Re: [PATCH 09/23] md: rewrite md_setup_drive to avoid ioctls

NeilBrown
2020-07-15T23:51:04Z

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On Tue, Jul 14 2020, Christoph Hellwig wrote:

> md_setup_drive knows it works with md devices, so it is rather pointless
> to open a file descriptor and issue ioctls. Just call directly into the
> relevant low-level md routines after getting a handle to the device using
> blkdev_get_by_dev instead.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> Acked-by: Song Liu <song@kernel.org>
> ---
> drivers/md/md-autodetect.c | 127 ++++++++++++++++---------------------
> drivers/md/md.c | 20 +++---
> drivers/md/md.h | 6 ++
> 3 files changed, 71 insertions(+), 82 deletions(-)
>
> diff --git a/drivers/md/md-autodetect.c b/drivers/md/md-autodetect.c
> index a43a8f1580584c..5b24b5616d3acc 100644
> --- a/drivers/md/md-autodetect.c
> +++ b/drivers/md/md-autodetect.c
> @@ -2,7 +2,6 @@
> #include <linux/kernel.h>
> #include <linux/blkdev.h>
> #include <linux/init.h>
> -#include <linux/syscalls.h>
> #include <linux/mount.h>
> #include <linux/major.h>
> #include <linux/delay.h>
> @@ -120,37 +119,29 @@ static int __init md_setup(char *str)
> return 1;
> }
>
> -static inline int create_dev(char *name, dev_t dev)
> -{
> - ksys_unlink(name);
> - return ksys_mknod(name, S_IFBLK|0600, new_encode_dev(dev));
> -}
> -
> static void __init md_setup_drive(struct md_setup_args *args)
> {
> - int minor, i, partitioned;
> - dev_t dev;
> - dev_t devices[MD_SB_DISKS+1];
> - int fd;
> - int err = 0;
> - char *devname;
> - mdu_disk_info_t dinfo;
> + char *devname = args->device_names;
> + dev_t devices[MD_SB_DISKS + 1], mdev;
> + struct mdu_array_info_s ainfo = { };
> + struct block_device *bdev;
> + struct mddev *mddev;
> + int err = 0, i;
> char name[16];
>
> - minor = args->minor;
> - partitioned = args->partitioned;
> - devname = args->device_names;
> + if (args->partitioned) {
> + mdev = MKDEV(mdp_major, args->minor << MdpMinorShift);
> + sprintf(name, "md_d%d", args->minor);
> + } else {
> + mdev = MKDEV(MD_MAJOR, args->minor);
> + sprintf(name, "md%d", args->minor);
> + }
>
> - sprintf(name, "/dev/md%s%d", partitioned?"_d":"", minor);
> - if (partitioned)
> - dev = MKDEV(mdp_major, minor << MdpMinorShift);
> - else
> - dev = MKDEV(MD_MAJOR, minor);
> - create_dev(name, dev);
> for (i = 0; i < MD_SB_DISKS && devname != NULL; i++) {
> struct kstat stat;
> char *p;
> char comp_name[64];
> + dev_t dev;
>
> p = strchr(devname, ',');
> if (p)
> @@ -163,7 +154,7 @@ static void __init md_setup_drive(struct md_setup_args *args)
> if (vfs_stat(comp_name, &stat) == 0 && S_ISBLK(stat.mode))
> dev = new_decode_dev(stat.rdev);
> if (!dev) {
> - printk(KERN_WARNING "md: Unknown device name: %s\n", devname);
> + pr_warn("md: Unknown device name: %s\n", devname);
> break;
> }
>
> @@ -175,68 +166,64 @@ static void __init md_setup_drive(struct md_setup_args *args)
> if (!i)
> return;
>
> - printk(KERN_INFO "md: Loading md%s%d: %s\n",
> - partitioned ? "_d" : "", minor,
> - args->device_names);
> + pr_info("md: Loading %s: %s\n", name, args->device_names);
>
> - fd = ksys_open(name, 0, 0);
> - if (fd < 0) {
> - printk(KERN_ERR "md: open failed - cannot start "
> - "array %s\n", name);
> + bdev = blkdev_get_by_dev(mdev, FMODE_READ, NULL);
> + if (IS_ERR(bdev)) {
> + pr_err("md: open failed - cannot start array %s\n", name);
> return;
> }
> - if (ksys_ioctl(fd, SET_ARRAY_INFO, 0) == -EBUSY) {
> - printk(KERN_WARNING
> - "md: Ignoring md=%d, already autodetected. (Use raid=noautodetect)\n",
> - minor);
> - ksys_close(fd);
> - return;

