if (!strcmp(this_char, "preallocsize")) {
                        REISERFS_SB(s)->s_alloc_options.preallocsize =
                            (value
                             && *value) ? simple_strtoul(value, &value,
                                                         0) :
                            PREALLOCATION_SIZE;
                        continue;
                }

                reiserfs_warning(s, "zam-4001", "unknown option - %s",
                                 this_char);
                return 1;
        }

        reiserfs_info(s, "allocator options = [%08x]\n", SB_ALLOC_OPTS(s));
        return 0;
}

static void print_sep(struct seq_file *seq, int *first)
{
        if (!*first)
                seq_puts(seq, ":");
        else
                *first = 0;
}

void show_alloc_options(struct seq_file *seq, struct super_block *s)
{
        int first = 1;

        if (SB_ALLOC_OPTS(s) == ((1 << _ALLOC_skip_busy) |
                (1 << _ALLOC_dirid_groups) | (1 << _ALLOC_packing_groups)))
                return;

        seq_puts(seq, ",alloc=");

        if (TEST_OPTION(concentrating_formatted_nodes, s)) {
                print_sep(seq, &first);
                if (REISERFS_SB(s)->s_alloc_options.border != 10) {
                        seq_printf(seq, "concentrating_formatted_nodes=%d",
                                100 / REISERFS_SB(s)->s_alloc_options.border);
                } else
                        seq_puts(seq, "concentrating_formatted_nodes");
        }
        if (TEST_OPTION(displacing_large_files, s)) {
                print_sep(seq, &first);
                if (REISERFS_SB(s)->s_alloc_options.large_file_size != 16) {
                        seq_printf(seq, "displacing_large_files=%lu",
                            REISERFS_SB(s)->s_alloc_options.large_file_size);
                } else
                        seq_puts(seq, "displacing_large_files");
        }
        if (TEST_OPTION(displacing_new_packing_localities, s)) {
                print_sep(seq, &first);
                seq_puts(seq, "displacing_new_packing_localities");
        }
        if (TEST_OPTION(old_hashed_relocation, s)) {
                print_sep(seq, &first);
                seq_puts(seq, "old_hashed_relocation");
        }
        if (TEST_OPTION(new_hashed_relocation, s)) {
                print_sep(seq, &first);
                seq_puts(seq, "new_hashed_relocation");
        }
        if (TEST_OPTION(dirid_groups, s)) {
                print_sep(seq, &first);
                seq_puts(seq, "dirid_groups");
        }
        if (TEST_OPTION(oid_groups, s)) {
                print_sep(seq, &first);
                seq_puts(seq, "oid_groups");
        }
        if (TEST_OPTION(packing_groups, s)) {
                print_sep(seq, &first);
                seq_puts(seq, "packing_groups");
        }
        if (TEST_OPTION(hashed_formatted_nodes, s)) {
                print_sep(seq, &first);
                seq_puts(seq, "hashed_formatted_nodes");
        }
        if (TEST_OPTION(skip_busy, s)) {
                print_sep(seq, &first);
                seq_puts(seq, "skip_busy");
        }
        if (TEST_OPTION(hundredth_slices, s)) {
                print_sep(seq, &first);
                seq_puts(seq, "hundredth_slices");
        }
        if (TEST_OPTION(old_way, s)) {
                print_sep(seq, &first);
                seq_puts(seq, "old_way");
        }
        if (TEST_OPTION(displace_based_on_dirid, s)) {
                print_sep(seq, &first);
                seq_puts(seq, "displace_based_on_dirid");
        }
        if (REISERFS_SB(s)->s_alloc_options.preallocmin != 0) {
                print_sep(seq, &first);
                seq_printf(seq, "preallocmin=%d",
                                REISERFS_SB(s)->s_alloc_options.preallocmin);
        }
        if (REISERFS_SB(s)->s_alloc_options.preallocsize != 17) {
                print_sep(seq, &first);
                seq_printf(seq, "preallocsize=%d",
                                REISERFS_SB(s)->s_alloc_options.preallocsize);
        }
}

