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-rw-r--r--fs/btrfs/ordered-data.c67
1 files changed, 67 insertions, 0 deletions
diff --git a/fs/btrfs/ordered-data.c b/fs/btrfs/ordered-data.c
index f4621f6deca..ae7737e352c 100644
--- a/fs/btrfs/ordered-data.c
+++ b/fs/btrfs/ordered-data.c
@@ -250,6 +250,73 @@ int btrfs_add_ordered_sum(struct inode *inode,
/*
* this is used to account for finished IO across a given range
+ * of the file. The IO may span ordered extents. If
+ * a given ordered_extent is completely done, 1 is returned, otherwise
+ * 0.
+ *
+ * test_and_set_bit on a flag in the struct btrfs_ordered_extent is used
+ * to make sure this function only returns 1 once for a given ordered extent.
+ *
+ * file_offset is updated to one byte past the range that is recorded as
+ * complete. This allows you to walk forward in the file.
+ */
+int btrfs_dec_test_first_ordered_pending(struct inode *inode,
+ struct btrfs_ordered_extent **cached,
+ u64 *file_offset, u64 io_size)
+{
+ struct btrfs_ordered_inode_tree *tree;
+ struct rb_node *node;
+ struct btrfs_ordered_extent *entry = NULL;
+ int ret;
+ u64 dec_end;
+ u64 dec_start;
+ u64 to_dec;
+
+ tree = &BTRFS_I(inode)->ordered_tree;
+ spin_lock(&tree->lock);
+ node = tree_search(tree, *file_offset);
+ if (!node) {
+ ret = 1;
+ goto out;
+ }
+
+ entry = rb_entry(node, struct btrfs_ordered_extent, rb_node);
+ if (!offset_in_entry(entry, *file_offset)) {
+ ret = 1;
+ goto out;
+ }
+
+ dec_start = max(*file_offset, entry->file_offset);
+ dec_end = min(*file_offset + io_size, entry->file_offset +
+ entry->len);
+ *file_offset = dec_end;
+ if (dec_start > dec_end) {
+ printk(KERN_CRIT "bad ordering dec_start %llu end %llu\n",
+ (unsigned long long)dec_start,
+ (unsigned long long)dec_end);
+ }
+ to_dec = dec_end - dec_start;
+ if (to_dec > entry->bytes_left) {
+ printk(KERN_CRIT "bad ordered accounting left %llu size %llu\n",
+ (unsigned long long)entry->bytes_left,
+ (unsigned long long)to_dec);
+ }
+ entry->bytes_left -= to_dec;
+ if (entry->bytes_left == 0)
+ ret = test_and_set_bit(BTRFS_ORDERED_IO_DONE, &entry->flags);
+ else
+ ret = 1;
+out:
+ if (!ret && cached && entry) {
+ *cached = entry;
+ atomic_inc(&entry->refs);
+ }
+ spin_unlock(&tree->lock);
+ return ret == 0;
+}
+
+/*
+ * this is used to account for finished IO across a given range
* of the file. The IO should not span ordered extents. If
* a given ordered_extent is completely done, 1 is returned, otherwise
* 0.