Btrfs: don't call readahead hook until we have read the entire eb

Martin Steigerwald reported a BUG_ON() where we were given a bogus bytenr to
map.  Turns out he is using > PAGESIZE leafsizes.  The readahead stuff is called
every time we do a completion, but we may not have finished reading in all the
pages, so the bytenr we read off the node could be completely bogus.  Fix this
by only calling the readahead hook once all pages have been read in.  Thanks,

Reported-by: Martin Steigerwald <Martin@lichtvoll.de>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index aab7d89f3ff0aa8aa6f69722f890a86a707aa599..bb6cdbda4f56a6539a7310ee51292df609add146 100644 (file)
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -636,10 +636,9 @@ static int btree_readpage_end_io_hook(struct page *page, u64 start, u64 end,
        if (!ret)
                set_extent_buffer_uptodate(eb);
 err:
-       if (test_bit(EXTENT_BUFFER_READAHEAD, &eb->bflags)) {
-               clear_bit(EXTENT_BUFFER_READAHEAD, &eb->bflags);
+       if (reads_done &&
+           test_and_clear_bit(EXTENT_BUFFER_READAHEAD, &eb->bflags))
                btree_readahead_hook(root, eb, eb->start, ret);
-       }
 
        if (ret) {
                /*