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root/fs/udf/balloc.c

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DEFINITIONS

This source file includes following definitions.
  1. find_next_one_bit
  2. read_block_bitmap
  3. __load_block_bitmap
  4. load_block_bitmap
  5. udf_add_free_space
  6. udf_bitmap_free_blocks
  7. udf_bitmap_prealloc_blocks
  8. udf_bitmap_new_block
  9. udf_table_free_blocks
  10. udf_table_prealloc_blocks
  11. udf_table_new_block
  12. udf_free_blocks
  13. udf_prealloc_blocks
  14. udf_new_block

/*
 * balloc.c
 *
 * PURPOSE
 *      Block allocation handling routines for the OSTA-UDF(tm) filesystem.
 *
 * COPYRIGHT
 *      This file is distributed under the terms of the GNU General Public
 *      License (GPL). Copies of the GPL can be obtained from:
 *              ftp://prep.ai.mit.edu/pub/gnu/GPL
 *      Each contributing author retains all rights to their own work.
 *
 *  (C) 1999-2001 Ben Fennema
 *  (C) 1999 Stelias Computing Inc
 *
 * HISTORY
 *
 *  02/24/99 blf  Created.
 *
 */

#include "udfdecl.h"

#include <linux/quotaops.h>
#include <linux/buffer_head.h>
#include <linux/bitops.h>

#include "udf_i.h"
#include "udf_sb.h"

#define udf_clear_bit(nr, addr) ext2_clear_bit(nr, addr)
#define udf_set_bit(nr, addr) ext2_set_bit(nr, addr)
#define udf_test_bit(nr, addr) ext2_test_bit(nr, addr)
#define udf_find_first_one_bit(addr, size) find_first_one_bit(addr, size)
#define udf_find_next_one_bit(addr, size, offset) \
                find_next_one_bit(addr, size, offset)

#define leBPL_to_cpup(x) leNUM_to_cpup(BITS_PER_LONG, x)
#define leNUM_to_cpup(x, y) xleNUM_to_cpup(x, y)
#define xleNUM_to_cpup(x, y) (le ## x ## _to_cpup(y))
#define uintBPL_t uint(BITS_PER_LONG)
#define uint(x) xuint(x)
#define xuint(x) __le ## x

static inline int find_next_one_bit(void *addr, int size, int offset)
{
        uintBPL_t *p = ((uintBPL_t *) addr) + (offset / BITS_PER_LONG);
        int result = offset & ~(BITS_PER_LONG - 1);
        unsigned long tmp;

        if (offset >= size)
                return size;
        size -= result;
        offset &= (BITS_PER_LONG - 1);
        if (offset) {
                tmp = leBPL_to_cpup(p++);
                tmp &= ~0UL << offset;
                if (size < BITS_PER_LONG)
                        goto found_first;
                if (tmp)
                        goto found_middle;
                size -= BITS_PER_LONG;
                result += BITS_PER_LONG;
        }
        while (size & ~(BITS_PER_LONG - 1)) {
                tmp = leBPL_to_cpup(p++);
                if (tmp)
                        goto found_middle;
                result += BITS_PER_LONG;
                size -= BITS_PER_LONG;
        }
        if (!size)
                return result;
        tmp = leBPL_to_cpup(p);
found_first:
        tmp &= ~0UL >> (BITS_PER_LONG - size);
found_middle:
        return result + ffz(~tmp);
}

#define find_first_one_bit(addr, size)\
        find_next_one_bit((addr), (size), 0)

static int read_block_bitmap(struct super_block *sb,
                             struct udf_bitmap *bitmap, unsigned int block,
                             unsigned long bitmap_nr)
{
        struct buffer_head *bh = NULL;
        int retval = 0;
        kernel_lb_addr loc;

        loc.logicalBlockNum = bitmap->s_extPosition;
        loc.partitionReferenceNum = UDF_SB(sb)->s_partition;

        bh = udf_tread(sb, udf_get_lb_pblock(sb, loc, block));
        if (!bh)
                retval = -EIO;

        bitmap->s_block_bitmap[bitmap_nr] = bh;
        return retval;
}

static int __load_block_bitmap(struct super_block *sb,
                               struct udf_bitmap *bitmap,
                               unsigned int block_group)
{
        int retval = 0;
        int nr_groups = bitmap->s_nr_groups;

