BKL: Explicitly add BKL around get_sb/fill_super

This patch is a preparation necessary to remove the BKL from do_new_mount().
It explicitly adds calls to lock_kernel()/unlock_kernel() around
get_sb/fill_super operations for filesystems that still uses the BKL.

I've read through all the code formerly covered by the BKL inside
do_kern_mount() and have satisfied myself that it doesn't need the BKL
any more.

do_kern_mount() is already called without the BKL when mounting the rootfs
and in nfsctl. do_kern_mount() calls vfs_kern_mount(), which is called
from various places without BKL: simple_pin_fs(), nfs_do_clone_mount()
through nfs_follow_mountpoint(), afs_mntpt_do_automount() through
afs_mntpt_follow_link(). Both later functions are actually the filesystems
follow_link inode operation. vfs_kern_mount() is calling the specified
get_sb function and lets the filesystem do its job by calling the given
fill_super function.

Therefore I think it is safe to push down the BKL from the VFS to the
low-level filesystems get_sb/fill_super operation.

[arnd: do not add the BKL to those file systems that already
       don't use it elsewhere]

Signed-off-by: Jan Blunck <jblunck@infradead.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Matthew Wilcox <matthew@wil.cx>
Cc: Christoph Hellwig <hch@infradead.org>

fs/adfs/super.c

@@ -352,11 +352,15 @@ static int adfs_fill_super(struct super_block *sb, void *data, int silent)
 	struct adfs_sb_info *asb;
 	struct inode *root;
 
+	lock_kernel();
+
 	sb->s_flags |= MS_NODIRATIME;
 
 	asb = kzalloc(sizeof(*asb), GFP_KERNEL);
-	if (!asb)
+	if (!asb) {
+		unlock_kernel();
 		return -ENOMEM;
+	}
 	sb->s_fs_info = asb;
 
 	/* set default options */
@@ -474,13 +478,15 @@ static int adfs_fill_super(struct super_block *sb, void *data, int silent)
 		goto error;
 	} else
 		sb->s_root->d_op = &adfs_dentry_operations;
+	unlock_kernel();
 	return 0;
 
 error_free_bh:
 	brelse(bh);
 error:
 	sb->s_fs_info = NULL;
 	kfree(asb);
+	unlock_kernel();
 	return -EINVAL;
 }
 

fs/affs/super.c

@@ -291,6 +291,8 @@ static int affs_fill_super(struct super_block *sb, void *data, int silent)
 	u8			 sig[4];
 	int			 ret = -EINVAL;
 
+	lock_kernel();
+
 	save_mount_options(sb, data);
 
 	pr_debug("AFFS: read_super(%s)\n",data ? (const char *)data : "no options");
@@ -300,8 +302,10 @@ static int affs_fill_super(struct super_block *sb, void *data, int silent)
 	sb->s_flags |= MS_NODIRATIME;
 
 	sbi = kzalloc(sizeof(struct affs_sb_info), GFP_KERNEL);
-	if (!sbi)
+	if (!sbi) {
+		unlock_kernel();
 		return -ENOMEM;
+	}
 	sb->s_fs_info = sbi;
 	mutex_init(&sbi->s_bmlock);
 	spin_lock_init(&sbi->symlink_lock);
@@ -312,6 +316,7 @@ static int affs_fill_super(struct super_block *sb, void *data, int silent)
 		printk(KERN_ERR "AFFS: Error parsing options\n");
 		kfree(sbi->s_prefix);
 		kfree(sbi);
+		unlock_kernel();
 		return -EINVAL;
 	}
 	/* N.B. after this point s_prefix must be released */
@@ -482,6 +487,7 @@ static int affs_fill_super(struct super_block *sb, void *data, int silent)
 	sb->s_root->d_op = &affs_dentry_operations;
 
 	pr_debug("AFFS: s_flags=%lX\n",sb->s_flags);
+	unlock_kernel();
 	return 0;
 
 	/*
@@ -496,6 +502,7 @@ static int affs_fill_super(struct super_block *sb, void *data, int silent)
 	kfree(sbi->s_prefix);
 	kfree(sbi);
 	sb->s_fs_info = NULL;
+	unlock_kernel();
 	return ret;
 }
 

fs/afs/super.c

@@ -302,12 +302,15 @@ static int afs_fill_super(struct super_block *sb, void *data)
 	struct inode *inode = NULL;
 	int ret;
 
+	lock_kernel();
+
 	_enter("");
 
 	/* allocate a superblock info record */
 	as = kzalloc(sizeof(struct afs_super_info), GFP_KERNEL);
 	if (!as) {
 		_leave(" = -ENOMEM");
+		unlock_kernel();
 		return -ENOMEM;
 	}
 
@@ -341,6 +344,7 @@ static int afs_fill_super(struct super_block *sb, void *data)
 	sb->s_root = root;
 