static inline void new_hashed_relocation(reiserfs_blocknr_hint_t * hint)
{
        char *hash_in;

        if (hint->formatted_node) {
                hash_in = (char *)&hint->key.k_dir_id;
        } else {
                if (!hint->inode) {
                        /*hint->search_start = hint->beg;*/
                        hash_in = (char *)&hint->key.k_dir_id;
                } else
                    if (TEST_OPTION(displace_based_on_dirid, hint->th->t_super))
                        hash_in = (char *)(&INODE_PKEY(hint->inode)->k_dir_id);
                else
                        hash_in =
                            (char *)(&INODE_PKEY(hint->inode)->k_objectid);
        }

        hint->search_start =
            hint->beg + keyed_hash(hash_in, 4) % (hint->end - hint->beg);
}

/*
 * Relocation based on dirid, hashing them into a given bitmap block
 * files. Formatted nodes are unaffected, a separate policy covers them
 */
static void dirid_groups(reiserfs_blocknr_hint_t * hint)
{
        unsigned long hash;
        __u32 dirid = 0;
        int bm = 0;
        struct super_block *sb = hint->th->t_super;

        if (hint->inode)
                dirid = le32_to_cpu(INODE_PKEY(hint->inode)->k_dir_id);
        else if (hint->formatted_node)
                dirid = hint->key.k_dir_id;

        if (dirid) {
                bm = bmap_hash_id(sb, dirid);
                hash = bm * (sb->s_blocksize << 3);
                /* give a portion of the block group to metadata */
                if (hint->inode)
                        hash += sb->s_blocksize / 2;
                hint->search_start = hash;
        }
}

/*
 * Relocation based on oid, hashing them into a given bitmap block
 * files. Formatted nodes are unaffected, a separate policy covers them
 */
static void oid_groups(reiserfs_blocknr_hint_t * hint)
{
        if (hint->inode) {
                unsigned long hash;
                __u32 oid;
                __u32 dirid;
                int bm;

                dirid = le32_to_cpu(INODE_PKEY(hint->inode)->k_dir_id);

                /*
                 * keep the root dir and it's first set of subdirs close to
                 * the start of the disk
                 */
                if (dirid <= 2)
                        hash = (hint->inode->i_sb->s_blocksize << 3);
                else {
                        oid = le32_to_cpu(INODE_PKEY(hint->inode)->k_objectid);
                        bm = bmap_hash_id(hint->inode->i_sb, oid);
                        hash = bm * (hint->inode->i_sb->s_blocksize << 3);
                }
                hint->search_start = hash;
        }
}

/*
 * returns 1 if it finds an indirect item and gets valid hint info
 * from it, otherwise 0
 */
static int get_left_neighbor(reiserfs_blocknr_hint_t * hint)
{
        struct treepath *path;
        struct buffer_head *bh;
        struct item_head *ih;
        int pos_in_item;
        __le32 *item;
        int ret = 0;

        /*
         * reiserfs code can call this function w/o pointer to path
         * structure supplied; then we rely on supplied search_start
         */
        if (!hint->path)
                return 0;

        path = hint->path;
        bh = get_last_bh(path);
        RFALSE(!bh, "green-4002: Illegal path specified to get_left_neighbor");
        ih = tp_item_head(path);
        pos_in_item = path->pos_in_item;
        item = tp_item_body(path);

        hint->search_start = bh->b_blocknr;

        /*
         * for indirect item: go to left and look for the first non-hole entry
         * in the indirect item
         */
        if (!hint->formatted_node && is_indirect_le_ih(ih)) {
                if (pos_in_item == I_UNFM_NUM(ih))
                        pos_in_item--;
                while (pos_in_item >= 0) {
                        int t = get_block_num(item, pos_in_item);
                        if (t) {
                                hint->search_start = t;
                                ret = 1;
                                break;
                        }
                        pos_in_item--;
                }
        }