        if (block_group >= nr_groups) {
                udf_debug("block_group (%d) > nr_groups (%d)\n", block_group,
                          nr_groups);
        }

        if (bitmap->s_block_bitmap[block_group]) {
                return block_group;
        } else {
                retval = read_block_bitmap(sb, bitmap, block_group,
                                           block_group);
                if (retval < 0)
                        return retval;
                return block_group;
        }
}

static inline int load_block_bitmap(struct super_block *sb,
                                    struct udf_bitmap *bitmap,
                                    unsigned int block_group)
{
        int slot;

        slot = __load_block_bitmap(sb, bitmap, block_group);

        if (slot < 0)
                return slot;

        if (!bitmap->s_block_bitmap[slot])
                return -EIO;

        return slot;
}

static bool udf_add_free_space(struct udf_sb_info *sbi,
                                u16 partition, u32 cnt)
{
        struct logicalVolIntegrityDesc *lvid;

        if (sbi->s_lvid_bh == NULL)
                return false;

        lvid = (struct logicalVolIntegrityDesc *)sbi->s_lvid_bh->b_data;
        le32_add_cpu(&lvid->freeSpaceTable[partition], cnt);
        return true;
}

static void udf_bitmap_free_blocks(struct super_block *sb,
                                   struct inode *inode,
                                   struct udf_bitmap *bitmap,
                                   kernel_lb_addr bloc, uint32_t offset,
                                   uint32_t count)
{
        struct udf_sb_info *sbi = UDF_SB(sb);
        struct buffer_head *bh = NULL;
        unsigned long block;
        unsigned long block_group;
        unsigned long bit;
        unsigned long i;
        int bitmap_nr;
        unsigned long overflow;

        mutex_lock(&sbi->s_alloc_mutex);
        if (bloc.logicalBlockNum < 0 ||
            (bloc.logicalBlockNum + count) >
                sbi->s_partmaps[bloc.partitionReferenceNum].s_partition_len) {
                udf_debug("%d < %d || %d + %d > %d\n",
                          bloc.logicalBlockNum, 0, bloc.logicalBlockNum, count,
                          sbi->s_partmaps[bloc.partitionReferenceNum].
                                                        s_partition_len);
                goto error_return;
        }

        block = bloc.logicalBlockNum + offset +
                (sizeof(struct spaceBitmapDesc) << 3);

        do {
                overflow = 0;
                block_group = block >> (sb->s_blocksize_bits + 3);
                bit = block % (sb->s_blocksize << 3);

                /*
                * Check to see if we are freeing blocks across a group boundary.
                */
                if (bit + count > (sb->s_blocksize << 3)) {
                        overflow = bit + count - (sb->s_blocksize << 3);
                        count -= overflow;
                }
                bitmap_nr = load_block_bitmap(sb, bitmap, block_group);
                if (bitmap_nr < 0)
                        goto error_return;

                bh = bitmap->s_block_bitmap[bitmap_nr];
                for (i = 0; i < count; i++) {
                        if (udf_set_bit(bit + i, bh->b_data)) {
                                udf_debug("bit %ld already set\n", bit + i);
                                udf_debug("byte=%2x\n",
                                        ((char *)bh->b_data)[(bit + i) >> 3]);
                        } else {
                                if (inode)
                                        DQUOT_FREE_BLOCK(inode, 1);
                                udf_add_free_space(sbi, sbi->s_partition, 1);
                        }
                }
                mark_buffer_dirty(bh);
                if (overflow) {
                        block += count;
                        count = overflow;
                }
        } while (overflow);

error_return:
        sb->s_dirt = 1;
        if (sbi->s_lvid_bh)
                mark_buffer_dirty(sbi->s_lvid_bh);
        mutex_unlock(&sbi->s_alloc_mutex);
}

static int udf_bitmap_prealloc_blocks(struct super_block *sb,
                                      struct inode *inode,
                                      struct udf_bitmap *bitmap,
                                      uint16_t partition, uint32_t first_block,
                                      uint32_t block_count)
{
        struct udf_sb_info *sbi = UDF_SB(sb);
        int alloc_count = 0;
        int bit, block, block_group, group_start;
        int nr_groups, bitmap_nr;
        struct buffer_head *bh;
        __u32 part_len;

