From: Josef Bacik Date: Mon, 14 Oct 2013 16:08:38 +0000 (-0400) Subject: Btrfs: handle a missing extent for the first file extent X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=25a50341b6269b0622434d9360f0c771d219681a;p=openwrt%2Fstaging%2Fblogic.git Btrfs: handle a missing extent for the first file extent While trying to kill our hole extents I noticed I was seeing problems where we seek into a file and then start writing and then try to fiemap that file later. This is because we search for offset 0, don't find anything and so back up one slot, which puts us at the inode ref or something like that, which means we goto not_found and create an extent map for our entire search area. This isn't quite what we want, we want to move forward one slot and see if there is an extent there so we can limit our hole extent. This patch fixes this problem, I will add a testcase for this as well. Thanks, Signed-off-by: Josef Bacik Signed-off-by: Chris Mason --- diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index b5c2ad8fe2ca..9d39d08a1555 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -5982,7 +5982,14 @@ again: found_type = btrfs_key_type(&found_key); if (found_key.objectid != objectid || found_type != BTRFS_EXTENT_DATA_KEY) { - goto not_found; + /* + * If we backup past the first extent we want to move forward + * and see if there is an extent in front of us, otherwise we'll + * say there is a hole for our whole search range which can + * cause problems. + */ + extent_end = start; + goto next; } found_type = btrfs_file_extent_type(leaf, item); @@ -5997,7 +6004,7 @@ again: size = btrfs_file_extent_inline_len(leaf, item); extent_end = ALIGN(extent_start + size, root->sectorsize); } - +next: if (start >= extent_end) { path->slots[0]++; if (path->slots[0] >= btrfs_header_nritems(leaf)) {