        /* does result value fit into specified region? */
        return ret;
}

/*
 * should be, if formatted node, then try to put on first part of the device
 * specified as number of percent with mount option device, else try to put
 * on last of device.  This is not to say it is good code to do so,
 * but the effect should be measured.
 */
static inline void set_border_in_hint(struct super_block *s,
                                      reiserfs_blocknr_hint_t * hint)
{
        b_blocknr_t border =
            SB_BLOCK_COUNT(s) / REISERFS_SB(s)->s_alloc_options.border;

        if (hint->formatted_node)
                hint->end = border - 1;
        else
                hint->beg = border;
}

static inline void displace_large_file(reiserfs_blocknr_hint_t * hint)
{
        if (TEST_OPTION(displace_based_on_dirid, hint->th->t_super))
                hint->search_start =
                    hint->beg +
                    keyed_hash((char *)(&INODE_PKEY(hint->inode)->k_dir_id),
                               4) % (hint->end - hint->beg);
        else
                hint->search_start =
                    hint->beg +
                    keyed_hash((char *)(&INODE_PKEY(hint->inode)->k_objectid),
                               4) % (hint->end - hint->beg);
}

static inline void hash_formatted_node(reiserfs_blocknr_hint_t * hint)
{
        char *hash_in;

        if (!hint->inode)
                hash_in = (char *)&hint->key.k_dir_id;
        else if (TEST_OPTION(displace_based_on_dirid, hint->th->t_super))
                hash_in = (char *)(&INODE_PKEY(hint->inode)->k_dir_id);
        else
                hash_in = (char *)(&INODE_PKEY(hint->inode)->k_objectid);

        hint->search_start =
            hint->beg + keyed_hash(hash_in, 4) % (hint->end - hint->beg);
}

static inline int
this_blocknr_allocation_would_make_it_a_large_file(reiserfs_blocknr_hint_t *
                                                   hint)
{
        return hint->block ==
            REISERFS_SB(hint->th->t_super)->s_alloc_options.large_file_size;
}

#ifdef DISPLACE_NEW_PACKING_LOCALITIES
static inline void displace_new_packing_locality(reiserfs_blocknr_hint_t * hint)
{
        struct in_core_key *key = &hint->key;

        hint->th->displace_new_blocks = 0;
        hint->search_start =
            hint->beg + keyed_hash((char *)(&key->k_objectid),
                                   4) % (hint->end - hint->beg);
}
#endif

static inline int old_hashed_relocation(reiserfs_blocknr_hint_t * hint)
{
        b_blocknr_t border;
        u32 hash_in;

        if (hint->formatted_node || hint->inode == NULL) {
                return 0;
        }

        hash_in = le32_to_cpu((INODE_PKEY(hint->inode))->k_dir_id);
        border =
            hint->beg + (u32) keyed_hash(((char *)(&hash_in)),
                                         4) % (hint->end - hint->beg - 1);
        if (border > hint->search_start)
                hint->search_start = border;

        return 1;
}

static inline int old_way(reiserfs_blocknr_hint_t * hint)
{
        b_blocknr_t border;

        if (hint->formatted_node || hint->inode == NULL) {
                return 0;
        }

        border =
            hint->beg +
            le32_to_cpu(INODE_PKEY(hint->inode)->k_dir_id) % (hint->end -
                                                              hint->beg);
        if (border > hint->search_start)
                hint->search_start = border;

        return 1;
}

static inline void hundredth_slices(reiserfs_blocknr_hint_t * hint)
{
        struct in_core_key *key = &hint->key;
        b_blocknr_t slice_start;

        slice_start =
            (keyed_hash((char *)(&key->k_dir_id), 4) % 100) * (hint->end / 100);
        if (slice_start > hint->search_start
            || slice_start + (hint->end / 100) <= hint->search_start) {
                hint->search_start = slice_start;
        }
}

static void determine_search_start(reiserfs_blocknr_hint_t * hint,
                                   int amount_needed)
{
        struct super_block *s = hint->th->t_super;
        int unfm_hint;

        hint->beg = 0;
        hint->end = SB_BLOCK_COUNT(s) - 1;

        /* This is former border algorithm. Now with tunable border offset */
        if (concentrating_formatted_nodes(s))
                set_border_in_hint(s, hint);