        mutex_lock(&sbi->s_alloc_mutex);
        part_len = sbi->s_partmaps[partition].s_partition_len;
        if (first_block < 0 || first_block >= part_len)
                goto out;

        if (first_block + block_count > part_len)
                block_count = part_len - first_block;

        do {
                nr_groups = udf_compute_nr_groups(sb, partition);
                block = first_block + (sizeof(struct spaceBitmapDesc) << 3);
                block_group = block >> (sb->s_blocksize_bits + 3);
                group_start = block_group ? 0 : sizeof(struct spaceBitmapDesc);

                bitmap_nr = load_block_bitmap(sb, bitmap, block_group);
                if (bitmap_nr < 0)
                        goto out;
                bh = bitmap->s_block_bitmap[bitmap_nr];

                bit = block % (sb->s_blocksize << 3);

                while (bit < (sb->s_blocksize << 3) && block_count > 0) {
                        if (!udf_test_bit(bit, bh->b_data))
                                goto out;
                        else if (DQUOT_PREALLOC_BLOCK(inode, 1))
                                goto out;
                        else if (!udf_clear_bit(bit, bh->b_data)) {
                                udf_debug("bit already cleared for block %d\n", bit);
                                DQUOT_FREE_BLOCK(inode, 1);
                                goto out;
                        }
                        block_count--;
                        alloc_count++;
                        bit++;
                        block++;
                }
                mark_buffer_dirty(bh);
        } while (block_count > 0);

out:
        if (udf_add_free_space(sbi, partition, -alloc_count))
                mark_buffer_dirty(sbi->s_lvid_bh);
        sb->s_dirt = 1;
        mutex_unlock(&sbi->s_alloc_mutex);
        return alloc_count;
}

static int udf_bitmap_new_block(struct super_block *sb,
                                struct inode *inode,
                                struct udf_bitmap *bitmap, uint16_t partition,
                                uint32_t goal, int *err)
{
        struct udf_sb_info *sbi = UDF_SB(sb);
        int newbit, bit = 0, block, block_group, group_start;
        int end_goal, nr_groups, bitmap_nr, i;
        struct buffer_head *bh = NULL;
        char *ptr;
        int newblock = 0;

        *err = -ENOSPC;
        mutex_lock(&sbi->s_alloc_mutex);

repeat:
        if (goal < 0 || goal >= sbi->s_partmaps[partition].s_partition_len)
                goal = 0;

        nr_groups = bitmap->s_nr_groups;
        block = goal + (sizeof(struct spaceBitmapDesc) << 3);
        block_group = block >> (sb->s_blocksize_bits + 3);
        group_start = block_group ? 0 : sizeof(struct spaceBitmapDesc);

        bitmap_nr = load_block_bitmap(sb, bitmap, block_group);
        if (bitmap_nr < 0)
                goto error_return;
        bh = bitmap->s_block_bitmap[bitmap_nr];
        ptr = memscan((char *)bh->b_data + group_start, 0xFF,
                      sb->s_blocksize - group_start);

        if ((ptr - ((char *)bh->b_data)) < sb->s_blocksize) {
                bit = block % (sb->s_blocksize << 3);
                if (udf_test_bit(bit, bh->b_data))
                        goto got_block;

                end_goal = (bit + 63) & ~63;
                bit = udf_find_next_one_bit(bh->b_data, end_goal, bit);
                if (bit < end_goal)
                        goto got_block;

                ptr = memscan((char *)bh->b_data + (bit >> 3), 0xFF,
                              sb->s_blocksize - ((bit + 7) >> 3));
                newbit = (ptr - ((char *)bh->b_data)) << 3;
                if (newbit < sb->s_blocksize << 3) {
                        bit = newbit;
                        goto search_back;
                }

                newbit = udf_find_next_one_bit(bh->b_data,
                                               sb->s_blocksize << 3, bit);
                if (newbit < sb->s_blocksize << 3) {
                        bit = newbit;
                        goto got_block;
                }
        }

