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-rw-r--r--packfile.c79
1 files changed, 51 insertions, 28 deletions
diff --git a/packfile.c b/packfile.c
index 355066de17..99dd1a7d09 100644
--- a/packfile.c
+++ b/packfile.c
@@ -510,7 +510,6 @@ static int open_packed_git_1(struct packed_git *p)
struct pack_header hdr;
unsigned char hash[GIT_MAX_RAWSZ];
unsigned char *idx_hash;
- long fd_flag;
ssize_t read_result;
const unsigned hashsz = the_hash_algo->rawsz;
@@ -554,16 +553,6 @@ static int open_packed_git_1(struct packed_git *p)
} else if (p->pack_size != st.st_size)
return error("packfile %s size changed", p->pack_name);
- /* We leave these file descriptors open with sliding mmap;
- * there is no point keeping them open across exec(), though.
- */
- fd_flag = fcntl(p->pack_fd, F_GETFD, 0);
- if (fd_flag < 0)
- return error("cannot determine file descriptor flags");
- fd_flag |= FD_CLOEXEC;
- if (fcntl(p->pack_fd, F_SETFD, fd_flag) == -1)
- return error("cannot set FD_CLOEXEC");
-
/* Verify we recognize this pack file format. */
read_result = read_in_full(p->pack_fd, &hdr, sizeof(hdr));
if (read_result < 0)
@@ -587,9 +576,8 @@ static int open_packed_git_1(struct packed_git *p)
" while index indicates %"PRIu32" objects",
p->pack_name, ntohl(hdr.hdr_entries),
p->num_objects);
- if (lseek(p->pack_fd, p->pack_size - hashsz, SEEK_SET) == -1)
- return error("end of packfile %s is unavailable", p->pack_name);
- read_result = read_in_full(p->pack_fd, hash, hashsz);
+ read_result = pread_in_full(p->pack_fd, hash, hashsz,
+ p->pack_size - hashsz);
if (read_result < 0)
return error_errno("error reading from %s", p->pack_name);
if (read_result != hashsz)
@@ -757,6 +745,9 @@ void install_packed_git(struct repository *r, struct packed_git *pack)
pack->next = r->objects->packed_git;
r->objects->packed_git = pack;
+
+ hashmap_entry_init(&pack->packmap_ent, strhash(pack->pack_name));
+ hashmap_add(&r->objects->pack_map, &pack->packmap_ent);
}
void (*report_garbage)(unsigned seen_bits, const char *path);
@@ -856,20 +847,18 @@ static void prepare_pack(const char *full_name, size_t full_name_len,
if (strip_suffix_mem(full_name, &base_len, ".idx") &&
!(data->m && midx_contains_pack(data->m, file_name))) {
- /* Don't reopen a pack we already have. */
- for (p = data->r->objects->packed_git; p; p = p->next) {
- size_t len;
- if (strip_suffix(p->pack_name, ".pack", &len) &&
- len == base_len &&
- !memcmp(p->pack_name, full_name, len))
- break;
- }
+ struct hashmap_entry hent;
+ char *pack_name = xstrfmt("%.*s.pack", (int)base_len, full_name);
+ unsigned int hash = strhash(pack_name);
+ hashmap_entry_init(&hent, hash);
- if (!p) {
+ /* Don't reopen a pack we already have. */
+ if (!hashmap_get(&data->r->objects->pack_map, &hent, pack_name)) {
p = add_packed_git(full_name, full_name_len, data->local);
if (p)
install_packed_git(data->r, p);
}
+ free(pack_name);
}
if (!report_garbage)
@@ -1015,12 +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)
@@ -1097,7 +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));
@@ -1173,11 +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;
@@ -1456,6 +1463,14 @@ 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) {
@@ -1585,7 +1600,15 @@ 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;
generated by cgit v1.2.3 (git 2.25.1) at 2024-12-24 05:16:04 +0000