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https://github.com/torvalds/linux
synced 2024-09-22 03:55:39 +00:00
b1eaa950f7
An overlayfs instance can be the lower layer of another overlayfs instance. This setup triggers a lockdep splat of possible recursive locking of sb->s_type->i_mutex_key in iterate_dir(). Trimmed snip: [ INFO: possible recursive locking detected ] bash/2468 is trying to acquire lock: &sb->s_type->i_mutex_key#14, at: iterate_dir+0x7d/0x15c but task is already holding lock: &sb->s_type->i_mutex_key#14, at: iterate_dir+0x7d/0x15c One problem observed with this splat is that ovl_new_inode() does not call lockdep_annotate_inode_mutex_key() to annotate the dir inode lock as &sb->s_type->i_mutex_dir_key like other fs do. The other problem is that the 2 nested levels of overlayfs inode lock are annotated using the same key, which is the cause of the false positive lockdep warning. Fix this by annotating overlayfs inode lock in ovl_fill_inode() according to stack level of the super block instance and use different key for dir vs. non-dir like other fs do. Here is an edited snip from /proc/lockdep_chains after iterate_dir() of nested overlayfs: [...] &ovl_i_mutex_dir_key[depth] (stack_depth=2) [...] &ovl_i_mutex_dir_key[depth]#2 (stack_depth=1) [...] &type->i_mutex_dir_key (stack_depth=0) Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> |
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| .. | ||
| copy_up.c | ||
| dir.c | ||
| inode.c | ||
| Kconfig | ||
| Makefile | ||
| namei.c | ||
| overlayfs.h | ||
| ovl_entry.h | ||
| readdir.c | ||
| super.c | ||
| util.c | ||