static int __seq_set_init(const struct lu_env *env,
struct lu_server_seq *seq)
{
struct lu_seq_range *space = &seq->lss_space;
int rc;
range_alloc(&seq->lss_lowater_set, space, seq->lss_set_width);
range_alloc(&seq->lss_hiwater_set, space, seq->lss_set_width);
rc = seq_store_update(env, seq, NULL, 1);
return rc;
}
static int __seq_server_alloc_super(struct lu_server_seq *seq,
struct lu_seq_range *out,
const struct lu_env *env)
{
struct lu_seq_range *space = &seq->lss_space;
int rc;
ENTRY;
LASSERT(range_is_sane(space));
if (range_is_exhausted(space)) {
CERROR("%s: Sequences space is exhausted\n",
seq->lss_name);
RETURN(-ENOSPC);
} else {
range_alloc(out, space, seq->lss_width);
}
rc = seq_store_update(env, seq, out, 1 /* sync */);
LCONSOLE_INFO("%s: super-sequence allocation rc = %d " DRANGE"\n",
seq->lss_name, rc, PRANGE(out));
RETURN(rc);
}
/*
* This function implements new seq allocation algorithm using async
* updates to seq file on disk. ref bug 18857 for details.
* there are four variable to keep track of this process
*
* lss_space; - available lss_space
* lss_lowater_set; - lu_seq_range for all seqs before barrier, i.e. safe to use
* lss_hiwater_set; - lu_seq_range after barrier, i.e. allocated but may be
* not yet committed
*
* when lss_lowater_set reaches the end it is replaced with hiwater one and
* a write operation is initiated to allocate new hiwater range.
* if last seq write opearion is still not commited, current operation is
* flaged as sync write op.
*/
static int range_alloc_set(const struct lu_env *env,
struct lu_seq_range *out,
struct lu_server_seq *seq)
{
struct lu_seq_range *space = &seq->lss_space;
struct lu_seq_range *loset = &seq->lss_lowater_set;
struct lu_seq_range *hiset = &seq->lss_hiwater_set;
int rc = 0;
if (lu_seq_range_is_zero(loset))
__seq_set_init(env, seq);
if (OBD_FAIL_CHECK(OBD_FAIL_SEQ_ALLOC)) /* exhaust set */
loset->lsr_start = loset->lsr_end;
if (lu_seq_range_is_exhausted(loset)) {
/* reached high water mark. */
struct lu_device *dev = seq->lss_site->ss_lu->ls_top_dev;
int obd_num_clients = dev->ld_obd->obd_num_exports;
__u64 set_sz;
/* calculate new seq width based on number of clients */
set_sz = max(seq->lss_set_width,
obd_num_clients * seq->lss_width);
set_sz = min(lu_seq_range_space(space), set_sz);
/* Switch to hiwater range now */
*loset = *hiset;
/* allocate new hiwater range */
range_alloc(hiset, space, set_sz);
/* update ondisk seq with new *space */
rc = seq_store_update(env, seq, NULL, seq->lss_need_sync);
}
LASSERTF(!lu_seq_range_is_exhausted(loset) ||
lu_seq_range_is_sane(loset),
DRANGE"\n", PRANGE(loset));
if (rc == 0)
range_alloc(out, loset, seq->lss_width);
RETURN(rc);
}