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![Artem Bityutskiy](/assets/img/avatar_default.png)
This is a new flash file system. See http://www.linux-mtd.infradead.org/doc/ubifs.html Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com> Signed-off-by: Adrian Hunter <ext-adrian.hunter@nokia.com>
731 lines
22 KiB
C
731 lines
22 KiB
C
/*
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* This file is part of UBIFS.
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*
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* Copyright (C) 2006-2008 Nokia Corporation.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 as published by
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* the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License along with
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* this program; if not, write to the Free Software Foundation, Inc., 51
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* Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*
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* Authors: Adrian Hunter
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* Artem Bityutskiy (Битюцкий Артём)
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*/
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/*
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* This file implements the budgeting sub-system which is responsible for UBIFS
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* space management.
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*
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* Factors such as compression, wasted space at the ends of LEBs, space in other
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* journal heads, the effect of updates on the index, and so on, make it
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* impossible to accurately predict the amount of space needed. Consequently
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* approximations are used.
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*/
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#include "ubifs.h"
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#include <linux/writeback.h>
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#include <asm/div64.h>
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/*
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* When pessimistic budget calculations say that there is no enough space,
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* UBIFS starts writing back dirty inodes and pages, doing garbage collection,
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* or committing. The below constants define maximum number of times UBIFS
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* repeats the operations.
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*/
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#define MAX_SHRINK_RETRIES 8
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#define MAX_GC_RETRIES 4
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#define MAX_CMT_RETRIES 2
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#define MAX_NOSPC_RETRIES 1
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/*
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* The below constant defines amount of dirty pages which should be written
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* back at when trying to shrink the liability.
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*/
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#define NR_TO_WRITE 16
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/**
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* struct retries_info - information about re-tries while making free space.
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* @prev_liability: previous liability
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* @shrink_cnt: how many times the liability was shrinked
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* @shrink_retries: count of liability shrink re-tries (increased when
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* liability does not shrink)
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* @try_gc: GC should be tried first
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* @gc_retries: how many times GC was run
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* @cmt_retries: how many times commit has been done
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* @nospc_retries: how many times GC returned %-ENOSPC
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*
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* Since we consider budgeting to be the fast-path, and this structure has to
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* be allocated on stack and zeroed out, we make it smaller using bit-fields.
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*/
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struct retries_info {
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long long prev_liability;
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unsigned int shrink_cnt;
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unsigned int shrink_retries:5;
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unsigned int try_gc:1;
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unsigned int gc_retries:4;
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unsigned int cmt_retries:3;
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unsigned int nospc_retries:1;
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};
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/**
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* shrink_liability - write-back some dirty pages/inodes.
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* @c: UBIFS file-system description object
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* @nr_to_write: how many dirty pages to write-back
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*
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* This function shrinks UBIFS liability by means of writing back some amount
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* of dirty inodes and their pages. Returns the amount of pages which were
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* written back. The returned value does not include dirty inodes which were
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* synchronized.
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*
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* Note, this function synchronizes even VFS inodes which are locked
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* (@i_mutex) by the caller of the budgeting function, because write-back does
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* not touch @i_mutex.
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*/
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static int shrink_liability(struct ubifs_info *c, int nr_to_write)
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{
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int nr_written;
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struct writeback_control wbc = {
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.sync_mode = WB_SYNC_NONE,
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.range_end = LLONG_MAX,
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.nr_to_write = nr_to_write,
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};
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generic_sync_sb_inodes(c->vfs_sb, &wbc);
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nr_written = nr_to_write - wbc.nr_to_write;
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if (!nr_written) {
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/*
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* Re-try again but wait on pages/inodes which are being
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* written-back concurrently (e.g., by pdflush).
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*/
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memset(&wbc, 0, sizeof(struct writeback_control));
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wbc.sync_mode = WB_SYNC_ALL;
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wbc.range_end = LLONG_MAX;
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wbc.nr_to_write = nr_to_write;
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generic_sync_sb_inodes(c->vfs_sb, &wbc);
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nr_written = nr_to_write - wbc.nr_to_write;
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}
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dbg_budg("%d pages were written back", nr_written);
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return nr_written;
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}
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/**
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* run_gc - run garbage collector.
