From 41e963368c2f810a200929ac2dc06df83aa7671e 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 (cherry picked from commit 1430cd67d8f7bd7d98b241a7511fa3ceb7e5ba2e) Conflicts: src/include/filepath.cc - Unlike main branch, this file is absent in squid --- src/include/filepath.h | 11 +++++++++++ src/mds/CDentry.cc | 41 ++++++++++++++++++++++++++++++++++++----- src/mds/CDentry.h | 5 ++++- src/mds/CInode.cc | 4 ++-- src/mds/CInode.h | 1 - 5 files changed, 53 insertions(+), 9 deletions(-) diff --git a/src/include/filepath.h b/src/include/filepath.h index 03ae03ee239..92d4b06b2b0 100644 --- a/src/include/filepath.h +++ b/src/include/filepath.h @@ -39,6 +39,9 @@ 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. @@ -93,6 +96,14 @@ class filepath { filepath(std::string_view s) { set_path(s); } filepath(const char* s) { set_path(s); } + void set_trimmed() { + if (trimmed) + return; + // indicates that the path has been shortened. + path += "..."; + trimmed = true; + } + void set_path(std::string_view s, inodeno_t b) { path = s; ino = b; diff --git a/src/mds/CDentry.cc b/src/mds/CDentry.cc index 78fbaf72e1c..f1169049760 100644 --- a/src/mds/CDentry.cc +++ b/src/mds/CDentry.cc @@ -47,7 +47,7 @@ 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; @@ -254,13 +254,44 @@ 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 99f4911ca55..745397c8733 100644 --- a/src/mds/CDentry.h +++ b/src/mds/CDentry.h @@ -241,7 +241,10 @@ 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 e3dcaa04960..c71156a9c1b 100644 --- a/src/mds/CInode.cc +++ b/src/mds/CInode.cc @@ -1089,12 +1089,12 @@ 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 004468800fe..6734d908c97 100644 --- a/src/mds/CInode.h +++ b/src/mds/CInode.h @@ -721,7 +721,6 @@ class CInode : public MDSCacheObject, public InodeStoreBase, public Counter