Btrfs: Add mount option to enforce a max extent size

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 18 insertions, 10 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 91f3fc43e2a9..686dd03f34f2 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -78,6 +78,7 @@ static int cow_file_range(struct inode *inode, u64 start, u64 end)
         struct btrfs_trans_handle *trans;
         u64 alloc_hint = 0;
         u64 num_bytes;
+        u64 cur_alloc_size;
         u64 blocksize = root->sectorsize;
         struct btrfs_key ins;
         int ret;
@@ -94,17 +95,24 @@ static int cow_file_range(struct inode *inode, u64 start, u64 end)
         if (alloc_hint == EXTENT_MAP_INLINE)
                 goto out;
 
-        ret = btrfs_alloc_extent(trans, root, num_bytes,
-                                 root->root_key.objectid, trans->transid,
-                                 inode->i_ino, start, 0,
-                                 alloc_hint, (u64)-1, &ins, 1);
-        if (ret) {
-                WARN_ON(1);
-                goto out;
+        while(num_bytes > 0) {
+                cur_alloc_size = min(num_bytes, root->fs_info->max_extent);
+                ret = btrfs_alloc_extent(trans, root, cur_alloc_size,
+                                         root->root_key.objectid,
+                                         trans->transid,
+                                         inode->i_ino, start, 0,
+                                         alloc_hint, (u64)-1, &ins, 1);
+                if (ret) {
+                        WARN_ON(1);
+                        goto out;
+                }
+                ret = btrfs_insert_file_extent(trans, root, inode->i_ino,
+                                               start, ins.objectid, ins.offset,
+                                               ins.offset);
+                num_bytes -= cur_alloc_size;
+                alloc_hint = ins.objectid + ins.offset;
+                start += cur_alloc_size;
         }
-        ret = btrfs_insert_file_extent(trans, root, inode->i_ino,
-                                       start, ins.objectid, ins.offset,
-                                       ins.offset);
 out:
         btrfs_end_transaction(trans, root);
         return ret;