[Devel] [PATCH RHEL7 COMMIT] fuse: Refactor fuse_open_common()

[Konstantin Khorenko]

The commit is pushed to "branch-rh7-3.10.0-862.3.2.vz7.61.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-862.3.2.vz7.61.15
------>
commit c27d883edbae9041e8145b82112a26b92f3e4a05
Author: Kirill Tkhai <ktkhai at virtuozzo.com>
Date:   Fri Jul 6 12:41:48 2018 +0300

    fuse: Refactor fuse_open_common()
    
    Make this function to lock and unlock in only place.
    Improve its readability.
    
    Signed-off-by: Kirill Tkhai <ktkhai at virtuozzo.com>
    Acked-by: Alexey Kuznetsov <kuznet at virtuozzo.com>
---
 fs/fuse/file.c | 30 ++++++++++++------------------
 1 file changed, 12 insertions(+), 18 deletions(-)

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index e870697be5ee..313f81191ada 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -302,33 +302,27 @@ int fuse_open_common(struct inode *inode, struct file *file, bool isdir)
 		u64 size;
 
 		mutex_lock(&inode->i_mutex);
-
 		spin_lock(&fc->lock);
-		atomic_inc(&fi->num_openers);
 
-		if (atomic_read(&fi->num_openers) == 1) {
+		if (atomic_inc_return(&fi->num_openers) == 1) {
 			fi->i_size_unstable = 1;
 			spin_unlock(&fc->lock);
 			err = fuse_getattr_size(inode, file, &size);
-			if (err) {
-				spin_lock(&fc->lock);
-				atomic_dec(&fi->num_openers);
-				fi->i_size_unstable = 0;
-				spin_unlock(&fc->lock);
-
-				mutex_unlock(&inode->i_mutex);
-				fuse_release_common(file, FUSE_RELEASE);
-				return err;
-			}
-
 			spin_lock(&fc->lock);
-			i_size_write(inode, size);
 			fi->i_size_unstable = 0;
-			spin_unlock(&fc->lock);
-		} else
-			spin_unlock(&fc->lock);
+			if (err)
+				atomic_dec(&fi->num_openers);
+			else
+				i_size_write(inode, size);
+		}
 
+		spin_unlock(&fc->lock);
 		mutex_unlock(&inode->i_mutex);
+
+		if (err) {
+			fuse_release_common(file, FUSE_RELEASE);
+			return err;
+		}
 	}
 
 	fuse_finish_open(inode, file);