Exemple #1
0
/**
 * ubifs_get_free_space_nolock - return amount of free space.
 * @c: UBIFS file-system description object
 *
 * This function calculates amount of free space to report to user-space.
 *
 * Because UBIFS may introduce substantial overhead (the index, node headers,
 * alignment, wastage at the end of LEBs, etc), it cannot report real amount of
 * free flash space it has (well, because not all dirty space is reclaimable,
 * UBIFS does not actually know the real amount). If UBIFS did so, it would
 * bread user expectations about what free space is. Users seem to accustomed
 * to assume that if the file-system reports N bytes of free space, they would
 * be able to fit a file of N bytes to the FS. This almost works for
 * traditional file-systems, because they have way less overhead than UBIFS.
 * So, to keep users happy, UBIFS tries to take the overhead into account.
 */
long long ubifs_get_free_space_nolock(struct ubifs_info *c)
{
	int rsvd_idx_lebs, lebs;
	long long available, outstanding, free;

	ubifs_assert(c->bi.min_idx_lebs == ubifs_calc_min_idx_lebs(c));
	outstanding = c->bi.data_growth + c->bi.dd_growth;
	available = ubifs_calc_available(c, c->bi.min_idx_lebs);

	/*
	 * When reporting free space to user-space, UBIFS guarantees that it is
	 * possible to write a file of free space size. This means that for
	 * empty LEBs we may use more precise calculations than
	 * 'ubifs_calc_available()' is using. Namely, we know that in empty
	 * LEBs we would waste only @c->leb_overhead bytes, not @c->dark_wm.
	 * Thus, amend the available space.
	 *
	 * Note, the calculations below are similar to what we have in
	 * 'do_budget_space()', so refer there for comments.
	 */
	if (c->bi.min_idx_lebs > c->lst.idx_lebs)
		rsvd_idx_lebs = c->bi.min_idx_lebs - c->lst.idx_lebs;
	else
		rsvd_idx_lebs = 0;
	lebs = c->lst.empty_lebs + c->freeable_cnt + c->idx_gc_cnt -
	       c->lst.taken_empty_lebs;
	lebs -= rsvd_idx_lebs;
	available += lebs * (c->dark_wm - c->leb_overhead);

	if (available > outstanding)
		free = ubifs_reported_space(c, available - outstanding);
	else
		free = 0;
	return free;
}
Exemple #2
0
/**
 * do_budget_space - reserve flash space for index and data growth.
 * @c: UBIFS file-system description object
 *
 * This function makes sure UBIFS has enough free LEBs for index growth and
 * data.
 *
 * When budgeting index space, UBIFS reserves thrice as many LEBs as the index
 * would take if it was consolidated and written to the flash. This guarantees
 * that the "in-the-gaps" commit method always succeeds and UBIFS will always
 * be able to commit dirty index. So this function basically adds amount of
 * budgeted index space to the size of the current index, multiplies this by 3,
 * and makes sure this does not exceed the amount of free LEBs.
 *
 * Notes about @c->bi.min_idx_lebs and @c->lst.idx_lebs variables:
 * o @c->lst.idx_lebs is the number of LEBs the index currently uses. It might
 *    be large, because UBIFS does not do any index consolidation as long as
 *    there is free space. IOW, the index may take a lot of LEBs, but the LEBs
 *    will contain a lot of dirt.
 * o @c->bi.min_idx_lebs is the number of LEBS the index presumably takes. IOW,
 *    the index may be consolidated to take up to @c->bi.min_idx_lebs LEBs.
 *
 * This function returns zero in case of success, and %-ENOSPC in case of
 * failure.
 */
static int do_budget_space(struct ubifs_info *c)
{
	long long outstanding, available;
	int lebs, rsvd_idx_lebs, min_idx_lebs;

	/* First budget index space */
	min_idx_lebs = ubifs_calc_min_idx_lebs(c);

	/* Now 'min_idx_lebs' contains number of LEBs to reserve */
	if (min_idx_lebs > c->lst.idx_lebs)
		rsvd_idx_lebs = min_idx_lebs - c->lst.idx_lebs;
	else
		rsvd_idx_lebs = 0;

