| Message ID | 20230911163846.27197-25-mwilck@suse.com (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Delegated to: | christophe varoqui |
| Headers | show |
| Series | multipath-tools: user-friendly names rework | expand |
On Mon, Sep 11, 2023 at 06:38:33PM +0200, mwilck@suse.com wrote: > From: Martin Wilck <mwilck@suse.com> > > If we can assume that the bindings array is totally ordered for every > prefix, which the previous patch guarantees, the search for a free ID can be > simplified. > Reviewed-by: Benjamin Marzinski <bmarzins@redhat.com> > Signed-off-by: Martin Wilck <mwilck@suse.com> > --- > libmultipath/alias.c | 87 ++++++++++---------------------------------- > 1 file changed, 19 insertions(+), 68 deletions(-) > > diff --git a/libmultipath/alias.c b/libmultipath/alias.c > index af6565b..66e34e3 100644 > --- a/libmultipath/alias.c > +++ b/libmultipath/alias.c > @@ -356,83 +356,34 @@ int get_free_id(const Bindings *bindings, const char *prefix, const char *map_ww > { > const struct binding *bdg; > int i, id = 1; > - int biggest_id = 1; > - int smallest_bigger_id = INT_MAX; > > vector_foreach_slot(bindings, bdg, i) { > int curr_id = scan_devname(bdg->alias, prefix); > > - /* > - * Find an unused index - explanation of the algorithm > - * > - * ID: 1 = mpatha, 2 = mpathb, ... > - * > - * We assume the bindings are unsorted. The only constraint > - * is that no ID occurs more than once. IDs that occur in the > - * bindings are called "used". > - * > - * We call the list 1,2,3,..., exactly in this order, the list > - * of "expected" IDs. The variable "id" always holds the next > - * "expected" ID, IOW the last "expected" ID encountered plus 1. > - * Thus all IDs below "id" are known to be used. However, at the > - * end of the loop, the value of "id" isn't necessarily unused. > - * > - * "smallest_bigger_id" is the smallest used ID that was > - * encountered while it was larger than the next "expected" ID > - * at that iteration. Let X be some used ID. If all IDs below X > - * are used and encountered in the right sequence before X, "id" > - * will be > X when the loop ends. Otherwise, X was encountered > - * "out of order", the condition (X > id) holds when X is > - * encountered, and "smallest_bigger_id" will be set to X; i.e. > - * it will be less or equal than X when the loop ends. > - * > - * At the end of the loop, (id < smallest_bigger_id) means that > - * the value of "id" had been encountered neither in order nor > - * out of order, and is thus unused. (id >= smallest_bigger_id) > - * means that "id"'s value is in use. In this case, we play safe > - * and use "biggest_id + 1" as the next value to try. > - * > - * biggest_id is always > smallest_bigger_id, except in the > - * "perfectly ordered" case. > - */ > - if (curr_id == id) { > - if (id < INT_MAX) > - id++; > - else { > - id = -1; > - break; > - } > + if (curr_id == -1) > + continue; > + if (id > curr_id) { > + condlog(0, "%s: ERROR: bindings are not sorted", __func__); > + return -1; > } > - if (curr_id > biggest_id) > - biggest_id = curr_id; > - > - if (curr_id > id && curr_id < smallest_bigger_id) > - smallest_bigger_id = curr_id; > - } > - > - if (id >= smallest_bigger_id) > - id = biggest_id < INT_MAX ? biggest_id + 1 : -1; > - > - if (id > 0) { > - while(id_already_taken(id, prefix, map_wwid)) { > - if (id == INT_MAX) { > - id = -1; > - break; > - } > + while (id < curr_id && id_already_taken(id, prefix, map_wwid)) > id++; > - if (id == smallest_bigger_id) { > - if (biggest_id == INT_MAX) { > - id = -1; > - break; > - } > - if (biggest_id >= smallest_bigger_id) > - id = biggest_id + 1; > - } > - } > + if (id < curr_id) > + return id; > + id++; > + if (id <= 0) > + break; > } > > - if (id < 0) > + for (; id > 0; id++) { > + if (!id_already_taken(id, prefix, map_wwid)) > + break; > + } > + > + if (id <= 0) { > + id = -1; > condlog(0, "no more available user_friendly_names"); > + } > return id; > } > > -- > 2.42.0 -- dm-devel mailing list dm-devel@redhat.com https://listman.redhat.com/mailman/listinfo/dm-devel
diff --git a/libmultipath/alias.c b/libmultipath/alias.c index af6565b..66e34e3 100644 --- a/libmultipath/alias.c +++ b/libmultipath/alias.c @@ -356,83 +356,34 @@ int get_free_id(const Bindings *bindings, const char *prefix, const char *map_ww { const struct binding *bdg; int i, id = 1; - int biggest_id = 1; - int smallest_bigger_id = INT_MAX; vector_foreach_slot(bindings, bdg, i) { int curr_id = scan_devname(bdg->alias, prefix); - /* - * Find an unused index - explanation of the algorithm - * - * ID: 1 = mpatha, 2 = mpathb, ... - * - * We assume the bindings are unsorted. The only constraint - * is that no ID occurs more than once. IDs that occur in the - * bindings are called "used". - * - * We call the list 1,2,3,..., exactly in this order, the list - * of "expected" IDs. The variable "id" always holds the next - * "expected" ID, IOW the last "expected" ID encountered plus 1. - * Thus all IDs below "id" are known to be used. However, at the - * end of the loop, the value of "id" isn't necessarily unused. - * - * "smallest_bigger_id" is the smallest used ID that was - * encountered while it was larger than the next "expected" ID - * at that iteration. Let X be some used ID. If all IDs below X - * are used and encountered in the right sequence before X, "id" - * will be > X when the loop ends. Otherwise, X was encountered - * "out of order", the condition (X > id) holds when X is - * encountered, and "smallest_bigger_id" will be set to X; i.e. - * it will be less or equal than X when the loop ends. - * - * At the end of the loop, (id < smallest_bigger_id) means that - * the value of "id" had been encountered neither in order nor - * out of order, and is thus unused. (id >= smallest_bigger_id) - * means that "id"'s value is in use. In this case, we play safe - * and use "biggest_id + 1" as the next value to try. - * - * biggest_id is always > smallest_bigger_id, except in the - * "perfectly ordered" case. - */ - if (curr_id == id) { - if (id < INT_MAX) - id++; - else { - id = -1; - break; - } + if (curr_id == -1) + continue; + if (id > curr_id) { + condlog(0, "%s: ERROR: bindings are not sorted", __func__); + return -1; } - if (curr_id > biggest_id) - biggest_id = curr_id; - - if (curr_id > id && curr_id < smallest_bigger_id) - smallest_bigger_id = curr_id; - } - - if (id >= smallest_bigger_id) - id = biggest_id < INT_MAX ? biggest_id + 1 : -1; - - if (id > 0) { - while(id_already_taken(id, prefix, map_wwid)) { - if (id == INT_MAX) { - id = -1; - break; - } + while (id < curr_id && id_already_taken(id, prefix, map_wwid)) id++; - if (id == smallest_bigger_id) { - if (biggest_id == INT_MAX) { - id = -1; - break; - } - if (biggest_id >= smallest_bigger_id) - id = biggest_id + 1; - } - } + if (id < curr_id) + return id; + id++; + if (id <= 0) + break; } - if (id < 0) + for (; id > 0; id++) { + if (!id_already_taken(id, prefix, map_wwid)) + break; + } + + if (id <= 0) { + id = -1; condlog(0, "no more available user_friendly_names"); + } return id; }