diff options
Diffstat (limited to 'packfile.c')
| -rw-r--r-- | packfile.c | 113 |
1 files changed, 68 insertions, 45 deletions
diff --git a/packfile.c b/packfile.c index 7e7c04e4d8..f4e752996d 100644 --- a/packfile.c +++ b/packfile.c @@ -1004,12 +1004,14 @@ void reprepare_packed_git(struct repository *r) { struct object_directory *odb; + obj_read_lock(); for (odb = r->objects->odb; odb; odb = odb->next) odb_clear_loose_cache(odb); r->objects->approximate_object_count_valid = 0; r->objects->packed_git_initialized = 0; prepare_packed_git(r); + obj_read_unlock(); } struct packed_git *get_packed_git(struct repository *r) @@ -1086,7 +1088,23 @@ unsigned long get_size_from_delta(struct packed_git *p, do { in = use_pack(p, w_curs, curpos, &stream.avail_in); stream.next_in = in; + /* + * Note: the window section returned by use_pack() must be + * available throughout git_inflate()'s unlocked execution. To + * ensure no other thread will modify the window in the + * meantime, we rely on the packed_window.inuse_cnt. This + * counter is incremented before window reading and checked + * before window disposal. + * + * Other worrying sections could be the call to close_pack_fd(), + * which can close packs even with in-use windows, and to + * reprepare_packed_git(). Regarding the former, mmap doc says: + * "closing the file descriptor does not unmap the region". And + * for the latter, it won't re-open already available packs. + */ + obj_read_unlock(); st = git_inflate(&stream, Z_FINISH); + obj_read_lock(); curpos += stream.next_in - in; } while ((st == Z_OK || st == Z_BUF_ERROR) && stream.total_out < sizeof(delta_head)); @@ -1162,11 +1180,11 @@ const struct packed_git *has_packed_and_bad(struct repository *r, return NULL; } -static off_t get_delta_base(struct packed_git *p, - struct pack_window **w_curs, - off_t *curpos, - enum object_type type, - off_t delta_obj_offset) +off_t get_delta_base(struct packed_git *p, + struct pack_window **w_curs, + off_t *curpos, + enum object_type type, + off_t delta_obj_offset) { unsigned char *base_info = use_pack(p, w_curs, *curpos, NULL); off_t base_offset; @@ -1207,30 +1225,32 @@ static off_t get_delta_base(struct packed_git *p, * the final object lookup), but more expensive for OFS deltas (we * have to load the revidx to convert the offset back into a sha1). */ -static const unsigned char *get_delta_base_sha1(struct packed_git *p, - struct pack_window **w_curs, - off_t curpos, - enum object_type type, - off_t delta_obj_offset) +static int get_delta_base_oid(struct packed_git *p, + struct pack_window **w_curs, + off_t curpos, + struct object_id *oid, + enum object_type type, + off_t delta_obj_offset) { if (type == OBJ_REF_DELTA) { unsigned char *base = use_pack(p, w_curs, curpos, NULL); - return base; + oidread(oid, base); + return 0; } else if (type == OBJ_OFS_DELTA) { struct revindex_entry *revidx; off_t base_offset = get_delta_base(p, w_curs, &curpos, type, delta_obj_offset); if (!base_offset) - return NULL; + return -1; revidx = find_pack_revindex(p, base_offset); if (!revidx) - return NULL; + return -1; - return nth_packed_object_sha1(p, revidx->nr); + return nth_packed_object_id(oid, p, revidx->nr); } else - return NULL; + return -1; } static int retry_bad_packed_offset(struct repository *r, @@ -1243,7 +1263,7 @@ static int retry_bad_packed_offset(struct repository *r, revidx = find_pack_revindex(p, obj_offset); if (!revidx) return OBJ_BAD; - nth_packed_object_oid(&oid, p, revidx->nr); + nth_packed_object_id(&oid, p, revidx->nr); mark_bad_packed_object(p, oid.hash); type = oid_object_info(r, &oid, NULL); if (type <= OBJ_NONE) @@ -1445,6 +1465,14 @@ static void add_delta_base_cache(struct packed_git *p, off_t base_offset, struct delta_base_cache_entry *ent = xmalloc(sizeof(*ent)); struct