	/*
	 * The number of LEBs that are available to be used by the index is:
	 *
	 *    @c->lst.empty_lebs + @c->freeable_cnt + @c->idx_gc_cnt -
	 *    @c->lst.taken_empty_lebs
	 *
	 * @c->lst.empty_lebs are available because they are empty.
	 * @c->freeable_cnt are available because they contain only free and
	 * dirty space, @c->idx_gc_cnt are available because they are index
	 * LEBs that have been garbage collected and are awaiting the commit
	 * before they can be used. And the in-the-gaps method will grab these
	 * if it needs them. @c->lst.taken_empty_lebs are empty LEBs that have
	 * already been allocated for some purpose.
	 *
	 * Note, @c->idx_gc_cnt is included to both @c->lst.empty_lebs (because
	 * these LEBs are empty) and to @c->lst.taken_empty_lebs (because they
	 * are taken until after the commit).
	 *
	 * Note, @c->lst.taken_empty_lebs may temporarily be higher by one
	 * because of the way we serialize LEB allocations and budgeting. See a
	 * comment in 'ubifs_find_free_space()'.
	 */
	lebs = c->lst.empty_lebs + c->freeable_cnt + c->idx_gc_cnt -
	       c->lst.taken_empty_lebs;
	if (unlikely(rsvd_idx_lebs > lebs)) {
		dbg_budg("out of indexing space: min_idx_lebs %d (old %d), "
			 "rsvd_idx_lebs %d", min_idx_lebs, c->bi.min_idx_lebs,
			 rsvd_idx_lebs);
		return -ENOSPC;
	}

	available = ubifs_calc_available(c, min_idx_lebs);
	outstanding = c->bi.data_growth + c->bi.dd_growth;

	if (unlikely(available < outstanding)) {
		dbg_budg("out of data space: available %lld, outstanding %lld",
			 available, outstanding);
		return -ENOSPC;
	}

	if (available - outstanding <= c->rp_size && !can_use_rp(c))
		return -ENOSPC;

	c->bi.min_idx_lebs = min_idx_lebs;
	return 0;
}
Exemple #3
0
/**
 * do_budget_space - reserve flash space for index and data growth.
 * @c: UBIFS file-system description object
 *
 * This function makes sure UBIFS has enough free eraseblocks for index growth
 * and data.
 *
 * When budgeting index space, UBIFS reserves twice as more LEBs as the index
 * would take if it was consolidated and written to the flash. This guarantees
 * that the "in-the-gaps" commit method always succeeds and UBIFS will always
 * be able to commit dirty index. So this function basically adds amount of
 * budgeted index space to the size of the current index, multiplies this by 2,
 * and makes sure this does not exceed the amount of free eraseblocks.
 *
 * Notes about @c->min_idx_lebs and @c->lst.idx_lebs variables:
 * o @c->lst.idx_lebs is the number of LEBs the index currently uses. It might
 *    be large, because UBIFS does not do any index consolidation as long as
 *    there is free space. IOW, the index may take a lot of LEBs, but the LEBs
 *    will contain a lot of dirt.
 * o @c->min_idx_lebs is the the index presumably takes. IOW, the index may be
 *   consolidated to take up to @c->min_idx_lebs LEBs.
 *
 * This function returns zero in case of success, and %-ENOSPC in case of
 * failure.
 */
static int do_budget_space(struct ubifs_info *c)
{
	long long outstanding, available;
	int lebs, rsvd_idx_lebs, min_idx_lebs;

	/* First budget index space */
	min_idx_lebs = ubifs_calc_min_idx_lebs(c);

	/* Now 'min_idx_lebs' contains number of LEBs to reserve */
	if (min_idx_lebs > c->lst.idx_lebs)
		rsvd_idx_lebs = min_idx_lebs - c->lst.idx_lebs;
	else
		rsvd_idx_lebs = 0;

	/*
	 * The number of LEBs that are available to be used by the index is:
	 *
	 *    @c->lst.empty_lebs + @c->freeable_cnt + @c->idx_gc_cnt -
	 *    @c->lst.taken_empty_lebs
	 *
	 * @empty_lebs are available because they are empty. @freeable_cnt are
	 * available because they contain only free and dirty space and the
	 * index allocation always occurs after wbufs are synch'ed.
	 * @idx_gc_cnt are available because they are index LEBs that have been
	 * garbage collected (including trivial GC) and are awaiting the commit
	 * before they can be unmapped - note that the in-the-gaps method will
	 * grab these if it needs them. @taken_empty_lebs are empty_lebs that
	 * have already been allocated for some purpose (also includes those
	 * LEBs on the @idx_gc list).
	 *
	 * Note, @taken_empty_lebs may temporarily be higher by one because of
	 * the way we serialize LEB allocations and budgeting. See a comment in
	 * 'ubifs_find_free_space()'.
	 */
	lebs = c->lst.empty_lebs + c->freeable_cnt + c->idx_gc_cnt -
	       c->lst.taken_empty_lebs;
	if (unlikely(rsvd_idx_lebs > lebs)) {
		dbg_budg("out of indexing space: min_idx_lebs %d (old %d), "
			 "rsvd_idx_lebs %d", min_idx_lebs, c->min_idx_lebs,
			 rsvd_idx_lebs);
		return -ENOSPC;
	}

	available = ubifs_calc_available(c, min_idx_lebs);
	outstanding = c->budg_data_growth + c->budg_dd_growth;

	if (unlikely(available < outstanding)) {
		dbg_budg("out of data space: available %lld, outstanding %lld",
			 available, outstanding);
		return -ENOSPC;
	}

