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roots: rework open_root_nocache to use btrfs-tree

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This gets rid of one open-coded btrfs tree search.

Also reduce the log noise level for subvol open failures, and remove
some ancient references to `BEESLOG`.

Signed-off-by: Zygo Blaxell <bees@furryterror.org>
This commit is contained in:
Zygo Blaxell 2025-02-02 23:30:26 -05:00
parent d32f31f411
commit b6446d7316
1 changed files with 61 additions and 79 deletions
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140
src/bees-roots.cc
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@ -1797,90 +1797,72 @@ BeesRoots::open_root_nocache(uint64_t rootid)
}
// Find backrefs for this rootid and follow up to root
BtrfsIoctlSearchKey sk;
sk.tree_id = BTRFS_ROOT_TREE_OBJECTID;
sk.min_objectid = sk.max_objectid = rootid;
sk.min_type = sk.max_type = BTRFS_ROOT_BACKREF_KEY;
BtrfsRootFetcher brf(m_ctx->root_fd());
const auto bti = brf.root_backref(rootid);
if (!bti) {
BEESLOGDEBUG("No path for rootid " << rootid);
BEESCOUNT(root_notfound);
return Fd();
}
BEESTRACE("sk " << sk);
while (sk.min_objectid <= rootid) {
sk.do_ioctl(m_ctx->root_fd());
// Get dirid (path from parent subvol's root to this subvol) and basename (in that dirid)
const auto dirid = bti.root_ref_dirid();
const auto name = bti.root_ref_name();
const auto parent_rootid = bti.offset();
BEESTRACE("parent_rootid " << parent_rootid << " dirid " << dirid << " name " << name);
if (sk.m_result.empty()) {
break;
// Try to open the parent recursively
BEESCOUNT(root_parent_open_try);
Fd parent_fd = open_root(parent_rootid);
if (!parent_fd) {
BEESLOGTRACE("no parent_fd");
BEESCOUNT(root_parent_open_fail);
return Fd();
}
BEESCOUNT(root_parent_open_ok);
if (dirid != BTRFS_FIRST_FREE_OBJECTID) {
BEESTRACE("dirid " << dirid << " root " << rootid << " INO_PATH");
BtrfsIoctlInoPathArgs ino(dirid);
if (!ino.do_ioctl_nothrow(parent_fd)) {
BEESLOGDEBUG("dirid " << dirid << " inode path lookup failed in parent_fd " << name_fd(parent_fd) << ": " << strerror(errno));
BEESCOUNT(root_parent_path_fail);
return Fd();
}
for (auto i : sk.m_result) {
sk.next_min(i, BTRFS_ROOT_BACKREF_KEY);
if (i.type == BTRFS_ROOT_BACKREF_KEY && i.objectid == rootid) {
const auto dirid = btrfs_get_member(&btrfs_root_ref::dirid, i.m_data);
const auto name_len = btrfs_get_member(&btrfs_root_ref::name_len, i.m_data);
const auto name_start = sizeof(struct btrfs_root_ref);
const auto name_end = name_len + name_start;
THROW_CHECK2(runtime_error, i.m_data.size(), name_end, i.m_data.size() >= name_end);
const string name(i.m_data.data() + name_start, i.m_data.data() + name_end);
const auto parent_rootid = i.offset;
// BEESLOG("parent_rootid " << parent_rootid << " dirid " << dirid << " name " << name);
BEESTRACE("parent_rootid " << parent_rootid << " dirid " << dirid << " name " << name);
BEESCOUNT(root_parent_open_try);
Fd parent_fd = open_root(parent_rootid);
if (!parent_fd) {
BEESLOGTRACE("no parent_fd");
