3 files changed, 116 insertions, 30 deletions

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 74c03fb0ca1..8af24da983b 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -2333,6 +2333,7 @@ static noinline int __push_leaf_right(struct btrfs_trans_handle *trans,
 {
         struct extent_buffer *left = path->nodes[0];
         struct extent_buffer *upper = path->nodes[1];
+        struct btrfs_map_token token;
         struct btrfs_disk_key disk_key;
         int slot;
         u32 i;
@@ -2344,6 +2345,8 @@ static noinline int __push_leaf_right(struct btrfs_trans_handle *trans,
         u32 data_end;
         u32 this_item_size;
 
+        btrfs_init_map_token(&token);
+
         if (empty)
                 nr = 0;
         else
@@ -2421,8 +2424,8 @@ static noinline int __push_leaf_right(struct btrfs_trans_handle *trans,
         push_space = BTRFS_LEAF_DATA_SIZE(root);
         for (i = 0; i < right_nritems; i++) {
                 item = btrfs_item_nr(right, i);
-                push_space -= btrfs_item_size(right, item);
-                btrfs_set_item_offset(right, item, push_space);
+                push_space -= btrfs_token_item_size(right, item, &token);
+                btrfs_set_token_item_offset(right, item, push_space, &token);
         }
 
         left_nritems -= push_items;
@@ -2553,6 +2556,9 @@ static noinline int __push_leaf_left(struct btrfs_trans_handle *trans,
         int wret;
         u32 this_item_size;
         u32 old_left_item_size;
+        struct btrfs_map_token token;
+
+        btrfs_init_map_token(&token);
 
         if (empty)
                 nr = min(right_nritems, max_slot);
@@ -2613,9 +2619,10 @@ static noinline int __push_leaf_left(struct btrfs_trans_handle *trans,
 
                 item = btrfs_item_nr(left, i);
 
-                ioff = btrfs_item_offset(left, item);
-                btrfs_set_item_offset(left, item,
-                      ioff - (BTRFS_LEAF_DATA_SIZE(root) - old_left_item_size));
+                ioff = btrfs_token_item_offset(left, item, &token);
+                btrfs_set_token_item_offset(left, item,
+                      ioff - (BTRFS_LEAF_DATA_SIZE(root) - old_left_item_size),
+                      &token);
         }
         btrfs_set_header_nritems(left, old_left_nritems + push_items);
 
@@ -2645,8 +2652,9 @@ static noinline int __push_leaf_left(struct btrfs_trans_handle *trans,
         for (i = 0; i < right_nritems; i++) {
                 item = btrfs_item_nr(right, i);
 
-                push_space = push_space - btrfs_item_size(right, item);
-                btrfs_set_item_offset(right, item, push_space);
+                push_space = push_space - btrfs_token_item_size(right,
+                                                                item, &token);
+                btrfs_set_token_item_offset(right, item, push_space, &token);
         }
 
         btrfs_mark_buffer_dirty(left);
@@ -2767,6 +2775,9 @@ static noinline int copy_for_split(struct btrfs_trans_handle *trans,
         int ret = 0;
         int wret;
         struct btrfs_disk_key disk_key;
+        struct btrfs_map_token token;
+
+        btrfs_init_map_token(&token);
 
         nritems = nritems - mid;
         btrfs_set_header_nritems(right, nritems);
@@ -2788,8 +2799,9 @@ static noinline int copy_for_split(struct btrfs_trans_handle *trans,
                 struct btrfs_item *item = btrfs_item_nr(right, i);
                 u32 ioff;
 
-                ioff = btrfs_item_offset(right, item);
-                btrfs_set_item_offset(right, item, ioff + rt_data_off);
+                ioff = btrfs_token_item_offset(right, item, &token);
+                btrfs_set_token_item_offset(right, item,
+                                            ioff + rt_data_off, &token);
         }
 
         btrfs_set_header_nritems(l, mid);
@@ -3284,6 +3296,9 @@ int btrfs_truncate_item(struct btrfs_trans_handle *trans,
         unsigned int old_size;
         unsigned int size_diff;
         int i;
+        struct btrfs_map_token token;
+
+        btrfs_init_map_token(&token);
 
         leaf = path->nodes[0];
         slot = path->slots[0];
@@ -3310,8 +3325,9 @@ int btrfs_truncate_item(struct btrfs_trans_handle *trans,
                 u32 ioff;
                 item = btrfs_item_nr(leaf, i);
 
