dm: refactor ioctl handling

This moves the call to blkdev_ioctl and the argument checking to DM core
code, and only leaves a callout to find the block device to operate on
in the targets.  This simplifies the code and allows us to pass through
ioctl-like command using other methods in the next patch.

Also split out a helper around calling the prepare_ioctl method that
will be reused for persistent reservation handling.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

8 files changed, 94 insertions, 75 deletions

diff --git a/drivers/md/dm-flakey.c b/drivers/md/dm-flakey.c
index 645e8b4f808e..09e2afcafd2d 100644
--- a/drivers/md/dm-flakey.c
+++ b/drivers/md/dm-flakey.c
@@ -373,20 +373,20 @@ static void flakey_status(struct dm_target *ti, status_type_t type,
         }
 }
 
-static int flakey_ioctl(struct dm_target *ti, unsigned int cmd, unsigned long arg)
+static int flakey_prepare_ioctl(struct dm_target *ti,
+                struct block_device **bdev, fmode_t *mode)
 {
         struct flakey_c *fc = ti->private;
-        struct dm_dev *dev = fc->dev;
-        int r = 0;
+
+        *bdev = fc->dev->bdev;
 
         /*
          * Only pass ioctls through if the device sizes match exactly.
          */
         if (fc->start ||
-            ti->len != i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT)
-                r = scsi_verify_blk_ioctl(NULL, cmd);
-
-        return r ? : __blkdev_driver_ioctl(dev->bdev, dev->mode, cmd, arg);
+            ti->len != i_size_read((*bdev)->bd_inode) >> SECTOR_SHIFT)
+                return 1;
+        return 0;
 }
 
 static int flakey_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data)
@@ -405,7 +405,7 @@ static struct target_type flakey_target = {
         .map    = flakey_map,
         .end_io = flakey_end_io,
         .status = flakey_status,
-        .ioctl  = flakey_ioctl,
+        .prepare_ioctl = flakey_prepare_ioctl,
         .iterate_devices = flakey_iterate_devices,
 };
 
diff --git a/drivers/md/dm-linear.c b/drivers/md/dm-linear.c
index 436f5c9b6aea..de52864d60fa 100644
--- a/drivers/md/dm-linear.c
+++ b/drivers/md/dm-linear.c
@@ -116,21 +116,21 @@ static void linear_status(struct dm_target *ti, status_type_t type,
         }
 }
 
-static int linear_ioctl(struct dm_target *ti, unsigned int cmd,
-                        unsigned long arg)
+static int linear_prepare_ioctl(struct dm_target *ti,
+                struct block_device **bdev, fmode_t *mode)
 {
         struct linear_c *lc = (struct linear_c *) ti->private;
         struct dm_dev *dev = lc->dev;
-        int r = 0;
+
+        *bdev = dev->bdev;
 
         /*
          * Only pass ioctls through if the device sizes match exactly.
          */
         if (lc->start ||
             ti->len != i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT)
-                r = scsi_verify_blk_ioctl(NULL, cmd);
-
-        return r ? : __blkdev_driver_ioctl(dev->bdev, dev->mode, cmd, arg);
+                return 1;
+        return 0;
 }
 
 static int linear_iterate_devices(struct dm_target *ti,
@@ -149,7 +149,7 @@ static struct target_type linear_target = {
         .dtr    = linear_dtr,
         .map    = linear_map,
         .status = linear_status,
-        .ioctl  = linear_ioctl,
+        .prepare_ioctl = linear_prepare_ioctl,
         .iterate_devices = linear_iterate_devices,
 };
 
diff --git a/drivers/md/dm-log-writes.c b/drivers/md/dm-log-writes.c
index b2912dbac8bc..624589d51c2c 100644
--- a/drivers/md/dm-log-writes.c
+++ b/drivers/md/dm-log-writes.c
@@ -714,20 +714,19 @@ static void log_writes_status(struct dm_target *ti, status_type_t type,
         }
 }
 
