/**
* 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;
}
/**
* make_reservation - reserve journal space.
* @c: UBIFS file-system description object
* @jhead: journal head
* @len: how many bytes to reserve
*
* This function makes space reservation in journal head @jhead. The function
* takes the commit lock and locks the journal head, and the caller has to
* unlock the head and finish the reservation with 'finish_reservation()'.
* Returns zero in case of success and a negative error code in case of
* failure.
*
* Note, the journal head may be unlocked as soon as the data is written, while
* the commit lock has to be released after the data has been added to the
* TNC.
*/
static int make_reservation(struct ubifs_info *c, int jhead, int len)
{
int err, cmt_retries = 0, nospc_retries = 0;
ubifs_assert(len <= c->dark_wm);
again:
down_read(&c->commit_sem);
err = reserve_space(c, jhead, len);
if (!err)
return 0;
up_read(&c->commit_sem);
if (err == -ENOSPC) {
/*
* GC could not make any progress. We should try to commit
* once because it could make some dirty space and GC would
* make progress, so make the error -EAGAIN so that the below
* will commit and re-try.
*/
if (nospc_retries++ < 2) {
dbg_jrn("no space, retry");
err = -EAGAIN;
}
/*
* This means that the budgeting is incorrect. We always have
* to be able to write to the media, because all operations are
* budgeted. Deletions are not budgeted, though, but we reserve
* an extra LEB for them.
*/
}
if (err != -EAGAIN)
goto out;
/*
* -EAGAIN means that the journal is full or too large, or the above
* code wants to do one commit. Do this and re-try.
*/
if (cmt_retries > 128) {
/*
* This should not happen unless the journal size limitations
* are too tough.
*/
ubifs_err("stuck in space allocation");
err = -ENOSPC;
goto out;
} else if (cmt_retries > 32)
ubifs_warn("too many space allocation re-tries (%d)",
cmt_retries);
dbg_jrn("-EAGAIN, commit and retry (retried %d times)",
cmt_retries);
cmt_retries += 1;
err = ubifs_run_commit(c);
if (err)
return err;
goto again;
out:
ubifs_err("cannot reserve %d bytes in jhead %d, error %d",
len, jhead, err);
if (err == -ENOSPC) {
/* This are some budgeting problems, print useful information */
down_write(&c->commit_sem);
spin_lock(&c->space_lock);
dbg_dump_stack();
dbg_dump_budg(c);
spin_unlock(&c->space_lock);
dbg_dump_lprops(c);
cmt_retries = dbg_check_lprops(c);
up_write(&c->commit_sem);
}
return err;
}
/**
* make_free_space - make more free space on the file-system.
* @c: UBIFS file-system description object
* @ri: information about previous invocations of this function
*
* This function is called when an operation cannot be budgeted because there
* is supposedly no free space. But in most cases there is some free space:
* o budgeting is pessimistic, so it always budgets more then it is actually
* needed, so shrinking the liability is one way to make free space - the
* cached data will take less space then it was budgeted for;
* o GC may turn some dark space into free space (budgeting treats dark space
* as not available);
* o commit may free some LEB, i.e., turn freeable LEBs into free LEBs.
*
* So this function tries to do the above. Returns %-EAGAIN if some free space
* was presumably made and the caller has to re-try budgeting the operation.
* Returns %-ENOSPC if it couldn't do more free space, and other negative error
* codes on failures.
*/
static int make_free_space(struct ubifs_info *c, struct retries_info *ri)
{
int err;
/*
* If we have some dirty pages and inodes (liability), try to write
* them back unless this was tried too many times without effect
* already.
*/
if (ri->shrink_retries < MAX_SHRINK_RETRIES && !ri->try_gc) {
long long liability;
spin_lock(&c->space_lock);
liability = c->budg_idx_growth + c->budg_data_growth +
c->budg_dd_growth;
spin_unlock(&c->space_lock);
if (ri->prev_liability >= liability) {
/* Liability does not shrink, next time try GC then */
ri->shrink_retries += 1;
if (ri->gc_retries < MAX_GC_RETRIES)
ri->try_gc = 1;
dbg_budg("liability did not shrink: retries %d of %d",
ri->shrink_retries, MAX_SHRINK_RETRIES);
}
dbg_budg("force write-back (count %d)", ri->shrink_cnt);
shrink_liability(c, NR_TO_WRITE + ri->shrink_cnt);
ri->prev_liability = liability;
ri->shrink_cnt += 1;
return -EAGAIN;
}
/*
* Try to run garbage collector unless it was already tried too many
* times.
*/
if (ri->gc_retries < MAX_GC_RETRIES) {
ri->gc_retries += 1;
dbg_budg("run GC, retries %d of %d",
ri->gc_retries, MAX_GC_RETRIES);
ri->try_gc = 0;
err = run_gc(c);
if (!err)
return -EAGAIN;
if (err == -EAGAIN) {
dbg_budg("GC asked to commit");
err = ubifs_run_commit(c);
if (err)
return err;
return -EAGAIN;
}
if (err != -ENOSPC)
return err;
/*
* GC could not make any progress. If this is the first time,
* then it makes sense to try to commit, because it might make
* some dirty space.
*/
dbg_budg("GC returned -ENOSPC, retries %d",
ri->nospc_retries);
if (ri->nospc_retries >= MAX_NOSPC_RETRIES)
return err;
ri->nospc_retries += 1;
}
/* Neither GC nor write-back helped, try to commit */
if (ri->cmt_retries < MAX_CMT_RETRIES) {
ri->cmt_retries += 1;
dbg_budg("run commit, retries %d of %d",
ri->cmt_retries, MAX_CMT_RETRIES);
err = ubifs_run_commit(c);
if (err)
return err;
return -EAGAIN;
}
return -ENOSPC;
}
