ext4: enforce bigalloc restrictions (e.g., no online resizing, etc.)

At least initially if the bigalloc feature is enabled, we will not
support non-extent mapped inodes, online resizing, online defrag, or
the FITRIM ioctl.  This simplifies the initial implementation.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

fs/ext4/indirect.c

@@ -699,6 +699,13 @@ int ext4_ind_map_blocks(handle_t *handle, struct inode *inode,
 	/*
 	 * Okay, we need to do block allocation.
 	*/
+	if (EXT4_HAS_RO_COMPAT_FEATURE(inode->i_sb,
+				       EXT4_FEATURE_RO_COMPAT_BIGALLOC)) {
+		EXT4_ERROR_INODE(inode, "Can't allocate blocks for "
+				 "non-extent mapped inodes with bigalloc");
+		return -ENOSPC;
+	}
+
 	goal = ext4_find_goal(inode, map->m_lblk, partial);
 
 	/* the number of blocks need to allocate for [d,t]indirect blocks */

fs/ext4/inode.c

@@ -3358,6 +3358,11 @@ int ext4_punch_hole(struct file *file, loff_t offset, loff_t length)
 		return -ENOTSUPP;
 	}
 
+	if (EXT4_SB(inode->i_sb)->s_cluster_ratio > 1) {
+		/* TODO: Add support for bigalloc file systems */
+		return -ENOTSUPP;
+	}
+
 	return ext4_ext_punch_hole(file, offset, length);
 }
 

fs/ext4/ioctl.c

@@ -21,6 +21,7 @@
 long ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 {
 	struct inode *inode = filp->f_dentry->d_inode;
+	struct super_block *sb = inode->i_sb;
 	struct ext4_inode_info *ei = EXT4_I(inode);
 	unsigned int flags;
 
@@ -183,7 +184,6 @@ setversion_out:
 		 * Returns 1 if it slept, else zero.
 		 */
 		{
-			struct super_block *sb = inode->i_sb;
 			DECLARE_WAITQUEUE(wait, current);
 			int ret = 0;
 
@@ -199,7 +199,6 @@ setversion_out:
 #endif
 	case EXT4_IOC_GROUP_EXTEND: {
 		ext4_fsblk_t n_blocks_count;
-		struct super_block *sb = inode->i_sb;
 		int err, err2=0;
 
 		err = ext4_resize_begin(sb);
@@ -209,6 +208,13 @@ setversion_out:
 		if (get_user(n_blocks_count, (__u32 __user *)arg))
 			return -EFAULT;
 
+		if (EXT4_HAS_RO_COMPAT_FEATURE(sb,
+			       EXT4_FEATURE_RO_COMPAT_BIGALLOC)) {
+			ext4_msg(sb, KERN_ERR,
+				 "Online resizing not supported with bigalloc");
+			return -EOPNOTSUPP;
+		}
+
 		err = mnt_want_write(filp->f_path.mnt);
 		if (err)
 			return err;
@@ -250,6 +256,13 @@ setversion_out:
 			goto mext_out;
 		}
 
+		if (EXT4_HAS_RO_COMPAT_FEATURE(sb,
+			       EXT4_FEATURE_RO_COMPAT_BIGALLOC)) {
+			ext4_msg(sb, KERN_ERR,
+				 "Online defrag not supported with bigalloc");
+			return -EOPNOTSUPP;
+		}
+
 		err = mnt_want_write(filp->f_path.mnt);
 		if (err)
 			goto mext_out;
@@ -270,7 +283,6 @@ mext_out:
 
 	case EXT4_IOC_GROUP_ADD: {
 		struct ext4_new_group_data input;
-		struct super_block *sb = inode->i_sb;
 		int err, err2=0;
 
 		err = ext4_resize_begin(sb);
@@ -281,6 +293,13 @@ mext_out:
 				sizeof(input)))
 			return -EFAULT;
 
+		if (EXT4_HAS_RO_COMPAT_FEATURE(sb,
+			       EXT4_FEATURE_RO_COMPAT_BIGALLOC)) {
+			ext4_msg(sb, KERN_ERR,
+				 "Online resizing not supported with bigalloc");
+			return -EOPNOTSUPP;
+		}
+
 		err = mnt_want_write(filp->f_path.mnt);
 		if (err)
 			return err;
@@ -337,7 +356,6 @@ mext_out:
 
 	case FITRIM:
 	{
-		struct super_block *sb = inode->i_sb;
 		struct request_queue *q = bdev_get_queue(sb->s_bdev);
 		struct fstrim_range range;
 		int ret = 0;
@@ -348,6 +366,13 @@ mext_out:
 		if (!blk_queue_discard(q))
 			return -EOPNOTSUPP;
 
+		if (EXT4_HAS_RO_COMPAT_FEATURE(sb,
+			       EXT4_FEATURE_RO_COMPAT_BIGALLOC)) {
+			ext4_msg(sb, KERN_ERR,
+				 "FITRIM not supported with bigalloc");
+			return -EOPNOTSUPP;
+		}
+
 		if (copy_from_user(&range, (struct fstrim_range *)arg,
 		    sizeof(range)))
 			return -EFAULT;

fs/ext4/super.c

@@ -2701,6 +2701,13 @@ static int ext4_feature_set_ok(struct super_block *sb, int readonly)
 			return 0;
 		}
 	}
+	if (EXT4_HAS_RO_COMPAT_FEATURE(sb, EXT4_FEATURE_RO_COMPAT_BIGALLOC) &&
+	    !EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_EXTENTS)) {
+		ext4_msg(sb, KERN_ERR,
+			 "Can't support bigalloc feature without "
+			 "extents feature\n");
+		return 0;
+	}
 	return 1;
 }