[Devel] [PATCH RHEL7 COMMIT] ext4: Add ioctl EXT4_IOC_SET_RSV_BLOCKS V2

[Konstantin Khorenko]

The commit is pushed to "branch-rh7-3.10.0-123.1.2-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-123.1.2.vz7.5.15
------>
commit d7f53fb77a6fe22a6383a530e2f4bf12b1cc486b
Author: Dmitry Monakhov <dmonakhov at openvz.org>
Date:   Mon Jun 22 14:38:38 2015 +0400

    ext4: Add ioctl EXT4_IOC_SET_RSV_BLOCKS V2
    
    We have to update reservation block counts according to balloon size.
    One can do that directly via tune2fs which is not good for mounted fs,
    and should use this ioctl instead.
    
    changes from v1:
    - add missed ext4_handle_dirty_metadata
    - change error code
    
    https://jira.sw.ru/browse/PSBM-25929
    
    Orig-patch:diff-ext4-add-ioctl-EXT4_IOC_SET_RSV_BLOCKS-v2
    
    Signed-off-by: Dmitry Monakhov <dmonakhov at openvz.org>
---
 fs/ext4/ext4.h  |  1 +
 fs/ext4/ioctl.c | 60 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 61 insertions(+)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index a4c98cc..e53ceed 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -621,6 +621,7 @@ enum {
 #define EXT4_IOC_SWAP_BOOT		_IO('f', 17)
 #define EXT4_IOC_OPEN_BALLOON		_IO('f', 42)
 #define EXT4_IOC_MFSYNC			_IO('f', 43)
+#define EXT4_IOC_SET_RSV_BLOCKS		_IOW('f', 44, __u64)
 
 #if defined(__KERNEL__) && defined(CONFIG_COMPAT)
 /*
diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
index 597ab44..fc18911 100644
--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -648,6 +648,66 @@ resizefs_out:
 		ext4_resize_end(sb);
 		return err;
 	}
+	case EXT4_IOC_SET_RSV_BLOCKS: {
+		ext4_fsblk_t n_blocks_count;
+		struct super_block *sb = inode->i_sb;
+		handle_t *handle;
+		int err = 0, err2 = 0;
+
+		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;
+		}
+
+		if (n_blocks_count > ext4_blocks_count(EXT4_SB(sb)->s_es))
+			return -EINVAL;
+
+		err = ext4_resize_begin(sb);
+		if (err)
+			return err;
+
+		err = mnt_want_write(filp->f_path.mnt);
+		if (err)
+			goto resize_out;
+
+		handle = ext4_journal_start_sb(sb, EXT4_HT_MISC, 1);
+		if (IS_ERR(handle)) {
+			err = PTR_ERR(handle);
+			goto mnt_out;
+		}
+		err = ext4_journal_get_write_access(handle, EXT4_SB(sb)->s_sbh);
+		if (err) {
+			goto journal_out;
+		}
+		ext4_r_blocks_count_set(EXT4_SB(sb)->s_es, n_blocks_count);
+		ext4_handle_dirty_metadata(handle, NULL, EXT4_SB(sb)->s_sbh);
+journal_out:
+		err2 = ext4_journal_stop(handle);
+		if (err == 0)
+			err = err2;
+
+		if (!err && 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_out:
+		mnt_drop_write(filp->f_path.mnt);
+resize_out:
+		ext4_resize_end(sb);
+		return err;
+	}
+
 
 	case FITRIM:
 	{