[PATCH 4.5 085/101] Btrfs: fix truncate_space_check

Greg Kroah-Hartman
2016-05-17T01:27:14Z

From: Josef Bacik <jbacik@fb.com>

commit dc95f7bfc57fa4b75a77d0da84d5db249d74aa3f upstream.

truncate_space_check is using btrfs_csum_bytes_to_leaves() but forgetting to
multiply by nodesize so we get an actual byte count. We need a tracepoint here
so that we have the matching reserve for the release that will come later. Also
add a comment to make clear what the intent of truncate_space_check is.

Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/btrfs/inode.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)

--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -4211,11 +4211,20 @@ static int truncate_space_check(struct b
{
int ret;

+ /*
+ * This is only used to apply pressure to the enospc system, we don't
+ * intend to use this reservation at all.
+ */
bytes_deleted = btrfs_csum_bytes_to_leaves(root, bytes_deleted);
+ bytes_deleted *= root->nodesize;
ret = btrfs_block_rsv_add(root, &root->fs_info->trans_block_rsv,
bytes_deleted, BTRFS_RESERVE_NO_FLUSH);
- if (!ret)
+ if (!ret) {
+ trace_btrfs_space_reservation(root->fs_info, "transaction",
+ trans->transid,
+ bytes_deleted, 1);
trans->bytes_reserved += bytes_deleted;
+ }
return ret;

}