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Diffstat (limited to 'fs/ubifs/budget.c')
| -rw-r--r-- | fs/ubifs/budget.c | 730 |
1 files changed, 730 insertions, 0 deletions
diff --git a/fs/ubifs/budget.c b/fs/ubifs/budget.c new file mode 100644 index 000000000..11a11b32a --- /dev/null +++ b/fs/ubifs/budget.c @@ -0,0 +1,730 @@ +/* + * 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 <linux/math64.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 constant defines maximum number of times UBIFS + * repeats the operations. + */ +#define MAX_MKSPC_RETRIES 3 + +/* + * 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 + +/** + * 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. + * + * 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 void shrink_liability(struct ubifs_info *c, int nr_to_write) +{ + down_read(&c->vfs_sb->s_umount); + writeback_inodes_sb(c->vfs_sb, WB_REASON_FS_FREE_SPACE); + up_read(&c->vfs_sb->s_umount); +} + +/** + * 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; +} + +/** + * get_liability - calculate current liability. + * @c: UBIFS file-system description object + * + * This function calculates and returns current UBIFS liability, i.e. the + * amount of bytes UBIFS has "promised" to write to the media. + */ +static long long get_liability(struct ubifs_info *c) +{ + long long liab; + + spin_lock(&c->space_lock); + liab = c->bi.idx_growth + c->bi.data_growth + c->bi.dd_growth; + spin_unlock(&c->space_lock); + return liab; +} + +/** + * 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; +} + +/** + * ubifs_calc_min_idx_lebs - calculate amount of LEBs for the index. + * @c: UBIFS file-system description object + * + * This function calculates and returns the number of LEBs which should be kept + * for index usage. + */ +int ubifs_calc_min_idx_lebs(struct ubifs_info *c) +{ + int idx_lebs; + long long idx_size; + + idx_size = c->bi.old_idx_sz + c->bi.idx_growth + c->bi.uncommitted_idx; + /* And make sure we have thrice the index size of space reserved */ + idx_size += 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. + */ + idx_lebs = div_u64(idx_size + c->idx_leb_size - 1, c->idx_leb_size); + /* + * The index head is not available for the in-the-gaps method, so add an + * extra LEB to compensate. + */ + idx_lebs += 1; + if (idx_lebs < MIN_INDEX_LEBS) + idx_lebs = MIN_INDEX_LEBS; + return idx_lebs; +} + +/** + * 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; + + 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 (uid_eq(current_fsuid(), c->rp_uid) || capable(CAP_SYS_RESOURCE) || + (!gid_eq(c->rp_gid, GLOBAL_ROOT_GID) && 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 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; +} + +/** + * 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->bi.inode_budget : 0; + if (req->new_page) + data_growth += c->bi.page_budget; + if (req->new_dent) + data_growth += c->bi.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->bi.page_budget : 0; + + if (req->dirtied_ino) + dd_growth += c->bi.inode_budget << (req->dirtied_ino - 1); + if (req->mod_dent) + dd_growth += c->bi.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 err, idx_growth, data_growth, dd_growth, retried = 0; + + ubifs_assert(req->new_page <= 1); + ubifs_assert(req->dirtied_page <= 1); + ubifs_assert(req->new_dent <= 1); + ubifs_assert(req->mod_dent <= 1); + ubifs_assert(req->new_ino <= 1); + ubifs_assert(req->new_ino_d <= UBIFS_MAX_INO_DATA); + ubifs_assert(req->dirtied_ino <= 4); + ubifs_assert(req->dirtied_ino_d <= UBIFS_MAX_INO_DATA * 4); + ubifs_assert(!(req->new_ino_d & 7)); + ubifs_assert(!(req->dirtied_ino_d & 7)); + + 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); + +again: + spin_lock(&c->space_lock); + ubifs_assert(c->bi.idx_growth >= 0); + ubifs_assert(c->bi.data_growth >= 0); + ubifs_assert(c->bi.dd_growth >= 0); + + if (unlikely(c->bi.nospace) && (c->bi.nospace_rp || !can_use_rp(c))) { + dbg_budg("no space"); + spin_unlock(&c->space_lock); + return -ENOSPC; + } + + c->bi.idx_growth += idx_growth; + c->bi.data_growth += data_growth; + c->bi.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->bi.idx_growth -= idx_growth; + c->bi.data_growth -= data_growth; + c->bi.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); + cond_resched(); + if (err == -EAGAIN) { + dbg_budg("try again"); + goto again; + } else if (err == -ENOSPC) { + if (!retried) { + retried = 1; + dbg_budg("-ENOSPC, but anyway try once again"); + goto again; + } + dbg_budg("FS is full, -ENOSPC"); + c->bi.nospace = 1; + if (can_use_rp(c) || c->rp_size == 0) + c->bi.nospace_rp = 1; + smp_wmb(); + } else + ubifs_err(c, "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->bi.idx_growth to @c->bi.