UBIFS: add new flash file system (1e51764a) · Commits · e / devices / android_kernel_oneplus_sm7250

fs/ubifs/budget.c

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		/*
		* This file is part of UBIFS.
		*
		* Copyright (C) 2006-2008 Nokia Corporation.
		*
		* This program is free software; you can redistribute it and/or modify it
		* under the terms of the GNU General Public License version 2 as published by
		* the Free Software Foundation.
		*
		* This program is distributed in the hope that it will be useful, but WITHOUT
		* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
		* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
		* more details.
		*
		* You should have received a copy of the GNU General Public License along with
		* this program; if not, write to the Free Software Foundation, Inc., 51
		* Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
		*
		* Authors: Adrian Hunter
		* Artem Bityutskiy (Битюцкий Артём)
		*/

		/*
		* This file implements the budgeting sub-system which is responsible for UBIFS
		* space management.
		*
		* Factors such as compression, wasted space at the ends of LEBs, space in other
		* journal heads, the effect of updates on the index, and so on, make it
		* impossible to accurately predict the amount of space needed. Consequently
		* approximations are used.
		*/

		#include "ubifs.h"
		#include <linux/writeback.h>
		#include <asm/div64.h>

		/*
		* When pessimistic budget calculations say that there is no enough space,
		* UBIFS starts writing back dirty inodes and pages, doing garbage collection,
		* or committing. The below constants define maximum number of times UBIFS
		* repeats the operations.
		*/
		#define MAX_SHRINK_RETRIES 8
		#define MAX_GC_RETRIES 4
		#define MAX_CMT_RETRIES 2
		#define MAX_NOSPC_RETRIES 1

		/*
		* The below constant defines amount of dirty pages which should be written
		* back at when trying to shrink the liability.
		*/
		#define NR_TO_WRITE 16

		/**
		* struct retries_info - information about re-tries while making free space.
		* @prev_liability: previous liability
		* @shrink_cnt: how many times the liability was shrinked
		* @shrink_retries: count of liability shrink re-tries (increased when
		* liability does not shrink)
		* @try_gc: GC should be tried first
		* @gc_retries: how many times GC was run
		* @cmt_retries: how many times commit has been done
		* @nospc_retries: how many times GC returned %-ENOSPC
		*
		* Since we consider budgeting to be the fast-path, and this structure has to
		* be allocated on stack and zeroed out, we make it smaller using bit-fields.
		*/
		struct retries_info {
		long long prev_liability;
		unsigned int shrink_cnt;
		unsigned int shrink_retries:5;
		unsigned int try_gc:1;
		unsigned int gc_retries:4;
		unsigned int cmt_retries:3;
		unsigned int nospc_retries:1;
		};

		/**
		* shrink_liability - write-back some dirty pages/inodes.
		* @c: UBIFS file-system description object
		* @nr_to_write: how many dirty pages to write-back
		*
		* This function shrinks UBIFS liability by means of writing back some amount
		* of dirty inodes and their pages. Returns the amount of pages which were
		* written back. The returned value does not include dirty inodes which were
		* synchronized.
		*
		* Note, this function synchronizes even VFS inodes which are locked
		* (@i_mutex) by the caller of the budgeting function, because write-back does
		* not touch @i_mutex.
		*/
		static int shrink_liability(struct ubifs_info *c, int nr_to_write)
		{
		int nr_written;
		struct writeback_control wbc = {
		.sync_mode = WB_SYNC_NONE,
		.range_end = LLONG_MAX,
		.nr_to_write = nr_to_write,
		};

		generic_sync_sb_inodes(c->vfs_sb, &wbc);
		nr_written = nr_to_write - wbc.nr_to_write;

		if (!nr_written) {
		/*
		* Re-try again but wait on pages/inodes which are being
		* written-back concurrently (e.g., by pdflush).
		*/
		memset(&wbc, 0, sizeof(struct writeback_control));
		wbc.sync_mode = WB_SYNC_ALL;
		wbc.range_end = LLONG_MAX;
		wbc.nr_to_write = nr_to_write;
		generic_sync_sb_inodes(c->vfs_sb, &wbc);
		nr_written = nr_to_write - wbc.nr_to_write;
		}

		dbg_budg("%d pages were written back", nr_written);
		return nr_written;
		}


		/**
		* run_gc - run garbage collector.
		* @c: UBIFS file-system description object
		*
		* This function runs garbage collector to make some more free space. Returns
		* zero if a free LEB has been produced, %-EAGAIN if commit is required, and a
		* negative error code in case of failure.
		*/
		static int run_gc(struct ubifs_info *c)
		{
		int err, lnum;

