[PATCH] fs: make block fiemap mapping length at least blocksize long

[Josef Bacik <josef@redhat.com>]

Some filesystems don't deal well with being asked to map less than blocksize
blocks (GFS2 for example).  Since we are always mapping at least blocksize
sections anyway, just make sure len is at least as big as a blocksize so we
don't trip up any filesystems.  Thanks,

Signed-off-by: Josef Bacik <josef@redhat.com>
---
 fs/ioctl.c |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/fs/ioctl.c b/fs/ioctl.c
index d6cc164..6b53c24 100644
--- a/fs/ioctl.c
+++ b/fs/ioctl.c
@@ -273,6 +273,13 @@ int __generic_block_fiemap(struct inode *inode,
 		len = isize;
 	}
 
+	/*
+	 * Some filesystems can't deal with being asked to map less than
+	 * blocksize, so make sure our len is at least block length.
+	 */
+	if (logical_to_blk(inode, len) == 0)
+		len = blk_to_logical(inode, 1);
+
 	start_blk = logical_to_blk(inode, start);
 	last_blk = logical_to_blk(inode, start + len - 1);
 
-- 
1.6.6.1