Btrfs: readahead checksums during btrfs_finish_ordered_io

[linux-2.6-omap-h63xx.git] / fs / btrfs / extent_map.c

diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c
index 8a502ee2f2316e74d2c39c8633c75e62a2ccd17e..50da69da20cec141fca63ffba2a4e92b8f93f875 100644 (file)
--- a/fs/btrfs/extent_map.c
+++ b/fs/btrfs/extent_map.c
@@ -3,7 +3,6 @@
 #include <linux/slab.h>
 #include <linux/module.h>
 #include <linux/spinlock.h>
-#include <linux/version.h>
 #include <linux/hardirq.h>
 #include "extent_map.h"
 
@@ -89,11 +88,11 @@ EXPORT_SYMBOL(free_extent_map);
 static struct rb_node *tree_insert(struct rb_root *root, u64 offset,
                                   struct rb_node *node)
 {
-       struct rb_node ** p = &root->rb_node;
-       struct rb_node * parent = NULL;
+       struct rb_node **p = &root->rb_node;
+       struct rb_node *parent = NULL;
        struct extent_map *entry;
 
-       while(*p) {
+       while (*p) {
                parent = *p;
                entry = rb_entry(parent, struct extent_map, rb_node);
 
@@ -114,17 +113,21 @@ static struct rb_node *tree_insert(struct rb_root *root, u64 offset,
        return NULL;
 }
 
+/*
+ * search through the tree for an extent_map with a given offset.  If
+ * it can't be found, try to find some neighboring extents
+ */
 static struct rb_node *__tree_search(struct rb_root *root, u64 offset,
                                     struct rb_node **prev_ret,
                                     struct rb_node **next_ret)
 {
-       struct rb_node * n = root->rb_node;
+       struct rb_node *n = root->rb_node;
        struct rb_node *prev = NULL;
        struct rb_node *orig_prev = NULL;
        struct extent_map *entry;
        struct extent_map *prev_entry = NULL;
 
-       while(n) {
+       while (n) {
                entry = rb_entry(n, struct extent_map, rb_node);
                prev = n;
                prev_entry = entry;
@@ -141,7 +144,7 @@ static struct rb_node *__tree_search(struct rb_root *root, u64 offset,
 
        if (prev_ret) {
                orig_prev = prev;
-               while(prev && offset >= extent_map_end(prev_entry)) {
+               while (prev && offset >= extent_map_end(prev_entry)) {
                        prev = rb_next(prev);
                        prev_entry = rb_entry(prev, struct extent_map, rb_node);
                }
@@ -151,7 +154,7 @@ static struct rb_node *__tree_search(struct rb_root *root, u64 offset,
 
        if (next_ret) {
                prev_entry = rb_entry(prev, struct extent_map, rb_node);
-               while(prev && offset < prev_entry->start) {
+               while (prev && offset < prev_entry->start) {
                        prev = rb_prev(prev);
                        prev_entry = rb_entry(prev, struct extent_map, rb_node);
                }
@@ -160,6 +163,10 @@ static struct rb_node *__tree_search(struct rb_root *root, u64 offset,
        return NULL;
 }
 
+/*
+ * look for an offset in the tree, and if it can't be found, return
+ * the first offset we can find smaller than 'offset'.
+ */
 static inline struct rb_node *tree_search(struct rb_root *root, u64 offset)
 {
        struct rb_node *prev;
@@ -170,11 +177,19 @@ static inline struct rb_node *tree_search(struct rb_root *root, u64 offset)
        return ret;
 }
 
+/* check to see if two extent_map structs are adjacent and safe to merge */
 static int mergable_maps(struct extent_map *prev, struct extent_map *next)
 {
        if (test_bit(EXTENT_FLAG_PINNED, &prev->flags))
                return 0;
 
+       /*
+        * don't merge compressed extents, we need to know their
+        * actual size
+        */
+       if (test_bit(EXTENT_FLAG_COMPRESSED, &prev->flags))
+               return 0;
+
        if (extent_map_end(prev) == next->start &&
            prev->flags == next->flags &&
            prev->bdev == next->bdev &&
@@ -207,8 +222,15 @@ int add_extent_mapping(struct extent_map_tree *tree,
        int ret = 0;
        struct extent_map *merge = NULL;
        struct rb_node *rb;
+       struct extent_map *exist;
 
-       BUG_ON(spin_trylock(&tree->lock));
+       exist = lookup_extent_mapping(tree, em->start, em->len);
+       if (exist) {
+               free_extent_map(exist);
+               ret = -EEXIST;
+               goto out;
+       }
+       assert_spin_locked(&tree->lock);
        rb = tree_insert(&tree->map, em->start, &em->rb_node);
        if (rb) {
                ret = -EEXIST;
@@ -223,6 +245,7 @@ int add_extent_mapping(struct extent_map_tree *tree,
                if (rb && mergable_maps(merge, em)) {
                        em->start = merge->start;
                        em->len += merge->len;
+                       em->block_len += merge->block_len;
                        em->block_start = merge->block_start;
                        merge->in_tree = 0;
                        rb_erase(&merge->rb_node, &tree->map);
@@ -234,6 +257,7 @@ int add_extent_mapping(struct extent_map_tree *tree,
                merge = rb_entry(rb, struct extent_map, rb_node);
        if (rb && mergable_maps(em, merge)) {
                em->len += merge->len;
+               em->block_len += merge->len;
                rb_erase(&merge->rb_node, &tree->map);
                merge->in_tree = 0;
                free_extent_map(merge);
@@ -243,6 +267,7 @@ out:
 }
 EXPORT_SYMBOL(add_extent_mapping);
 
+/* simple helper to do math around the end of an extent, handling wrap */
 static u64 range_end(u64 start, u64 len)
 {
        if (start + len < start)
@@ -270,7 +295,7 @@ struct extent_map *lookup_extent_mapping(struct extent_map_tree *tree,
        struct rb_node *next = NULL;
        u64 end = range_end(start, len);
 
-       BUG_ON(spin_trylock(&tree->lock));
+       assert_spin_locked(&tree->lock);
        rb_node = __tree_search(&tree->map, start, &prev, &next);
        if (!rb_node && prev) {
                em = rb_entry(prev, struct extent_map, rb_node);
@@ -317,7 +342,7 @@ int remove_extent_mapping(struct extent_map_tree *tree, struct extent_map *em)
        int ret = 0;
 
        WARN_ON(test_bit(EXTENT_FLAG_PINNED, &em->flags));
-       BUG_ON(spin_trylock(&tree->lock));
+       assert_spin_locked(&tree->lock);
        rb_erase(&em->rb_node, &tree->map);
        em->in_tree = 0;
        return ret;