ext4: Add EXT4_IOC_CLR_GLOBAL_ALLOC_RULE clears block allocation restriction

ext4: Add EXT4_IOC_CLR_GLOBAL_ALLOC_RULE clears block allocation restriction

From: Akira Fujita <[email protected]>

Block allocation restriction is cleared with this ioctl or umount filesystem.

  #define EXT4_IOC_CLR_GLOBAL_ALLOC_RULE _IOW('f', 17, struct ext4_alloc_rule);

struct ext4_alloc_rule {

        __u64 start;            /* start physical offset to clear rule */
        __u64 len;              /* number of blocks to be clear */
        __u32 alloc_flag;       /* not used, should be zero */

};

For example, block allocation restriction (1) has been already set on FS, and call EXT4_IOC_CLR_GLOBAL_ALLOC_RULE (2),
As a result, block allocation restriction is divided into two.

(1) start:5000, len:1000, flag:0
(2) start:5500, len:100
(3) start:5000, len:500, flag:0
(4) start:5600, len:400, flag:0

<Before>
BG#0 |-------------------------------|

       0       |***********|           32767
            5000    (1)    5999

<After>
BG#0 |-------------------------------|

       0       |****|  |***|         32767
            5000  5499 5600 5999
                 (3)    (4)

---
 fs/ext4/ext4.h    |    3 +
 fs/ext4/ioctl.c   |   16 +++++
 fs/ext4/mballoc.c |  186 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 205 insertions(+), 0 deletions(-)

index 1d2d550..d2cac27 100644
@@ -357,6 +357,7 @@ struct ext4_new_group_data {
 #define EXT4_IOC_ALLOC_DA_BLKS		_IO('f', 12)
 #define EXT4_IOC_MOVE_EXT		_IOWR('f', 15, struct move_extent)
 #define EXT4_IOC_ADD_GLOBAL_ALLOC_RULE	_IOW('f', 16, struct ext4_alloc_rule)
+#define EXT4_IOC_CLR_GLOBAL_ALLOC_RULE	_IOW('f', 17, struct ext4_alloc_rule)
 
 /*
  * ioctl commands in 32 bit emulation

@@ -1386,6 +1387,8 @@ extern int ext4_mb_get_buddy_cache_lock(struct super_block *, ext4_group_t);
 extern void ext4_mb_put_buddy_cache_lock(struct super_block *,
 						ext4_group_t, int);
 extern int ext4_mb_add_global_arule(struct inode *, struct ext4_alloc_rule *);
+extern int ext4_mb_del_global_arule(struct inode *, struct ext4_alloc_rule *);
+extern void ext4_mb_release_arule_list(struct ext4_sb_info *);
 
 /* inode.c */
 int ext4_forget(handle_t *handle, int is_metadata, struct inode *inode,

index 8505e3a..955bb08 100644
@@ -276,6 +276,22 @@ setversion_out:
 		return err;
 	}
 
+	case EXT4_IOC_CLR_GLOBAL_ALLOC_RULE: {
+		struct ext4_alloc_rule arule;
+		int err;
+
+		if (copy_from_user(&arule,
+				(struct ext4_alloc_rule __user *)arg,
+				sizeof(arule)))
+			return -EFAULT;
+
+		if (!capable(CAP_SYS_ADMIN))
+			return -EPERM;
+
+		err = ext4_mb_del_global_arule(inode, &arule);
+		return err;
+	}
+
 	case EXT4_IOC_GROUP_ADD: {
 		struct ext4_new_group_data input;
 		struct super_block *sb = inode->i_sb;

Why not call EXT4_IOC_ADD_GLOBAL_ALLOC_RULE with a "clear" flag?

Cheers, Andreas
--
Andreas Dilger
Sr. Staff Engineer, Lustre Group
Sun Microsystems of Canada, Inc.

Hi Andreas,

Yes, having "clear" flag makes more sense
than implementing ioctls separately.

I will add "clear" flag (EXT4_MB_CLEAR_ALLOC_RULE) to alloc_flag and remove EXT4_IOC_CLR_GLOBAL_ALLOC_RULE ioctl in the next version.

Thanks,
Akira Fujita