 	_leave(" = 0");
+	unlock_kernel();
 	return 0;
 
 error_inode:
@@ -354,6 +358,7 @@ static int afs_fill_super(struct super_block *sb, void *data)
 	sb->s_fs_info = NULL;
 
 	_leave(" = %d", ret);
+	unlock_kernel();
 	return ret;
 }
 

fs/bfs/inode.c

@@ -322,9 +322,13 @@ static int bfs_fill_super(struct super_block *s, void *data, int silent)
 	int ret = -EINVAL;
 	unsigned long i_sblock, i_eblock, i_eoff, s_size;
 
+	lock_kernel();
+
 	info = kzalloc(sizeof(*info), GFP_KERNEL);
-	if (!info)
+	if (!info) {
+		unlock_kernel();
 		return -ENOMEM;
+	}
 	mutex_init(&info->bfs_lock);
 	s->s_fs_info = info;
 
@@ -439,6 +443,7 @@ static int bfs_fill_super(struct super_block *s, void *data, int silent)
 	brelse(bh);
 	brelse(sbh);
 	dump_imap("read_super", s);
+	unlock_kernel();
 	return 0;
 
 out3:
@@ -452,6 +457,7 @@ static int bfs_fill_super(struct super_block *s, void *data, int silent)
 	mutex_destroy(&info->bfs_lock);
 	kfree(info);
 	s->s_fs_info = NULL;
+	unlock_kernel();
 	return ret;
 }
 

fs/cifs/cifsfs.c

@@ -514,22 +514,30 @@ cifs_get_sb(struct file_system_type *fs_type,
 	    int flags, const char *dev_name, void *data, struct vfsmount *mnt)
 {
 	int rc;
-	struct super_block *sb = sget(fs_type, NULL, set_anon_super, NULL);
+	struct super_block *sb;
+
+	lock_kernel();
+
+	sb = sget(fs_type, NULL, set_anon_super, NULL);
 
 	cFYI(1, "Devname: %s flags: %d ", dev_name, flags);
 
-	if (IS_ERR(sb))
+	if (IS_ERR(sb)) {
+		unlock_kernel();
 		return PTR_ERR(sb);
+	}
 
 	sb->s_flags = flags;
 
 	rc = cifs_read_super(sb, data, dev_name, flags & MS_SILENT ? 1 : 0);
 	if (rc) {
 		deactivate_locked_super(sb);
+		unlock_kernel();
 		return rc;
 	}
 	sb->s_flags |= MS_ACTIVE;
 	simple_set_mnt(mnt, sb);
+	unlock_kernel();
 	return 0;
 }
 

fs/coda/inode.c

@@ -148,6 +148,8 @@ static int coda_fill_super(struct super_block *sb, void *data, int silent)
 	int error;
 	int idx;
 
+	lock_kernel();
+
 	idx = get_device_index((struct coda_mount_data *) data);
 
 	/* Ignore errors in data, for backward compatibility */
@@ -159,11 +161,13 @@ static int coda_fill_super(struct super_block *sb, void *data, int silent)
 	vc = &coda_comms[idx];
 	if (!vc->vc_inuse) {
 		printk("coda_read_super: No pseudo device\n");
+		unlock_kernel();
 		return -EINVAL;
 	}
 
         if ( vc->vc_sb ) {
 		printk("coda_read_super: Device already mounted\n");
+		unlock_kernel();
 		return -EBUSY;
 	}
 
@@ -202,7 +206,8 @@ static int coda_fill_super(struct super_block *sb, void *data, int silent)
 	sb->s_root = d_alloc_root(root);
 	if (!sb->s_root)
 		goto error;
-        return 0;
+	unlock_kernel();
+	return 0;
 
  error:
 	bdi_destroy(&vc->bdi);
@@ -212,6 +217,7 @@ static int coda_fill_super(struct super_block *sb, void *data, int silent)
 	if (vc)
 		vc->vc_sb = NULL;
 
+	unlock_kernel();
 	return -EINVAL;
 }
 

fs/ecryptfs/main.c

@@ -36,6 +36,7 @@
 #include <linux/parser.h>
 #include <linux/fs_stack.h>
 #include <linux/slab.h>
+#include <linux/smp_lock.h>     /* For lock_kernel() */
 #include "ecryptfs_kernel.h"
 
 /**
@@ -550,6 +551,7 @@ static int ecryptfs_get_sb(struct file_system_type *fs_type, int flags,
 	const char *err = "Getting sb failed";
 	int rc;
 
