From 1430cd67d8f7bd7d98b241a7511fa3ceb7e5ba2e Mon Sep 17 00:00:00 2001 From: Rishabh Dave Date: Thu, 21 Aug 2025 17:21:48 +0530 Subject: [PATCH] mds: for logging generate only 10 final components of dentry path Generating full absolute path for dentries for printing in MDS logs slows the down the FS to a great extent especially when the path is very long (imagine a path with 2000 components). Printing such long paths in MDS logs is not only pointless but also greatly reduces the readability of MDS logs. Therefore, generate only 10 final components of the dentry paths for logging. Fixes: https://tracker.ceph.com/issues/72779 Signed-off-by: Rishabh Dave --- src/include/filepath.cc | 8 ++++++++ src/include/filepath.h | 4 ++++ src/mds/CDentry.cc | 41 ++++++++++++++++++++++++++++++++++++----- src/mds/CDentry.h | 5 ++++- src/mds/CInode.cc | 4 ++-- src/mds/CInode.h | 1 - 6 files changed, 54 insertions(+), 9 deletions(-) diff --git a/src/include/filepath.cc b/src/include/filepath.cc index 243bf127d0bbc..f0324f603c4cb 100644 --- a/src/include/filepath.cc +++ b/src/include/filepath.cc @@ -41,6 +41,14 @@ void filepath::parse_bits() const { } } +void filepath::set_trimmed() { + if (trimmed) + return; + // indicates that the path has been shortened. + path += "..."; + trimmed = true; +} + void filepath::set_path(std::string_view s) { if (!s.empty() && s[0] == '/') { path = s.substr(1); diff --git a/src/include/filepath.h b/src/include/filepath.h index 67be4a08759ab..920ffcb95cb44 100644 --- a/src/include/filepath.h +++ b/src/include/filepath.h @@ -38,6 +38,9 @@ namespace ceph { class Formatter; } class filepath { inodeno_t ino = 0; // base inode. ino=0 implies pure relative path. std::string path; // relative path. + // tells get_path() whether it should prefix path with "..." to indicate that + // it was shortened. + bool trimmed = false; /** bits - path segments * this is ['a', 'b', 'c'] for both the aboslute and relative case. @@ -82,6 +85,7 @@ class filepath { // accessors inodeno_t get_ino() const { return ino; } const std::string& get_path() const { return path; } + void set_trimmed(); const char *c_str() const { return path.c_str(); } int length() const { return path.length(); } diff --git a/src/mds/CDentry.cc b/src/mds/CDentry.cc index d2796d4c70935..9a593b60be524 100644 --- a/src/mds/CDentry.cc +++ b/src/mds/CDentry.cc @@ -85,7 +85,7 @@ const LockType CDentry::versionlock_type(CEPH_LOCK_DVERSION); ostream& operator<<(ostream& out, const CDentry& dn) { filepath path; - dn.make_path(path); + dn.make_trimmed_path(path); out << "[dentry " << path; @@ -312,13 +312,44 @@ void CDentry::make_path_string(string& s, bool projected, s.append(name.data(), name.length()); } -void CDentry::make_path(filepath& fp, bool projected) const +/* path_comp_count = path component count. default value is -1 which implies + * generate entire path. + */ +void CDentry::make_path(filepath& fp, bool projected, + int path_comp_count) const { - ceph_assert(dir); - dir->inode->make_path(fp, projected); - fp.push_dentry(get_name()); + fp.set_trimmed(); + + if (path_comp_count == -1) { + ceph_assert(dir); + dir->inode->make_path(fp, projected, path_comp_count); + fp.push_dentry(get_name()); + } else if (path_comp_count >= 1) { + --path_comp_count; + + ceph_assert(dir); + dir->inode->make_path(fp, projected, path_comp_count); + fp.push_dentry(get_name()); + } } +/* path_comp_count = path component count. default value is 10 which implies + * generate entire path. + * + * XXX Generating more than 10 components of a path for printing in logs will + * consume too much time when the path is too long (imagine a path with 2000 + * components) since the path would've to be generated indidividually for each + * log entry. + * + * Besides consuming too much time, such long paths in logs are not only not + * useful but also it makes reading logs harder. Therefore, shorten the path + * when used for logging. + */ +void CDentry::make_trimmed_path(filepath& fp, bool projected, + int path_comp_count) const +{ + make_path(fp, projected, path_comp_count); +} /* * we only add ourselves to remote_parents when the linkage is * active (no longer projected). if the passed dnl is projected, diff --git a/src/mds/CDentry.h b/src/mds/CDentry.h index 67cf9323666e5..769ca4bdc7584 100644 --- a/src/mds/CDentry.h +++ b/src/mds/CDentry.h @@ -254,7 +254,10 @@ public: // misc void make_path_string(std::string& s, bool projected=false, int path_comp_count=-1) const; - void make_path(filepath& fp, bool projected=false) const; + void make_path(filepath& fp, bool projected=false, + int path_comp_count=-1) const; + void make_trimmed_path(filepath& fp, bool projected=false, + int path_comp_count=10) const; // -- version -- version_t get_version() const { return version; } diff --git a/src/mds/CInode.cc b/src/mds/CInode.cc index 2686e887a7aa3..a314023d57559 100644 --- a/src/mds/CInode.cc +++ b/src/mds/CInode.cc @@ -1153,12 +1153,12 @@ void CInode::make_trimmed_path_string(string& s, bool projected, make_path_string(s, projected, use_parent, path_comp_count); } -void CInode::make_path(filepath& fp, bool projected) const +void CInode::make_path(filepath& fp, bool projected, int path_comp_count) const { const CDentry *use_parent = projected ? get_projected_parent_dn() : parent; if (use_parent) { ceph_assert(!is_base()); - use_parent->make_path(fp, projected); + use_parent->make_path(fp, projected, path_comp_count); } else { fp = filepath(ino()); } diff --git a/src/mds/CInode.h b/src/mds/CInode.h index 53ff63ceaefbf..2010085701a28 100644 --- a/src/mds/CInode.h +++ b/src/mds/CInode.h @@ -745,7 +745,6 @@ class CInode : public MDSCacheObject, public InodeStoreBase, public Counter