        for (i = 0; i < (nr_groups * 2); i++) {
                block_group++;
                if (block_group >= nr_groups)
                        block_group = 0;
                group_start = block_group ? 0 : sizeof(struct spaceBitmapDesc);

                bitmap_nr = load_block_bitmap(sb, bitmap, block_group);
                if (bitmap_nr < 0)
                        goto error_return;
                bh = bitmap->s_block_bitmap[bitmap_nr];
                if (i < nr_groups) {
                        ptr = memscan((char *)bh->b_data + group_start, 0xFF,
                                      sb->s_blocksize - group_start);
                        if ((ptr - ((char *)bh->b_data)) < sb->s_blocksize) {
                                bit = (ptr - ((char *)bh->b_data)) << 3;
                                break;
                        }
                } else {
                        bit = udf_find_next_one_bit((char *)bh->b_data,
                                                    sb->s_blocksize << 3,
                                                    group_start << 3);
                        if (bit < sb->s_blocksize << 3)
                                break;
                }
        }
        if (i >= (nr_groups * 2)) {
                mutex_unlock(&sbi->s_alloc_mutex);
                return newblock;
        }
        if (bit < sb->s_blocksize << 3)
                goto search_back;
        else
                bit = udf_find_next_one_bit(bh->b_data, sb->s_blocksize << 3,
                                            group_start << 3);
        if (bit >= sb->s_blocksize << 3) {
                mutex_unlock(&sbi->s_alloc_mutex);
                return 0;
        }

search_back:
        i = 0;
        while (i < 7 && bit > (group_start << 3) &&
               udf_test_bit(bit - 1, bh->b_data)) {
                ++i;
                --bit;
        }

got_block:

        /*
         * Check quota for allocation of this block.
         */
        if (inode && DQUOT_ALLOC_BLOCK(inode, 1)) {
                mutex_unlock(&sbi->s_alloc_mutex);
                *err = -EDQUOT;
                return 0;
        }

        newblock = bit + (block_group << (sb->s_blocksize_bits + 3)) -
                (sizeof(struct spaceBitmapDesc) << 3);

        if (!udf_clear_bit(bit, bh->b_data)) {
                udf_debug("bit already cleared for block %d\n", bit);
                goto repeat;
        }

        mark_buffer_dirty(bh);

        if (udf_add_free_space(sbi, partition, -1))
                mark_buffer_dirty(sbi->s_lvid_bh);
        sb->s_dirt = 1;
        mutex_unlock(&sbi->s_alloc_mutex);
        *err = 0;
        return newblock;

error_return:
        *err = -EIO;
        mutex_unlock(&sbi->s_alloc_mutex);
        return 0;
}

static void udf_table_free_blocks(struct super_block *sb,
                                  struct inode *inode,
                                  struct inode *table,
                                  kernel_lb_addr bloc, uint32_t offset,
                                  uint32_t count)
{
        struct udf_sb_info *sbi = UDF_SB(sb);
        uint32_t start, end;
        uint32_t elen;
        kernel_lb_addr eloc;
        struct extent_position oepos, epos;
        int8_t etype;
        int i;
        struct udf_inode_info *iinfo;

        mutex_lock(&sbi->s_alloc_mutex);
        if (bloc.logicalBlockNum < 0 ||
            (bloc.logicalBlockNum + count) >
                sbi->s_partmaps[bloc.partitionReferenceNum].s_partition_len) {
                udf_debug("%d < %d || %d + %d > %d\n",
                          bloc.logicalBlockNum, 0, bloc.logicalBlockNum, count,
                          sbi->s_partmaps[bloc.partitionReferenceNum].
                                                        s_partition_len);
                goto error_return;
        }

        iinfo = UDF_I(table);
        /* We do this up front - There are some error conditions that
           could occure, but.. oh well */
        if (inode)
                DQUOT_FREE_BLOCK(inode, count);
        if (udf_add_free_space(sbi, sbi->s_partition, count))
                mark_buffer_dirty(sbi->s_lvid_bh);

        start = bloc.logicalBlockNum + offset;
        end = bloc.logicalBlockNum + offset + count - 1;

        epos.offset = oepos.offset = sizeof(struct unallocSpaceEntry);
        elen = 0;
        epos.block = oepos.block = iinfo->i_location;
        epos.bh = oepos.bh = NULL;

