ocfs2: De-magic the in-memory slot map.

The in-memory slot map uses the same magic as the on-disk one.  There is
a special value to mark a slot as invalid.  It relies on the size of
certain types and so on.

Write a new in-memory map that keeps validity as a separate field.  Outside
of the I/O functions, OCFS2_INVALID_SLOT now means what it is supposed to.
It also is no longer tied to the type size.

This also means that only the I/O functions refer to 16bit quantities.

Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>

1 files changed, 72 insertions, 58 deletions

diff --git a/fs/ocfs2/slot_map.c b/fs/ocfs2/slot_map.c
index 5bddee110091..65a61bfa3f2e 100644
--- a/fs/ocfs2/slot_map.c
+++ b/fs/ocfs2/slot_map.c
@@ -42,21 +42,41 @@
 
 #include "buffer_head_io.h"
 
+
+struct ocfs2_slot {
+        int sl_valid;
+        unsigned int sl_node_num;
+};
+
 struct ocfs2_slot_info {
         struct inode *si_inode;
         unsigned int si_blocks;
         struct buffer_head **si_bh;
         unsigned int si_num_slots;
-        unsigned int si_size;
-        s16 si_global_node_nums[OCFS2_MAX_SLOTS];
+        struct ocfs2_slot *si_slots;
 };
 
 
-static s16 __ocfs2_node_num_to_slot(struct ocfs2_slot_info *si,
-                                    s16 global);
-static void __ocfs2_fill_slot(struct ocfs2_slot_info *si,
-                              s16 slot_num,
-                              s16 node_num);
+static int __ocfs2_node_num_to_slot(struct ocfs2_slot_info *si,
+                                    unsigned int node_num);
+
+static void ocfs2_invalidate_slot(struct ocfs2_slot_info *si,
+                                  int slot_num)
+{
+        BUG_ON((slot_num < 0) || (slot_num >= si->si_num_slots));
+        si->si_slots[slot_num].sl_valid = 0;
+}
+
+static void ocfs2_set_slot(struct ocfs2_slot_info *si,
+                           int slot_num, unsigned int node_num)
+{
+        BUG_ON((slot_num < 0) || (slot_num >= si->si_num_slots));
+        BUG_ON((node_num == O2NM_INVALID_NODE_NUM) ||
+               (node_num >= O2NM_MAX_NODES));
+
+        si->si_slots[slot_num].sl_valid = 1;
+        si->si_slots[slot_num].sl_node_num = node_num;
+}
 
 /*
  * Post the slot information on disk into our slot_info struct.
@@ -71,8 +91,12 @@ static void ocfs2_update_slot_info(struct ocfs2_slot_info *si)
          * should've made sure we have the most recent copy. */
         disk_info = (__le16 *) si->si_bh[0]->b_data;
 
-        for (i = 0; i < si->si_size; i++)
-                si->si_global_node_nums[i] = le16_to_cpu(disk_info[i]);
+        for (i = 0; i < si->si_num_slots; i++) {
+                if (le16_to_cpu(disk_info[i]) == (u16)OCFS2_INVALID_SLOT)
+                        ocfs2_invalidate_slot(si, i);
+                else
+                        ocfs2_set_slot(si, i, le16_to_cpu(disk_info[i]));
+        }
 }
 
 int ocfs2_refresh_slot_info(struct ocfs2_super *osb)
@@ -114,8 +138,13 @@ static int ocfs2_update_disk_slots(struct ocfs2_super *osb,
         __le16 *disk_info = (__le16 *) si->si_bh[0]->b_data;
 
         spin_lock(&osb->osb_lock);
-        for (i = 0; i < si->si_size; i++)
-                disk_info[i] = cpu_to_le16(si->si_global_node_nums[i]);
+        for (i = 0; i < si->si_num_slots; i++) {
+                if (si->si_slots[i].sl_valid)
+                        disk_info[i] =
+                                cpu_to_le16(si->si_slots[i].sl_node_num);
+                else
+                        disk_info[i] = cpu_to_le16(OCFS2_INVALID_SLOT);
+        }
         spin_unlock(&osb->osb_lock);
 
         status = ocfs2_write_block(osb, si->si_bh[0], si->si_inode);
@@ -147,39 +176,39 @@ static int ocfs2_slot_map_physical_size(struct ocfs2_super *osb,
         return 0;
 }
 
