Commit e681c047 authored Nov 19, 2010 by Lukas Czerner Committed by Theodore Ts'o Nov 19, 2010

ext4: Add EXT4_IOC_TRIM ioctl to handle batched discard



Filesystem independent ioctl was rejected as not common enough to be in
core vfs ioctl. Since we still need to access to this functionality this
commit adds ext4 specific ioctl EXT4_IOC_TRIM to dispatch
ext4_trim_fs().

It takes fstrim_range structure as an argument. fstrim_range is definec in
the include/linux/fs.h and its definition is as follows.

struct fstrim_range {
	__u64 start;
	__u64 len;
	__u64 minlen;
}

start	- first Byte to trim
len	- number of Bytes to trim from start
minlen	- minimum extent length to trim, free extents shorter than this
  number of Bytes will be ignored. This will be rounded up to fs
  block size.

After the FITRIM is done, the number of actually discarded Bytes is stored
in fstrim_range.len to give the user better insight on how much storage
space has been really released for wear-leveling.

Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

parent 93bb41f4

fs/ext4/ioctl.c

+24 −0

Original line number	Diff line number	Diff line
		@@ -331,6 +331,30 @@ mext_out:
		return err;
		}

		case FITRIM:
		{
		struct super_block *sb = inode->i_sb;
		struct fstrim_range range;
		int ret = 0;

		if (!capable(CAP_SYS_ADMIN))
		return -EPERM;

		if (copy_from_user(&range, (struct fstrim_range *)arg,
		sizeof(range)))
		return -EFAULT;

		ret = ext4_trim_fs(sb, &range);
		if (ret < 0)
		return ret;

		if (copy_to_user((struct fstrim_range *)arg, &range,
		sizeof(range)))
		return -EFAULT;

		return 0;
		}

		default:
		return -ENOTTY;
		}

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