-                ioff = btrfs_item_offset(leaf, item);
-                btrfs_set_item_offset(leaf, item, ioff + size_diff);
+                ioff = btrfs_token_item_offset(leaf, item, &token);
+                btrfs_set_token_item_offset(leaf, item,
+                                            ioff + size_diff, &token);
         }
 
         /* shift the data */
@@ -3381,6 +3397,9 @@ int btrfs_extend_item(struct btrfs_trans_handle *trans,
         unsigned int old_data;
         unsigned int old_size;
         int i;
+        struct btrfs_map_token token;
+
+        btrfs_init_map_token(&token);
 
         leaf = path->nodes[0];
 
@@ -3410,8 +3429,9 @@ int btrfs_extend_item(struct btrfs_trans_handle *trans,
                 u32 ioff;
                 item = btrfs_item_nr(leaf, i);
 
-                ioff = btrfs_item_offset(leaf, item);
-                btrfs_set_item_offset(leaf, item, ioff - data_size);
+                ioff = btrfs_token_item_offset(leaf, item, &token);
+                btrfs_set_token_item_offset(leaf, item,
+                                            ioff - data_size, &token);
         }
 
         /* shift the data */
@@ -3454,6 +3474,9 @@ int btrfs_insert_some_items(struct btrfs_trans_handle *trans,
         unsigned int data_end;
         struct btrfs_disk_key disk_key;
         struct btrfs_key found_key;
+        struct btrfs_map_token token;
+
+        btrfs_init_map_token(&token);
 
         for (i = 0; i < nr; i++) {
                 if (total_size + data_size[i] + sizeof(struct btrfs_item) >
@@ -3519,8 +3542,9 @@ int btrfs_insert_some_items(struct btrfs_trans_handle *trans,
                         u32 ioff;
 
                         item = btrfs_item_nr(leaf, i);
-                        ioff = btrfs_item_offset(leaf, item);
-                        btrfs_set_item_offset(leaf, item, ioff - total_data);
+                        ioff = btrfs_token_item_offset(leaf, item, &token);
+                        btrfs_set_token_item_offset(leaf, item,
+                                                    ioff - total_data, &token);
                 }
                 /* shift the items */
                 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + nr),
@@ -3547,9 +3571,10 @@ int btrfs_insert_some_items(struct btrfs_trans_handle *trans,
                 btrfs_cpu_key_to_disk(&disk_key, cpu_key + i);
                 btrfs_set_item_key(leaf, &disk_key, slot + i);
                 item = btrfs_item_nr(leaf, slot + i);
-                btrfs_set_item_offset(leaf, item, data_end - data_size[i]);
+                btrfs_set_token_item_offset(leaf, item,
+                                            data_end - data_size[i], &token);
                 data_end -= data_size[i];
-                btrfs_set_item_size(leaf, item, data_size[i]);
+                btrfs_set_token_item_size(leaf, item, data_size[i], &token);
         }
         btrfs_set_header_nritems(leaf, nritems + nr);
         btrfs_mark_buffer_dirty(leaf);
@@ -3588,6 +3613,9 @@ int setup_items_for_insert(struct btrfs_trans_handle *trans,
         int ret;
         struct extent_buffer *leaf;
         int slot;
+        struct btrfs_map_token token;
+
+        btrfs_init_map_token(&token);
 
         leaf = path->nodes[0];
         slot = path->slots[0];
@@ -3619,8 +3647,9 @@ int setup_items_for_insert(struct btrfs_trans_handle *trans,
                         u32 ioff;
 
