fat: Push mnt_want_write() outside of i_mutex

When mnt_want_write() starts to handle freezing it will get a full lock
semantics requiring proper lock ordering. So push mnt_want_write() call
outside of i_mutex as in other places.

CC: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 7 insertions, 8 deletions

diff --git a/fs/fat/file.c b/fs/fat/file.c
index a71fe3715ee8..e007b8bd8e5e 100644
--- a/fs/fat/file.c
+++ b/fs/fat/file.c
@@ -43,10 +43,10 @@ static int fat_ioctl_set_attributes(struct file *file, u32 __user *user_attr)
         if (err)
                 goto out;
 
-        mutex_lock(&inode->i_mutex);
         err = mnt_want_write_file(file);
         if (err)
-                goto out_unlock_inode;
+                goto out;
+        mutex_lock(&inode->i_mutex);
 
         /*
          * ATTR_VOLUME and ATTR_DIR cannot be changed; this also
@@ -73,14 +73,14 @@ static int fat_ioctl_set_attributes(struct file *file, u32 __user *user_attr)
         /* The root directory has no attributes */
         if (inode->i_ino == MSDOS_ROOT_INO && attr != ATTR_DIR) {
                 err = -EINVAL;
-                goto out_drop_write;
+                goto out_unlock_inode;
         }
 
         if (sbi->options.sys_immutable &&
             ((attr | oldattr) & ATTR_SYS) &&
             !capable(CAP_LINUX_IMMUTABLE)) {
                 err = -EPERM;
-                goto out_drop_write;
+                goto out_unlock_inode;
         }
 
         /*
@@ -90,12 +90,12 @@ static int fat_ioctl_set_attributes(struct file *file, u32 __user *user_attr)
          */
         err = security_inode_setattr(file->f_path.dentry, &ia);
         if (err)
-                goto out_drop_write;
+                goto out_unlock_inode;
 
         /* This MUST be done before doing anything irreversible... */
         err = fat_setattr(file->f_path.dentry, &ia);
         if (err)
-                goto out_drop_write;
+                goto out_unlock_inode;
 
         fsnotify_change(file->f_path.dentry, ia.ia_valid);
         if (sbi->options.sys_immutable) {
@@ -107,10 +107,9 @@ static int fat_ioctl_set_attributes(struct file *file, u32 __user *user_attr)
 
         fat_save_attrs(inode, attr);
         mark_inode_dirty(inode);
-out_drop_write:
-        mnt_drop_write_file(file);
 out_unlock_inode:
         mutex_unlock(&inode->i_mutex);
+        mnt_drop_write_file(file);
 out:
         return err;
 }