From: Amir Goldstein amir73il@gmail.com
commit 4d8e7055a4058ee191296699803c5090e14f0dff upstream.
__fsnotify_parent() has an optimization in place to avoid unneeded take_dentry_name_snapshot(). When fsnotify_nameremove() was changed not to call __fsnotify_parent(), we left out the optimization. Kernel test robot reported a 5% performance regression in concurrent unlink() workload.
Reported-by: kernel test robot rong.a.chen@intel.com Link: https://lore.kernel.org/lkml/20190505062153.GG29809@shao2-debian/ Link: https://lore.kernel.org/linux-fsdevel/20190104090357.GD22409@quack2.suse.cz/ Fixes: 5f02a8776384 ("fsnotify: annotate directory entry modification events") CC: stable@vger.kernel.org Signed-off-by: Amir Goldstein amir73il@gmail.com Signed-off-by: Jan Kara jack@suse.cz Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/notify/fsnotify.c | 41 +++++++++++++++++++++++++++++++++++++++ include/linux/fsnotify.h | 33 ------------------------------- include/linux/fsnotify_backend.h | 4 +++ 3 files changed, 45 insertions(+), 33 deletions(-)
--- a/fs/notify/fsnotify.c +++ b/fs/notify/fsnotify.c @@ -108,6 +108,47 @@ void fsnotify_sb_delete(struct super_blo }
/* + * fsnotify_nameremove - a filename was removed from a directory + * + * This is mostly called under parent vfs inode lock so name and + * dentry->d_parent should be stable. However there are some corner cases where + * inode lock is not held. So to be on the safe side and be reselient to future + * callers and out of tree users of d_delete(), we do not assume that d_parent + * and d_name are stable and we use dget_parent() and + * take_dentry_name_snapshot() to grab stable references. + */ +void fsnotify_nameremove(struct dentry *dentry, int isdir) +{ + struct dentry *parent; + struct name_snapshot name; + __u32 mask = FS_DELETE; + + /* d_delete() of pseudo inode? (e.g. __ns_get_path() playing tricks) */ + if (IS_ROOT(dentry)) + return; + + if (isdir) + mask |= FS_ISDIR; + + parent = dget_parent(dentry); + /* Avoid unneeded take_dentry_name_snapshot() */ + if (!(d_inode(parent)->i_fsnotify_mask & FS_DELETE) && + !(dentry->d_sb->s_fsnotify_mask & FS_DELETE)) + goto out_dput; + + take_dentry_name_snapshot(&name, dentry); + + fsnotify(d_inode(parent), mask, d_inode(dentry), FSNOTIFY_EVENT_INODE, + name.name, 0); + + release_dentry_name_snapshot(&name); + +out_dput: + dput(parent); +} +EXPORT_SYMBOL(fsnotify_nameremove); + +/* * Given an inode, first check if we care what happens to our children. Inotify * and dnotify both tell their parents about events. If we care about any event * on a child we run all of our children and set a dentry flag saying that the --- a/include/linux/fsnotify.h +++ b/include/linux/fsnotify.h @@ -152,39 +152,6 @@ static inline void fsnotify_vfsmount_del }
/* - * fsnotify_nameremove - a filename was removed from a directory - * - * This is mostly called under parent vfs inode lock so name and - * dentry->d_parent should be stable. However there are some corner cases where - * inode lock is not held. So to be on the safe side and be reselient to future - * callers and out of tree users of d_delete(), we do not assume that d_parent - * and d_name are stable and we use dget_parent() and - * take_dentry_name_snapshot() to grab stable references. - */ -static inline void fsnotify_nameremove(struct dentry *dentry, int isdir) -{ - struct dentry *parent; - struct name_snapshot name; - __u32 mask = FS_DELETE; - - /* d_delete() of pseudo inode? (e.g. __ns_get_path() playing tricks) */ - if (IS_ROOT(dentry)) - return; - - if (isdir) - mask |= FS_ISDIR; - - parent = dget_parent(dentry); - take_dentry_name_snapshot(&name, dentry); - - fsnotify(d_inode(parent), mask, d_inode(dentry), FSNOTIFY_EVENT_INODE, - name.name, 0); - - release_dentry_name_snapshot(&name); - dput(parent); -} - -/* * fsnotify_inoderemove - an inode is going away */ static inline void fsnotify_inoderemove(struct inode *inode) --- a/include/linux/fsnotify_backend.h +++ b/include/linux/fsnotify_backend.h @@ -355,6 +355,7 @@ extern int __fsnotify_parent(const struc extern void __fsnotify_inode_delete(struct inode *inode); extern void __fsnotify_vfsmount_delete(struct vfsmount *mnt); extern void fsnotify_sb_delete(struct super_block *sb); +extern void fsnotify_nameremove(struct dentry *dentry, int isdir); extern u32 fsnotify_get_cookie(void);
static inline int fsnotify_inode_watches_children(struct inode *inode) @@ -524,6 +525,9 @@ static inline void __fsnotify_vfsmount_d static inline void fsnotify_sb_delete(struct super_block *sb) {}
+static inline void fsnotify_nameremove(struct dentry *dentry, int isdir) +{} + static inline void fsnotify_update_flags(struct dentry *dentry) {}