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* @c: UBIFS file-system description object
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*
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* This function runs garbage collector to make some more free space. Returns
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* zero if a free LEB has been produced, %-EAGAIN if commit is required, and a
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* negative error code in case of failure.
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*/
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static int run_gc(struct ubifs_info *c)
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{
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int err, lnum;
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/* Make some free space by garbage-collecting dirty space */
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down_read(&c->commit_sem);
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lnum = ubifs_garbage_collect(c, 1);
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up_read(&c->commit_sem);
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if (lnum < 0)
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return lnum;
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/* GC freed one LEB, return it to lprops */
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dbg_budg("GC freed LEB %d", lnum);
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err = ubifs_return_leb(c, lnum);
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if (err)
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return err;
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return 0;
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}
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/**
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* make_free_space - make more free space on the file-system.
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* @c: UBIFS file-system description object
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* @ri: information about previous invocations of this function
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*
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* This function is called when an operation cannot be budgeted because there
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* is supposedly no free space. But in most cases there is some free space:
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* o budgeting is pessimistic, so it always budgets more then it is actually
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* needed, so shrinking the liability is one way to make free space - the
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* cached data will take less space then it was budgeted for;
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* o GC may turn some dark space into free space (budgeting treats dark space
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* as not available);
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* o commit may free some LEB, i.e., turn freeable LEBs into free LEBs.
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*
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* So this function tries to do the above. Returns %-EAGAIN if some free space
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* was presumably made and the caller has to re-try budgeting the operation.
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* Returns %-ENOSPC if it couldn't do more free space, and other negative error
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* codes on failures.
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*/
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static int make_free_space(struct ubifs_info *c, struct retries_info *ri)
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{
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int err;
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/*
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* If we have some dirty pages and inodes (liability), try to write
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* them back unless this was tried too many times without effect
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* already.
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*/
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if (ri->shrink_retries < MAX_SHRINK_RETRIES && !ri->try_gc) {
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long long liability;
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spin_lock(&c->space_lock);
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liability = c->budg_idx_growth + c->budg_data_growth +
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c->budg_dd_growth;
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spin_unlock(&c->space_lock);
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if (ri->prev_liability >= liability) {
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/* Liability does not shrink, next time try GC then */
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ri->shrink_retries += 1;
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if (ri->gc_retries < MAX_GC_RETRIES)
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ri->try_gc = 1;
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dbg_budg("liability did not shrink: retries %d of %d",
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ri->shrink_retries, MAX_SHRINK_RETRIES);
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}
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dbg_budg("force write-back (count %d)", ri->shrink_cnt);
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shrink_liability(c, NR_TO_WRITE + ri->shrink_cnt);
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ri->prev_liability = liability;
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ri->shrink_cnt += 1;
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return -EAGAIN;
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}
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/*
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* Try to run garbage collector unless it was already tried too many
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* times.
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*/
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if (ri->gc_retries < MAX_GC_RETRIES) {
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ri->gc_retries += 1;
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dbg_budg("run GC, retries %d of %d",
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ri->gc_retries, MAX_GC_RETRIES);
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ri->try_gc = 0;
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err = run_gc(c);
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if (!err)
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return -EAGAIN;
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if (err == -EAGAIN) {
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dbg_budg("GC asked to commit");
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err = ubifs_run_commit(c);
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if (err)
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return err;
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return -EAGAIN;
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}
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if (err != -ENOSPC)
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return err;
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/*
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* GC could not make any progress. If this is the first time,
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* then it makes sense to try to commit, because it might make
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* some dirty space.
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*/
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dbg_budg("GC returned -ENOSPC, retries %d",
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ri->nospc_retries);
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if (ri->nospc_retries >= MAX_NOSPC_RETRIES)
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return err;
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ri->nospc_retries += 1;
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}
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/* Neither GC nor write-back helped, try to commit */
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if (ri->cmt_retries < MAX_CMT_RETRIES) {
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ri->cmt_retries += 1;
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dbg_budg("run commit, retries %d of %d",
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ri->cmt_retries, MAX_CMT_RETRIES);
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err = ubifs_run_commit(c);
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if (err)
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return err;
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return -EAGAIN;
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}
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return -ENOSPC;
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}
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/**
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* ubifs_calc_min_idx_lebs - calculate amount of eraseblocks for the index.
