libfs: Add a lock class for the offset map's xa_lock

Tie the dynamically-allocated xarray locks into a single class so
contention on the directory offset xarrays can be observed.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Message-Id: <169020933088.160441.9405180953116076087.stgit@manet.1015granger.net>
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/fs/libfs.c b/fs/libfs.c
index a7e56ba..3495f07 100644 (file)
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -249,6 +249,8 @@ static u32 dentry2offset(struct dentry *dentry)
        return (u32)((uintptr_t)(dentry->d_fsdata));
 }
 
+static struct lock_class_key simple_offset_xa_lock;
+
 /**
  * simple_offset_init - initialize an offset_ctx
  * @octx: directory offset map to be initialized
@@ -257,6 +259,7 @@ static u32 dentry2offset(struct dentry *dentry)
 void simple_offset_init(struct offset_ctx *octx)
 {
        xa_init_flags(&octx->xa, XA_FLAGS_ALLOC1);
+       lockdep_set_class(&octx->xa.xa_lock, &simple_offset_xa_lock);
 
        /* 0 is '.', 1 is '..', so always start with offset 2 */
        octx->next_offset = 2;