-static int log_writes_ioctl(struct dm_target *ti, unsigned int cmd,
-                            unsigned long arg)
+static int log_writes_prepare_ioctl(struct dm_target *ti,
+                struct block_device **bdev, fmode_t *mode)
 {
         struct log_writes_c *lc = ti->private;
         struct dm_dev *dev = lc->dev;
-        int r = 0;
 
+        *bdev = dev->bdev;
         /*
          * Only pass ioctls through if the device sizes match exactly.
          */
         if (ti->len != i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT)
-                r = scsi_verify_blk_ioctl(NULL, cmd);
-
-        return r ? : __blkdev_driver_ioctl(dev->bdev, dev->mode, cmd, arg);
+                return 1;
+        return 0;
 }
 
 static int log_writes_iterate_devices(struct dm_target *ti,
@@ -782,7 +781,7 @@ static struct target_type log_writes_target = {
         .map    = log_writes_map,
         .end_io = normal_end_io,
         .status = log_writes_status,
-        .ioctl  = log_writes_ioctl,
+        .prepare_ioctl = log_writes_prepare_ioctl,
         .message = log_writes_message,
         .iterate_devices = log_writes_iterate_devices,
         .io_hints = log_writes_io_hints,
diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index bdc96cd838b8..77066a199984 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -1533,18 +1533,14 @@ out:
         return r;
 }
 
-static int multipath_ioctl(struct dm_target *ti, unsigned int cmd,
-                           unsigned long arg)
+static int multipath_prepare_ioctl(struct dm_target *ti,
+                struct block_device **bdev, fmode_t *mode)
 {
         struct multipath *m = ti->private;
         struct pgpath *pgpath;
-        struct block_device *bdev;
-        fmode_t mode;
         unsigned long flags;
         int r;
 
-        bdev = NULL;
-        mode = 0;
         r = 0;
 
         spin_lock_irqsave(&m->lock, flags);
@@ -1555,23 +1551,17 @@ static int multipath_ioctl(struct dm_target *ti, unsigned int cmd,
         pgpath = m->current_pgpath;
 
         if (pgpath) {
-                bdev = pgpath->path.dev->bdev;
-                mode = pgpath->path.dev->mode;
+                *bdev = pgpath->path.dev->bdev;
+                *mode = pgpath->path.dev->mode;
         }
 
         if ((pgpath && m->queue_io) || (!pgpath && m->queue_if_no_path))
                 r = -ENOTCONN;
-        else if (!bdev)
+        else if (!*bdev)
                 r = -EIO;
 
         spin_unlock_irqrestore(&m->lock, flags);
 
-        /*
-         * Only pass ioctls through if the device sizes match exactly.
-         */
-        if (!r && ti->len != i_size_read(bdev->bd_inode) >> SECTOR_SHIFT)
-                r = scsi_verify_blk_ioctl(NULL, cmd);
-
         if (r == -ENOTCONN && !fatal_signal_pending(current)) {
                 spin_lock_irqsave(&m->lock, flags);
                 if (!m->current_pg) {
@@ -1584,7 +1574,12 @@ static int multipath_ioctl(struct dm_target *ti, unsigned int cmd,
                 dm_table_run_md_queue_async(m->ti->table);
         }
 
-        return r ? : __blkdev_driver_ioctl(bdev, mode, cmd, arg);
+        /*
+         * Only pass ioctls through if the device sizes match exactly.
+         */
+        if (!r && ti->len != i_size_read((*bdev)->bd_inode) >> SECTOR_SHIFT)
+                return 1;
+        return r;
 }
 
