forked from Qortal/Brooklyn
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
718 lines
23 KiB
718 lines
23 KiB
// SPDX-License-Identifier: GPL-2.0-only |
|
/* |
|
* This file is part of UBIFS. |
|
* |
|
* Copyright (C) 2006-2008 Nokia Corporation. |
|
* |
|
* 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_nr(c->vfs_sb, nr_to_write, 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(c, req->new_page <= 1); |
|
ubifs_assert(c, req->dirtied_page <= 1); |
|
ubifs_assert(c, req->new_dent <= 1); |
|
ubifs_assert(c, req->mod_dent <= 1); |
|
ubifs_assert(c, req->new_ino <= 1); |
|
ubifs_assert(c, req->new_ino_d <= UBIFS_MAX_INO_DATA); |
|
ubifs_assert(c, req->dirtied_ino <= 4); |
|
ubifs_assert(c, req->dirtied_ino_d <= UBIFS_MAX_INO_DATA * 4); |
|
ubifs_assert(c, !(req->new_ino_d & 7)); |
|
ubifs_assert(c, !(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, c->bi.idx_growth >= 0); |
|
ubifs_assert(c, c->bi.data_growth >= 0); |
|
ubifs_assert(c, 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(c, req->new_page <= 1); |
|
ubifs_assert(c, req->dirtied_page <= 1); |
|
ubifs_assert(c, req->new_dent <= 1); |
|
ubifs_assert(c, req->mod_dent <= 1); |
|
ubifs_assert(c, req->new_ino <= 1); |
|
ubifs_assert(c, req->new_ino_d <= UBIFS_MAX_INO_DATA); |
|
ubifs_assert(c, req->dirtied_ino <= 4); |
|
ubifs_assert(c, req->dirtied_ino_d <= UBIFS_MAX_INO_DATA * 4); |
|
ubifs_assert(c, !(req->new_ino_d & 7)); |
|
ubifs_assert(c, !(req->dirtied_ino_d & 7)); |
|
if (!req->recalculate) { |
|
ubifs_assert(c, req->idx_growth >= 0); |
|
ubifs_assert(c, req->data_growth >= 0); |
|
ubifs_assert(c, 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, c->bi.idx_growth >= 0); |
|
ubifs_assert(c, c->bi.data_growth >= 0); |
|
ubifs_assert(c, c->bi.dd_growth >= 0); |
|
ubifs_assert(c, c->bi.min_idx_lebs < c->main_lebs); |
|
ubifs_assert(c, !(c->bi.idx_growth & 7)); |
|
ubifs_assert(c, !(c->bi.data_growth & 7)); |
|
ubifs_assert(c, !(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, 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; |
|
}
|
|
|