		/* Make some free space by garbage-collecting dirty space */
		down_read(&c->commit_sem);
		lnum = ubifs_garbage_collect(c, 1);
		up_read(&c->commit_sem);
		if (lnum < 0)
		return lnum;

		/* GC freed one LEB, return it to lprops */
		dbg_budg("GC freed LEB %d", lnum);
		err = ubifs_return_leb(c, lnum);
		if (err)
		return err;
		return 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;
		}

		/**
		* ubifs_calc_min_idx_lebs - calculate amount of eraseblocks for the index.
		* @c: UBIFS file-system description object
		*
		* This function calculates and returns the number of eraseblocks which should
		* be kept for index usage.
		*/
		int ubifs_calc_min_idx_lebs(struct ubifs_info *c)
		{
		int ret;
		uint64_t idx_size;

		idx_size = c->old_idx_sz + c->budg_idx_growth + c->budg_uncommitted_idx;

		/* And make sure we have twice the index size of space reserved */
		idx_size <<= 1;

		/*
		* We do not maintain 'old_idx_size' as 'old_idx_lebs'/'old_idx_bytes'
		* pair, nor similarly the two variables for the new index size, so we
		* have to do this costly 64-bit division on fast-path.
		*/
		if (do_div(idx_size, c->leb_size - c->max_idx_node_sz))
		ret = idx_size + 1;
		else
		ret = idx_size;
		/*
		* The index head is not available for the in-the-gaps method, so add an
		* extra LEB to compensate.
		*/
		ret += 1;
		/*
		* At present the index needs at least 2 LEBs: one for the index head
		* and one for in-the-gaps method (which currently does not cater for
		* the index head and so excludes it from consideration).
		*/
		if (ret < 2)
		ret = 2;
		return ret;
		}

		/**
		* ubifs_calc_available - calculate available FS space.
		* @c: UBIFS file-system description object
		* @min_idx_lebs: minimum number of LEBs reserved for the index
		*
		* This function calculates and returns amount of FS space available for use.
		*/
		long long ubifs_calc_available(const struct ubifs_info *c, int min_idx_lebs)
		{
		int subtract_lebs;
		long long available;

		/*
		* Force the amount available to the total size reported if the used
		* space is zero.
		*/
		if (c->lst.total_used <= UBIFS_INO_NODE_SZ &&
		c->budg_data_growth + c->budg_dd_growth == 0) {
		/* Do the same calculation as for c->block_cnt */
		available = c->main_lebs - 2;
		available *= c->leb_size - c->dark_wm;
		return available;
		}

		available = c->main_bytes - c->lst.total_used;

		/*
		* Now 'available' contains theoretically available flash space
		* assuming there is no index, so we have to subtract the space which
		* is reserved for the index.
		*/
		subtract_lebs = min_idx_lebs;

		/* Take into account that GC reserves one LEB for its own needs */
		subtract_lebs += 1;

		/*
		* The GC journal head LEB is not really accessible. And since
		* different write types go to different heads, we may count only on
		* one head's space.
		*/
		subtract_lebs += c->jhead_cnt - 1;

		/* We also reserve one LEB for deletions, which bypass budgeting */
		subtract_lebs += 1;

		available -= (long long)subtract_lebs * c->leb_size;

		/* Subtract the dead space which is not available for use */
		available -= c->lst.total_dead;

		/*
		* Subtract dark space, which might or might not be usable - it depends
		* on the data which we have on the media and which will be written. If
		* this is a lot of uncompressed or not-compressible data, the dark
		* space cannot be used.
		*/
		available -= c->lst.total_dark;

		/*
		* However, there is more dark space. The index may be bigger than
		* @min_idx_lebs. Those extra LEBs are assumed to be available, but
		* their dark space is not included in total_dark, so it is subtracted
		* here.
		*/
		if (c->lst.idx_lebs > min_idx_lebs) {
		subtract_lebs = c->lst.idx_lebs - min_idx_lebs;
		available -= subtract_lebs * c->dark_wm;
		}