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* @c: UBIFS file-system description object
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*
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* This function calculates and returns the number of eraseblocks which should
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* be kept for index usage.
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*/
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int ubifs_calc_min_idx_lebs(struct ubifs_info *c)
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{
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int ret;
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uint64_t idx_size;
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idx_size = c->old_idx_sz + c->budg_idx_growth + c->budg_uncommitted_idx;
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/* And make sure we have twice the index size of space reserved */
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idx_size <<= 1;
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/*
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* We do not maintain 'old_idx_size' as 'old_idx_lebs'/'old_idx_bytes'
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* pair, nor similarly the two variables for the new index size, so we
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* have to do this costly 64-bit division on fast-path.
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*/
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if (do_div(idx_size, c->leb_size - c->max_idx_node_sz))
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ret = idx_size + 1;
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else
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ret = idx_size;
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/*
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* The index head is not available for the in-the-gaps method, so add an
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* extra LEB to compensate.
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*/
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ret += 1;
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/*
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* At present the index needs at least 2 LEBs: one for the index head
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* and one for in-the-gaps method (which currently does not cater for
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* the index head and so excludes it from consideration).
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*/
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if (ret < 2)
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ret = 2;
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return ret;
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}
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/**
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* ubifs_calc_available - calculate available FS space.
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* @c: UBIFS file-system description object
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* @min_idx_lebs: minimum number of LEBs reserved for the index
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*
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* This function calculates and returns amount of FS space available for use.
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*/
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long long ubifs_calc_available(const struct ubifs_info *c, int min_idx_lebs)
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{
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int subtract_lebs;
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long long available;
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/*
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* Force the amount available to the total size reported if the used
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* space is zero.
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*/
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if (c->lst.total_used <= UBIFS_INO_NODE_SZ &&
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c->budg_data_growth + c->budg_dd_growth == 0) {
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/* Do the same calculation as for c->block_cnt */
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available = c->main_lebs - 2;
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available *= c->leb_size - c->dark_wm;
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return available;
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}
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available = c->main_bytes - c->lst.total_used;
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/*
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* Now 'available' contains theoretically available flash space
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* assuming there is no index, so we have to subtract the space which
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* is reserved for the index.
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*/
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subtract_lebs = min_idx_lebs;
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/* Take into account that GC reserves one LEB for its own needs */
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subtract_lebs += 1;
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/*
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* The GC journal head LEB is not really accessible. And since
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* different write types go to different heads, we may count only on
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* one head's space.
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*/
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subtract_lebs += c->jhead_cnt - 1;
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/* We also reserve one LEB for deletions, which bypass budgeting */
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subtract_lebs += 1;
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available -= (long long)subtract_lebs * c->leb_size;
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/* Subtract the dead space which is not available for use */
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available -= c->lst.total_dead;
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/*
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* Subtract dark space, which might or might not be usable - it depends
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* on the data which we have on the media and which will be written. If
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* this is a lot of uncompressed or not-compressible data, the dark
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* space cannot be used.
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*/
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available -= c->lst.total_dark;
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/*
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* However, there is more dark space. The index may be bigger than
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* @min_idx_lebs. Those extra LEBs are assumed to be available, but
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* their dark space is not included in total_dark, so it is subtracted
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* here.
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*/
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if (c->lst.idx_lebs > min_idx_lebs) {
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subtract_lebs = c->lst.idx_lebs - min_idx_lebs;
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available -= subtract_lebs * c->dark_wm;
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}
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/* The calculations are rough and may end up with a negative number */
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return available > 0 ? available : 0;
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}
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/**
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* can_use_rp - check whether the user is allowed to use reserved pool.
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* @c: UBIFS file-system description object
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*
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* UBIFS has so-called "reserved pool" which is flash space reserved
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* for the superuser and for uses whose UID/GID is recorded in UBIFS superblock.
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* This function checks whether current user is allowed to use reserved pool.
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* Returns %1 current user is allowed to use reserved pool and %0 otherwise.
