/* 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,
unsigned long *start, unsigned long finish,
int min, int max, int unfm, unsigned long file_block)
{
int nr_allocated=0;
struct super_block * s = th->t_super;
/* find every bm and bmap and bmap_nr in this file, and change them all to bitmap_blocknr
* - Hans, it is not a block number - Zam. */
int bm, off;
int end_bm, end_off;
int off_max = s->s_blocksize << 3;
PROC_INFO_INC( s, scan_bitmap.call );
if ( SB_FREE_BLOCKS(s) <= 0)
return 0; // No point in looking for more free blocks
get_bit_address (s, *start, &bm, &off);
get_bit_address (s, finish, &end_bm, &end_off);
// With this option set first we try to find a bitmap that is at least 10%
// free, and if that fails, then we fall back to old whole bitmap scanning
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;
}
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;
}
/* 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, unsigned long file_block)
{
int nr_allocated=0;
struct super_block * s = th->t_super;
/* find every bm and bmap and bmap_nr in this file, and change them all to bitmap_blocknr
* - Hans, it is not a block number - Zam. */
int bm, off;
int end_bm, end_off;
int off_max = s->s_blocksize << 3;
BUG_ON (!th->t_trans_id);
PROC_INFO_INC( s, scan_bitmap.call );
if ( SB_FREE_BLOCKS(s) <= 0)
return 0; // No point in looking for more free blocks
get_bit_address (s, *start, &bm, &off);
get_bit_address (s, finish, &end_bm, &end_off);
if (bm > SB_BMAP_NR(s))
return 0;
if (end_bm > SB_BMAP_NR(s))
end_bm = SB_BMAP_NR(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;
}
