ore/exofs: Change the type of the devices array (API change)

In the pNFS obj-LD the device table at the layout level needs
to point to a device_cache node, where it is possible and likely
that many layouts will point to the same device-nodes.

In Exofs we have a more orderly structure where we have a single
array of devices that repeats twice for a round-robin view of the
device table

This patch moves to a model that can be used by the pNFS obj-LD
where struct ore_components holds an array of ore_dev-pointers.
(ore_dev is newly defined and contains a struct osd_dev *od
 member)

Each pointer in the array of pointers will point to a bigger
user-defined dev_struct. That can be accessed by use of the
container_of macro.

In Exofs an __alloc_dev_table() function allocates the
ore_dev-pointers array as well as an exofs_dev array, in one
allocation and does the addresses dance to set everything pointing
correctly. It still keeps the double allocation trick for the
inodes round-robin view of the table.

The device table is always allocated dynamically, also for the
single device case. So it is unconditionally freed at umount.

Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>

1 files changed, 7 insertions, 3 deletions

diff --git a/fs/exofs/exofs.h b/fs/exofs/exofs.h
index 3b2e0478f363..006fd6f33571 100644
--- a/fs/exofs/exofs.h
+++ b/fs/exofs/exofs.h
@@ -53,6 +53,10 @@
 /* u64 has problems with printk this will cast it to unsigned long long */
 #define _LLU(x) (unsigned long long)(x)
 
+struct exofs_dev {
+        struct ore_dev ored;
+        unsigned did;
+};
 /*
  * our extension to the in-memory superblock
  */
@@ -69,7 +73,6 @@ struct exofs_sb_info {
         struct ore_layout       layout;         /* Default files layout       */
         struct ore_comp one_comp;               /* id & cred of partition id=0*/
         struct ore_components oc;               /* comps for the partition    */
-        struct osd_dev  *_min_one_dev[1];       /* Place holder for one dev   */
 };
 
 /*
@@ -214,13 +217,14 @@ static inline void exofs_init_comps(struct ore_components *oc,
         one_comp->obj.id = oid;
         exofs_make_credential(one_comp->cred, &one_comp->obj);
 
-        oc->numdevs = sbi->oc.numdevs;
+        oc->numdevs = sbi->layout.group_width * sbi->layout.mirrors_p1 *
+                                                        sbi->layout.group_count;
         oc->single_comp = EC_SINGLE_COMP;
         oc->comps = one_comp;
 
         /* Round robin device view of the table */
         first_dev = (dev_mod * sbi->layout.mirrors_p1) % sbi->oc.numdevs;
-        oc->ods = sbi->oc.ods + first_dev;
+        oc->ods = &sbi->oc.ods[first_dev];
 }
 
 #endif