fs: remove FS_COW_FL

FS_COW_FL and FS_NOCOW_FL were newly introduced to control per file
COW in btrfs, but FS_NOCOW_FL is sufficient.

The fact is we don't have corresponding BTRFS_INODE_COW flag.

COW is default, and FS_NOCOW_FL can be used to switch off COW for
a single file.

If we mount btrfs with nodatacow, a newly created file will be set with
the FS_NOCOW_FL flag. So to turn on COW for it, we can just clear the
FS_NOCOW_FL flag.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 6 insertions, 9 deletions

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index f580a3a5d2fc..3240dd90da42 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -144,16 +144,13 @@ static int check_flags(unsigned int flags)
         if (flags & ~(FS_IMMUTABLE_FL | FS_APPEND_FL | \
                       FS_NOATIME_FL | FS_NODUMP_FL | \
                       FS_SYNC_FL | FS_DIRSYNC_FL | \
-                      FS_NOCOMP_FL | FS_COMPR_FL | \
-                      FS_NOCOW_FL | FS_COW_FL))
+                      FS_NOCOMP_FL | FS_COMPR_FL |
+                      FS_NOCOW_FL))
                 return -EOPNOTSUPP;
 
         if ((flags & FS_NOCOMP_FL) && (flags & FS_COMPR_FL))
                 return -EINVAL;
 
-        if ((flags & FS_NOCOW_FL) && (flags & FS_COW_FL))
-                return -EINVAL;
-
         return 0;
 }
 
@@ -218,6 +215,10 @@ static int btrfs_ioctl_setflags(struct file *file, void __user *arg)
                 ip->flags |= BTRFS_INODE_DIRSYNC;
         else
                 ip->flags &= ~BTRFS_INODE_DIRSYNC;
+        if (flags & FS_NOCOW_FL)
+                ip->flags |= BTRFS_INODE_NODATACOW;
+        else
+                ip->flags &= ~BTRFS_INODE_NODATACOW;
 
         /*
          * The COMPRESS flag can only be changed by users, while the NOCOMPRESS
@@ -231,10 +232,6 @@ static int btrfs_ioctl_setflags(struct file *file, void __user *arg)
                 ip->flags |= BTRFS_INODE_COMPRESS;
                 ip->flags &= ~BTRFS_INODE_NOCOMPRESS;
         }
-        if (flags & FS_NOCOW_FL)
-                ip->flags |= BTRFS_INODE_NODATACOW;
-        else if (flags & FS_COW_FL)
-                ip->flags &= ~BTRFS_INODE_NODATACOW;
 
         trans = btrfs_join_transaction(root, 1);
         BUG_ON(IS_ERR(trans));