/*
* shrink_fork()
*
* Try to remove enough allocation blocks from 'fork'
* so that it is 'ablocks' allocation blocks long.
*/
static void shrink_fork(struct hfs_fork *fork, int ablocks)
{
struct hfs_mdb *mdb = fork->entry->mdb;
struct hfs_extent *ext;
int i, error, next, count;
hfs_u32 ablksz = mdb->alloc_blksz;
next = (fork->psize / ablksz) - 1;
ext = find_ext(fork, next);
while (ext && ext->start && (ext->start >= ablocks)) {
next = ext->start - 1;
delete_extent(fork, ext);
ext = find_ext(fork, next);
}
if (!ext) {
fork->psize = (next + 1) * ablksz;
return;
}
if ((count = next + 1 - ablocks) > 0) {
for (i=2; (i>=0) && !ext->length[i]; --i) {};
lock_bitmap(mdb);
while (count && (ext->length[i] <= count)) {
ext->end -= ext->length[i];
count -= ext->length[i];
error = hfs_clear_vbm_bits(mdb, ext->block[i],
ext->length[i]);
if (error) {
hfs_warn("hfs_truncate: error %d freeing "
"blocks.\n", error);
}
ext->block[i] = ext->length[i] = 0;
--i;
}
if (count) {
ext->end -= count;
ext->length[i] -= count;
error = hfs_clear_vbm_bits(mdb, ext->block[i] +
ext->length[i], count);
if (error) {
hfs_warn("hfs_truncate: error %d freeing "
"blocks.\n", error);
}
}
unlock_bitmap(mdb);
update_ext(fork, ext);
}
fork->psize = ablocks * ablksz;
}
static int hfs_free_extents(struct super_block *sb, struct hfs_extent *extent,
u16 offset, u16 block_nr)
{
u16 count, start;
int i;
hfs_dump_extent(extent);
for (i = 0; i < 3; extent++, i++) {
count = be16_to_cpu(extent->count);
if (offset == count)
goto found;
else if (offset < count)
break;
offset -= count;
}
/* panic? */
return -EIO;
found:
for (;;) {
start = be16_to_cpu(extent->block);
if (count <= block_nr) {
hfs_clear_vbm_bits(sb, start, count);
extent->block = 0;
extent->count = 0;
block_nr -= count;
} else {
count -= block_nr;
hfs_clear_vbm_bits(sb, start + count, block_nr);
extent->count = cpu_to_be16(count);
block_nr = 0;
}
if (!block_nr || !i)
return 0;
i--;
extent--;
count = be16_to_cpu(extent->count);
}
}
/*
* delete_extent()
*
* Description:
* Deletes an extent record from a fork, reducing its physical length.
* Input Variable(s):
* struct hfs_fork *fork: the fork
* struct hfs_extent *ext: the current last extent for 'fork'
* Output Variable(s):
* NONE
* Returns:
* void
* Preconditions:
* 'fork' points to a valid (struct hfs_fork)
* 'ext' point to a valid (struct hfs_extent) which is the last in 'fork'
* and which is not also the first extent in 'fork'.
* Postconditions:
* The extent record has been removed if possible, and a warning has been
* printed otherwise.
*/
static void delete_extent(struct hfs_fork *fork, struct hfs_extent *ext)
{
struct hfs_mdb *mdb = fork->entry->mdb;
struct hfs_ext_key key;
int error;
if (fork->cache == ext) {
set_cache(fork, ext->prev);
}
ext->prev->next = NULL;
if (ext->count != 1) {
hfs_warn("hfs_truncate: extent has count %d.\n", ext->count);
}
lock_bitmap(mdb);
error = hfs_clear_vbm_bits(mdb, ext->block[2], ext->length[2]);
if (error) {
hfs_warn("hfs_truncate: error %d freeing blocks.\n", error);
}
error = hfs_clear_vbm_bits(mdb, ext->block[1], ext->length[1]);
if (error) {
hfs_warn("hfs_truncate: error %d freeing blocks.\n", error);
}
error = hfs_clear_vbm_bits(mdb, ext->block[0], ext->length[0]);
if (error) {
hfs_warn("hfs_truncate: error %d freeing blocks.\n", error);
}
unlock_bitmap(mdb);
build_key(&key, fork, ext->start);
error = hfs_bdelete(mdb->ext_tree, HFS_BKEY(&key));
if (error) {
hfs_warn("hfs_truncate: error %d deleting an extent.\n", error);
}
HFS_DELETE(ext);
}
/*
* grow_fork()
*
* Try to add enough allocation blocks to 'fork'
* so that it is 'ablock' allocation blocks long.
*/
static int grow_fork(struct hfs_fork *fork, int ablocks)
{
struct hfs_cat_entry *entry = fork->entry;
struct hfs_mdb *mdb = entry->mdb;
struct hfs_extent *ext;
int i, start, err;
hfs_u16 need, len=0;
hfs_u32 ablksz = mdb->alloc_blksz;
hfs_u32 blocks, clumpablks;
blocks = fork->psize;
need = ablocks - blocks/ablksz;
if (need < 1) { /* no need to grow the fork */
return 0;
}
/* round up to clumpsize */
if (entry->u.file.clumpablks) {
clumpablks = entry->u.file.clumpablks;
} else {
clumpablks = mdb->clumpablks;
}
need = ((need + clumpablks - 1) / clumpablks) * clumpablks;
/* find last extent record and try to extend it */
if (!(ext = find_ext(fork, blocks/ablksz - 1))) {
/* somehow we couldn't find the end of the file! */
return -1;
}
/* determine which is the last used extent in the record */
/* then try to allocate the blocks immediately following it */
for (i=2; (i>=0) && !ext->length[i]; --i) {};
if (i>=0) {
/* try to extend the last extent */
start = ext->block[i] + ext->length[i];
err = 0;
lock_bitmap(mdb);
len = hfs_vbm_count_free(mdb, start);
if (!len) {
unlock_bitmap(mdb);
goto more_extents;
}
if (need < len) {
len = need;
}
err = hfs_set_vbm_bits(mdb, start, len);
unlock_bitmap(mdb);
if (err) {
relse_ext(ext);
return -1;
}
zero_blocks(mdb, start, len);
ext->length[i] += len;
ext->end += len;
blocks = (fork->psize += len * ablksz);
need -= len;
update_ext(fork, ext);
}
more_extents:
/* add some more extents */
while (need) {
len = need;
err = 0;
lock_bitmap(mdb);
start = hfs_vbm_search_free(mdb, &len);
if (need < len) {
len = need;
}
err = hfs_set_vbm_bits(mdb, start, len);
unlock_bitmap(mdb);
if (!len || err) {
relse_ext(ext);
return -1;
}
zero_blocks(mdb, start, len);
/* determine which is the first free extent in the record */
for (i=0; (i<3) && ext->length[i]; ++i) {};
if (i < 3) {
ext->block[i] = start;
ext->length[i] = len;
ext->end += len;
update_ext(fork, ext);
} else {
if (!(ext = new_extent(fork, ext, blocks/ablksz,
start, len, ablksz))) {
lock_bitmap(mdb);
hfs_clear_vbm_bits(mdb, start, len);
unlock_bitmap(mdb);
return -1;
}
}
blocks = (fork->psize += len * ablksz);
need -= len;
}
set_cache(fork, ext);
relse_ext(ext);
return 0;
}
