On Wed, Mar 03, 2021 at 03:30:18PM +0300, Sergei Shtepa wrote: > DM_INTERPOSED_FLAG allow to create dm targets on "the fly". > Underlying block device opens without a flag FMODE_EXCL. > Dm target receives bio from the original device via > blk_interposer. > > Signed-off-by: Sergei Shtepa <sergei.shtepa@xxxxxxxxx> > --- > drivers/md/dm-core.h | 6 ++ > drivers/md/dm-ioctl.c | 9 +++ > drivers/md/dm-table.c | 115 +++++++++++++++++++++++++++++++--- > drivers/md/dm.c | 38 +++++++---- > include/linux/device-mapper.h | 1 + > include/uapi/linux/dm-ioctl.h | 6 ++ > 6 files changed, 154 insertions(+), 21 deletions(-) > > diff --git a/drivers/md/dm-core.h b/drivers/md/dm-core.h > index 5953ff2bd260..e5c845f9b1df 100644 > --- a/drivers/md/dm-core.h > +++ b/drivers/md/dm-core.h > @@ -21,6 +21,8 @@ > > #define DM_RESERVED_MAX_IOS 1024 > > +struct dm_interposed_dev; > + > struct dm_kobject_holder { > struct kobject kobj; > struct completion completion; > @@ -114,6 +116,10 @@ struct mapped_device { > bool init_tio_pdu:1; > > struct srcu_struct io_barrier; > + > + /* for interposers logic */ > + bool is_interposed; > + struct dm_interposed_dev *ip_dev; > }; > > void disable_discard(struct mapped_device *md); > diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c > index 5e306bba4375..2bcb316144a1 100644 > --- a/drivers/md/dm-ioctl.c > +++ b/drivers/md/dm-ioctl.c > @@ -1267,6 +1267,11 @@ static inline fmode_t get_mode(struct dm_ioctl *param) > return mode; > } > > +static inline bool get_interposer_flag(struct dm_ioctl *param) > +{ > + return (param->flags & DM_INTERPOSED_FLAG); > +} > + > static int next_target(struct dm_target_spec *last, uint32_t next, void *end, > struct dm_target_spec **spec, char **target_params) > { > @@ -1338,6 +1343,8 @@ static int table_load(struct file *filp, struct dm_ioctl *param, size_t param_si > if (!md) > return -ENXIO; > > + md->is_interposed = get_interposer_flag(param); > + > r = dm_table_create(&t, get_mode(param), param->target_count, md); > if (r) > goto err; > @@ -2098,6 +2105,8 @@ int __init dm_early_create(struct dm_ioctl *dmi, > if (r) > goto err_hash_remove; > > + md->is_interposed = get_interposer_flag(dmi); > + > /* add targets */ > for (i = 0; i < dmi->target_count; i++) { > r = dm_table_add_target(t, spec_array[i]->target_type, > diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c > index 95391f78b8d5..0b2f9b66ade5 100644 > --- a/drivers/md/dm-table.c > +++ b/drivers/md/dm-table.c > @@ -6,6 +6,7 @@ > */ > > #include "dm-core.h" > +#include "dm-interposer.h" > > #include <linux/module.h> > #include <linux/vmalloc.h> > @@ -225,12 +226,13 @@ void dm_table_destroy(struct dm_table *t) > /* > * See if we've already got a device in the list. > */ > -static struct dm_dev_internal *find_device(struct list_head *l, dev_t dev) > +static struct dm_dev_internal *find_device(struct list_head *l, dev_t dev, bool is_interposed) > { > struct dm_dev_internal *dd; > > list_for_each_entry (dd, l, list) > - if (dd->dm_dev->bdev->bd_dev == dev) > + if ((dd->dm_dev->bdev->bd_dev == dev) && > + (dd->dm_dev->is_interposed == is_interposed)) > return dd; > > return NULL; > @@ -358,6 +360,90 @@ dev_t dm_get_dev_t(const char *path) > } > EXPORT_SYMBOL_GPL(dm_get_dev_t); > > +/* > + * Redirect bio from interposed device to dm device > + */ > +static void dm_interpose_fn(struct dm_interposed_dev *ip_dev, struct bio *bio) > +{ > + struct mapped_device *md = ip_dev->private; > + > + if (bio_flagged(bio, BIO_REMAPPED)) { > + /* > + * Since bio has already been remapped, we need to subtract > + * the block device offset from the beginning of the disk. > + */ > + bio->bi_iter.bi_sector -= get_start_sect(bio->bi_bdev); > + > + bio_clear_flag(bio, BIO_REMAPPED); > + } So instead of doing this shoudn't the imposer just always submit to the whole device? But if we keep it, the logic in this funtion should go into a block layer helper, passing a block device instead of the dm_interposed_dev. This avoids having such fragile logic in drivers. > + if ((ofs + len) > bdev_nr_sectors(bdev)) { > + DMERR("The specified range of sectors exceeds of the size of the block device."); > + return -ERANGE; > + } > + > + md->ip_dev = kzalloc(sizeof(struct dm_interposed_dev), GFP_KERNEL); > + if (!md->ip_dev) > + return -ENOMEM; > + > + if ((ofs == 0) && (len == 0)) Lots of superflous inner braces. -- dm-devel mailing list dm-devel@xxxxxxxxxx https://listman.redhat.com/mailman/listinfo/dm-devel