list_head *lru, *tmp; + /* + * Check required to avoid redundant entries when more than one thread + * is unpacking the same object, in unpack_entry() (since its phases I + * and III might run concurrently across multiple threads). + */ + if (in_delta_base_cache(p, base_offset)) + return; + delta_base_cached += base_size; list_for_each_safe(lru, tmp, &delta_base_cache_lru) { @@ -1530,20 +1558,16 @@ int packed_object_info(struct repository *r, struct packed_git *p, } } - if (oi->delta_base_sha1) { + if (oi->delta_base_oid) { if (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) { - const unsigned char *base; - - base = get_delta_base_sha1(p, &w_curs, curpos, - type, obj_offset); - if (!base) { + if (get_delta_base_oid(p, &w_curs, curpos, + oi->delta_base_oid, + type, obj_offset) < 0) { type = OBJ_BAD; goto out; } - - hashcpy(oi->delta_base_sha1, base); } else - hashclr(oi->delta_base_sha1); + oidclr(oi->delta_base_oid); } oi->whence = in_delta_base_cache(p, obj_offset) ? OI_DBCACHED : @@ -1574,7 +1598,15 @@ static void *unpack_compressed_entry(struct packed_git *p, do { in = use_pack(p, w_curs, curpos, &stream.avail_in); stream.next_in = in; + /* + * Note: we must ensure the window section returned by + * use_pack() will be available throughout git_inflate()'s + * unlocked execution. Please refer to the comment at + * get_size_from_delta() to see how this is done. + */ + obj_read_unlock(); st = git_inflate(&stream, Z_FINISH); + obj_read_lock(); if (!stream.avail_out) break; /* the payload is larger than it should be */ curpos += stream.next_in - in; @@ -1659,7 +1691,7 @@ void *unpack_entry(struct repository *r, struct packed_git *p, off_t obj_offset, off_t len = revidx[1].offset - obj_offset; if (check_pack_crc(p, &w_curs, obj_offset, len, revidx->nr)) { struct object_id oid; - nth_packed_object_oid(&oid, p, revidx->nr); + nth_packed_object_id(&oid, p, revidx->nr); error("bad packed object CRC for %s", oid_to_hex(&oid)); mark_bad_packed_object(p, oid.hash); @@ -1748,7 +1780,7 @@ void *unpack_entry(struct repository *r, struct packed_git *p, off_t obj_offset, struct object_id base_oid; revidx = find_pack_revindex(p, obj_offset); if (revidx) { - nth_packed_object_oid(&base_oid, p, revidx->nr); + nth_packed_object_id(&base_oid, p, revidx->nr); error("failed to read delta base object %s" " at offset %"PRIuMAX" from %s", oid_to_hex(&base_oid), (uintmax_t)obj_offset, @@ -1835,36 +1867,27 @@ int bsearch_pack(const struct object_id *oid, const struct packed_git *p, uint32 index_lookup, index_lookup_width, result); } -const unsigned char *nth_packed_object_sha1(struct packed_git *p, - uint32_t n) +int nth_packed_object_id(struct object_id *oid, + struct packed_git *p, + uint32_t n) { const unsigned char *index = p->index_data; const unsigned int hashsz = the_hash_algo->rawsz; if (!index) { if (open_pack_index(p)) - return NULL; + return -1; index = p->index_data; } if (n >= p->num_objects) - return NULL; + return -1; index += 4 * 256; if (p->index_version == 1) { - return index + (hashsz + 4) * n + 4; + oidread(oid, index + (hashsz + 4) * n + 4); } else { index += 8; - return index + hashsz * n; + oidread(oid, index + hashsz * n); } -} - -const struct object_id *nth_packed_object_oid(struct object_id *oid, - struct packed_git *p, - uint32_t n) -{ - const unsigned char *hash = nth_packed_object_sha1(p, n); - if (!hash) - return NULL; - hashcpy(oid->hash, hash); - return oid; + return 0; } void check_pack_index_ptr(const struct packed_git *p, const void *vptr) @@ -2043,7 +2066,7 @@ int for_each_object_in_pack(struct packed_git *p, else pos = i; - if (!nth_packed_object_oid(&oid, p, pos)) + if (nth_packed_object_id(&oid, p, pos) < 0) return error("unable to get sha1 of object %u in %s", pos, p->pack_name); |