        while (count &&
               (etype = udf_next_aext(table, &epos, &eloc, &elen, 1)) != -1) {
                if (((eloc.logicalBlockNum +
                        (elen >> sb->s_blocksize_bits)) == start)) {
                        if ((0x3FFFFFFF - elen) <
                                        (count << sb->s_blocksize_bits)) {
                                uint32_t tmp = ((0x3FFFFFFF - elen) >>
                                                        sb->s_blocksize_bits);
                                count -= tmp;
                                start += tmp;
                                elen = (etype << 30) |
                                        (0x40000000 - sb->s_blocksize);
                        } else {
                                elen = (etype << 30) |
                                        (elen +
                                        (count << sb->s_blocksize_bits));
                                start += count;
                                count = 0;
                        }
                        udf_write_aext(table, &oepos, eloc, elen, 1);
                } else if (eloc.logicalBlockNum == (end + 1)) {
                        if ((0x3FFFFFFF - elen) <
                                        (count << sb->s_blocksize_bits)) {
                                uint32_t tmp = ((0x3FFFFFFF - elen) >>
                                                sb->s_blocksize_bits);
                                count -= tmp;
                                end -= tmp;
                                eloc.logicalBlockNum -= tmp;
                                elen = (etype << 30) |
                                        (0x40000000 - sb->s_blocksize);
                        } else {
                                eloc.logicalBlockNum = start;
                                elen = (etype << 30) |
                                        (elen +
                                        (count << sb->s_blocksize_bits));
                                end -= count;
                                count = 0;
                        }
                        udf_write_aext(table, &oepos, eloc, elen, 1);
                }

                if (epos.bh != oepos.bh) {
                        i = -1;
                        oepos.block = epos.block;
                        brelse(oepos.bh);
                        get_bh(epos.bh);
                        oepos.bh = epos.bh;
                        oepos.offset = 0;
                } else {
                        oepos.offset = epos.offset;
                }
        }

        if (count) {
                /*
                 * NOTE: we CANNOT use udf_add_aext here, as it can try to
                 * allocate a new block, and since we hold the super block
                 * lock already very bad things would happen :)
                 *
                 * We copy the behavior of udf_add_aext, but instead of
                 * trying to allocate a new block close to the existing one,
                 * we just steal a block from the extent we are trying to add.
                 *
                 * It would be nice if the blocks were close together, but it
                 * isn't required.
                 */

                int adsize;
                short_ad *sad = NULL;
                long_ad *lad = NULL;
                struct allocExtDesc *aed;

                eloc.logicalBlockNum = start;
                elen = EXT_RECORDED_ALLOCATED |
                        (count << sb->s_blocksize_bits);

                if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_SHORT)
                        adsize = sizeof(short_ad);
                else if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_LONG)
                        adsize = sizeof(long_ad);
                else {
                        brelse(oepos.bh);
                        brelse(epos.bh);
                        goto error_return;
                }

                if (epos.offset + (2 * adsize) > sb->s_blocksize) {
                        char *sptr, *dptr;
                        int loffset;

                        brelse(oepos.bh);
                        oepos = epos;

                        /* Steal a block from the extent being free'd */
                        epos.block.logicalBlockNum = eloc.logicalBlockNum;
                        eloc.logicalBlockNum++;
                        elen -= sb->s_blocksize;