-/* try to find global node in the slot info. Returns
- * OCFS2_INVALID_SLOT if nothing is found. */
-static s16 __ocfs2_node_num_to_slot(struct ocfs2_slot_info *si,
-                                    s16 global)
+/* try to find global node in the slot info. Returns -ENOENT
+ * if nothing is found. */
+static int __ocfs2_node_num_to_slot(struct ocfs2_slot_info *si,
+                                    unsigned int node_num)
 {
-        int i;
-        s16 ret = OCFS2_INVALID_SLOT;
+        int i, ret = -ENOENT;
 
         for(i = 0; i < si->si_num_slots; i++) {
-                if (global == si->si_global_node_nums[i]) {
-                        ret = (s16) i;
+                if (si->si_slots[i].sl_valid &&
+                    (node_num == si->si_slots[i].sl_node_num)) {
+                        ret = i;
                         break;
                 }
         }
+
         return ret;
 }
 
-static s16 __ocfs2_find_empty_slot(struct ocfs2_slot_info *si,
-                                   s16 preferred)
+static int __ocfs2_find_empty_slot(struct ocfs2_slot_info *si,
+                                   int preferred)
 {
-        int i;
-        s16 ret = OCFS2_INVALID_SLOT;
+        int i, ret = -ENOSPC;
 
-        if (preferred >= 0 && preferred < si->si_num_slots) {
-                if (OCFS2_INVALID_SLOT == si->si_global_node_nums[preferred]) {
+        if ((preferred >= 0) && (preferred < si->si_num_slots)) {
+                if (!si->si_slots[preferred].sl_valid) {
                         ret = preferred;
                         goto out;
                 }
         }
 
         for(i = 0; i < si->si_num_slots; i++) {
-                if (OCFS2_INVALID_SLOT == si->si_global_node_nums[i]) {
-                        ret = (s16) i;
+                if (!si->si_slots[i].sl_valid) {
+                        ret = i;
                         break;
                 }
         }
@@ -189,16 +218,13 @@ out:
 
 int ocfs2_node_num_to_slot(struct ocfs2_super *osb, unsigned int node_num)
 {
-        s16 slot;
+        int slot;
         struct ocfs2_slot_info *si = osb->slot_info;
 
         spin_lock(&osb->osb_lock);
         slot = __ocfs2_node_num_to_slot(si, node_num);
         spin_unlock(&osb->osb_lock);
 
-        if (slot == OCFS2_INVALID_SLOT)
-                return -ENOENT;
-
         return slot;
 }
 
@@ -212,10 +238,10 @@ int ocfs2_slot_to_node_num_locked(struct ocfs2_super *osb, int slot_num,
         BUG_ON(slot_num < 0);
         BUG_ON(slot_num > osb->max_slots);
 
-        if (si->si_global_node_nums[slot_num] == OCFS2_INVALID_SLOT)
+        if (!si->si_slots[slot_num].sl_valid)
                 return -ENOENT;
 
-        *node_num = si->si_global_node_nums[slot_num];
+        *node_num = si->si_slots[slot_num].sl_node_num;
         return 0;
 }
 
@@ -241,19 +267,7 @@ static void __ocfs2_free_slot_info(struct ocfs2_slot_info *si)
         kfree(si);
 }
 
-static void __ocfs2_fill_slot(struct ocfs2_slot_info *si,
-                              s16 slot_num,
-                              s16 node_num)
-{
-        BUG_ON(slot_num == OCFS2_INVALID_SLOT);
-        BUG_ON(slot_num >= si->si_num_slots);
-        BUG_ON((node_num != O2NM_INVALID_NODE_NUM) &&
-               (node_num >= O2NM_MAX_NODES));
-
-        si->si_global_node_nums[slot_num] = node_num;
-}
-
-int ocfs2_clear_slot(struct ocfs2_super *osb, s16 slot_num)
+int ocfs2_clear_slot(struct ocfs2_super *osb, int slot_num)
 {
         struct ocfs2_slot_info *si = osb->slot_info;
 
