Esempio n. 1
0
/**
 * make_free_space - make more free space on the file-system.
 * @c: UBIFS file-system description object
 *
 * This function is called when an operation cannot be budgeted because there
 * is supposedly no free space. But in most cases there is some free space:
 *   o budgeting is pessimistic, so it always budgets more than it is actually
 *     needed, so shrinking the liability is one way to make free space - the
 *     cached data will take less space then it was budgeted for;
 *   o GC may turn some dark space into free space (budgeting treats dark space
 *     as not available);
 *   o commit may free some LEB, i.e., turn freeable LEBs into free LEBs.
 *
 * So this function tries to do the above. Returns %-EAGAIN if some free space
 * was presumably made and the caller has to re-try budgeting the operation.
 * Returns %-ENOSPC if it couldn't do more free space, and other negative error
 * codes on failures.
 */
static int make_free_space(struct ubifs_info *c)
{
	int err, retries = 0;
	long long liab1, liab2;

	do {
		liab1 = get_liability(c);
		/*
		 * We probably have some dirty pages or inodes (liability), try
		 * to write them back.
		 */
		dbg_budg("liability %lld, run write-back", liab1);
		shrink_liability(c, NR_TO_WRITE);

		liab2 = get_liability(c);
		if (liab2 < liab1)
			return -EAGAIN;

		dbg_budg("new liability %lld (not shrunk)", liab2);

		/* Liability did not shrink again, try GC */
		dbg_budg("Run GC");
		err = run_gc(c);
		if (!err)
			return -EAGAIN;

		if (err != -EAGAIN && err != -ENOSPC)
			/* Some real error happened */
			return err;

		dbg_budg("Run commit (retries %d)", retries);
		err = ubifs_run_commit(c);
		if (err)
			return err;
	} while (retries++ < MAX_MKSPC_RETRIES);

	return -ENOSPC;
}
Esempio n. 2
0
/**
 * make_free_space - make more free space on the file-system.
 * @c: UBIFS file-system description object
 * @ri: information about previous invocations of this function
 *
 * This function is called when an operation cannot be budgeted because there
 * is supposedly no free space. But in most cases there is some free space:
 *   o budgeting is pessimistic, so it always budgets more then it is actually
 *     needed, so shrinking the liability is one way to make free space - the
 *     cached data will take less space then it was budgeted for;
 *   o GC may turn some dark space into free space (budgeting treats dark space
 *     as not available);
 *   o commit may free some LEB, i.e., turn freeable LEBs into free LEBs.
 *
 * So this function tries to do the above. Returns %-EAGAIN if some free space
 * was presumably made and the caller has to re-try budgeting the operation.
 * Returns %-ENOSPC if it couldn't do more free space, and other negative error
 * codes on failures.
 */
static int make_free_space(struct ubifs_info *c, struct retries_info *ri)
{
	int err;

	/*
	 * If we have some dirty pages and inodes (liability), try to write
	 * them back unless this was tried too many times without effect
	 * already.
	 */
	if (ri->shrink_retries < MAX_SHRINK_RETRIES && !ri->try_gc) {
		long long liability;

		spin_lock(&c->space_lock);
		liability = c->budg_idx_growth + c->budg_data_growth +
			    c->budg_dd_growth;
		spin_unlock(&c->space_lock);

		if (ri->prev_liability >= liability) {
			/* Liability does not shrink, next time try GC then */
			ri->shrink_retries += 1;
			if (ri->gc_retries < MAX_GC_RETRIES)
				ri->try_gc = 1;
			dbg_budg("liability did not shrink: retries %d of %d",
				 ri->shrink_retries, MAX_SHRINK_RETRIES);
		}

		dbg_budg("force write-back (count %d)", ri->shrink_cnt);
		shrink_liability(c, NR_TO_WRITE + ri->shrink_cnt);

		ri->prev_liability = liability;
		ri->shrink_cnt += 1;
		return -EAGAIN;
	}

	/*
	 * Try to run garbage collector unless it was already tried too many
	 * times.
	 */
	if (ri->gc_retries < MAX_GC_RETRIES) {
		ri->gc_retries += 1;
		dbg_budg("run GC, retries %d of %d",
			 ri->gc_retries, MAX_GC_RETRIES);

		ri->try_gc = 0;
		err = run_gc(c);
		if (!err)
			return -EAGAIN;

		if (err == -EAGAIN) {
			dbg_budg("GC asked to commit");
			err = ubifs_run_commit(c);
			if (err)
				return err;
			return -EAGAIN;
		}

		if (err != -ENOSPC)
			return err;

		/*
		 * GC could not make any progress. If this is the first time,
		 * then it makes sense to try to commit, because it might make
		 * some dirty space.
		 */
		dbg_budg("GC returned -ENOSPC, retries %d",
			 ri->nospc_retries);
		if (ri->nospc_retries >= MAX_NOSPC_RETRIES)
			return err;
		ri->nospc_retries += 1;
	}

	/* Neither GC nor write-back helped, try to commit */
	if (ri->cmt_retries < MAX_CMT_RETRIES) {
		ri->cmt_retries += 1;
		dbg_budg("run commit, retries %d of %d",
			 ri->cmt_retries, MAX_CMT_RETRIES);
		err = ubifs_run_commit(c);
		if (err)
			return err;
		return -EAGAIN;
	}
	return -ENOSPC;
}