ext4: prevent parallel resizers by atomic bit ops
Before this patch, parallel resizers are allowed and protected by a
mutex lock, actually, there is no need to support parallel resizer, so
this patch prevents parallel resizers by atmoic bit ops, like
lock_page() and unlock_page() do.
To do this, the patch removed the mutex lock s_resize_lock from struct
ext4_sb_info and added a unsigned long field named s_resize_flags
which inidicates if there is a resizer.
Signed-off-by: Yongqiang Yang <xiaoqiangnk@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 143d763..cfe9f39 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3500,7 +3500,7 @@
INIT_LIST_HEAD(&sbi->s_orphan); /* unlinked but open files */
mutex_init(&sbi->s_orphan_lock);
- mutex_init(&sbi->s_resize_lock);
+ sbi->s_resize_flags = 0;
sb->s_root = NULL;