Commit 367a51a3 authored by Lukas Czerner's avatar Lukas Czerner Committed by Theodore Ts'o
Browse files

fs: Add FITRIM ioctl 



Adds an filesystem independent ioctl to allow implementation of file
system batched discard support. I takes fstrim_range structure as an
argument. fstrim_range is definec in the include/fs.h and its
definition is as follows.

struct fstrim_range {
	start;
	len;
	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.

It is also possible to specify NULL as an argument. In this case the
arguments will set itself as follows:

start = 0;
len = ULLONG_MAX;
minlen = 0;

So it will trim the whole file system at one run.

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: default avatarLukas Czerner <lczerner@redhat.com>
Reviewed-by: default avatarDmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent 77ca6cdf

fs/ioctl.c

+39 −0
Original line number Diff line number Diff line
@@ -530,6 +530,41 @@ static int ioctl_fsthaw(struct file *filp) 
	return thaw_super(sb);

}



static int ioctl_fstrim(struct file *filp, void __user *argp)

{

	struct super_block *sb = filp->f_path.dentry->d_inode->i_sb;

	struct fstrim_range range;

	int ret = 0;



	if (!capable(CAP_SYS_ADMIN))

		return -EPERM;



	/* If filesystem doesn't support trim feature, return. */

	if (sb->s_op->trim_fs == NULL)

		return -EOPNOTSUPP;



	/* If a blockdevice-backed filesystem isn't specified, return EINVAL. */

	if (sb->s_bdev == NULL)

		return -EINVAL;



	if (argp == NULL) {

		range.start = 0;

		range.len = ULLONG_MAX;

		range.minlen = 0;

	} else if (copy_from_user(&range, argp, sizeof(range)))

		return -EFAULT;



	ret = sb->s_op->trim_fs(sb, &range);

	if (ret < 0)

		return ret;



	if ((argp != NULL) &&

	    (copy_to_user(argp, &range, sizeof(range))))

		return -EFAULT;



	return 0;

}



/*

 * When you add any new common ioctls to the switches above and below

 * please update compat_sys_ioctl() too.
@@ -580,6 +615,10 @@ int do_vfs_ioctl(struct file *filp, unsigned int fd, unsigned int cmd, 
		error = ioctl_fsthaw(filp);

		break;



	case FITRIM:

		error = ioctl_fstrim(filp, argp);

		break;



	case FS_IOC_FIEMAP:

		return ioctl_fiemap(filp, arg);

include/linux/fs.h

+8 −0
Original line number Diff line number Diff line
@@ -32,6 +32,12 @@ 
#define SEEK_END	2	/* seek relative to end of file */

#define SEEK_MAX	SEEK_END



struct fstrim_range {

	uint64_t start;

	uint64_t len;

	uint64_t minlen;

};



/* And dynamically-tunable limits and defaults: */

struct files_stat_struct {

	int nr_files;		/* read only */
@@ -316,6 +322,7 @@ struct inodes_stat_t { 
#define FIGETBSZ   _IO(0x00,2)	/* get the block size used for bmap */

#define FIFREEZE	_IOWR('X', 119, int)	/* Freeze */

#define FITHAW		_IOWR('X', 120, int)	/* Thaw */

#define FITRIM		_IOWR('X', 121, struct fstrim_range)	/* Trim */



#define	FS_IOC_GETFLAGS			_IOR('f', 1, long)

#define	FS_IOC_SETFLAGS			_IOW('f', 2, long)
@@ -1581,6 +1588,7 @@ struct super_operations { 
	ssize_t (*quota_write)(struct super_block *, int, const char *, size_t, loff_t);

#endif

	int (*bdev_try_to_free_page)(struct super_block*, struct page*, gfp_t);

	int (*trim_fs) (struct super_block *, struct fstrim_range *);

};



/*

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