Add support to create a cdev multipath device. The functionality is much the same as NVMe, where the cdev is created when a mpath device is set live.
The driver must provide a mpath_head_template.cdev_ioctl callback to actually handle the ioctl. Structure mpath_generic_chr_fops would be used for setting the cdev fops in the mpath_head_template.add_cdev callback. Signed-off-by: John Garry <[email protected]> --- include/linux/multipath.h | 15 +++++ lib/multipath.c | 116 ++++++++++++++++++++++++++++++++++++++ 2 files changed, 131 insertions(+) diff --git a/include/linux/multipath.h b/include/linux/multipath.h index 4255b73de56b2..0dcfdd205237c 100644 --- a/include/linux/multipath.h +++ b/include/linux/multipath.h @@ -4,8 +4,11 @@ #include <linux/blkdev.h> #include <linux/blk-mq.h> +#include <linux/cdev.h> #include <linux/srcu.h> +#include <linux/io_uring/cmd.h> +extern const struct file_operations mpath_generic_chr_fops; extern const struct block_device_operations mpath_ops; enum mpath_iopolicy_e { @@ -45,9 +48,18 @@ struct mpath_device { struct mpath_head_template { bool (*available_path)(struct mpath_device *, bool *); + int (*add_cdev)(struct mpath_head *); + void (*del_cdev)(struct mpath_head *); bool (*is_disabled)(struct mpath_device *); bool (*is_optimized)(struct mpath_device *); enum mpath_access_state (*get_access_state)(struct mpath_device *); + int (*cdev_ioctl)(struct mpath_head *, struct mpath_device *, + blk_mode_t mode, unsigned int cmd, unsigned long arg, int srcu_idx); + int (*chr_uring_cmd)(struct mpath_device *, struct io_uring_cmd *ioucmd, + unsigned int issue_flags); + int (*chr_uring_cmd_iopoll)(struct io_uring_cmd *ioucmd, + struct io_comp_batch *iob, + unsigned int poll_flags); enum mpath_iopolicy_e (*get_iopolicy)(struct mpath_head *); struct bio *(*clone_bio)(struct bio *); const struct attribute_group **device_groups; @@ -66,6 +78,9 @@ struct mpath_head { spinlock_t requeue_lock; struct work_struct requeue_work; /* work struct for requeue */ + struct cdev cdev; + struct device cdev_device; + unsigned long flags; struct mpath_device __rcu *current_path[MAX_NUMNODES]; const struct mpath_head_template *mpdt; diff --git a/lib/multipath.c b/lib/multipath.c index 7f3b0cccf053b..ce12d42918fdd 100644 --- a/lib/multipath.c +++ b/lib/multipath.c @@ -469,6 +469,113 @@ const struct block_device_operations mpath_ops = { }; EXPORT_SYMBOL_GPL(mpath_ops); +static int mpath_generic_chr_open(struct inode *inode, struct file *file) +{ + struct cdev *cdev = file_inode(file)->i_cdev; + struct mpath_head *mpath_head = + container_of(cdev, struct mpath_head, cdev); + + return mpath_get_head(mpath_head); +} + +static int mpath_generic_chr_release(struct inode *inode, struct file *file) +{ + struct cdev *cdev = file_inode(file)->i_cdev; + struct mpath_head *mpath_head = + container_of(cdev, struct mpath_head, cdev); + + mpath_put_head(mpath_head); + return 0; +} + +static long mpath_generic_chr_ioctl(struct file *file, unsigned int cmd, + unsigned long arg) +{ + struct cdev *cdev = file_inode(file)->i_cdev; + struct mpath_head *mpath_head = + container_of(cdev, struct mpath_head, cdev); + struct mpath_device *mpath_device; + fmode_t mode = file->f_mode; + int srcu_idx, err = -EWOULDBLOCK; + + srcu_idx = srcu_read_lock(&mpath_head->srcu); + mpath_device = mpath_find_path(mpath_head); + if (!mpath_device) + goto out_unlock; + + /* + * If we are in the middle of error recovery, don't let anyone + * else try and use this device. Also, if error recovery fails, it + * may try and take the device offline, in which case all further + * access to the device is prohibited. + */ + err = mpath_head->mpdt->cdev_ioctl(mpath_head, mpath_device, + mode, cmd, arg, srcu_idx); + lockdep_assert_not_held(&mpath_head->srcu); + return err;// ioctl must unlock + +out_unlock: + srcu_read_unlock(&mpath_head->srcu, srcu_idx); + return err; +} + +static int mpath_generic_chr_uring_cmd(struct io_uring_cmd *ioucmd, + unsigned int issue_flags) +{ + struct cdev *cdev = file_inode(ioucmd->file)->i_cdev; + struct mpath_head *mpath_head = + container_of(cdev, struct mpath_head, cdev); + struct mpath_device *mpath_device; + int srcu_idx, ret = -EWOULDBLOCK; + + if (!mpath_head->mpdt->chr_uring_cmd) + return -EOPNOTSUPP; + + srcu_idx = srcu_read_lock(&mpath_head->srcu); + mpath_device = mpath_find_path(mpath_head); + + if (!mpath_device) + goto out_unlock; + + ret = mpath_head->mpdt->chr_uring_cmd(mpath_device, ioucmd, + issue_flags); +out_unlock: + srcu_read_unlock(&mpath_head->srcu, srcu_idx); + return ret; +} + +static int mpath_generic_chr_uring_cmd_iopoll(struct io_uring_cmd *ioucmd, + struct io_comp_batch *iob, + unsigned int poll_flags) +{ + struct cdev *cdev = file_inode(ioucmd->file)->i_cdev; + struct mpath_head *mpath_head = + container_of(cdev, struct mpath_head, cdev); + + if (!mpath_head->mpdt->chr_uring_cmd_iopoll) + return -EOPNOTSUPP; + + return mpath_head->mpdt->chr_uring_cmd_iopoll(ioucmd, iob, poll_flags); +} + +const struct file_operations mpath_generic_chr_fops = { + .owner = THIS_MODULE, + .open = mpath_generic_chr_open, + .release = mpath_generic_chr_release, + .unlocked_ioctl = mpath_generic_chr_ioctl, + .compat_ioctl = compat_ptr_ioctl, + .uring_cmd = mpath_generic_chr_uring_cmd, + .uring_cmd_iopoll = mpath_generic_chr_uring_cmd_iopoll, +}; +EXPORT_SYMBOL_GPL(mpath_generic_chr_fops); + +static int mpath_head_add_cdev(struct mpath_head *mpath_head) +{ + if (mpath_head->mpdt->add_cdev) + return mpath_head->mpdt->add_cdev(mpath_head); + return 0; +} + static void multipath_partition_scan_work(struct work_struct *work) { struct mpath_disk *mpath_disk = @@ -501,6 +608,12 @@ void mpath_requeue_work(struct work_struct *work) } EXPORT_SYMBOL_GPL(mpath_requeue_work); +static void mpath_head_del_cdev(struct mpath_head *mpath_head) +{ + if (mpath_head->mpdt->del_cdev) + mpath_head->mpdt->del_cdev(mpath_head); +} + void mpath_remove_disk(struct mpath_disk *mpath_disk) { struct mpath_head *mpath_head = mpath_disk->mpath_head; @@ -514,6 +627,7 @@ void mpath_remove_disk(struct mpath_disk *mpath_disk) */ kblockd_schedule_work(&mpath_head->requeue_work); + mpath_head_del_cdev(mpath_head); mpath_synchronize(mpath_head); del_gendisk(disk); } @@ -572,6 +686,8 @@ void mpath_device_set_live(struct mpath_disk *mpath_disk, clear_bit(MPATH_HEAD_DISK_LIVE, &mpath_head->flags); return; } + + mpath_head_add_cdev(mpath_head); queue_work(mpath_wq, &mpath_disk->partition_scan_work); } -- 2.43.5
