ceph: refactor wake_up_bit() pattern of calling

The wake_up_bit() is called in ceph_async_unlink_cb(),
wake_async_create_waiters(), and ceph_finish_async_create().
It makes sense to switch on clear_bit() function, because
it makes the code much cleaner and easier to understand.
More important rework is the adding of smp_mb__after_atomic()
memory barrier after the bit modification and before
wake_up_bit() call. It can prevent potential race condition
of accessing the modified bit in other threads. Luckily,
clear_and_wake_up_bit() already implements the required
functionality pattern:

static inline void clear_and_wake_up_bit(int bit, unsigned long *word)
{
	clear_bit_unlock(bit, word);
	/* See wake_up_bit() for which memory barrier you need to use. */
	smp_mb__after_atomic();
	wake_up_bit(word, bit);
}

Reviewed-by: Alex Markuze amarkuze@redhat.com
Link: https://lore.kernel.org/r/20250708192057.539725-1-slava@dubeyko.com
Signed-off-by: Viacheslav Dubeyko <Slava.Dubeyko@ibm.com>

diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
index a321aa6d0ed22680fbfd1c2939c7da47e8607d26..1535b6540e9d4463fee41a74a9f25a23d497a51e 100644 (file)
--- a/fs/ceph/dir.c
+++ b/fs/ceph/dir.c
@@ -1261,8 +1261,7 @@ static void ceph_async_unlink_cb(struct ceph_mds_client *mdsc,
        spin_unlock(&fsc->async_unlink_conflict_lock);
 
        spin_lock(&dentry->d_lock);
-       di->flags &= ~CEPH_DENTRY_ASYNC_UNLINK;
-       wake_up_bit(&di->flags, CEPH_DENTRY_ASYNC_UNLINK_BIT);
+       clear_and_wake_up_bit(CEPH_DENTRY_ASYNC_UNLINK_BIT, &di->flags);
        spin_unlock(&dentry->d_lock);
 
        synchronize_rcu();

diff --git a/fs/ceph/file.c b/fs/ceph/file.c
index 246786e2c44755255b985f0bc0419fb8937ab1a0..c92ef1fc5b8a68ce820373c9ea2f93bfd3e419a1 100644 (file)
--- a/fs/ceph/file.c
+++ b/fs/ceph/file.c
@@ -580,8 +580,7 @@ static void wake_async_create_waiters(struct inode *inode,
 
        spin_lock(&ci->i_ceph_lock);
        if (ci->i_ceph_flags & CEPH_I_ASYNC_CREATE) {
-               ci->i_ceph_flags &= ~CEPH_I_ASYNC_CREATE;
-               wake_up_bit(&ci->i_ceph_flags, CEPH_ASYNC_CREATE_BIT);
+               clear_and_wake_up_bit(CEPH_ASYNC_CREATE_BIT, &ci->i_ceph_flags);
 
                if (ci->i_ceph_flags & CEPH_I_ASYNC_CHECK_CAPS) {
                        ci->i_ceph_flags &= ~CEPH_I_ASYNC_CHECK_CAPS;
@@ -765,8 +764,7 @@ static int ceph_finish_async_create(struct inode *dir, struct inode *inode,
        }
 
        spin_lock(&dentry->d_lock);
-       di->flags &= ~CEPH_DENTRY_ASYNC_CREATE;
-       wake_up_bit(&di->flags, CEPH_DENTRY_ASYNC_CREATE_BIT);
+       clear_and_wake_up_bit(CEPH_DENTRY_ASYNC_CREATE_BIT, &di->flags);
        spin_unlock(&dentry->d_lock);
 
        return ret;