#ifdef DISPLACE_NEW_PACKING_LOCALITIES
        /*
         * whenever we create a new directory, we displace it.  At first
         * we will hash for location, later we might look for a moderately
         * empty place for it
         */
        if (displacing_new_packing_localities(s)
            && hint->th->displace_new_blocks) {
                displace_new_packing_locality(hint);

                /*
                 * we do not continue determine_search_start,
                 * if new packing locality is being displaced
                 */
                return;
        }
#endif

        /*
         * all persons should feel encouraged to add more special cases
         * here and test them
         */

        if (displacing_large_files(s) && !hint->formatted_node
            && this_blocknr_allocation_would_make_it_a_large_file(hint)) {
                displace_large_file(hint);
                return;
        }

        /*
         * if none of our special cases is relevant, use the left
         * neighbor in the tree order of the new node we are allocating for
         */
        if (hint->formatted_node && TEST_OPTION(hashed_formatted_nodes, s)) {
                hash_formatted_node(hint);
                return;
        }

        unfm_hint = get_left_neighbor(hint);

        /*
         * Mimic old block allocator behaviour, that is if VFS allowed for
         * preallocation, new blocks are displaced based on directory ID.
         * Also, if suggested search_start is less than last preallocated
         * block, we start searching from it, assuming that HDD dataflow
         * is faster in forward direction
         */
        if (TEST_OPTION(old_way, s)) {
                if (!hint->formatted_node) {
                        if (!reiserfs_hashed_relocation(s))
                                old_way(hint);
                        else if (!reiserfs_no_unhashed_relocation(s))
                                old_hashed_relocation(hint);

                        if (hint->inode
                            && hint->search_start <
                            REISERFS_I(hint->inode)->i_prealloc_block)
                                hint->search_start =
                                    REISERFS_I(hint->inode)->i_prealloc_block;
                }
                return;
        }

        /* This is an approach proposed by Hans */
        if (TEST_OPTION(hundredth_slices, s)
            && !(displacing_large_files(s) && !hint->formatted_node)) {
                hundredth_slices(hint);
                return;
        }

        /* old_hashed_relocation only works on unformatted */
        if (!unfm_hint && !hint->formatted_node &&
            TEST_OPTION(old_hashed_relocation, s)) {
                old_hashed_relocation(hint);
        }

        /* new_hashed_relocation works with both formatted/unformatted nodes */
        if ((!unfm_hint || hint->formatted_node) &&
            TEST_OPTION(new_hashed_relocation, s)) {
                new_hashed_relocation(hint);
        }

        /* dirid grouping works only on unformatted nodes */
        if (!unfm_hint && !hint->formatted_node && TEST_OPTION(dirid_groups, s)) {
                dirid_groups(hint);
        }
#ifdef DISPLACE_NEW_PACKING_LOCALITIES
        if (hint->formatted_node && TEST_OPTION(dirid_groups, s)) {
                dirid_groups(hint);
        }
#endif

        /* oid grouping works only on unformatted nodes */
        if (!unfm_hint && !hint->formatted_node && TEST_OPTION(oid_groups, s)) {
                oid_groups(hint);
        }
        return;
}

static int determine_prealloc_size(reiserfs_blocknr_hint_t * hint)
{
        /* make minimum size a mount option and benchmark both ways */
        /* we preallocate blocks only for regular files, specific size */
        /* benchmark preallocating always and see what happens */

        hint->prealloc_size = 0;

        if (!hint->formatted_node && hint->preallocate) {
                if (S_ISREG(hint->inode->i_mode)
                    && hint->inode->i_size >=
                    REISERFS_SB(hint->th->t_super)->s_alloc_options.
                    preallocmin * hint->inode->i_sb->s_blocksize)
                        hint->prealloc_size =
                            REISERFS_SB(hint->th->t_super)->s_alloc_options.
                            preallocsize - 1;
        }
        return CARRY_ON;
}

static inline int allocate_without_wrapping_disk(reiserfs_blocknr_hint_t * hint,
                                                 b_blocknr_t * new_blocknrs,
                                                 b_blocknr_t start,
                                                 b_blocknr_t finish, int min,
                                                 int amount_needed,
                                                 int prealloc_size)
{
        int rest = amount_needed;
        int nr_allocated;

        while (rest > 0 && start <= finish) {
                nr_allocated = scan_bitmap(hint->th, &start, finish, min,
                                           rest + prealloc_size,
                                           !hint->formatted_node, hint->block);

                if (nr_allocated == 0)  /* no new blocks allocated, return */
                        break;