I'd be more comfortable if you added something like
if (WARN(bdev->bd_disk->fops != md_fops,
"Opening block device %x resulted in non-md device\"))
return;
here. However even without that

Reviewed-by: NeilBrown <neilb@suse.de>

Thanks,
NeilBrown

> + mddev = bdev->bd_disk->private_data;
> +
> + err = mddev_lock(mddev);
> + if (err) {
> + pr_err("md: failed to lock array %s\n", name);
> + goto out_blkdev_put;
> + }
> +
> + if (!list_empty(&mddev->disks) || mddev->raid_disks) {
> + pr_warn("md: Ignoring %s, already autodetected. (Use raid=noautodetect)\n",
> + name);
> + goto out_unlock;
> }
>
> if (args->level != LEVEL_NONE) {
> /* non-persistent */
> - mdu_array_info_t ainfo;
> ainfo.level = args->level;
> - ainfo.size = 0;
> - ainfo.nr_disks =0;
> - ainfo.raid_disks =0;
> - while (devices[ainfo.raid_disks])
> - ainfo.raid_disks++;
> - ainfo.md_minor =minor;
> + ainfo.md_minor = args->minor;
> ainfo.not_persistent = 1;
> -
> ainfo.state = (1 << MD_SB_CLEAN);
> - ainfo.layout = 0;
> ainfo.chunk_size = args->chunk;
> - err = ksys_ioctl(fd, SET_ARRAY_INFO, (long)&ainfo);
> - for (i = 0; !err && i <= MD_SB_DISKS; i++) {
> - dev = devices[i];
> - if (!dev)
> - break;
> + while (devices[ainfo.raid_disks])
> + ainfo.raid_disks++;
> + }
> +
> + err = md_set_array_info(mddev, &ainfo);
> +
> + for (i = 0; i <= MD_SB_DISKS && devices[i]; i++) {
> + struct mdu_disk_info_s dinfo = {
> + .major = MAJOR(devices[i]),
> + .minor = MINOR(devices[i]),
> + };
> +
> + if (args->level != LEVEL_NONE) {
> dinfo.number = i;
> dinfo.raid_disk = i;
> - dinfo.state = (1<<MD_DISK_ACTIVE)|(1<<MD_DISK_SYNC);
> - dinfo.major = MAJOR(dev);
> - dinfo.minor = MINOR(dev);
> - err = ksys_ioctl(fd, ADD_NEW_DISK,
> - (long)&dinfo);
> - }
> - } else {
> - /* persistent */
> - for (i = 0; i <= MD_SB_DISKS; i++) {
> - dev = devices[i];
> - if (!dev)
> - break;
> - dinfo.major = MAJOR(dev);
> - dinfo.minor = MINOR(dev);
> - ksys_ioctl(fd, ADD_NEW_DISK, (long)&dinfo);
> + dinfo.state =
> + (1 << MD_DISK_ACTIVE) | (1 << MD_DISK_SYNC);
> }
> +
> + md_add_new_disk(mddev, &dinfo);
> }
> +
> if (!err)
> - err = ksys_ioctl(fd, RUN_ARRAY, 0);
> + err = do_md_run(mddev);
> if (err)
> - printk(KERN_WARNING "md: starting md%d failed\n", minor);
> - ksys_close(fd);
> + pr_warn("md: starting %s failed\n", name);
> +out_unlock:
> + mddev_unlock(mddev);
> +out_blkdev_put:
> + blkdev_put(bdev, FMODE_READ);
> }
>
> static int __init raid_setup(char *str)
> @@ -286,8 +273,6 @@ void __init md_run_setup(void)
> {
> int ent;
>
> - create_dev("/dev/md0", MKDEV(MD_MAJOR, 0));
> -
> if (raid_noautodetect)
> printk(KERN_INFO "md: Skipping autodetection of RAID arrays. (raid=autodetect will force)\n");
> else
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index 6e9a48da474848..9960cfeb59a50c 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -4368,7 +4368,6 @@ array_state_show(struct mddev *mddev, char *page)
>
> static int do_md_stop(struct mddev *mddev, int ro, struct block_device *bdev);
> static int md_set_readonly(struct mddev *mddev, struct block_device *bdev);
> -static int do_md_run(struct mddev *mddev);
> static int restart_array(struct mddev *mddev);
>
> static ssize_t
> @@ -6015,7 +6014,7 @@ int md_run(struct mddev *mddev)
> }
> EXPORT_SYMBOL_GPL(md_run);
>
> -static int do_md_run(struct mddev *mddev)
