diff options
| -rw-r--r-- | fs/dcache.c | 2 | ||||
| -rw-r--r-- | fs/super.c | 6 | ||||
| -rw-r--r-- | include/linux/list.h | 15 |
3 files changed, 23 insertions, 0 deletions
diff --git a/fs/dcache.c b/fs/dcache.c index d96047b4a633..c8c78ba07827 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -590,6 +590,8 @@ static void prune_dcache(int count) up_read(&sb->s_umount); } spin_lock(&sb_lock); + /* lock was dropped, must reset next */ + list_safe_reset_next(sb, n, s_list); count -= pruned; __put_super(sb); /* more work left to do? */ diff --git a/fs/super.c b/fs/super.c index 5c35bc7a499e..938119ab8dcb 100644 --- a/fs/super.c +++ b/fs/super.c @@ -374,6 +374,8 @@ void sync_supers(void) up_read(&sb->s_umount); spin_lock(&sb_lock); + /* lock was dropped, must reset next */ + list_safe_reset_next(sb, n, s_list); __put_super(sb); } } @@ -405,6 +407,8 @@ void iterate_supers(void (*f)(struct super_block *, void *), void *arg) up_read(&sb->s_umount); spin_lock(&sb_lock); + /* lock was dropped, must reset next */ + list_safe_reset_next(sb, n, s_list); __put_super(sb); } spin_unlock(&sb_lock); @@ -585,6 +589,8 @@ static void do_emergency_remount(struct work_struct *work) } up_write(&sb->s_umount); spin_lock(&sb_lock); + /* lock was dropped, must reset next */ + list_safe_reset_next(sb, n, s_list); __put_super(sb); } spin_unlock(&sb_lock); diff --git a/include/linux/list.h b/include/linux/list.h index 8392884a2977..5d57a3a1fa1b 100644 --- a/include/linux/list.h +++ b/include/linux/list.h @@ -544,6 +544,21 @@ static inline void list_splice_tail_init(struct list_head *list, &pos->member != (head); \ pos = n, n = list_entry(n->member.prev, typeof(*n), member)) +/** + * list_safe_reset_next - reset a stale list_for_each_entry_safe loop + * @pos: the loop cursor used in the list_for_each_entry_safe loop + * @n: temporary storage used in list_for_each_entry_safe + * @member: the name of the list_struct within the struct. + * + * list_safe_reset_next is not safe to use in general if the list may be + * modified concurrently (eg. the lock is dropped in the loop body). An + * exception to this is if the cursor element (pos) is pinned in the list, + * and list_safe_reset_next is called after re-taking the lock and before + * completing the current iteration of the loop body. + */ +#define list_safe_reset_next(pos, n, member) \ + n = list_entry(pos->member.next, typeof(*pos), member) + /* * Double linked lists with a single pointer list head. * Mostly useful for hash tables where the two pointer list head is |