                         item = btrfs_item_nr(leaf, i);
-                        ioff = btrfs_item_offset(leaf, item);
-                        btrfs_set_item_offset(leaf, item, ioff - total_data);
+                        ioff = btrfs_token_item_offset(leaf, item, &token);
+                        btrfs_set_token_item_offset(leaf, item,
+                                                    ioff - total_data, &token);
                 }
                 /* shift the items */
                 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + nr),
@@ -3639,9 +3668,10 @@ int setup_items_for_insert(struct btrfs_trans_handle *trans,
                 btrfs_cpu_key_to_disk(&disk_key, cpu_key + i);
                 btrfs_set_item_key(leaf, &disk_key, slot + i);
                 item = btrfs_item_nr(leaf, slot + i);
-                btrfs_set_item_offset(leaf, item, data_end - data_size[i]);
+                btrfs_set_token_item_offset(leaf, item,
+                                            data_end - data_size[i], &token);
                 data_end -= data_size[i];
-                btrfs_set_item_size(leaf, item, data_size[i]);
+                btrfs_set_token_item_size(leaf, item, data_size[i], &token);
         }
 
         btrfs_set_header_nritems(leaf, nritems + nr);
@@ -3814,6 +3844,9 @@ int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
         int wret;
         int i;
         u32 nritems;
+        struct btrfs_map_token token;
+
+        btrfs_init_map_token(&token);
 
         leaf = path->nodes[0];
         last_off = btrfs_item_offset_nr(leaf, slot + nr - 1);
@@ -3835,8 +3868,9 @@ int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
                         u32 ioff;
 
                         item = btrfs_item_nr(leaf, i);
-                        ioff = btrfs_item_offset(leaf, item);
-                        btrfs_set_item_offset(leaf, item, ioff + dsize);
+                        ioff = btrfs_token_item_offset(leaf, item, &token);
+                        btrfs_set_token_item_offset(leaf, item,
+                                                    ioff + dsize, &token);
                 }
 
                 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot),
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 85ab1c5844a..c2e17cd299b 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -1546,6 +1546,17 @@ struct btrfs_ioctl_defrag_range_args {
 
 #define BTRFS_INODE_ROOT_ITEM_INIT      (1 << 31)
 
+struct btrfs_map_token {
+        struct extent_buffer *eb;
+        char *kaddr;
+        unsigned long offset;
+};
+
+static inline void btrfs_init_map_token (struct btrfs_map_token *token)
+{
+        memset(token, 0, sizeof(*token));
+}
+
 /* some macros to generate set/get funcs for the struct fields.  This
  * assumes there is a lefoo_to_cpu for every type, so lets make a simple
  * one for u8:
@@ -1569,6 +1580,8 @@ struct btrfs_ioctl_defrag_range_args {
 #ifndef BTRFS_SETGET_FUNCS
 #define BTRFS_SETGET_FUNCS(name, type, member, bits)                    \
 u##bits btrfs_##name(struct extent_buffer *eb, type *s);                \
+u##bits btrfs_token_##name(struct extent_buffer *eb, type *s, struct btrfs_map_token *token);           \
+void btrfs_set_token_##name(struct extent_buffer *eb, type *s, u##bits val, struct btrfs_map_token *token);\
 void btrfs_set_##name(struct extent_buffer *eb, type *s, u##bits val);
 #endif
 
