Make FAT users happier by not deadlocking

The FAT BKL removal patch can cause deadlocks.  It turns out that the new
lock_super() calls are unneeded, remove them (as directed by Linus).
Reported-by: "Tony Luck" <tony.luck@intel.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

fs/fat/file.c

@@ -11,7 +11,6 @@
 #include <linux/mount.h>
 #include <linux/time.h>
 #include <linux/msdos_fs.h>
-#include <linux/smp_lock.h>
 #include <linux/buffer_head.h>
 #include <linux/writeback.h>
 #include <linux/backing-dev.h>
@@ -229,8 +228,7 @@ static int fat_free(struct inode *inode, int skip)
 
 void fat_truncate(struct inode *inode)
 {
-	struct super_block *sb = inode->i_sb;
-	struct msdos_sb_info *sbi = MSDOS_SB(sb);
+	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 	const unsigned int cluster_size = sbi->cluster_size;
 	int nr_clusters;
 
@@ -243,9 +241,7 @@ void fat_truncate(struct inode *inode)
 
 	nr_clusters = (inode->i_size + (cluster_size - 1)) >> sbi->cluster_bits;
 
-	lock_super(sb);
 	fat_free(inode, nr_clusters);
-	unlock_super(sb);
 	fat_flush_inodes(inode->i_sb, inode, NULL);
 }
 
@@ -298,14 +294,11 @@ static int fat_allow_set_time(struct msdos_sb_info *sbi, struct inode *inode)
 
 int fat_setattr(struct dentry *dentry, struct iattr *attr)
 {
-	struct super_block *sb = dentry->d_sb;
 	struct msdos_sb_info *sbi = MSDOS_SB(dentry->d_sb);
 	struct inode *inode = dentry->d_inode;
 	int mask, error = 0;
 	unsigned int ia_valid;
 
-	lock_super(sb);
-
 	/*
 	 * Expand the file. Since inode_setattr() updates ->i_size
 	 * before calling the ->truncate(), but FAT needs to fill the
@@ -358,7 +351,6 @@ int fat_setattr(struct dentry *dentry, struct iattr *attr)
 		mask = sbi->options.fs_fmask;
 	inode->i_mode &= S_IFMT | (S_IRWXUGO & ~mask);
 out:
-	unlock_super(sb);
 	return error;
 }
 EXPORT_SYMBOL_GPL(fat_setattr);