                /* fill free_blocknrs array first */
                while (rest > 0 && nr_allocated > 0) {
                        *new_blocknrs++ = start++;
                        rest--;
                        nr_allocated--;
                }

                /* do we have something to fill prealloc. array also ? */
                if (nr_allocated > 0) {
                        /*
                         * it means prealloc_size was greater that 0 and
                         * we do preallocation
                         */
                        list_add(&REISERFS_I(hint->inode)->i_prealloc_list,
                                 &SB_JOURNAL(hint->th->t_super)->
                                 j_prealloc_list);
                        REISERFS_I(hint->inode)->i_prealloc_block = start;
                        REISERFS_I(hint->inode)->i_prealloc_count =
                            nr_allocated;
                        break;
                }
        }

        return (amount_needed - rest);
}

static inline int blocknrs_and_prealloc_arrays_from_search_start
    (reiserfs_blocknr_hint_t * hint, b_blocknr_t * new_blocknrs,
     int amount_needed) {
        struct super_block *s = hint->th->t_super;
        b_blocknr_t start = hint->search_start;
        b_blocknr_t finish = SB_BLOCK_COUNT(s) - 1;
        int passno = 0;
        int nr_allocated = 0;
        int depth;

        determine_prealloc_size(hint);
        if (!hint->formatted_node) {
                int quota_ret;
#ifdef REISERQUOTA_DEBUG
                reiserfs_debug(s, REISERFS_DEBUG_CODE,
                               "reiserquota: allocating %d blocks id=%u",
                               amount_needed, hint->inode->i_uid);
#endif
                depth = reiserfs_write_unlock_nested(s);
                quota_ret =
                    dquot_alloc_block_nodirty(hint->inode, amount_needed);
                if (quota_ret) {        /* Quota exceeded? */
                        reiserfs_write_lock_nested(s, depth);
                        return QUOTA_EXCEEDED;
                }
                if (hint->preallocate && hint->prealloc_size) {
#ifdef REISERQUOTA_DEBUG
                        reiserfs_debug(s, REISERFS_DEBUG_CODE,
                                       "reiserquota: allocating (prealloc) %d blocks id=%u",
                                       hint->prealloc_size, hint->inode->i_uid);
#endif
                        quota_ret = dquot_prealloc_block_nodirty(hint->inode,
                                                         hint->prealloc_size);
                        if (quota_ret)
                                hint->preallocate = hint->prealloc_size = 0;
                }
                /* for unformatted nodes, force large allocations */
                reiserfs_write_lock_nested(s, depth);
        }

        do {
                switch (passno++) {
                case 0: /* Search from hint->search_start to end of disk */
                        start = hint->search_start;
                        finish = SB_BLOCK_COUNT(s) - 1;
                        break;
                case 1: /* Search from hint->beg to hint->search_start */
                        start = hint->beg;
                        finish = hint->search_start;
                        break;
                case 2: /* Last chance: Search from 0 to hint->beg */
                        start = 0;
                        finish = hint->beg;
                        break;
                default:
                        /* We've tried searching everywhere, not enough space */
                        /* Free the blocks */
                        if (!hint->formatted_node) {
#ifdef REISERQUOTA_DEBUG
                                reiserfs_debug(s, REISERFS_DEBUG_CODE,
                                               "reiserquota: freeing (nospace) %d blocks id=%u",
                                               amount_needed +
                                               hint->prealloc_size -
                                               nr_allocated,
                                               hint->inode->i_uid);
#endif
                                /* Free not allocated blocks */
                                depth = reiserfs_write_unlock_nested(s);
                                dquot_free_block_nodirty(hint->inode,
                                        amount_needed + hint->prealloc_size -
                                        nr_allocated);
                                reiserfs_write_lock_nested(s, depth);
                        }
                        while (nr_allocated--)
                                reiserfs_free_block(hint->th, hint->inode,
                                                    new_blocknrs[nr_allocated],
                                                    !hint->formatted_node);

