ovl: narrow locking in ovl_indexdir_cleanup()

Instead of taking the directory lock for the whole cleanup, only take it
when needed.

Signed-off-by: NeilBrown <neil@brown.name>
Link: https://lore.kernel.org/20250716004725.1206467-14-neil@brown.name
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c
index 2a222b8185a345e3884dade747fcd1f1542c88fa..95d5284daf8d915ef5d728b43c07dc58a7297a62 100644 (file)
--- a/fs/overlayfs/readdir.c
+++ b/fs/overlayfs/readdir.c
@@ -1194,7 +1194,6 @@ int ovl_indexdir_cleanup(struct ovl_fs *ofs)
        if (err)
                goto out;
 
-       inode_lock_nested(dir, I_MUTEX_PARENT);
        list_for_each_entry(p, &list, l_node) {
                if (p->name[0] == '.') {
                        if (p->len == 1)
@@ -1202,7 +1201,7 @@ int ovl_indexdir_cleanup(struct ovl_fs *ofs)
                        if (p->len == 2 && p->name[1] == '.')
                                continue;
                }
-               index = ovl_lookup_upper(ofs, p->name, indexdir, p->len);
+               index = ovl_lookup_upper_unlocked(ofs, p->name, indexdir, p->len);
                if (IS_ERR(index)) {
                        err = PTR_ERR(index);
                        index = NULL;
@@ -1210,7 +1209,11 @@ int ovl_indexdir_cleanup(struct ovl_fs *ofs)
                }
                /* Cleanup leftover from index create/cleanup attempt */
                if (index->d_name.name[0] == '#') {
-                       err = ovl_workdir_cleanup(ofs, dir, path.mnt, index, 1);
+                       err = ovl_parent_lock(indexdir, index);
+                       if (!err) {
+                               err = ovl_workdir_cleanup(ofs, dir, path.mnt, index, 1);
+                               ovl_parent_unlock(indexdir);
+                       }
                        if (err)
                                break;
                        goto next;
@@ -1220,7 +1223,7 @@ int ovl_indexdir_cleanup(struct ovl_fs *ofs)
                        goto next;
                } else if (err == -ESTALE) {
                        /* Cleanup stale index entries */
-                       err = ovl_cleanup(ofs, dir, index);
+                       err = ovl_cleanup_unlocked(ofs, indexdir, index);
                } else if (err != -ENOENT) {
                        /*
                         * Abort mount to avoid corrupting the index if
@@ -1233,10 +1236,14 @@ int ovl_indexdir_cleanup(struct ovl_fs *ofs)
                         * Whiteout orphan index to block future open by
                         * handle after overlay nlink dropped to zero.
                         */
-                       err = ovl_cleanup_and_whiteout(ofs, indexdir, index);
+                       err = ovl_parent_lock(indexdir, index);
+                       if (!err) {
+                               err = ovl_cleanup_and_whiteout(ofs, indexdir, index);
+                               ovl_parent_unlock(indexdir);
+                       }
                } else {
                        /* Cleanup orphan index entries */
-                       err = ovl_cleanup(ofs, dir, index);
+                       err = ovl_cleanup_unlocked(ofs, indexdir, index);
                }
 
                if (err)
@@ -1247,7 +1254,6 @@ next:
                index = NULL;
        }
        dput(index);
-       inode_unlock(dir);
 out:
        ovl_cache_free(&list);
        if (err)