	if (available - outstanding <= c->rp_size && !can_use_rp(c))
		return -ENOSPC;

	c->min_idx_lebs = min_idx_lebs;
	return 0;
}
/**
 * ubifs_get_free_space - return amount of free space.
 * @c: UBIFS file-system description object
 *
 * This function calculates amount of free space to report to user-space.
 *
 * Because UBIFS may introduce substantial overhead (the index, node headers,
 * alighment, wastage at the end of eraseblocks, etc), it cannot report real
 * amount of free flash space it has (well, because not all dirty space is
 * reclamable, UBIFS does not actually know the real amount). If UBIFS did so,
 * it would bread user expectetion about what free space is. Users seem to
 * accustomed to assume that if the file-system reports N bytes of free space,
 * they would be able to fit a file of N bytes to the FS. This almost works for
 * traditional file-systems, because they have way less overhead than UBIFS.
 * So, to keep users happy, UBIFS tries to take the overhead into account.
 */
long long ubifs_get_free_space(struct ubifs_info *c)
{
	int min_idx_lebs, rsvd_idx_lebs, lebs;
	long long available, outstanding, free;

	spin_lock(&c->space_lock);
	min_idx_lebs = ubifs_calc_min_idx_lebs(c);
	outstanding = c->budg_data_growth + c->budg_dd_growth;

	/*
	 * Force the amount available to the total size reported if the used
	 * space is zero.
	 */
	if (c->lst.total_used <= UBIFS_INO_NODE_SZ && !outstanding) {
		spin_unlock(&c->space_lock);
		return (long long)c->block_cnt << UBIFS_BLOCK_SHIFT;
	}

	available = ubifs_calc_available(c, min_idx_lebs);

	/*
	 * When reporting free space to user-space, UBIFS guarantees that it is
	 * possible to write a file of free space size. This means that for
	 * empty LEBs we may use more precise calculations than
	 * 'ubifs_calc_available()' is using. Namely, we know that in empty
	 * LEBs we would waste only @c->leb_overhead bytes, not @c->dark_wm.
	 * Thus, amend the available space.
	 *
	 * Note, the calculations below are similar to what we have in
	 * 'do_budget_space()', so refer there for comments.
	 */
	if (min_idx_lebs > c->lst.idx_lebs)
		rsvd_idx_lebs = min_idx_lebs - c->lst.idx_lebs;
	else
		rsvd_idx_lebs = 0;
	lebs = c->lst.empty_lebs + c->freeable_cnt + c->idx_gc_cnt -
	       c->lst.taken_empty_lebs;
	lebs -= rsvd_idx_lebs;
	available += lebs * (c->dark_wm - c->leb_overhead);
	spin_unlock(&c->space_lock);

	if (available > outstanding)
		free = ubifs_reported_space(c, available - outstanding);
	else
		free = 0;
	return free;
}
Exemple #5
0
/**
 * ubifs_release_dirty_inode_budget - release dirty inode budget.
 * @c: UBIFS file-system description object
 * @ui: UBIFS inode to release the budget for
 *
 * This function releases budget corresponding to a dirty inode. It is usually
 * called when after the inode has been written to the media and marked as
 * clean.
 */
void ubifs_release_dirty_inode_budget(struct ubifs_info *c,
				      struct ubifs_inode *ui)
{
	struct ubifs_budget_req req = {.dd_growth = c->inode_budget,
				       .dirtied_ino_d = ui->data_len};

	ubifs_release_budget(c, &req);
}

/**
 * ubifs_budg_get_free_space - return amount of free space.
 * @c: UBIFS file-system description object
 *
 * This function returns amount of free space on the file-system.
 */
long long ubifs_budg_get_free_space(struct ubifs_info *c)
{
	int min_idx_lebs, rsvd_idx_lebs;
	long long available, outstanding, free;

	/* Do exactly the same calculations as in 'do_budget_space()' */
	spin_lock(&c->space_lock);
	min_idx_lebs = ubifs_calc_min_idx_lebs(c);

	if (min_idx_lebs > c->lst.idx_lebs)
		rsvd_idx_lebs = min_idx_lebs - c->lst.idx_lebs;
	else
		rsvd_idx_lebs = 0;

	if (rsvd_idx_lebs > c->lst.empty_lebs + c->freeable_cnt + c->idx_gc_cnt
				- c->lst.taken_empty_lebs) {
		spin_unlock(&c->space_lock);
		return 0;
	}

	available = ubifs_calc_available(c, min_idx_lebs);
	outstanding = c->budg_data_growth + c->budg_dd_growth;
	c->min_idx_lebs = min_idx_lebs;
	spin_unlock(&c->space_lock);

	if (available > outstanding)
		free = ubifs_reported_space(c, available - outstanding);
	else
		free = 0;
	return free;
}