ext4: add new online resize interface

This patch adds new online resize interface, whose input argument is a
64-bit integer indicating how many blocks there are in the resized fs.

In new resize impelmentation, all work like allocating group tables
are done by kernel side, so the new resize interface can support
flex_bg feature and prepares ground for suppoting resize with features
like bigalloc and exclude bitmap. Besides these, user-space tools just
passes in the new number of blocks.

We delay initializing the bitmaps and inode tables of added groups if
possible and add multi groups (a flex groups) each time, so new resize
is very fast like mkfs.

Signed-off-by: Yongqiang Yang <xiaoqiangnk@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 57 insertions, 0 deletions

diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
index ff1aab7cd6e..c1a98804a38 100644
--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -18,6 +18,8 @@
 #include "ext4_jbd2.h"
 #include "ext4.h"
 
+#define MAX_32_NUM ((((unsigned long long) 1) << 32) - 1)
+
 long ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 {
 	struct inode *inode = filp->f_dentry->d_inode;
@@ -329,6 +331,60 @@ mext_out:
 		return err;
 	}
 
+	case EXT4_IOC_RESIZE_FS: {
+		ext4_fsblk_t n_blocks_count;
+		struct super_block *sb = inode->i_sb;
+		int err = 0, err2 = 0;
+
+		if (EXT4_HAS_RO_COMPAT_FEATURE(sb,
+			       EXT4_FEATURE_RO_COMPAT_BIGALLOC)) {
+			ext4_msg(sb, KERN_ERR,
+				 "Online resizing not (yet) supported with bigalloc");
+			return -EOPNOTSUPP;
+		}
+
+		if (EXT4_HAS_INCOMPAT_FEATURE(sb,
+			       EXT4_FEATURE_INCOMPAT_META_BG)) {
+			ext4_msg(sb, KERN_ERR,
+				 "Online resizing not (yet) supported with meta_bg");
+			return -EOPNOTSUPP;
+		}
+
+		if (copy_from_user(&n_blocks_count, (__u64 __user *)arg,
+				   sizeof(__u64))) {
+			return -EFAULT;
+		}
+
+		if (n_blocks_count > MAX_32_NUM &&
+		    !EXT4_HAS_INCOMPAT_FEATURE(sb,
+					       EXT4_FEATURE_INCOMPAT_64BIT)) {
+			ext4_msg(sb, KERN_ERR,
+				 "File system only supports 32-bit block numbers");
+			return -EOPNOTSUPP;
+		}
+
+		err = ext4_resize_begin(sb);
+		if (err)
+			return err;
+
+		err = mnt_want_write(filp->f_path.mnt);
+		if (err)
+			goto resizefs_out;
+
+		err = ext4_resize_fs(sb, n_blocks_count);
+		if (EXT4_SB(sb)->s_journal) {
+			jbd2_journal_lock_updates(EXT4_SB(sb)->s_journal);
+			err2 = jbd2_journal_flush(EXT4_SB(sb)->s_journal);
+			jbd2_journal_unlock_updates(EXT4_SB(sb)->s_journal);
+		}
+		if (err == 0)
+			err = err2;
+		mnt_drop_write(filp->f_path.mnt);
+resizefs_out:
+		ext4_resize_end(sb);
+		return err;
+	}
+
 	case FITRIM:
 	{
 		struct request_queue *q = bdev_get_queue(sb->s_bdev);
@@ -427,6 +483,7 @@ long ext4_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 	}
 	case EXT4_IOC_MOVE_EXT:
 	case FITRIM:
+	case EXT4_IOC_RESIZE_FS:
 		break;
 	default:
 		return -ENOIOCTLCMD;