/**
* 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;
}
/**
* do_budget_space - reserve flash space for index and data growth.
* @c: UBIFS file-system description object
*
* This function makes sure UBIFS has enough free eraseblocks for index growth
* and data.
*
* When budgeting index space, UBIFS reserves twice as more LEBs as the index
* would take if it was consolidated and written to the flash. This guarantees
* that the "in-the-gaps" commit method always succeeds and UBIFS will always
* be able to commit dirty index. So this function basically adds amount of
* budgeted index space to the size of the current index, multiplies this by 2,
* and makes sure this does not exceed the amount of free eraseblocks.
*
* Notes about @c->min_idx_lebs and @c->lst.idx_lebs variables:
* o @c->lst.idx_lebs is the number of LEBs the index currently uses. It might
* be large, because UBIFS does not do any index consolidation as long as
* there is free space. IOW, the index may take a lot of LEBs, but the LEBs
* will contain a lot of dirt.
* o @c->min_idx_lebs is the the index presumably takes. IOW, the index may be
* consolidated to take up to @c->min_idx_lebs LEBs.
*
* This function returns zero in case of success, and %-ENOSPC in case of
* failure.
*/
static int do_budget_space(struct ubifs_info *c)
{
long long outstanding, available;
int lebs, rsvd_idx_lebs, min_idx_lebs;
/* First budget index space */
min_idx_lebs = ubifs_calc_min_idx_lebs(c);
/* Now 'min_idx_lebs' contains number of LEBs to reserve */
if (min_idx_lebs > c->lst.idx_lebs)
rsvd_idx_lebs = min_idx_lebs - c->lst.idx_lebs;
else
rsvd_idx_lebs = 0;
/*
* The number of LEBs that are available to be used by the index is:
*
* @c->lst.empty_lebs + @c->freeable_cnt + @c->idx_gc_cnt -
* @c->lst.taken_empty_lebs
*
* @empty_lebs are available because they are empty. @freeable_cnt are
* available because they contain only free and dirty space and the
* index allocation always occurs after wbufs are synch'ed.
* @idx_gc_cnt are available because they are index LEBs that have been
* garbage collected (including trivial GC) and are awaiting the commit
* before they can be unmapped - note that the in-the-gaps method will
* grab these if it needs them. @taken_empty_lebs are empty_lebs that
* have already been allocated for some purpose (also includes those
* LEBs on the @idx_gc list).
*
* Note, @taken_empty_lebs may temporarily be higher by one because of
* the way we serialize LEB allocations and budgeting. See a comment in
* 'ubifs_find_free_space()'.
*/
lebs = c->lst.empty_lebs + c->freeable_cnt + c->idx_gc_cnt -
c->lst.taken_empty_lebs;
if (unlikely(rsvd_idx_lebs > lebs)) {
dbg_budg("out of indexing space: min_idx_lebs %d (old %d), "
"rsvd_idx_lebs %d", min_idx_lebs, c->min_idx_lebs,
rsvd_idx_lebs);
return -ENOSPC;
}
available = ubifs_calc_available(c, min_idx_lebs);
outstanding = c->budg_data_growth + c->budg_dd_growth;
if (unlikely(available < outstanding)) {
dbg_budg("out of data space: available %lld, outstanding %lld",
available, outstanding);
return -ENOSPC;
}
if (available - outstanding <= c->rp_size && !can_use_rp(c))
return -ENOSPC;
c->min_idx_lebs = min_idx_lebs;
return 0;
}
/**
* 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_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;
}