+	lock_kernel();
 	sbi = kmem_cache_zalloc(ecryptfs_sb_info_cache, GFP_KERNEL);
 	if (!sbi) {
 		rc = -ENOMEM;
@@ -608,6 +610,7 @@ static int ecryptfs_get_sb(struct file_system_type *fs_type, int flags,
 		goto out;
 	}
 	simple_set_mnt(mnt, s);
+	unlock_kernel();
 	return 0;
 
 out:
@@ -616,6 +619,7 @@ static int ecryptfs_get_sb(struct file_system_type *fs_type, int flags,
 		kmem_cache_free(ecryptfs_sb_info_cache, sbi);
 	}
 	printk(KERN_ERR "%s; rc = [%d]\n", err, rc);
+	unlock_kernel();
 	return rc;
 }
 

fs/ext2/super.c

@@ -747,15 +747,18 @@ static int ext2_fill_super(struct super_block *sb, void *data, int silent)
 	__le32 features;
 	int err;
 
+	lock_kernel();
+
+	err = -ENOMEM;
 	sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
 	if (!sbi)
-		return -ENOMEM;
+		goto failed_unlock;
 
 	sbi->s_blockgroup_lock =
 		kzalloc(sizeof(struct blockgroup_lock), GFP_KERNEL);
 	if (!sbi->s_blockgroup_lock) {
 		kfree(sbi);
-		return -ENOMEM;
+		goto failed_unlock;
 	}
 	sb->s_fs_info = sbi;
 	sbi->s_sb_block = sb_block;
@@ -1083,6 +1086,7 @@ static int ext2_fill_super(struct super_block *sb, void *data, int silent)
 	if (ext2_setup_super (sb, es, sb->s_flags & MS_RDONLY))
 		sb->s_flags |= MS_RDONLY;
 	ext2_write_super(sb);
+	unlock_kernel();
 	return 0;
 
 cantfind_ext2:
@@ -1107,6 +1111,8 @@ static int ext2_fill_super(struct super_block *sb, void *data, int silent)
 	sb->s_fs_info = NULL;
 	kfree(sbi->s_blockgroup_lock);
 	kfree(sbi);
+failed_unlock:
+	unlock_kernel();
 	return ret;
 }
 

fs/ext3/super.c

@@ -1611,14 +1611,19 @@ static int ext3_fill_super (struct super_block *sb, void *data, int silent)
 	__le32 features;
 	int err;
 
+	lock_kernel();
+
 	sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
-	if (!sbi)
+	if (!sbi) {
+		unlock_kernel();
 		return -ENOMEM;
+	}
 
 	sbi->s_blockgroup_lock =
 		kzalloc(sizeof(struct blockgroup_lock), GFP_KERNEL);
 	if (!sbi->s_blockgroup_lock) {
 		kfree(sbi);
+		unlock_kernel();
 		return -ENOMEM;
 	}
 	sb->s_fs_info = sbi;
@@ -2026,6 +2031,7 @@ static int ext3_fill_super (struct super_block *sb, void *data, int silent)
 		"writeback");
 
 	lock_kernel();
+	unlock_kernel();
 	return 0;
 
 cantfind_ext3:
@@ -2056,6 +2062,7 @@ static int ext3_fill_super (struct super_block *sb, void *data, int silent)
 	kfree(sbi->s_blockgroup_lock);
 	kfree(sbi);
 	lock_kernel();
+	unlock_kernel();
 	return ret;
 }
 

fs/ext4/super.c

@@ -2568,6 +2568,8 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 	int err;
 	unsigned int journal_ioprio = DEFAULT_JOURNAL_IOPRIO;
 
+	lock_kernel();
+
 	sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
 	if (!sbi)
 		goto out_free_orig;
@@ -3166,7 +3168,6 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 	if (es->s_error_count)
 		mod_timer(&sbi->s_err_report, jiffies + 300*HZ); /* 5 minutes */
 
-	lock_kernel();
 	kfree(orig_data);
 	return 0;
 
@@ -3213,8 +3214,11 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 	sb->s_fs_info = NULL;
 	kfree(sbi->s_blockgroup_lock);
 	kfree(sbi);
-	lock_kernel();
+	kfree(orig_data);
+	return ret;
+
 out_free_orig:
+	unlock_kernel();
 	kfree(orig_data);
 	return ret;
 }

fs/fat/namei_msdos.c

@@ -9,6 +9,7 @@
 #include <linux/module.h>
 #include <linux/time.h>
 #include <linux/buffer_head.h>
+#include <linux/smp_lock.h>     /* For lock_kernel() */
 #include "fat.h"
 
 /* Characters that are undesirable in an MS-DOS file name */
@@ -662,12 +663,16 @@ static int msdos_fill_super(struct super_block *sb, void *data, int silent)
 {
 	int res;
 
+	lock_kernel();
 	res = fat_fill_super(sb, data, silent, &msdos_dir_inode_operations, 0);
-	if (res)
+	if (res) {
+		unlock_kernel();
 		return res;
+	}
 
 	sb->s_flags |= MS_NOATIME;
 	sb->s_root->d_op = &msdos_dentry_operations;
+	unlock_kernel();
 	return 0;
 }