                        epos.bh = udf_tread(sb,
                                        udf_get_lb_pblock(sb, epos.block, 0));
                        if (!epos.bh) {
                                brelse(oepos.bh);
                                goto error_return;
                        }
                        aed = (struct allocExtDesc *)(epos.bh->b_data);
                        aed->previousAllocExtLocation =
                                cpu_to_le32(oepos.block.logicalBlockNum);
                        if (epos.offset + adsize > sb->s_blocksize) {
                                loffset = epos.offset;
                                aed->lengthAllocDescs = cpu_to_le32(adsize);
                                sptr = iinfo->i_ext.i_data + epos.offset
                                                                - adsize;
                                dptr = epos.bh->b_data +
                                        sizeof(struct allocExtDesc);
                                memcpy(dptr, sptr, adsize);
                                epos.offset = sizeof(struct allocExtDesc) +
                                                adsize;
                        } else {
                                loffset = epos.offset + adsize;
                                aed->lengthAllocDescs = cpu_to_le32(0);
                                if (oepos.bh) {
                                        sptr = oepos.bh->b_data + epos.offset;
                                        aed = (struct allocExtDesc *)
                                                oepos.bh->b_data;
                                        le32_add_cpu(&aed->lengthAllocDescs,
                                                        adsize);
                                } else {
                                        sptr = iinfo->i_ext.i_data +
                                                                epos.offset;
                                        iinfo->i_lenAlloc += adsize;
                                        mark_inode_dirty(table);
                                }
                                epos.offset = sizeof(struct allocExtDesc);
                        }
                        if (sbi->s_udfrev >= 0x0200)
                                udf_new_tag(epos.bh->b_data, TAG_IDENT_AED,
                                            3, 1, epos.block.logicalBlockNum,
                                            sizeof(tag));
                        else
                                udf_new_tag(epos.bh->b_data, TAG_IDENT_AED,
                                            2, 1, epos.block.logicalBlockNum,
                                            sizeof(tag));

                        switch (iinfo->i_alloc_type) {
                        case ICBTAG_FLAG_AD_SHORT:
                                sad = (short_ad *)sptr;
                                sad->extLength = cpu_to_le32(
                                        EXT_NEXT_EXTENT_ALLOCDECS |
                                        sb->s_blocksize);
                                sad->extPosition =
                                        cpu_to_le32(epos.block.logicalBlockNum);
                                break;
                        case ICBTAG_FLAG_AD_LONG:
                                lad = (long_ad *)sptr;
                                lad->extLength = cpu_to_le32(
                                        EXT_NEXT_EXTENT_ALLOCDECS |
                                        sb->s_blocksize);
                                lad->extLocation =
                                        cpu_to_lelb(epos.block);
                                break;
                        }
                        if (oepos.bh) {
                                udf_update_tag(oepos.bh->b_data, loffset);
                                mark_buffer_dirty(oepos.bh);
                        } else {
                                mark_inode_dirty(table);
                        }
                }

                /* It's possible that stealing the block emptied the extent */
                if (elen) {
                        udf_write_aext(table, &epos, eloc, elen, 1);

                        if (!epos.bh) {
                                iinfo->i_lenAlloc += adsize;
                                mark_inode_dirty(table);
                        } else {
                                aed = (struct allocExtDesc *)epos.bh->b_data;
                                le32_add_cpu(&aed->lengthAllocDescs, adsize);
                                udf_update_tag(epos.bh->b_data, epos.offset);
                                mark_buffer_dirty(epos.bh);
                        }
                }
        }

        brelse(epos.bh);
        brelse(oepos.bh);

error_return:
        sb->s_dirt = 1;
        mutex_unlock(&sbi->s_alloc_mutex);
        return;
}

static int udf_table_prealloc_blocks(struct super_block *sb,
                                     struct inode *inode,
                                     struct inode *table, uint16_t partition,
                                     uint32_t first_block, uint32_t block_count)
{
        struct udf_sb_info *sbi = UDF_SB(sb);
        int alloc_count = 0;
        uint32_t elen, adsize;
        kernel_lb_addr eloc;
        struct extent_position epos;
        int8_t etype = -1;
        struct udf_inode_info *iinfo;

        if (first_block < 0 ||
                first_block >= sbi->s_partmaps[partition].s_partition_len)
                return 0;

        iinfo = UDF_I(table);
        if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_SHORT)
                adsize = sizeof(short_ad);
        else if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_LONG)
                adsize = sizeof(long_ad);
        else
                return 0;

        mutex_lock(&sbi->s_alloc_mutex);
        epos.offset = sizeof(struct unallocSpaceEntry);
        epos.block = iinfo->i_location;
        epos.bh = NULL;
        eloc.logicalBlockNum = 0xFFFFFFFF;

        while (first_block != eloc.logicalBlockNum &&
               (etype = udf_next_aext(table, &epos, &eloc, &elen, 1)) != -1) {
                udf_debug("eloc=%d, elen=%d, first_block=%d\n",
                          eloc.logicalBlockNum, elen, first_block);
                ; /* empty loop body */
        }