		/* The calculations are rough and may end up with a negative number */
		return available > 0 ? available : 0;
		}

		/**
		* can_use_rp - check whether the user is allowed to use reserved pool.
		* @c: UBIFS file-system description object
		*
		* UBIFS has so-called "reserved pool" which is flash space reserved
		* for the superuser and for uses whose UID/GID is recorded in UBIFS superblock.
		* This function checks whether current user is allowed to use reserved pool.
		* Returns %1 current user is allowed to use reserved pool and %0 otherwise.
		*/
		static int can_use_rp(struct ubifs_info *c)
		{
		if (current->fsuid == c->rp_uid \|\| capable(CAP_SYS_RESOURCE) \|\|
		(c->rp_gid != 0 && in_group_p(c->rp_gid)))
		return 1;
		return 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;
		}

		/**
		* calc_idx_growth - calculate approximate index growth from budgeting request.
		* @c: UBIFS file-system description object
		* @req: budgeting request
		*
		* For now we assume each new node adds one znode. But this is rather poor
		* approximation, though.
		*/
		static int calc_idx_growth(const struct ubifs_info *c,
		const struct ubifs_budget_req *req)
		{
		int znodes;

		znodes = req->new_ino + (req->new_page << UBIFS_BLOCKS_PER_PAGE_SHIFT) +
		req->new_dent;
		return znodes * c->max_idx_node_sz;
		}

		/**
		* calc_data_growth - calculate approximate amount of new data from budgeting
		* request.
		* @c: UBIFS file-system description object
		* @req: budgeting request
		*/
		static int calc_data_growth(const struct ubifs_info *c,
		const struct ubifs_budget_req *req)
		{
		int data_growth;

		data_growth = req->new_ino ? c->inode_budget : 0;
		if (req->new_page)
		data_growth += c->page_budget;
		if (req->new_dent)
		data_growth += c->dent_budget;
		data_growth += req->new_ino_d;
		return data_growth;
		}

		/**
		* calc_dd_growth - calculate approximate amount of data which makes other data
		* dirty from budgeting request.
		* @c: UBIFS file-system description object
		* @req: budgeting request
		*/
		static int calc_dd_growth(const struct ubifs_info *c,
		const struct ubifs_budget_req *req)
		{
		int dd_growth;

		dd_growth = req->dirtied_page ? c->page_budget : 0;

		if (req->dirtied_ino)
		dd_growth += c->inode_budget << (req->dirtied_ino - 1);
		if (req->mod_dent)
		dd_growth += c->dent_budget;
		dd_growth += req->dirtied_ino_d;
		return dd_growth;
		}

		/**
		* ubifs_budget_space - ensure there is enough space to complete an operation.
		* @c: UBIFS file-system description object
		* @req: budget request
		*
		* This function allocates budget for an operation. It uses pessimistic
		* approximation of how much flash space the operation needs. The goal of this
		* function is to make sure UBIFS always has flash space to flush all dirty
		* pages, dirty inodes, and dirty znodes (liability). This function may force
		* commit, garbage-collection or write-back. Returns zero in case of success,
		* %-ENOSPC if there is no free space and other negative error codes in case of
		* failures.
		*/
		int ubifs_budget_space(struct ubifs_info c, struct ubifs_budget_req req)
		{
		int uninitialized_var(cmt_retries), uninitialized_var(wb_retries);
		int err, idx_growth, data_growth, dd_growth;
		struct retries_info ri;

		ubifs_assert(req->dirtied_ino <= 4);
		ubifs_assert(req->dirtied_ino_d <= UBIFS_MAX_INO_DATA * 4);

		data_growth = calc_data_growth(c, req);
		dd_growth = calc_dd_growth(c, req);
		if (!data_growth && !dd_growth)
		return 0;
		idx_growth = calc_idx_growth(c, req);
		memset(&ri, 0, sizeof(struct retries_info));

		again:
		spin_lock(&c->space_lock);
		ubifs_assert(c->budg_idx_growth >= 0);
		ubifs_assert(c->budg_data_growth >= 0);
		ubifs_assert(c->budg_dd_growth >= 0);

		if (unlikely(c->nospace) && (c->nospace_rp \|\| !can_use_rp(c))) {
		dbg_budg("no space");
		spin_unlock(&c->space_lock);
		return -ENOSPC;
		}

		c->budg_idx_growth += idx_growth;
		c->budg_data_growth += data_growth;
		c->budg_dd_growth += dd_growth;

		err = do_budget_space(c);
		if (likely(!err)) {
		req->idx_growth = idx_growth;
		req->data_growth = data_growth;
		req->dd_growth = dd_growth;
		spin_unlock(&c->space_lock);
		return 0;
		}

