fs: Do not dispatch FITRIM through separate super_operation

There was concern that FITRIM ioctl is not common enough to be included
in core vfs ioctl, as Christoph Hellwig pointed out there's no real point
in dispatching this out to a separate vector instead of just through
->ioctl.

So this commit removes ioctl_fstrim() from vfs ioctl and trim_fs
from super_operation structure.
Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

fs/ext4/super.c

@@ -1197,7 +1197,6 @@ static const struct super_operations ext4_sops = {
 	.quota_write	= ext4_quota_write,
 #endif
 	.bdev_try_to_free_page = bdev_try_to_free_page,
-	.trim_fs	= ext4_trim_fs
 };
 
 static const struct super_operations ext4_nojournal_sops = {

fs/ioctl.c

@@ -530,41 +530,6 @@ 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.
@@ -615,10 +580,6 @@ 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

@@ -1612,7 +1612,6 @@ 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 *);
 };
 
 /*