There is a big mutex in kernfs_dop_revalidate which slows down the concurrent performance of kernfs.
Since kernfs_dop_revalidate only does some checks, the lock is largely unnecessary. Also, according to kernel filesystem locking document: https://www.kernel.org/doc/html/latest/filesystems/locking.html locking is not in the protocal for d_revalidate operation. This patch remove this mutex from kernfs_dop_revalidate, so kernfs_dop_revalidate can run concurrently. Signed-off-by: Fox Chen <foxhlc...@gmail.com> --- fs/kernfs/dir.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-) diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c index 9aec80b9d7c6..c2267c93f546 100644 --- a/fs/kernfs/dir.c +++ b/fs/kernfs/dir.c @@ -26,7 +26,6 @@ static DEFINE_SPINLOCK(kernfs_idr_lock); /* root->ino_idr */ static bool kernfs_active(struct kernfs_node *kn) { - lockdep_assert_held(&kernfs_mutex); return atomic_read(&kn->active) >= 0; } @@ -557,10 +556,9 @@ static int kernfs_dop_revalidate(struct dentry *dentry, unsigned int flags) /* Always perform fresh lookup for negatives */ if (d_really_is_negative(dentry)) - goto out_bad_unlocked; + goto out_bad; kn = kernfs_dentry_node(dentry); - mutex_lock(&kernfs_mutex); /* The kernfs node has been deactivated */ if (!kernfs_active(kn)) @@ -579,11 +577,8 @@ static int kernfs_dop_revalidate(struct dentry *dentry, unsigned int flags) kernfs_info(dentry->d_sb)->ns != kn->ns) goto out_bad; - mutex_unlock(&kernfs_mutex); return 1; out_bad: - mutex_unlock(&kernfs_mutex); -out_bad_unlocked: return 0; } @@ -650,6 +645,8 @@ static struct kernfs_node *__kernfs_new_node(struct kernfs_root *root, kn->mode = mode; kn->flags = flags; + rwlock_init(&kn->iattr_rwlock); + if (!uid_eq(uid, GLOBAL_ROOT_UID) || !gid_eq(gid, GLOBAL_ROOT_GID)) { struct iattr iattr = { .ia_valid = ATTR_UID | ATTR_GID, -- 2.29.2