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->new_page <= 1); + ubifs_assert(req->dirtied_page <= 1); + ubifs_assert(req->new_dent <= 1); + ubifs_assert(req->mod_dent <= 1); + ubifs_assert(req->new_ino <= 1); + ubifs_assert(req->new_ino_d <= UBIFS_MAX_INO_DATA); + ubifs_assert(req->dirtied_ino <= 4); + ubifs_assert(req->dirtied_ino_d <= UBIFS_MAX_INO_DATA * 4); + ubifs_assert(!(req->new_ino_d & 7)); + ubifs_assert(!(req->dirtied_ino_d & 7)); + 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->bi.nospace = c->bi.nospace_rp = 0; + smp_wmb(); + + spin_lock(&c->space_lock); + c->bi.idx_growth -= req->idx_growth; + c->bi.uncommitted_idx += req->idx_growth; + c->bi.data_growth -= req->data_growth; + c->bi.dd_growth -= req->dd_growth; + c->bi.min_idx_lebs = ubifs_calc_min_idx_lebs(c); + + ubifs_assert(c->bi.idx_growth >= 0); + ubifs_assert(c->bi.data_growth >= 0); + ubifs_assert(c->bi.dd_growth >= 0); + ubifs_assert(c->bi.min_idx_lebs < c->main_lebs); + ubifs_assert(!(c->bi.idx_growth & 7)); + ubifs_assert(!(c->bi.data_growth & 7)); + ubifs_assert(!(c->bi.dd_growth & 7)); + 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 than + * 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->bi.idx_growth -= c->max_idx_node_sz << UBIFS_BLOCKS_PER_PAGE_SHIFT; + /* Release the data growth reservation */ + c->bi.data_growth -= c->bi.page_budget; + /* Increase the dirty data growth reservation instead */ + c->bi.dd_growth += c->bi.page_budget; + /* And re-calculate the indexing space reservation */ + c->bi.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. It also causes the "no space" flags to be cleared. + */ +void ubifs_release_dirty_inode_budget(struct ubifs_info *c, + struct ubifs_inode *ui) +{ + struct ubifs_budget_req req; + + memset(&req, 0, sizeof(struct ubifs_budget_req)); + /* The "no space" flags will be cleared because dd_growth is > 0 */ + req.dd_growth = c->bi.inode_budget + ALIGN(ui->data_len, 8); + ubifs_release_budget(c, &req); +} + +/** + * ubifs_reported_space - calculate reported free space. + * @c: the UBIFS file-system description object + * @free: amount of free space + * + * This function calculates amount of free space which will be reported to + * user-space. User-space application tend to expect that if the file-system + * (e.g., via the 'statfs()' call) reports that it has N bytes available, they + * are able to write a file of size N. UBIFS attaches node headers to each data + * node and it has to write indexing nodes as well. This introduces additional + * overhead, and UBIFS has to report slightly less free space to meet the above + * expectations. + * + * This function assumes free space is made up of uncompressed data nodes and + * full index nodes (one per data node, tripled because we always allow enough + * space to write the index thrice). + * + * Note, the calculation is pessimistic, which means that most of the time + * UBIFS reports less space than it actually has. + */ +long long ubifs_reported_space(const struct ubifs_info *c, long long free) +{ + int divisor, factor, f; + + /* + * Reported space size is @free * X, where X is UBIFS block size + * divided by UBIFS block size + all overhead one data block + * introduces. The overhead is the node header + indexing overhead. + * + * Indexing overhead calculations are based on the following formula: + * I = N/(f - 1) + 1, where I - number of indexing nodes, N - number + * of data nodes, f - fanout. Because effective UBIFS fanout is twice + * as less than maximum fanout, we assume that each data node + * introduces 3 * @c->max_idx_node_sz / (@c->fanout/2 - 1) bytes. + * Note, the multiplier 3 is because UBIFS reserves thrice as more space + * for the index. + */ + f = c->fanout > 3 ? c->fanout >> 1 : 2; + factor = UBIFS_BLOCK_SIZE; + divisor = UBIFS_MAX_DATA_NODE_SZ; + divisor += (c->max_idx_node_sz * 3) / (f - 1); + free *= factor; + return div_u64(free, divisor); +} + +/** + * 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; +} + +/** + * ubifs_get_free_space - return amount of free space. + * @c: UBIFS file-system description object + * + * This function calculates and returns amount of free space to report to + * user-space. + */ +long long ubifs_get_free_space(struct ubifs_info *c) +{ + long long free; + + spin_lock(&c->space_lock); + free = ubifs_get_free_space_nolock(c); + spin_unlock(&c->space_lock); + + return free; +} |