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*/
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static int can_use_rp(struct ubifs_info *c)
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{
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if (current->fsuid == c->rp_uid || capable(CAP_SYS_RESOURCE) ||
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(c->rp_gid != 0 && in_group_p(c->rp_gid)))
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return 1;
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return 0;
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}
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/**
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* do_budget_space - reserve flash space for index and data growth.
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* @c: UBIFS file-system description object
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*
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* This function makes sure UBIFS has enough free eraseblocks for index growth
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* and data.
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*
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* When budgeting index space, UBIFS reserves twice as more LEBs as the index
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* would take if it was consolidated and written to the flash. This guarantees
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* that the "in-the-gaps" commit method always succeeds and UBIFS will always
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* be able to commit dirty index. So this function basically adds amount of
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* budgeted index space to the size of the current index, multiplies this by 2,
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* and makes sure this does not exceed the amount of free eraseblocks.
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*
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* Notes about @c->min_idx_lebs and @c->lst.idx_lebs variables:
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* o @c->lst.idx_lebs is the number of LEBs the index currently uses. It might
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* be large, because UBIFS does not do any index consolidation as long as
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* there is free space. IOW, the index may take a lot of LEBs, but the LEBs
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* will contain a lot of dirt.
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* o @c->min_idx_lebs is the the index presumably takes. IOW, the index may be
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* consolidated to take up to @c->min_idx_lebs LEBs.
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*
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* This function returns zero in case of success, and %-ENOSPC in case of
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* failure.
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*/
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static int do_budget_space(struct ubifs_info *c)
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{
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long long outstanding, available;
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int lebs, rsvd_idx_lebs, min_idx_lebs;
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/* First budget index space */
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min_idx_lebs = ubifs_calc_min_idx_lebs(c);
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/* Now 'min_idx_lebs' contains number of LEBs to reserve */
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if (min_idx_lebs > c->lst.idx_lebs)
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rsvd_idx_lebs = min_idx_lebs - c->lst.idx_lebs;
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else
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rsvd_idx_lebs = 0;
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/*
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* The number of LEBs that are available to be used by the index is:
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*
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* @c->lst.empty_lebs + @c->freeable_cnt + @c->idx_gc_cnt -
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* @c->lst.taken_empty_lebs
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*
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* @empty_lebs are available because they are empty. @freeable_cnt are
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* available because they contain only free and dirty space and the
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* index allocation always occurs after wbufs are synch'ed.
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* @idx_gc_cnt are available because they are index LEBs that have been
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* garbage collected (including trivial GC) and are awaiting the commit
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* before they can be unmapped - note that the in-the-gaps method will
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* grab these if it needs them. @taken_empty_lebs are empty_lebs that
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* have already been allocated for some purpose (also includes those
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* LEBs on the @idx_gc list).
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*
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* Note, @taken_empty_lebs may temporarily be higher by one because of
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* the way we serialize LEB allocations and budgeting. See a comment in
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* 'ubifs_find_free_space()'.
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*/
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lebs = c->lst.empty_lebs + c->freeable_cnt + c->idx_gc_cnt -
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c->lst.taken_empty_lebs;
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if (unlikely(rsvd_idx_lebs > lebs)) {
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dbg_budg("out of indexing space: min_idx_lebs %d (old %d), "
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"rsvd_idx_lebs %d", min_idx_lebs, c->min_idx_lebs,
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rsvd_idx_lebs);
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return -ENOSPC;
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}
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available = ubifs_calc_available(c, min_idx_lebs);
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outstanding = c->budg_data_growth + c->budg_dd_growth;
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if (unlikely(available < outstanding)) {
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dbg_budg("out of data space: available %lld, outstanding %lld",
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available, outstanding);
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return -ENOSPC;
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}
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if (available - outstanding <= c->rp_size && !can_use_rp(c))
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return -ENOSPC;
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c->min_idx_lebs = min_idx_lebs;
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return 0;
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}
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/**
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* calc_idx_growth - calculate approximate index growth from budgeting request.
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* @c: UBIFS file-system description object
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* @req: budgeting request
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*
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* 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;
|
|
}
|