btrfs: tweak free space tree bitmap allocation

The requested bitmap size varies, observed numbers were < 4K up to 16K.
Using vmalloc unconditionally would be too heavy, we'll try contiguous
allocations first and fall back to vmalloc if there's no contig memory.

Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/free-space-tree.c b/fs/btrfs/free-space-tree.c
index 393e36bd5845d996d216e14ef2c6ac6866fce746..0f33d58cb3219341039877f6e5e6d2df0562b157 100644 (file)
--- a/fs/btrfs/free-space-tree.c
+++ b/fs/btrfs/free-space-tree.c
@@ -153,6 +153,20 @@ static inline u32 free_space_bitmap_size(u64 size, u32 sectorsize)
 
 static unsigned long *alloc_bitmap(u32 bitmap_size)
 {
+       void *mem;
+
+       /*
+        * The allocation size varies, observed numbers were < 4K up to 16K.
+        * Using vmalloc unconditionally would be too heavy, we'll try
+        * contiguous allocations first.
+        */
+       if  (bitmap_size <= PAGE_SIZE)
+               return kzalloc(bitmap_size, GFP_NOFS);
+
+       mem = kzalloc(bitmap_size, GFP_NOFS | __GFP_HIGHMEM | __GFP_NOWARN);
+       if (mem)
+               return mem;
+
        return __vmalloc(bitmap_size, GFP_NOFS | __GFP_HIGHMEM | __GFP_ZERO,
                         PAGE_KERNEL);
 }
@@ -289,7 +303,7 @@ int convert_free_space_to_bitmaps(struct btrfs_trans_handle *trans,
 
        ret = 0;
 out:
-       vfree(bitmap);
+       kvfree(bitmap);
        if (ret)
                btrfs_abort_transaction(trans, root, ret);
        return ret;
@@ -438,7 +452,7 @@ int convert_free_space_to_extents(struct btrfs_trans_handle *trans,
 
        ret = 0;
 out:
-       vfree(bitmap);
+       kvfree(bitmap);
        if (ret)
                btrfs_abort_transaction(trans, root, ret);
        return ret;