From: Viacheslav Dubeyko <Slava.Dubeyko@xxxxxxx>
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.
Signed-off-by: Viacheslav Dubeyko <Slava.Dubeyko@xxxxxxx>
---
fs/ceph/dir.c | 4 +++-
fs/ceph/file.c | 8 ++++++--
2 files changed, 9 insertions(+), 3 deletions(-)
diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
index a321aa6d0ed2..7f4d1874a84f 100644
--- a/fs/ceph/dir.c
+++ b/fs/ceph/dir.c
@@ -1261,7 +1261,9 @@ 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;
+ clear_bit(CEPH_DENTRY_ASYNC_UNLINK_BIT, &di->flags);
+ /* ensure modified bit is visible */
+ smp_mb__after_atomic();
wake_up_bit(&di->flags, CEPH_DENTRY_ASYNC_UNLINK_BIT);
spin_unlock(&dentry->d_lock);
diff --git a/fs/ceph/file.c b/fs/ceph/file.c
index a7254cab44cc..b114b939cdc0 100644
--- a/fs/ceph/file.c
+++ b/fs/ceph/file.c
@@ -580,7 +580,9 @@ 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;
+ clear_bit(CEPH_ASYNC_CREATE_BIT, &ci->i_ceph_flags);
+ /* ensure modified bit is visible */
+ smp_mb__after_atomic();
wake_up_bit(&ci->i_ceph_flags, CEPH_ASYNC_CREATE_BIT);
if (ci->i_ceph_flags & CEPH_I_ASYNC_CHECK_CAPS) {
@@ -765,7 +767,9 @@ static int ceph_finish_async_create(struct inode *dir, struct inode *inode,
}
spin_lock(&dentry->d_lock);
- di->flags &= ~CEPH_DENTRY_ASYNC_CREATE;
+ clear_bit(CEPH_DENTRY_ASYNC_CREATE_BIT, &di->flags);
+ /* ensure modified bit is visible */
+ smp_mb__after_atomic();
wake_up_bit(&di->flags, CEPH_DENTRY_ASYNC_CREATE_BIT);
spin_unlock(&dentry->d_lock);
--
2.49.0
