[ Sasha's backport helper bot ]
Hi,
The upstream commit SHA1 provided is correct: 393c3714081a53795bbff0e985d24146def6f57f
WARNING: Author mismatch between patch and upstream commit:
Backport author: Jeremi Piotrowski <jpiotrowski@xxxxxxxxxxxxxxxxxxx>
Commit author: Minchan Kim <minchan@xxxxxxxxxx>
Status in newer kernel trees:
6.12.y | Present (exact SHA1)
6.11.y | Present (exact SHA1)
6.6.y | Present (exact SHA1)
6.1.y | Present (exact SHA1)
5.15.y | Not found
Note: The patch differs from the upstream commit:
---
1: 393c3714081a5 ! 1: b3f5272b13165 kernfs: switch global kernfs_rwsem lock to per-fs lock
@@ Metadata
## Commit message ##
kernfs: switch global kernfs_rwsem lock to per-fs lock
+ [ Upstream commit 393c3714081a53795bbff0e985d24146def6f57f ]
+
The kernfs implementation has big lock granularity(kernfs_rwsem) so
every kernfs-based(e.g., sysfs, cgroup) fs are able to compete the
lock. It makes trouble for some cases to wait the global lock
@@ Commit message
Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20211118230008.2679780-1-minchan@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
+ Signed-off-by: Jeremi Piotrowski <jpiotrowski@xxxxxxxxxxxxxxxxxxx>
## fs/kernfs/dir.c ##
@@
@@ fs/kernfs/dir.c
-DECLARE_RWSEM(kernfs_rwsem);
static DEFINE_SPINLOCK(kernfs_rename_lock); /* kn->parent and ->name */
- static char kernfs_pr_cont_buf[PATH_MAX]; /* protected by rename_lock */
- static DEFINE_SPINLOCK(kernfs_idr_lock); /* root->ino_idr */
+ /*
+ * Don't use rename_lock to piggy back on pr_cont_buf. We don't want to
@@ fs/kernfs/dir.c: static DEFINE_SPINLOCK(kernfs_idr_lock); /* root->ino_idr */
static bool kernfs_active(struct kernfs_node *kn)
@@ fs/kernfs/dir.c: static struct kernfs_node *kernfs_walk_ns(struct kernfs_node *p
- lockdep_assert_held_read(&kernfs_rwsem);
+ lockdep_assert_held_read(&kernfs_root(parent)->kernfs_rwsem);
- /* grab kernfs_rename_lock to piggy back on kernfs_pr_cont_buf */
- spin_lock_irq(&kernfs_rename_lock);
+ spin_lock_irq(&kernfs_pr_cont_lock);
+
@@ fs/kernfs/dir.c: struct kernfs_node *kernfs_find_and_get_ns(struct kernfs_node *parent,
const char *name, const void *ns)
{
@@ fs/kernfs/dir.c: int kernfs_remove_by_name_ns(struct kernfs_node *parent, const
+ down_write(&root->kernfs_rwsem);
kn = kernfs_find_ns(parent, name, ns);
- if (kn)
- __kernfs_remove(kn);
+ if (kn) {
+@@ fs/kernfs/dir.c: int kernfs_remove_by_name_ns(struct kernfs_node *parent, const char *name,
+ kernfs_put(kn);
+ }
- up_write(&kernfs_rwsem);
+ up_write(&root->kernfs_rwsem);
---
Results of testing on various branches:
| Branch | Patch Apply | Build Test |
|---------------------------|-------------|------------|
| stable/linux-5.15.y | Success | Success |