		/* Restore the old values */
		c->budg_idx_growth -= idx_growth;
		c->budg_data_growth -= data_growth;
		c->budg_dd_growth -= dd_growth;
		spin_unlock(&c->space_lock);

		if (req->fast) {
		dbg_budg("no space for fast budgeting");
		return err;
		}

		err = make_free_space(c, &ri);
		if (err == -EAGAIN) {
		dbg_budg("try again");
		cond_resched();
		goto again;
		} else if (err == -ENOSPC) {
		dbg_budg("FS is full, -ENOSPC");
		c->nospace = 1;
		if (can_use_rp(c) \|\| c->rp_size == 0)
		c->nospace_rp = 1;
		smp_wmb();
		} else
		ubifs_err("cannot budget space, error %d", err);
		return err;
		}

		/**
		* ubifs_release_budget - release budgeted free space.
		* @c: UBIFS file-system description object
		* @req: budget request
		*
		* This function releases the space budgeted by 'ubifs_budget_space()'. Note,
		* since the index changes (which were budgeted for in @req->idx_growth) will
		* only be written to the media on commit, this function moves the index budget
		* from @c->budg_idx_growth to @c->budg_uncommitted_idx. The latter will be
		* zeroed by the commit operation.
		*/
		void ubifs_release_budget(struct ubifs_info c, struct ubifs_budget_req req)
		{
		ubifs_assert(req->dirtied_ino <= 4);
		ubifs_assert(req->dirtied_ino_d <= UBIFS_MAX_INO_DATA * 4);
		if (!req->recalculate) {
		ubifs_assert(req->idx_growth >= 0);
		ubifs_assert(req->data_growth >= 0);
		ubifs_assert(req->dd_growth >= 0);
		}

		if (req->recalculate) {
		req->data_growth = calc_data_growth(c, req);
		req->dd_growth = calc_dd_growth(c, req);
		req->idx_growth = calc_idx_growth(c, req);
		}

		if (!req->data_growth && !req->dd_growth)
		return;

		c->nospace = c->nospace_rp = 0;
		smp_wmb();

		spin_lock(&c->space_lock);
		c->budg_idx_growth -= req->idx_growth;
		c->budg_uncommitted_idx += req->idx_growth;
		c->budg_data_growth -= req->data_growth;
		c->budg_dd_growth -= req->dd_growth;
		c->min_idx_lebs = ubifs_calc_min_idx_lebs(c);

		ubifs_assert(c->budg_idx_growth >= 0);
		ubifs_assert(c->budg_data_growth >= 0);
		ubifs_assert(c->min_idx_lebs < c->main_lebs);
		spin_unlock(&c->space_lock);
		}

		/**
		* ubifs_convert_page_budget - convert budget of a new page.
		* @c: UBIFS file-system description object
		*
		* This function converts budget which was allocated for a new page of data to
		* the budget of changing an existing page of data. The latter is smaller then
		* the former, so this function only does simple re-calculation and does not
		* involve any write-back.
		*/
		void ubifs_convert_page_budget(struct ubifs_info *c)
		{
		spin_lock(&c->space_lock);
		/* Release the index growth reservation */
		c->budg_idx_growth -= c->max_idx_node_sz << UBIFS_BLOCKS_PER_PAGE_SHIFT;
		/* Release the data growth reservation */
		c->budg_data_growth -= c->page_budget;
		/* Increase the dirty data growth reservation instead */
		c->budg_dd_growth += c->page_budget;
		/* And re-calculate the indexing space reservation */
		c->min_idx_lebs = ubifs_calc_min_idx_lebs(c);
		spin_unlock(&c->space_lock);
		}

		/**
		* 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;
		}