On Thu, 30 Jan 2014 09:42:50 +0100, Andreas Rohner wrote:
> With this ioctl the segment usage entries in the SUFILE can be
> updated from userspace.
>
> This is useful, because it allows the userspace GC to modify and update
> segment usage entries for specific segments, which enables it to avoid
> unnecessary write operations.
>
> If a segment needs to be cleaned, but there is no or very little
> reclaimable space in it, the cleaning operation basically degrades to
> a useless moving operation. In the end the only thing that changes is
> the location of the data and a timestamp in the segment usage
> information. With this ioctl the GC can skip the cleaning and update
> the segment usage entries directly instead.
>
> This is basically a shortcut to cleaning the segment. It is still
> necessary to read the segment summary information, but the writing of
> the live blocks can be skipped if it's not worth it.
>
> Signed-off-by: Andreas Rohner <andreas.rohner@xxxxxxx>
> ---
> fs/nilfs2/ioctl.c | 92 +++++++++++++++++++++++++++++++++++++++++++++++
> include/linux/nilfs2_fs.h | 2 ++
> 2 files changed, 94 insertions(+)
>
> diff --git a/fs/nilfs2/ioctl.c b/fs/nilfs2/ioctl.c
> index 2b34021..c19a231 100644
> --- a/fs/nilfs2/ioctl.c
> +++ b/fs/nilfs2/ioctl.c
> @@ -1163,6 +1163,95 @@ static int nilfs_ioctl_get_info(struct inode *inode, struct file *filp,
> return ret;
> }
>
> +/**
> + * nilfs_ioctl_set_suinfo - set segment usage info
> + * @inode: inode object
> + * @filp: file object
> + * @cmd: ioctl's request code
> + * @argp: pointer on argument from userspace
> + *
> + * Description: Expects an array of nilfs_suinfo_update structures
> + * encapsulated in nilfs_argv and updates the segment usage info
> + * according to the flags in nilfs_suinfo_update.
> + *
> + * Return Value: On success, 0 is returned. On error, one of the
> + * following negative error codes is returned.
> + *
> + * %-EPERM - Not enough permissions
> + *
> + * %-EFAULT - Error copying input data
> + *
> + * %-EIO - I/O error.
> + *
> + * %-ENOMEM - Insufficient amount of memory available.
> + *
> + * %-EINVAL - Invalid values in input (segment number, flags or nblocks)
> + */
> +static int nilfs_ioctl_set_suinfo(struct inode *inode, struct file *filp,
> + unsigned int cmd, void __user *argp)
> +{
> + struct the_nilfs *nilfs = inode->i_sb->s_fs_info;
> + struct nilfs_transaction_info ti;
> + struct nilfs_argv argv;
> + size_t len;
> + void __user *base;
> + void *kbuf;
> + int ret;
> +
> + if (!capable(CAP_SYS_ADMIN))
> + return -EPERM;
> +
> + ret = mnt_want_write_file(filp);
> + if (ret)
> + return ret;
> +
> + ret = -EFAULT;
> + if (copy_from_user(&argv, argp, sizeof(argv)))
> + goto out;
> +
> + ret = -EINVAL;
> + if (argv.v_size < sizeof(struct nilfs_suinfo_update))
> + goto out;
> +
> + if (argv.v_nmembs > nilfs->ns_nsegments)
> + goto out;
> +
> + if (argv.v_nmembs >= UINT_MAX / argv.v_size)
> + goto out;
> +
> + len = argv.v_size * argv.v_nmembs;
> + if (!len) {
> + ret = 0;
> + goto out;
> + }
> +
> + base = (void __user *)(unsigned long)argv.v_base;
> + kbuf = vmalloc(len);
> + if (!kbuf) {
> + ret = -ENOMEM;
> + goto out;
> + }
> +
> + if (copy_from_user(kbuf, base, len)) {
> + ret = -EFAULT;
> + goto out_free;
> + }
> +
> + nilfs_transaction_begin(inode->i_sb, &ti, 0);
> + ret = nilfs_sufile_set_suinfo(nilfs->ns_sufile, kbuf, argv.v_size,
> + argv.v_nmembs);
> + if (unlikely(ret < 0))
> + nilfs_transaction_abort(inode->i_sb);
> + else
> + nilfs_transaction_commit(inode->i_sb); /* never fails */
> +
> +out_free:
> + vfree(kbuf);
> +out:
> + mnt_drop_write_file(filp);
> + return ret;
> +}
> +
> long nilfs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
> {
> struct inode *inode = file_inode(filp);
> @@ -1189,6 +1278,8 @@ long nilfs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
> return nilfs_ioctl_get_info(inode, filp, cmd, argp,
> sizeof(struct nilfs_suinfo),
> nilfs_ioctl_do_get_suinfo);
> + case NILFS_IOCTL_SET_SUINFO:
> + return nilfs_ioctl_set_suinfo(inode, filp, cmd, argp);
> case NILFS_IOCTL_GET_SUSTAT:
> return nilfs_ioctl_get_sustat(inode, filp, cmd, argp);
> case NILFS_IOCTL_GET_VINFO:
> @@ -1228,6 +1319,7 @@ long nilfs_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
> case NILFS_IOCTL_GET_CPINFO:
> case NILFS_IOCTL_GET_CPSTAT:
> case NILFS_IOCTL_GET_SUINFO:
> + case NILFS_IOCTL_SET_SUINFO:
> case NILFS_IOCTL_GET_SUSTAT:
> case NILFS_IOCTL_GET_VINFO:
> case NILFS_IOCTL_GET_BDESCS:
> diff --git a/include/linux/nilfs2_fs.h b/include/linux/nilfs2_fs.h
> index 2526578..1fb465f 100644
> --- a/include/linux/nilfs2_fs.h
> +++ b/include/linux/nilfs2_fs.h
> @@ -905,5 +905,7 @@ struct nilfs_bdesc {
> _IOW(NILFS_IOCTL_IDENT, 0x8B, __u64)
> #define NILFS_IOCTL_SET_ALLOC_RANGE \
> _IOW(NILFS_IOCTL_IDENT, 0x8C, __u64[2])
> +#define NILFS_IOCTL_SET_SUINFO \
> + _IOW(NILFS_IOCTL_IDENT, 0x8D, struct nilfs_argv)
>
> #endif /* _LINUX_NILFS_FS_H */
> --
> 1.8.5.3
Looks OK to me.
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