@@ -261,7 +275,7 @@ int ocfs2_clear_slot(struct ocfs2_super *osb, s16 slot_num)
                 return 0;
 
         spin_lock(&osb->osb_lock);
-        __ocfs2_fill_slot(si, slot_num, OCFS2_INVALID_SLOT);
+        ocfs2_invalidate_slot(si, slot_num);
         spin_unlock(&osb->osb_lock);
 
         return ocfs2_update_disk_slots(osb, osb->slot_info);
@@ -324,11 +338,13 @@ bail:
 
 int ocfs2_init_slot_info(struct ocfs2_super *osb)
 {
-        int status, i;
+        int status;
         struct inode *inode = NULL;
         struct ocfs2_slot_info *si;
 
-        si = kzalloc(sizeof(struct ocfs2_slot_info), GFP_KERNEL);
+        si = kzalloc(sizeof(struct ocfs2_slot_info) +
+                     (sizeof(struct ocfs2_slot) * osb->max_slots),
+                     GFP_KERNEL);
         if (!si) {
                 status = -ENOMEM;
                 mlog_errno(status);
@@ -336,10 +352,8 @@ int ocfs2_init_slot_info(struct ocfs2_super *osb)
         }
 
         si->si_num_slots = osb->max_slots;
-        si->si_size = OCFS2_MAX_SLOTS;
-
-        for(i = 0; i < si->si_num_slots; i++)
-                si->si_global_node_nums[i] = OCFS2_INVALID_SLOT;
+        si->si_slots = (struct ocfs2_slot *)((char *)si +
+                                             sizeof(struct ocfs2_slot_info));
 
         inode = ocfs2_get_system_file_inode(osb, SLOT_MAP_SYSTEM_INODE,
                                             OCFS2_INVALID_SLOT);
@@ -375,7 +389,7 @@ void ocfs2_free_slot_info(struct ocfs2_super *osb)
 int ocfs2_find_slot(struct ocfs2_super *osb)
 {
         int status;
-        s16 slot;
+        int slot;
         struct ocfs2_slot_info *si;
 
         mlog_entry_void();
@@ -390,11 +404,11 @@ int ocfs2_find_slot(struct ocfs2_super *osb)
          * own journal recovery? Possibly not, though we certainly
          * need to warn to the user */
         slot = __ocfs2_node_num_to_slot(si, osb->node_num);
-        if (slot == OCFS2_INVALID_SLOT) {
+        if (slot < 0) {
                 /* if no slot yet, then just take 1st available
                  * one. */
                 slot = __ocfs2_find_empty_slot(si, osb->preferred_slot);
-                if (slot == OCFS2_INVALID_SLOT) {
+                if (slot < 0) {
                         spin_unlock(&osb->osb_lock);
                         mlog(ML_ERROR, "no free slots available!\n");
                         status = -EINVAL;
@@ -404,7 +418,7 @@ int ocfs2_find_slot(struct ocfs2_super *osb)
                 mlog(ML_NOTICE, "slot %d is already allocated to this node!\n",
                      slot);
 
-        __ocfs2_fill_slot(si, slot, osb->node_num);
+        ocfs2_set_slot(si, slot, osb->node_num);
         osb->slot_num = slot;
         spin_unlock(&osb->osb_lock);
 
@@ -430,7 +444,7 @@ void ocfs2_put_slot(struct ocfs2_super *osb)
         spin_lock(&osb->osb_lock);
         ocfs2_update_slot_info(si);
 
-        __ocfs2_fill_slot(si, osb->slot_num, OCFS2_INVALID_SLOT);
+        ocfs2_invalidate_slot(si, osb->slot_num);
         osb->slot_num = OCFS2_INVALID_SLOT;
         spin_unlock(&osb->osb_lock);