BEESCOUNT(root_parent_open_fail);
continue;
}
BEESCOUNT(root_parent_open_ok);
if (dirid != BTRFS_FIRST_FREE_OBJECTID) {
BEESTRACE("dirid " << dirid << " root " << rootid << " INO_PATH");
BtrfsIoctlInoPathArgs ino(dirid);
if (!ino.do_ioctl_nothrow(parent_fd)) {
BEESLOGINFO("dirid " << dirid << " inode path lookup failed in parent_fd " << name_fd(parent_fd) << ": " << strerror(errno));
BEESCOUNT(root_parent_path_fail);
continue;
}
if (ino.m_paths.empty()) {
BEESLOGINFO("dirid " << dirid << " inode has no paths in parent_fd " << name_fd(parent_fd));
BEESCOUNT(root_parent_path_empty);
continue;
}
// Theoretically there is only one, so don't bother looping.
BEESTRACE("dirid " << dirid << " path " << ino.m_paths.at(0));
parent_fd = bees_openat(parent_fd, ino.m_paths.at(0).c_str(), FLAGS_OPEN_DIR);
if (!parent_fd) {
BEESLOGTRACE("no parent_fd from dirid");
BEESCOUNT(root_parent_path_open_fail);
continue;
}
}
// BEESLOG("openat(" << name_fd(parent_fd) << ", " << name << ")");
BEESTRACE("openat(" << name_fd(parent_fd) << ", " << name << ")");
Fd rv = bees_openat(parent_fd, name.c_str(), FLAGS_OPEN_DIR);
if (!rv) {
BEESLOGTRACE("open failed for name " << name << ": " << strerror(errno));
BEESCOUNT(root_open_fail);
continue;
}
BEESCOUNT(root_found);
// Verify correct root ID
// Throw exceptions here because these are very rare events
// and unlike the file open case, we don't have alternatives to try
auto new_root_id = btrfs_get_root_id(rv);
THROW_CHECK2(runtime_error, new_root_id, rootid, new_root_id == rootid);
Stat st(rv);
THROW_CHECK1(runtime_error, st.st_ino, st.st_ino == BTRFS_FIRST_FREE_OBJECTID);
// BEESLOGDEBUG("open_root_nocache " << rootid << ": " << name_fd(rv));
BEESCOUNT(root_ok);
return rv;
}
if (ino.m_paths.empty()) {
BEESLOGDEBUG("dirid " << dirid << " inode has no paths in parent_fd " << name_fd(parent_fd));
BEESCOUNT(root_parent_path_empty);
return Fd();
}
// Theoretically there is only one, so don't bother looping.
BEESTRACE("dirid " << dirid << " path " << ino.m_paths.at(0));
parent_fd = bees_openat(parent_fd, ino.m_paths.at(0).c_str(), FLAGS_OPEN_DIR);
if (!parent_fd) {
BEESLOGTRACE("no parent_fd from dirid");
BEESCOUNT(root_parent_path_open_fail);
return Fd();
}
}
BEESLOGDEBUG("No path for rootid " << rootid);
BEESCOUNT(root_notfound);
return Fd();
BEESTRACE("openat(" << name_fd(parent_fd) << ", " << name << ")");
Fd rv = bees_openat(parent_fd, name.c_str(), FLAGS_OPEN_DIR);
if (!rv) {
BEESLOGTRACE("open failed for name " << name << ": " << strerror(errno));
BEESCOUNT(root_open_fail);
return rv;
}
BEESCOUNT(root_found);
// Verify correct root ID
// Throw exceptions here because these are very rare events
// and unlike the file open case, we don't have alternatives to try
const auto new_root_id = btrfs_get_root_id(rv);
THROW_CHECK2(runtime_error, new_root_id, rootid, new_root_id == rootid);
Stat st(rv);
THROW_CHECK1(runtime_error, st.st_ino, st.st_ino == BTRFS_FIRST_FREE_OBJECTID);
// BEESLOGDEBUG("open_root_nocache " << rootid << ": " << name_fd(rv));
BEESCOUNT(root_ok);
return rv;
}
Fd