[PATCH] dm: extract device limit setting

Separate the setting of device I/O limits from dm_get_device().  dm-loop will
use this.

Signed-off-by: Bryn Reeves <breeves@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 51 insertions, 41 deletions

diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 47412ae98fb9..4920998efeeb 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -522,56 +522,61 @@ static int __table_get_device(struct dm_table *t, struct dm_target *ti,
         return 0;
 }
 
-
-int dm_get_device(struct dm_target *ti, const char *path, sector_t start,
-                  sector_t len, int mode, struct dm_dev **result)
+void dm_set_device_limits(struct dm_target *ti, struct block_device *bdev)
 {
-        int r = __table_get_device(ti->table, ti, path,
-                                   start, len, mode, result);
-        if (!r) {
-                request_queue_t *q = bdev_get_queue((*result)->bdev);
-                struct io_restrictions *rs = &ti->limits;
-
-                /*
-                 * Combine the device limits low.
-                 *
-                 * FIXME: if we move an io_restriction struct
-                 *        into q this would just be a call to
-                 *        combine_restrictions_low()
-                 */
+        request_queue_t *q = bdev_get_queue(bdev);
+        struct io_restrictions *rs = &ti->limits;
+
+        /*
+         * Combine the device limits low.
+         *
+         * FIXME: if we move an io_restriction struct
+         *        into q this would just be a call to
+         *        combine_restrictions_low()
+         */
+        rs->max_sectors =
+                min_not_zero(rs->max_sectors, q->max_sectors);
+
+        /* FIXME: Device-Mapper on top of RAID-0 breaks because DM
+         *        currently doesn't honor MD's merge_bvec_fn routine.
+         *        In this case, we'll force DM to use PAGE_SIZE or
+         *        smaller I/O, just to be safe. A better fix is in the
+         *        works, but add this for the time being so it will at
+         *        least operate correctly.
+         */
+        if (q->merge_bvec_fn)
                 rs->max_sectors =
-                        min_not_zero(rs->max_sectors, q->max_sectors);
+                        min_not_zero(rs->max_sectors,
+                                     (unsigned int) (PAGE_SIZE >> 9));
 
-                /* FIXME: Device-Mapper on top of RAID-0 breaks because DM
-                 *        currently doesn't honor MD's merge_bvec_fn routine.
-                 *        In this case, we'll force DM to use PAGE_SIZE or
-                 *        smaller I/O, just to be safe. A better fix is in the
-                 *        works, but add this for the time being so it will at
-                 *        least operate correctly.
-                 */
-                if (q->merge_bvec_fn)
-                        rs->max_sectors =
-                                min_not_zero(rs->max_sectors,
-                                             (unsigned int) (PAGE_SIZE >> 9));
+        rs->max_phys_segments =
+                min_not_zero(rs->max_phys_segments,
+                             q->max_phys_segments);
 
-                rs->max_phys_segments =
-                        min_not_zero(rs->max_phys_segments,
-                                     q->max_phys_segments);
+        rs->max_hw_segments =
+                min_not_zero(rs->max_hw_segments, q->max_hw_segments);
 
-                rs->max_hw_segments =
-                        min_not_zero(rs->max_hw_segments, q->max_hw_segments);
+        rs->hardsect_size = max(rs->hardsect_size, q->hardsect_size);
 
-                rs->hardsect_size = max(rs->hardsect_size, q->hardsect_size);
+        rs->max_segment_size =
+                min_not_zero(rs->max_segment_size, q->max_segment_size);
 
-                rs->max_segment_size =
-                        min_not_zero(rs->max_segment_size, q->max_segment_size);
+        rs->seg_boundary_mask =
+                min_not_zero(rs->seg_boundary_mask,
+                             q->seg_boundary_mask);
 
-                rs->seg_boundary_mask =
-                        min_not_zero(rs->seg_boundary_mask,
-                                     q->seg_boundary_mask);
+        rs->no_cluster |= !test_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags);
+}
+EXPORT_SYMBOL_GPL(dm_set_device_limits);
 
-                rs->no_cluster |= !test_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags);
-        }
+int dm_get_device(struct dm_target *ti, const char *path, sector_t start,
+                  sector_t len, int mode, struct dm_dev **result)
+{
+        int r = __table_get_device(ti->table, ti, path,
+                                   start, len, mode, result);
+
+        if (!r)
+                dm_set_device_limits(ti, (*result)->bdev);
 
         return r;
 }
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index 8cbc46b8e3db..7a48d428d0a1 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -72,6 +72,11 @@ typedef int (*dm_ioctl_fn) (struct dm_target *ti, struct inode *inode,
 void dm_error(const char *message);
 
 /*
+ * Combine device limits.
+ */
+void dm_set_device_limits(struct dm_target *ti, struct block_device *bdev);
+
+/*
  * Constructors should call these functions to ensure destination devices
  * are opened/closed correctly.
  * FIXME: too many arguments.