 static int multipath_iterate_devices(struct dm_target *ti,
@@ -1700,7 +1695,7 @@ static struct target_type multipath_target = {
         .resume = multipath_resume,
         .status = multipath_status,
         .message = multipath_message,
-        .ioctl  = multipath_ioctl,
+        .prepare_ioctl = multipath_prepare_ioctl,
         .iterate_devices = multipath_iterate_devices,
         .busy = multipath_busy,
 };
diff --git a/drivers/md/dm-switch.c b/drivers/md/dm-switch.c
index 50fca469cafd..b1285753a5d4 100644
--- a/drivers/md/dm-switch.c
+++ b/drivers/md/dm-switch.c
@@ -511,27 +511,24 @@ static void switch_status(struct dm_target *ti, status_type_t type,
  *
  * Passthrough all ioctls to the path for sector 0
  */
-static int switch_ioctl(struct dm_target *ti, unsigned cmd,
-                        unsigned long arg)
+static int switch_prepare_ioctl(struct dm_target *ti,
+                struct block_device **bdev, fmode_t *mode)
 {
         struct switch_ctx *sctx = ti->private;
-        struct block_device *bdev;
-        fmode_t mode;
         unsigned path_nr;
-        int r = 0;
 
         path_nr = switch_get_path_nr(sctx, 0);
 
-        bdev = sctx->path_list[path_nr].dmdev->bdev;
-        mode = sctx->path_list[path_nr].dmdev->mode;
+        *bdev = sctx->path_list[path_nr].dmdev->bdev;
+        *mode = sctx->path_list[path_nr].dmdev->mode;
 
         /*
          * Only pass ioctls through if the device sizes match exactly.
          */
-        if (ti->len + sctx->path_list[path_nr].start != i_size_read(bdev->bd_inode) >> SECTOR_SHIFT)
-                r = scsi_verify_blk_ioctl(NULL, cmd);
-
-        return r ? : __blkdev_driver_ioctl(bdev, mode, cmd, arg);
+        if (ti->len + sctx->path_list[path_nr].start !=
+            i_size_read((*bdev)->bd_inode) >> SECTOR_SHIFT)
+                return 1;
+        return 0;
 }
 
 static int switch_iterate_devices(struct dm_target *ti,
@@ -560,7 +557,7 @@ static struct target_type switch_target = {
         .map = switch_map,
         .message = switch_message,
         .status = switch_status,
-        .ioctl = switch_ioctl,
+        .prepare_ioctl = switch_prepare_ioctl,
         .iterate_devices = switch_iterate_devices,
 };
 
diff --git a/drivers/md/dm-verity.c b/drivers/md/dm-verity.c
index edc624bccf9a..ccf41886ebcf 100644
--- a/drivers/md/dm-verity.c
+++ b/drivers/md/dm-verity.c
@@ -631,18 +631,17 @@ static void verity_status(struct dm_target *ti, status_type_t type,
         }
 }
 
-static int verity_ioctl(struct dm_target *ti, unsigned cmd,
-                        unsigned long arg)
+static int verity_prepare_ioctl(struct dm_target *ti,
+                struct block_device **bdev, fmode_t *mode)
 {
         struct dm_verity *v = ti->private;
-        int r = 0;
+
+        *bdev = v->data_dev->bdev;
 
         if (v->data_start ||
             ti->len != i_size_read(v->data_dev->bdev->bd_inode) >> SECTOR_SHIFT)
-                r = scsi_verify_blk_ioctl(NULL, cmd);
-
-        return r ? : __blkdev_driver_ioctl(v->data_dev->bdev, v->data_dev->mode,
-                                     cmd, arg);
+                return 1;
+        return 0;
 }
 
 static int verity_iterate_devices(struct dm_target *ti,
@@ -965,7 +964,7 @@ static struct target_type verity_target = {
         .dtr            = verity_dtr,
         .map            = verity_map,
         .status         = verity_status,
-        .ioctl          = verity_ioctl,
+        .prepare_ioctl  = verity_prepare_ioctl,
         .iterate_devices = verity_iterate_devices,
         .io_hints       = verity_io_hints,
 };
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 77ebb985154c..9b3fe5be0cee 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -555,18 +555,16 @@ static int dm_blk_getgeo(struct block_device *bdev, struct hd_geometry *geo)
         return dm_get_geometry(md, geo);
 }
 
