[PATCH 4/8] btrfs-progs: sub list: Update -a option and remove meaningless filter

[Misono Tomohiro <misono.tomohiro@jp.fujitsu.com>]

Currently, -a option add filter and change subvolume path as follows:
  - If a subvolume is a child of the specified path, nothing changes
  - otherwise, adds <FS_TREE> to head

This is rather meaningless, so let's remove this filter.

As a result, the behavior of -a option becomes the same as
default behavior of sub list in progs <= 4.19

[Example]
 $ mkfs.btrfs -f $DEV
 $ mount $DEV /mnt

 $ btrfs subvolume create /mnt/AAA
 $ btrfs subvolume create /mnt/AAA/BBB
 $ btrfs subvolume create /mnt/ZZZ

 $ btrfs subvolume list -a /mnt
 ID 256 gen 9 top level 5 path AAA
 ID 257 gen 9 top level 256 path AAA/BBB
 ID 258 gen 10 top level 5 path ZZZ

 ** output of progs <= 4.19
 $ btrfs subvolume list -a /mnt
 ID 256 gen 9 top level 5 path AAA
 ID 257 gen 9 top level 256 path <FS_TREE>/AAA/BBB
 ID 258 gen 10 top level 5 path ZZZ

Signed-off-by: Misono Tomohiro <misono.tomohiro@jp.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>
---
 Documentation/btrfs-subvolume.asciidoc |  6 +++--
 cmds-subvolume.c                       | 35 +++-----------------------
 2 files changed, 8 insertions(+), 33 deletions(-)

diff --git a/Documentation/btrfs-subvolume.asciidoc b/Documentation/btrfs-subvolume.asciidoc
index 99fff977..428a2faa 100644
--- a/Documentation/btrfs-subvolume.asciidoc
+++ b/Documentation/btrfs-subvolume.asciidoc
@@ -118,8 +118,10 @@ Path filtering;;
 -o::::
 print only subvolumes below specified <path>.
 -a::::
-print all the subvolumes in the filesystem and distinguish between
-absolute and relative path with respect to the given <path>.
+print all the subvolumes in the filesystem, including subvolumes
+which cannot be accessed from current mount point.
+path to be shown is relative to the top-level subvolume
+(require root privileges).
 
 Field selection;;
 -p::::
diff --git a/cmds-subvolume.c b/cmds-subvolume.c
index ef613662..cd2e4425 100644
--- a/cmds-subvolume.c
+++ b/cmds-subvolume.c
@@ -761,28 +761,6 @@ static int filter_topid_equal(struct listed_subvol *subvol, uint64_t data)
 	return subvol->info.parent_id == data;
 }
 
-static int filter_full_path(struct listed_subvol *subvol, uint64_t data)
-{
-	/*
-	 * This implements the same behavior as before the conversion to
-	 * libbtrfsutil, which is mostly nonsensical.
-	 */
-	if (subvol->info.parent_id != data) {
-		char *tmp;
-		int ret;
-
-		ret = asprintf(&tmp, "<FS_TREE>/%s", subvol->path);
-		if (ret == -1) {
-			error("out of memory");
-			exit(1);
-		}
-
-		free(subvol->path);
-		subvol->path = tmp;
-	}
-	return 1;
-}
-
 static int filter_by_parent(struct listed_subvol *subvol, uint64_t data)
 {
 	return !uuid_compare(subvol->info.parent_uuid,
@@ -800,7 +778,6 @@ static btrfs_list_filter_func_v2 all_filter_funcs[] = {
 	[BTRFS_LIST_FILTER_CGEN_LESS]		= filter_cgen_less,
 	[BTRFS_LIST_FILTER_CGEN_EQUAL]          = filter_cgen_equal,
 	[BTRFS_LIST_FILTER_TOPID_EQUAL]		= filter_topid_equal,
-	[BTRFS_LIST_FILTER_FULL_PATH]		= filter_full_path,
 	[BTRFS_LIST_FILTER_BY_PARENT]		= filter_by_parent,
 };
 
@@ -1411,9 +1388,9 @@ static const char * const cmd_subvol_list_usage[] = {
 	"",
 	"Path filtering:",
 	"-o           print only subvolumes below specified path",
-	"-a           print all the subvolumes in the filesystem and",
-	"             distinguish absolute and relative path with respect",
-	"             to the given <path> (require root privileges)",
+	"-a           print all the subvolumes in the filesystem.",
+	"             path to be shown is relative to the top-level",
+	"             subvolume (require root privileges)",
 	"",
 	"Field selection:",
 	"-p           print parent ID",
@@ -1581,11 +1558,7 @@ static int cmd_subvol_list(int argc, char **argv)
 	if (ret)
 		goto out;
 
-	if (is_list_all)
-		btrfs_list_setup_filter_v2(&filter_set,
-					BTRFS_LIST_FILTER_FULL_PATH,
-					top_id);
-	else if (is_only_in_path)
+	if (is_only_in_path)
 		btrfs_list_setup_filter_v2(&filter_set,
 					BTRFS_LIST_FILTER_TOPID_EQUAL,
 					top_id);
-- 
2.19.1