path: root/Documentation
diff options
authorOmar Sandoval <>2016-11-14 10:43:22 -0800
committerDavid Sterba <>2016-11-23 11:07:05 +0100
commit87895ef4da2819b0b3ffde6bcd45abf7b2533b7f (patch)
tree67d3e1899a67397bb25cae6a6ea71443717601d5 /Documentation
parent981441102199c5c9e3fca84ff3e723ddfa78de01 (diff)
btrfs-progs: implement btrfs check --clear-space-cache v2
Reviewed-by: Qu Wenruo <> Signed-off-by: Omar Sandoval <> [ adjusted error messages ] Signed-off-by: David Sterba <>
Diffstat (limited to 'Documentation')
1 files changed, 9 insertions, 5 deletions
diff --git a/Documentation/btrfs-check.asciidoc b/Documentation/btrfs-check.asciidoc
index 5ef414eb..633cbbf6 100644
--- a/Documentation/btrfs-check.asciidoc
+++ b/Documentation/btrfs-check.asciidoc
@@ -80,12 +80,16 @@ superblock is damaged.
--clear-space-cache v1|v2::
completely wipe all free space cache of given type
-NOTE: Only v1 free space cache supported is implemented.
-Kernel mount option 'clear_cache' is only designed to rebuild free space cache
-which is modified during the lifetime of that mount option. It doesn't rebuild
-all free space cache, nor clear them out.
+For free space cache 'v1', the 'clear_cache' kernel mount option only rebuilds
+the free space cache for block groups that are modified while the filesystem is
+mounted with that option. Thus, using this option with 'v1' makes it possible
+to actually clear the entire free space cache.
+For free space cache 'v2', the 'clear_cache' kernel mount option does destroy
+the entire free space cache. This option with 'v2' provides an alternative
+method of clearing the free space cache that doesn't require mounting the