                        return NO_DISK_SPACE;
                }
        } while ((nr_allocated += allocate_without_wrapping_disk(hint,
                                                                 new_blocknrs +
                                                                 nr_allocated,
                                                                 start, finish,
                                                                 1,
                                                                 amount_needed -
                                                                 nr_allocated,
                                                                 hint->
                                                                 prealloc_size))
                 < amount_needed);
        if (!hint->formatted_node &&
            amount_needed + hint->prealloc_size >
            nr_allocated + REISERFS_I(hint->inode)->i_prealloc_count) {
                /* Some of preallocation blocks were not allocated */
#ifdef REISERQUOTA_DEBUG
                reiserfs_debug(s, REISERFS_DEBUG_CODE,
                               "reiserquota: freeing (failed prealloc) %d blocks id=%u",
                               amount_needed + hint->prealloc_size -
                               nr_allocated -
                               REISERFS_I(hint->inode)->i_prealloc_count,
                               hint->inode->i_uid);
#endif

                depth = reiserfs_write_unlock_nested(s);
                dquot_free_block_nodirty(hint->inode, amount_needed +
                                         hint->prealloc_size - nr_allocated -
                                         REISERFS_I(hint->inode)->
                                         i_prealloc_count);
                reiserfs_write_lock_nested(s, depth);
        }

        return CARRY_ON;
}

/* grab new blocknrs from preallocated list */
/* return amount still needed after using them */
static int use_preallocated_list_if_available(reiserfs_blocknr_hint_t * hint,
                                              b_blocknr_t * new_blocknrs,
                                              int amount_needed)
{
        struct inode *inode = hint->inode;

        if (REISERFS_I(inode)->i_prealloc_count > 0) {
                while (amount_needed) {

                        *new_blocknrs++ = REISERFS_I(inode)->i_prealloc_block++;
                        REISERFS_I(inode)->i_prealloc_count--;

                        amount_needed--;

                        if (REISERFS_I(inode)->i_prealloc_count <= 0) {
                                list_del(&REISERFS_I(inode)->i_prealloc_list);
                                break;
                        }
                }
        }
        /* return amount still needed after using preallocated blocks */
        return amount_needed;
}

int reiserfs_allocate_blocknrs(reiserfs_blocknr_hint_t *hint,
                               b_blocknr_t *new_blocknrs,
                               int amount_needed,
                               /* Amount of blocks we have already reserved */
                               int reserved_by_us)
{
        int initial_amount_needed = amount_needed;
        int ret;
        struct super_block *s = hint->th->t_super;

        /* Check if there is enough space, taking into account reserved space */
        if (SB_FREE_BLOCKS(s) - REISERFS_SB(s)->reserved_blocks <
            amount_needed - reserved_by_us)
                return NO_DISK_SPACE;
        /* should this be if !hint->inode &&  hint->preallocate? */
        /* do you mean hint->formatted_node can be removed ? - Zam */
        /*
         * hint->formatted_node cannot be removed because we try to access
         * inode information here, and there is often no inode associated with
         * metadata allocations - green
         */

        if (!hint->formatted_node && hint->preallocate) {
                amount_needed = use_preallocated_list_if_available
                    (hint, new_blocknrs, amount_needed);

                /*
                 * We have all the block numbers we need from the
                 * prealloc list
                 */
                if (amount_needed == 0)
                        return CARRY_ON;
                new_blocknrs += (initial_amount_needed - amount_needed);
        }

        /* find search start and save it in hint structure */
        determine_search_start(hint, amount_needed);
        if (hint->search_start >= SB_BLOCK_COUNT(s))
                hint->search_start = SB_BLOCK_COUNT(s) - 1;