        if (first_block == eloc.logicalBlockNum) {
                epos.offset -= adsize;

                alloc_count = (elen >> sb->s_blocksize_bits);
                if (inode && DQUOT_PREALLOC_BLOCK(inode,
                        alloc_count > block_count ? block_count : alloc_count))
                        alloc_count = 0;
                else if (alloc_count > block_count) {
                        alloc_count = block_count;
                        eloc.logicalBlockNum += alloc_count;
                        elen -= (alloc_count << sb->s_blocksize_bits);
                        udf_write_aext(table, &epos, eloc,
                                        (etype << 30) | elen, 1);
                } else
                        udf_delete_aext(table, epos, eloc,
                                        (etype << 30) | elen);
        } else {
                alloc_count = 0;
        }

        brelse(epos.bh);

        if (alloc_count && udf_add_free_space(sbi, partition, -alloc_count)) {
                mark_buffer_dirty(sbi->s_lvid_bh);
                sb->s_dirt = 1;
        }
        mutex_unlock(&sbi->s_alloc_mutex);
        return alloc_count;
}

static int udf_table_new_block(struct super_block *sb,
                               struct inode *inode,
                               struct inode *table, uint16_t partition,
                               uint32_t goal, int *err)
{
        struct udf_sb_info *sbi = UDF_SB(sb);
        uint32_t spread = 0xFFFFFFFF, nspread = 0xFFFFFFFF;
        uint32_t newblock = 0, adsize;
        uint32_t elen, goal_elen = 0;
        kernel_lb_addr eloc, uninitialized_var(goal_eloc);
        struct extent_position epos, goal_epos;
        int8_t etype;
        struct udf_inode_info *iinfo = UDF_I(table);

        *err = -ENOSPC;

        if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_SHORT)
                adsize = sizeof(short_ad);
        else if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_LONG)
                adsize = sizeof(long_ad);
        else
                return newblock;

        mutex_lock(&sbi->s_alloc_mutex);
        if (goal < 0 || goal >= sbi->s_partmaps[partition].s_partition_len)
                goal = 0;

        /* We search for the closest matching block to goal. If we find
           a exact hit, we stop. Otherwise we keep going till we run out
           of extents. We store the buffer_head, bloc, and extoffset
           of the current closest match and use that when we are done.
         */
        epos.offset = sizeof(struct unallocSpaceEntry);
        epos.block = iinfo->i_location;
        epos.bh = goal_epos.bh = NULL;

        while (spread &&
               (etype = udf_next_aext(table, &epos, &eloc, &elen, 1)) != -1) {
                if (goal >= eloc.logicalBlockNum) {
                        if (goal < eloc.logicalBlockNum +
                                        (elen >> sb->s_blocksize_bits))
                                nspread = 0;
                        else
                                nspread = goal - eloc.logicalBlockNum -
                                        (elen >> sb->s_blocksize_bits);
                } else {
                        nspread = eloc.logicalBlockNum - goal;
                }

                if (nspread < spread) {
                        spread = nspread;
                        if (goal_epos.bh != epos.bh) {
                                brelse(goal_epos.bh);
                                goal_epos.bh = epos.bh;
                                get_bh(goal_epos.bh);
                        }
                        goal_epos.block = epos.block;
                        goal_epos.offset = epos.offset - adsize;
                        goal_eloc = eloc;
                        goal_elen = (etype << 30) | elen;
                }
        }

        brelse(epos.bh);

        if (spread == 0xFFFFFFFF) {
                brelse(goal_epos.bh);
                mutex_unlock(&sbi->s_alloc_mutex);
                return 0;
        }

