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Subject[PATCH v3] fs/locks: print full locks information
Date
Commit fd7732e033e3 ("fs/locks: create a tree of dependent requests.")
has put blocked locks into a tree.

So, with a for loop, we can't check all locks information.

To solve this problem, we should traverse the tree.

Signed-off-by: Luo Longjun <luolongjun@huawei.com>
---
fs/locks.c | 65 ++++++++++++++++++++++++++++++++++++++++++++++--------
1 file changed, 56 insertions(+), 9 deletions(-)

diff --git a/fs/locks.c b/fs/locks.c
index 99ca97e81b7a..ecaecd1f1b58 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -2828,7 +2828,7 @@ struct locks_iterator {
};

static void lock_get_status(struct seq_file *f, struct file_lock *fl,
- loff_t id, char *pfx)
+ loff_t id, char *pfx, int repeat)
{
struct inode *inode = NULL;
unsigned int fl_pid;
@@ -2844,7 +2844,11 @@ static void lock_get_status(struct seq_file *f, struct file_lock *fl,
if (fl->fl_file != NULL)
inode = locks_inode(fl->fl_file);

- seq_printf(f, "%lld:%s ", id, pfx);
+ seq_printf(f, "%lld: ", id);
+
+ if (repeat)
+ seq_printf(f, "%*s", repeat - 1 + (int)strlen(pfx), pfx);
+
if (IS_POSIX(fl)) {
if (fl->fl_flags & FL_ACCESS)
seq_puts(f, "ACCESS");
@@ -2906,21 +2910,64 @@ static void lock_get_status(struct seq_file *f, struct file_lock *fl,
}
}

+static struct file_lock *get_next_blocked_member(struct file_lock *node)
+{
+ struct file_lock *tmp;
+
+ /* NULL node or root node */
+ if (node == NULL || node->fl_blocker == NULL)
+ return NULL;
+
+ /* Next member in the linked list could be itself */
+ tmp = list_next_entry(node, fl_blocked_member);
+ if (list_entry_is_head(tmp, &node->fl_blocker->fl_blocked_requests, fl_blocked_member)
+ || tmp == node) {
+ return NULL;
+ }
+
+ return tmp;
+}
+
static int locks_show(struct seq_file *f, void *v)
{
struct locks_iterator *iter = f->private;
- struct file_lock *fl, *bfl;
+ struct file_lock *cur, *tmp;
struct pid_namespace *proc_pidns = proc_pid_ns(file_inode(f->file)->i_sb);
+ int level = 0;

- fl = hlist_entry(v, struct file_lock, fl_link);
+ cur = hlist_entry(v, struct file_lock, fl_link);

- if (locks_translate_pid(fl, proc_pidns) == 0)
+ if (locks_translate_pid(cur, proc_pidns) == 0)
return 0;

- lock_get_status(f, fl, iter->li_pos, "");
+ /* View this crossed linked list as a binary tree, the first member of fl_blocked_requests
+ * is the left child of current node, the next silibing in fl_blocked_member is the
+ * right child, we can alse get the parent of current node from fl_blocker, so this
+ * question becomes traversal of a binary tree
+ */
+ while (cur != NULL) {
+ if (level)
+ lock_get_status(f, cur, iter->li_pos, "-> ", level);
+ else
+ lock_get_status(f, cur, iter->li_pos, "", level);

- list_for_each_entry(bfl, &fl->fl_blocked_requests, fl_blocked_member)
- lock_get_status(f, bfl, iter->li_pos, " ->");
+ if (!list_empty(&cur->fl_blocked_requests)) {
+ /* Turn left */
+ cur = list_first_entry_or_null(&cur->fl_blocked_requests,
+ struct file_lock, fl_blocked_member);
+ level++;
+ } else {
+ /* Turn right */
+ tmp = get_next_blocked_member(cur);
+ /* Fall back to parent node */
+ while (tmp == NULL && cur->fl_blocker != NULL) {
+ cur = cur->fl_blocker;
+ level--;
+ tmp = get_next_blocked_member(cur);
+ }
+ cur = tmp;
+ }
+ }

return 0;
}
@@ -2941,7 +2988,7 @@ static void __show_fd_locks(struct seq_file *f,

(*id)++;
seq_puts(f, "lock:\t");
- lock_get_status(f, fl, *id, "");
+ lock_get_status(f, fl, *id, "", 0);
}
}

--
2.17.1
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