> +int do_md_run(struct mddev *mddev)
> {
> int err;
>
> @@ -6651,7 +6650,7 @@ static int get_disk_info(struct mddev *mddev, void __user * arg)
> return 0;
> }
>
> -static int add_new_disk(struct mddev *mddev, mdu_disk_info_t *info)
> +int md_add_new_disk(struct mddev *mddev, struct mdu_disk_info_s *info)
> {
> char b[BDEVNAME_SIZE], b2[BDEVNAME_SIZE];
> struct md_rdev *rdev;
> @@ -6697,7 +6696,7 @@ static int add_new_disk(struct mddev *mddev, mdu_disk_info_t *info)
> }
>
> /*
> - * add_new_disk can be used once the array is assembled
> + * md_add_new_disk can be used once the array is assembled
> * to add "hot spares". They must already have a superblock
> * written
> */
> @@ -6810,7 +6809,7 @@ static int add_new_disk(struct mddev *mddev, mdu_disk_info_t *info)
> return err;
> }
>
> - /* otherwise, add_new_disk is only allowed
> + /* otherwise, md_add_new_disk is only allowed
> * for major_version==0 superblocks
> */
> if (mddev->major_version != 0) {
> @@ -7055,7 +7054,7 @@ static int set_bitmap_file(struct mddev *mddev, int fd)
> }
>
> /*
> - * set_array_info is used two different ways
> + * md_set_array_info is used two different ways
> * The original usage is when creating a new array.
> * In this usage, raid_disks is > 0 and it together with
> * level, size, not_persistent,layout,chunksize determine the
> @@ -7067,9 +7066,8 @@ static int set_bitmap_file(struct mddev *mddev, int fd)
> * The minor and patch _version numbers are also kept incase the
> * super_block handler wishes to interpret them.
> */
> -static int set_array_info(struct mddev *mddev, mdu_array_info_t *info)
> +int md_set_array_info(struct mddev *mddev, struct mdu_array_info_s *info)
> {
> -
> if (info->raid_disks == 0) {
> /* just setting version number for superblock loading */
> if (info->major_version < 0 ||
> @@ -7560,7 +7558,7 @@ static int md_ioctl(struct block_device *bdev, fmode_t mode,
> err = -EBUSY;
> goto unlock;
> }
> - err = set_array_info(mddev, &info);
> + err = md_set_array_info(mddev, &info);
> if (err) {
> pr_warn("md: couldn't set array info. %d\n", err);
> goto unlock;
> @@ -7614,7 +7612,7 @@ static int md_ioctl(struct block_device *bdev, fmode_t mode,
> /* Need to clear read-only for this */
> break;
> else
> - err = add_new_disk(mddev, &info);
> + err = md_add_new_disk(mddev, &info);
> goto unlock;
> }
> break;
> @@ -7682,7 +7680,7 @@ static int md_ioctl(struct block_device *bdev, fmode_t mode,
> if (copy_from_user(&info, argp, sizeof(info)))
> err = -EFAULT;
> else
> - err = add_new_disk(mddev, &info);
> + err = md_add_new_disk(mddev, &info);
> goto unlock;
> }
>
> diff --git a/drivers/md/md.h b/drivers/md/md.h
> index 6f8fff77ce10a5..7ee81aa2eac862 100644
> --- a/drivers/md/md.h
> +++ b/drivers/md/md.h
> @@ -801,7 +801,13 @@ static inline void mddev_check_write_zeroes(struct mddev *mddev, struct bio *bio
> mddev->queue->limits.max_write_zeroes_sectors = 0;
> }
>
> +struct mdu_array_info_s;
> +struct mdu_disk_info_s;
> +
> extern int mdp_major;
> void md_autostart_arrays(int part);
> +int md_set_array_info(struct mddev *mddev, struct mdu_array_info_s *info);
> +int md_add_new_disk(struct mddev *mddev, struct mdu_disk_info_s *info);
> +int do_md_run(struct mddev *mddev);
>
> #endif /* _MD_MD_H */
> --
> 2.27.0

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