diff --git a/fs/btrfs/struct-funcs.c b/fs/btrfs/struct-funcs.c
index bc1f6ad1844..c6ffa581241 100644
--- a/fs/btrfs/struct-funcs.c
+++ b/fs/btrfs/struct-funcs.c
@@ -44,8 +44,9 @@
 #define BTRFS_SETGET_FUNCS(name, type, member, bits)                    \
 u##bits btrfs_##name(struct extent_buffer *eb, type *s);                \
 void btrfs_set_##name(struct extent_buffer *eb, type *s, u##bits val);  \
-u##bits btrfs_##name(struct extent_buffer *eb,                          \
-                                   type *s)                             \
+void btrfs_set_token_##name(struct extent_buffer *eb, type *s, u##bits val, struct btrfs_map_token *token);     \
+u##bits btrfs_token_##name(struct extent_buffer *eb,                            \
+                           type *s, struct btrfs_map_token *token)      \
 {                                                                       \
         unsigned long part_offset = (unsigned long)s;                   \
         unsigned long offset = part_offset + offsetof(type, member);    \
@@ -54,9 +55,18 @@ u##bits btrfs_##name(struct extent_buffer *eb,				\
         char *kaddr;                                            \
         unsigned long map_start;                                \
         unsigned long map_len;                                  \
+        unsigned long mem_len = sizeof(((type *)0)->member);    \
         u##bits res;                                            \
+        if (token && token->kaddr && token->offset <= offset && \
+            token->eb == eb &&                                  \
+           (token->offset + PAGE_CACHE_SIZE >= offset + mem_len)) { \
+                kaddr = token->kaddr;                           \
+                p = (type *)(kaddr + part_offset - token->offset);  \
+                res = le##bits##_to_cpu(p->member);             \
+                return res;                                     \
+        }                                                       \
         err = map_private_extent_buffer(eb, offset,             \
-                        sizeof(((type *)0)->member),            \
+                        mem_len,                                \
                         &kaddr, &map_start, &map_len);          \
         if (err) {                                              \
                 __le##bits leres;                               \
@@ -65,10 +75,15 @@ u##bits btrfs_##name(struct extent_buffer *eb,				\
         }                                                       \
         p = (type *)(kaddr + part_offset - map_start);          \
         res = le##bits##_to_cpu(p->member);                     \
+        if (token) {                                            \
+                token->kaddr = kaddr;                           \
+                token->offset = map_start;                      \
+                token->eb = eb;                                 \
+        }                                                       \
         return res;                                             \
 }                                                                       \
-void btrfs_set_##name(struct extent_buffer *eb,                         \
-                                    type *s, u##bits val)               \
+void btrfs_set_token_##name(struct extent_buffer *eb,                           \
+                            type *s, u##bits val, struct btrfs_map_token *token)                \
 {                                                                       \
         unsigned long part_offset = (unsigned long)s;                   \
         unsigned long offset = part_offset + offsetof(type, member);    \
@@ -77,8 +92,17 @@ void btrfs_set_##name(struct extent_buffer *eb,				\
         char *kaddr;                                            \
         unsigned long map_start;                                \
         unsigned long map_len;                                  \
+        unsigned long mem_len = sizeof(((type *)0)->member);    \
+        if (token && token->kaddr && token->offset <= offset && \
+            token->eb == eb &&                                  \
+           (token->offset + PAGE_CACHE_SIZE >= offset + mem_len)) { \
+                kaddr = token->kaddr;                           \
+                p = (type *)(kaddr + part_offset - token->offset);  \
+                p->member = cpu_to_le##bits(val);               \
+                return;                                         \
+        }                                                       \
         err = map_private_extent_buffer(eb, offset,             \
-                        sizeof(((type *)0)->member),            \
+                        mem_len,                                \
                         &kaddr, &map_start, &map_len);          \
         if (err) {                                              \
                 __le##bits val2;                                \
@@ -88,7 +112,22 @@ void btrfs_set_##name(struct extent_buffer *eb,				\
         }                                                       \
         p = (type *)(kaddr + part_offset - map_start);          \
         p->member = cpu_to_le##bits(val);                       \
-}
+        if (token) {                                            \
+                token->kaddr = kaddr;                           \
+                token->offset = map_start;                      \
+                token->eb = eb;                                 \
+        }                                                       \
+}                                                               \
+void btrfs_set_##name(struct extent_buffer *eb,                 \
+                      type *s, u##bits val)                     \
+{                                                               \
+        btrfs_set_token_##name(eb, s, val, NULL);               \
+}                                                               \
+u##bits btrfs_##name(struct extent_buffer *eb,                  \
+                      type *s)                                  \
+{                                                               \
+        return btrfs_token_##name(eb, s, NULL);                 \
+}                                                               \
 
 #include "ctree.h"