        /* allocation itself; fill new_blocknrs and preallocation arrays */
        ret = blocknrs_and_prealloc_arrays_from_search_start
            (hint, new_blocknrs, amount_needed);

        /*
         * We used prealloc. list to fill (partially) new_blocknrs array.
         * If final allocation fails we need to return blocks back to
         * prealloc. list or just free them. -- Zam (I chose second
         * variant)
         */
        if (ret != CARRY_ON) {
                while (amount_needed++ < initial_amount_needed) {
                        reiserfs_free_block(hint->th, hint->inode,
                                            *(--new_blocknrs), 1);
                }
        }
        return ret;
}

void reiserfs_cache_bitmap_metadata(struct super_block *sb,
                                    struct buffer_head *bh,
                                    struct reiserfs_bitmap_info *info)
{
        unsigned long *cur = (unsigned long *)(bh->b_data + bh->b_size);

        /* The first bit must ALWAYS be 1 */
        if (!reiserfs_test_le_bit(0, (unsigned long *)bh->b_data))
                reiserfs_error(sb, "reiserfs-2025", "bitmap block %lu is "
                               "corrupted: first bit must be 1", bh->b_blocknr);

        info->free_count = 0;

        while (--cur >= (unsigned long *)bh->b_data) {
                /* 0 and ~0 are special, we can optimize for them */
                if (*cur == 0)
                        info->free_count += BITS_PER_LONG;
                else if (*cur != ~0L)   /* A mix, investigate */
                        info->free_count += BITS_PER_LONG - hweight_long(*cur);
        }
}

struct buffer_head *reiserfs_read_bitmap_block(struct super_block *sb,
                                               unsigned int bitmap)
{
        b_blocknr_t block = (sb->s_blocksize << 3) * bitmap;
        struct reiserfs_bitmap_info *info = SB_AP_BITMAP(sb) + bitmap;
        struct buffer_head *bh;

        /*
         * Way old format filesystems had the bitmaps packed up front.
         * I doubt there are any of these left, but just in case...
         */
        if (unlikely(test_bit(REISERFS_OLD_FORMAT,
                              &REISERFS_SB(sb)->s_properties)))
                block = REISERFS_SB(sb)->s_sbh->b_blocknr + 1 + bitmap;
        else if (bitmap == 0)
                block = (REISERFS_DISK_OFFSET_IN_BYTES >> sb->s_blocksize_bits) + 1;

        bh = sb_bread(sb, block);
        if (bh == NULL)
                reiserfs_warning(sb, "sh-2029: %s: bitmap block (#%u) "
                                 "reading failed", __func__, block);
        else {
                if (buffer_locked(bh)) {
                        int depth;
                        PROC_INFO_INC(sb, scan_bitmap.wait);
                        depth = reiserfs_write_unlock_nested(sb);
                        __wait_on_buffer(bh);
                        reiserfs_write_lock_nested(sb, depth);
                }
                BUG_ON(!buffer_uptodate(bh));
                BUG_ON(atomic_read(&bh->b_count) == 0);

                if (info->free_count == UINT_MAX)
                        reiserfs_cache_bitmap_metadata(sb, bh, info);
        }

        return bh;
}

int reiserfs_init_bitmap_cache(struct super_block *sb)
{
        struct reiserfs_bitmap_info *bitmap;
        unsigned int bmap_nr = reiserfs_bmap_count(sb);

        bitmap = vmalloc(sizeof(*bitmap) * bmap_nr);
        if (bitmap == NULL)
                return -ENOMEM;

        memset(bitmap, 0xff, sizeof(*bitmap) * bmap_nr);

        SB_AP_BITMAP(sb) = bitmap;

        return 0;
}

void reiserfs_free_bitmap_cache(struct super_block *sb)
{
        if (SB_AP_BITMAP(sb)) {
                vfree(SB_AP_BITMAP(sb));
                SB_AP_BITMAP(sb) = NULL;
        }
}