On 2024-01-26 15:12, Steven Rostedt wrote:
[...]
diff --git a/fs/tracefs/inode.c b/fs/tracefs/inode.c
index e1b172c0e091..2187be6d7b23 100644
--- a/fs/tracefs/inode.c
+++ b/fs/tracefs/inode.c
@@ -223,13 +223,41 @@ static const struct inode_operations
tracefs_file_inode_operations = {
.setattr = tracefs_setattr,
};
+/* Copied from get_next_ino() but adds allocation for multiple inodes */
+#define LAST_INO_BATCH 1024
+#define LAST_INO_MASK (~(LAST_INO_BATCH - 1))
+static DEFINE_PER_CPU(unsigned int, last_ino);
+
+unsigned int tracefs_get_next_ino(int files)
+{
+ unsigned int *p = &get_cpu_var(last_ino);
+ unsigned int res = *p;
+
+#ifdef CONFIG_SMP
+ /* Check if adding files+1 overflows */
How does it handle a @files input where:
* (files+1 > LAST_INO_BATCH) ?
* (files+1 == LAST_INO_BATCH) ?
+ if (unlikely(!res || (res & LAST_INO_MASK) != ((res + files + 1) &
LAST_INO_MASK))) {
+ static atomic_t shared_last_ino;
+ int next = atomic_add_return(LAST_INO_BATCH, &shared_last_ino);
+
+ res = next - LAST_INO_BATCH;
+ }
+#endif
+
+ res++;
+ /* get_next_ino should not provide a 0 inode number */
+ if (unlikely(!res))
+ res++;
I suspect that bumping this res++ in the 0 case can cause inode range
reservation issues at (files+1 == LAST_INO_BATCH-1).
Thanks,
Mathieu
+ *p = res + files;
+ put_cpu_var(last_ino);
+ return res;
+}
--
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com
