From 2ed3155c841a35fe9309888fe466621f98d7eff3 Mon Sep 17 00:00:00 2001 From: Greg Kroah-Hartman Date: Thu, 3 Aug 2017 16:03:53 -0700 Subject: [PATCH] 4.12-stable patches added patches: dentry-name-snapshots.patch --- queue-4.12/dentry-name-snapshots.patch | 232 +++++++++++++++++++++++++ queue-4.12/series | 1 + 2 files changed, 233 insertions(+) create mode 100644 queue-4.12/dentry-name-snapshots.patch diff --git a/queue-4.12/dentry-name-snapshots.patch b/queue-4.12/dentry-name-snapshots.patch new file mode 100644 index 00000000000..16125a1b180 --- /dev/null +++ b/queue-4.12/dentry-name-snapshots.patch @@ -0,0 +1,232 @@ +From 49d31c2f389acfe83417083e1208422b4091cd9e Mon Sep 17 00:00:00 2001 +From: Al Viro +Date: Fri, 7 Jul 2017 14:51:19 -0400 +Subject: dentry name snapshots + +From: Al Viro + +commit 49d31c2f389acfe83417083e1208422b4091cd9e upstream. + +take_dentry_name_snapshot() takes a safe snapshot of dentry name; +if the name is a short one, it gets copied into caller-supplied +structure, otherwise an extra reference to external name is grabbed +(those are never modified). In either case the pointer to stable +string is stored into the same structure. + +dentry must be held by the caller of take_dentry_name_snapshot(), +but may be freely dropped afterwards - the snapshot will stay +until destroyed by release_dentry_name_snapshot(). + +Intended use: + struct name_snapshot s; + + take_dentry_name_snapshot(&s, dentry); + ... + access s.name + ... + release_dentry_name_snapshot(&s); + +Replaces fsnotify_oldname_...(), gets used in fsnotify to obtain the name +to pass down with event. + +Signed-off-by: Al Viro +Signed-off-by: Greg Kroah-Hartman + +--- + fs/dcache.c | 27 +++++++++++++++++++++++++++ + fs/debugfs/inode.c | 10 +++++----- + fs/namei.c | 8 ++++---- + fs/notify/fsnotify.c | 8 ++++++-- + include/linux/dcache.h | 6 ++++++ + include/linux/fsnotify.h | 31 ------------------------------- + 6 files changed, 48 insertions(+), 42 deletions(-) + +--- a/fs/dcache.c ++++ b/fs/dcache.c +@@ -277,6 +277,33 @@ static inline int dname_external(const s + return dentry->d_name.name != dentry->d_iname; + } + ++void take_dentry_name_snapshot(struct name_snapshot *name, struct dentry *dentry) ++{ ++ spin_lock(&dentry->d_lock); ++ if (unlikely(dname_external(dentry))) { ++ struct external_name *p = external_name(dentry); ++ atomic_inc(&p->u.count); ++ spin_unlock(&dentry->d_lock); ++ name->name = p->name; ++ } else { ++ memcpy(name->inline_name, dentry->d_iname, DNAME_INLINE_LEN); ++ spin_unlock(&dentry->d_lock); ++ name->name = name->inline_name; ++ } ++} ++EXPORT_SYMBOL(take_dentry_name_snapshot); ++ ++void release_dentry_name_snapshot(struct name_snapshot *name) ++{ ++ if (unlikely(name->name != name->inline_name)) { ++ struct external_name *p; ++ p = container_of(name->name, struct external_name, name[0]); ++ if (unlikely(atomic_dec_and_test(&p->u.count))) ++ kfree_rcu(p, u.head); ++ } ++} ++EXPORT_SYMBOL(release_dentry_name_snapshot); ++ + static inline void __d_set_inode_and_type(struct dentry *dentry, + struct inode *inode, + unsigned type_flags) +--- a/fs/debugfs/inode.c ++++ b/fs/debugfs/inode.c +@@ -766,7 +766,7 @@ struct dentry *debugfs_rename(struct den + { + int error; + struct dentry *dentry = NULL, *trap; +- const char *old_name; ++ struct name_snapshot old_name; + + trap = lock_rename(new_dir, old_dir); + /* Source or destination directories don't exist? */ +@@ -781,19 +781,19 @@ struct dentry *debugfs_rename(struct den + if (IS_ERR(dentry) || dentry == trap || d_really_is_positive(dentry)) + goto exit; + +- old_name = fsnotify_oldname_init(old_dentry->d_name.name); ++ take_dentry_name_snapshot(&old_name, old_dentry); + + error = simple_rename(d_inode(old_dir), old_dentry, d_inode(new_dir), + dentry, 0); + if (error) { +- fsnotify_oldname_free(old_name); ++ release_dentry_name_snapshot(&old_name); + goto exit; + } + d_move(old_dentry, dentry); +- fsnotify_move(d_inode(old_dir), d_inode(new_dir), old_name, ++ fsnotify_move(d_inode(old_dir), d_inode(new_dir), old_name.name, + d_is_dir(old_dentry), + NULL, old_dentry); +- fsnotify_oldname_free(old_name); ++ release_dentry_name_snapshot(&old_name); + unlock_rename(new_dir, old_dir); + dput(dentry); + return old_dentry; +--- a/fs/namei.c ++++ b/fs/namei.c +@@ -4362,11 +4362,11 @@ int vfs_rename(struct inode *old_dir, st + { + int error; + bool is_dir = d_is_dir(old_dentry); +- const unsigned char *old_name; + struct inode *source = old_dentry->d_inode; + struct inode *target = new_dentry->d_inode; + bool new_is_dir = false; + unsigned max_links = new_dir->i_sb->s_max_links; ++ struct name_snapshot old_name; + + if (source == target) + return 0; +@@ -4413,7 +4413,7 @@ int vfs_rename(struct inode *old_dir, st + if (error) + return error; + +- old_name = fsnotify_oldname_init(old_dentry->d_name.name); ++ take_dentry_name_snapshot(&old_name, old_dentry); + dget(new_dentry); + if (!is_dir || (flags & RENAME_EXCHANGE)) + lock_two_nondirectories(source, target); +@@ -4468,14 +4468,14 @@ out: + inode_unlock(target); + dput(new_dentry); + if (!error) { +- fsnotify_move(old_dir, new_dir, old_name, is_dir, ++ fsnotify_move(old_dir, new_dir, old_name.name, is_dir, + !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); + if (flags & RENAME_EXCHANGE) { + fsnotify_move(new_dir, old_dir, old_dentry->d_name.name, + new_is_dir, NULL, new_dentry); + } + } +- fsnotify_oldname_free(old_name); ++ release_dentry_name_snapshot(&old_name); + + return error; + } +--- a/fs/notify/fsnotify.c ++++ b/fs/notify/fsnotify.c +@@ -161,16 +161,20 @@ int __fsnotify_parent(const struct path + if (unlikely(!fsnotify_inode_watches_children(p_inode))) + __fsnotify_update_child_dentry_flags(p_inode); + else if (p_inode->i_fsnotify_mask & mask) { ++ struct name_snapshot name; ++ + /* we are notifying a parent so come up with the new mask which + * specifies these are events which came from a child. */ + mask |= FS_EVENT_ON_CHILD; + ++ take_dentry_name_snapshot(&name, dentry); + if (path) + ret = fsnotify(p_inode, mask, path, FSNOTIFY_EVENT_PATH, +- dentry->d_name.name, 0); ++ name.name, 0); + else + ret = fsnotify(p_inode, mask, dentry->d_inode, FSNOTIFY_EVENT_INODE, +- dentry->d_name.name, 0); ++ name.name, 0); ++ release_dentry_name_snapshot(&name); + } + + dput(parent); +--- a/include/linux/dcache.h ++++ b/include/linux/dcache.h +@@ -591,5 +591,11 @@ static inline struct inode *d_real_inode + return d_backing_inode(d_real((struct dentry *) dentry, NULL, 0)); + } + ++struct name_snapshot { ++ const char *name; ++ char inline_name[DNAME_INLINE_LEN]; ++}; ++void take_dentry_name_snapshot(struct name_snapshot *, struct dentry *); ++void release_dentry_name_snapshot(struct name_snapshot *); + + #endif /* __LINUX_DCACHE_H */ +--- a/include/linux/fsnotify.h ++++ b/include/linux/fsnotify.h +@@ -293,35 +293,4 @@ static inline void fsnotify_change(struc + } + } + +-#if defined(CONFIG_FSNOTIFY) /* notify helpers */ +- +-/* +- * fsnotify_oldname_init - save off the old filename before we change it +- */ +-static inline const unsigned char *fsnotify_oldname_init(const unsigned char *name) +-{ +- return kstrdup(name, GFP_KERNEL); +-} +- +-/* +- * fsnotify_oldname_free - free the name we got from fsnotify_oldname_init +- */ +-static inline void fsnotify_oldname_free(const unsigned char *old_name) +-{ +- kfree(old_name); +-} +- +-#else /* CONFIG_FSNOTIFY */ +- +-static inline const char *fsnotify_oldname_init(const unsigned char *name) +-{ +- return NULL; +-} +- +-static inline void fsnotify_oldname_free(const unsigned char *old_name) +-{ +-} +- +-#endif /* CONFIG_FSNOTIFY */ +- + #endif /* _LINUX_FS_NOTIFY_H */ diff --git a/queue-4.12/series b/queue-4.12/series index 958483e7c6d..b669f5408d9 100644 --- a/queue-4.12/series +++ b/queue-4.12/series @@ -27,3 +27,4 @@ drm-nouveau-bar-gf100-fix-access-to-upper-half-of-bar2.patch drm-i915-fix-scaler-init-during-crtc-hw-state-readout.patch isdn-i4l-fix-buffer-overflow.patch ipmi-watchdog-fix-watchdog-timeout-set-on-reboot.patch +dentry-name-snapshots.patch -- 2.47.3