        /* Only allocate blocks from the beginning of the extent.
           That way, we only delete (empty) extents, never have to insert an
           extent because of splitting */
        /* This works, but very poorly.... */

        newblock = goal_eloc.logicalBlockNum;
        goal_eloc.logicalBlockNum++;
        goal_elen -= sb->s_blocksize;

        if (inode && DQUOT_ALLOC_BLOCK(inode, 1)) {
                brelse(goal_epos.bh);
                mutex_unlock(&sbi->s_alloc_mutex);
                *err = -EDQUOT;
                return 0;
        }

        if (goal_elen)
                udf_write_aext(table, &goal_epos, goal_eloc, goal_elen, 1);
        else
                udf_delete_aext(table, goal_epos, goal_eloc, goal_elen);
        brelse(goal_epos.bh);

        if (udf_add_free_space(sbi, partition, -1))
                mark_buffer_dirty(sbi->s_lvid_bh);

        sb->s_dirt = 1;
        mutex_unlock(&sbi->s_alloc_mutex);
        *err = 0;
        return newblock;
}

inline void udf_free_blocks(struct super_block *sb,
                            struct inode *inode,
                            kernel_lb_addr bloc, uint32_t offset,
                            uint32_t count)
{
        uint16_t partition = bloc.partitionReferenceNum;
        struct udf_part_map *map = &UDF_SB(sb)->s_partmaps[partition];

        if (map->s_partition_flags & UDF_PART_FLAG_UNALLOC_BITMAP) {
                return udf_bitmap_free_blocks(sb, inode,
                                              map->s_uspace.s_bitmap,
                                              bloc, offset, count);
        } else if (map->s_partition_flags & UDF_PART_FLAG_UNALLOC_TABLE) {
                return udf_table_free_blocks(sb, inode,
                                             map->s_uspace.s_table,
                                             bloc, offset, count);
        } else if (map->s_partition_flags & UDF_PART_FLAG_FREED_BITMAP) {
                return udf_bitmap_free_blocks(sb, inode,
                                              map->s_fspace.s_bitmap,
                                              bloc, offset, count);
        } else if (map->s_partition_flags & UDF_PART_FLAG_FREED_TABLE) {
                return udf_table_free_blocks(sb, inode,
                                             map->s_fspace.s_table,
                                             bloc, offset, count);
        } else {
                return;
        }
}

inline int udf_prealloc_blocks(struct super_block *sb,
                               struct inode *inode,
                               uint16_t partition, uint32_t first_block,
                               uint32_t block_count)
{
        struct udf_part_map *map = &UDF_SB(sb)->s_partmaps[partition];

        if (map->s_partition_flags & UDF_PART_FLAG_UNALLOC_BITMAP)
                return udf_bitmap_prealloc_blocks(sb, inode,
                                                  map->s_uspace.s_bitmap,
                                                  partition, first_block,
                                                  block_count);
        else if (map->s_partition_flags & UDF_PART_FLAG_UNALLOC_TABLE)
                return udf_table_prealloc_blocks(sb, inode,
                                                 map->s_uspace.s_table,
                                                 partition, first_block,
                                                 block_count);
        else if (map->s_partition_flags & UDF_PART_FLAG_FREED_BITMAP)
                return udf_bitmap_prealloc_blocks(sb, inode,
                                                  map->s_fspace.s_bitmap,
                                                  partition, first_block,
                                                  block_count);
        else if (map->s_partition_flags & UDF_PART_FLAG_FREED_TABLE)
                return udf_table_prealloc_blocks(sb, inode,
                                                 map->s_fspace.s_table,
                                                 partition, first_block,
                                                 block_count);
        else
                return 0;
}

inline int udf_new_block(struct super_block *sb,
                         struct inode *inode,
                         uint16_t partition, uint32_t goal, int *err)
{
        struct udf_part_map *map = &UDF_SB(sb)->s_partmaps[partition];

        if (map->s_partition_flags & UDF_PART_FLAG_UNALLOC_BITMAP)
                return udf_bitmap_new_block(sb, inode,
                                           map->s_uspace.s_bitmap,
                                           partition, goal, err);
        else if (map->s_partition_flags & UDF_PART_FLAG_UNALLOC_TABLE)
                return udf_table_new_block(sb, inode,
                                           map->s_uspace.s_table,
                                           partition, goal, err);
        else if (map->s_partition_flags & UDF_PART_FLAG_FREED_BITMAP)
                return udf_bitmap_new_block(sb, inode,
                                            map->s_fspace.s_bitmap,
                                            partition, goal, err);
        else if (map->s_partition_flags & UDF_PART_FLAG_FREED_TABLE)
                return udf_table_new_block(sb, inode,
                                           map->s_fspace.s_table,
                                           partition, goal, err);
        else {
                *err = -EIO;
                return 0;
        }
}

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