-static int dm_blk_ioctl(struct block_device *bdev, fmode_t mode,
-                        unsigned int cmd, unsigned long arg)
+static int dm_get_live_table_for_ioctl(struct mapped_device *md,
+                struct dm_target **tgt, struct block_device **bdev,
+                fmode_t *mode, int *srcu_idx)
 {
-        struct mapped_device *md = bdev->bd_disk->private_data;
-        int srcu_idx;
         struct dm_table *map;
-        struct dm_target *tgt;
-        int r = -ENOTTY;
+        int r;
 
 retry:
-        map = dm_get_live_table(md, &srcu_idx);
-
+        r = -ENOTTY;
+        map = dm_get_live_table(md, srcu_idx);
         if (!map || !dm_table_get_size(map))
                 goto out;
 
@@ -574,8 +572,9 @@ retry:
         if (dm_table_get_num_targets(map) != 1)
                 goto out;
 
-        tgt = dm_table_get_target(map, 0);
-        if (!tgt->type->ioctl)
+        *tgt = dm_table_get_target(map, 0);
+
+        if (!(*tgt)->type->prepare_ioctl)
                 goto out;
 
         if (dm_suspended_md(md)) {
@@ -583,16 +582,46 @@ retry:
                 goto out;
         }
 
-        r = tgt->type->ioctl(tgt, cmd, arg);
+        r = (*tgt)->type->prepare_ioctl(*tgt, bdev, mode);
+        if (r < 0)
+                goto out;
 
-out:
-        dm_put_live_table(md, srcu_idx);
+        return r;
 
+out:
+        dm_put_live_table(md, *srcu_idx);
         if (r == -ENOTCONN) {
                 msleep(10);
                 goto retry;
         }
+        return r;
+}
+
+static int dm_blk_ioctl(struct block_device *bdev, fmode_t mode,
+                        unsigned int cmd, unsigned long arg)
+{
+        struct mapped_device *md = bdev->bd_disk->private_data;
+        struct dm_target *tgt;
+        int srcu_idx, r;
+
+        r = dm_get_live_table_for_ioctl(md, &tgt, &bdev, &mode, &srcu_idx);
+        if (r < 0)
+                return r;
+
+        if (r > 0) {
+                /*
+                 * Target determined this ioctl is being issued against
+                 * a logical partition of the parent bdev; so extra
+                 * validation is needed.
+                 */
+                r = scsi_verify_blk_ioctl(NULL, cmd);
+                if (r)
+                        goto out;
+        }
 
+        r =  __blkdev_driver_ioctl(bdev, mode, cmd, arg);
+out:
+        dm_put_live_table(md, srcu_idx);
         return r;
 }
 
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index 76d23fa8c7d3..ec1c61c87d89 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -79,8 +79,8 @@ typedef void (*dm_status_fn) (struct dm_target *ti, status_type_t status_type,
 
 typedef int (*dm_message_fn) (struct dm_target *ti, unsigned argc, char **argv);
 
-typedef int (*dm_ioctl_fn) (struct dm_target *ti, unsigned int cmd,
-                            unsigned long arg);
+typedef int (*dm_prepare_ioctl_fn) (struct dm_target *ti,
+                            struct block_device **bdev, fmode_t *mode);
 
 /*
  * These iteration functions are typically used to check (and combine)
@@ -156,7 +156,7 @@ struct target_type {
         dm_resume_fn resume;
         dm_status_fn status;
         dm_message_fn message;
-        dm_ioctl_fn ioctl;
+        dm_prepare_ioctl_fn prepare_ioctl;
         dm_busy_fn busy;
         dm_iterate_devices_fn iterate_devices;
         dm_io_hints_fn io_hints;