Using the libnbd format, pair of uint32_t per extent makes the code harder to understand. Add extent struct and convert the extent entries to simpler extent array. Signed-off-by: Nir Soffer <nsoffer@redhat.com> --- examples/copy-libev.c | 59 +++++++++++++++++++++++++------------------ 1 file changed, 34 insertions(+), 25 deletions(-) diff --git a/examples/copy-libev.c b/examples/copy-libev.c index 2e39465..c6ae5be 100644 --- a/examples/copy-libev.c +++ b/examples/copy-libev.c @@ -91,25 +91,23 @@ struct request { enum request_state state; }; +struct extent { + uint32_t length; + bool zero; +}; + static struct ev_loop *loop; static ev_prepare prepare; static struct connection src; static struct connection dst; static struct request requests[MAX_REQUESTS]; -/* List of extents received from source server. Using the same format returned - * by libnbd, array of uint32_t pairs. The first item is the length of the - * extent, and the second is the extent flags. - * - * The number of extents is extents_len / 2. extents_pos is the index of the - * current extent. - * - * extents_in_progress flag is set when we start asynchronous block status - * request. - */ -static uint32_t *extents; +/* List of extents received from source server. */ +static struct extent *extents; static size_t extents_len; static size_t extents_pos; + +/* Set when we start asynchronous block status request. */ static bool extents_in_progress; static int64_t size; @@ -191,15 +189,26 @@ extent_callback (void *user_data, const char *metacontext, uint64_t offset, return 1; } - extents = malloc (nr_entries * sizeof *extents); + /* Libnbd returns uint32_t pair (length, flags) for each extent. */ + extents_len = nr_entries / 2; + + extents = malloc (extents_len * sizeof *extents); if (extents == NULL) FAIL ("Cannot allocated extents: %s", strerror (errno)); - memcpy (extents, entries, nr_entries * sizeof *extents); - extents_len = nr_entries; + /* Copy libnbd entries to extents array. */ + for (int i = 0, j = 0; i < extents_len; i++, j=i*2) { + extents[i].length = entries[j]; + + /* Libnbd exposes both ZERO and HOLE flags. We care only about + * ZERO status, meaning we can copy this extent using efficinet + * zero method. + */ + extents[i].zero = (entries[j + 1] & LIBNBD_STATE_ZERO) != 0; + } DEBUG ("r%d: received %d extents for %s", - r->index, nr_entries / 2, metacontext); + r->index, extents_len, metacontext); return 1; } @@ -278,7 +287,7 @@ next_extent (struct request *r) assert (extents); - is_zero = extents[extents_pos + 1] & LIBNBD_STATE_ZERO; + is_zero = extents[extents_pos].zero; /* Zero can be much faster, so try to zero entire extent. */ if (is_zero && dst.can_zero) @@ -288,30 +297,30 @@ next_extent (struct request *r) while (length < limit) { DEBUG ("e%d: offset=%ld len=%ld zero=%d", - extents_pos / 2, offset, extents[extents_pos], is_zero); + extents_pos, offset, extents[extents_pos].length, is_zero); /* If this extent is too large, steal some data from it to * complete the request. */ - if (length + extents[extents_pos] > limit) { + if (length + extents[extents_pos].length > limit) { uint32_t stolen = limit - length; - extents[extents_pos] -= stolen; + extents[extents_pos].length -= stolen; length += stolen; break; } /* Consume the entire extent and start looking at the next one. */ - length += extents[extents_pos]; - extents[extents_pos] = 0; + length += extents[extents_pos].length; + extents[extents_pos].length = 0; - if (extents_pos + 2 == extents_len) + if (extents_pos + 1 == extents_len) break; - extents_pos += 2; + extents_pos++; /* If next extent is different, we are done. */ - if ((extents[extents_pos + 1] & LIBNBD_STATE_ZERO) != is_zero) + if (extents[extents_pos].zero != is_zero) break; } @@ -326,7 +335,7 @@ next_extent (struct request *r) offset += length; - if (extents_pos + 2 == extents_len && extents[extents_pos] == 0) { + if (extents_pos + 1 == extents_len && extents[extents_pos].length == 0) { /* Processed all extents, clear extents. */ DEBUG ("r%d: consumed all extents offset=%ld", r->index, offset); free (extents); -- 2.26.3