f2fs: checkpoint disabling

Note that, it requires "f2fs: return correct errno in f2fs_gc".

This adds a lightweight non-persistent snapshotting scheme to f2fs.

To use, mount with the option checkpoint=disable, and to return to
normal operation, remount with checkpoint=enable. If the filesystem
is shut down before remounting with checkpoint=enable, it will revert
back to its apparent state when it was first mounted with
checkpoint=disable. This is useful for situations where you wish to be
able to roll back the state of the disk in case of some critical
failure.

Signed-off-by: Daniel Rosenberg <drosen@google.com>
[Jaegeuk Kim: use SB_RDONLY instead of MS_RDONLY]
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

1 files changed, 15 insertions, 0 deletions

diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
index 086150028c6d..ab3465faddf1 100644
--- a/fs/f2fs/segment.h
+++ b/fs/f2fs/segment.h
@@ -339,6 +339,12 @@ static inline unsigned int get_valid_blocks(struct f2fs_sb_info *sbi,
 		return get_seg_entry(sbi, segno)->valid_blocks;
 }
 
+static inline unsigned int get_ckpt_valid_blocks(struct f2fs_sb_info *sbi,
+				unsigned int segno)
+{
+	return get_seg_entry(sbi, segno)->ckpt_valid_blocks;
+}
+
 static inline void seg_info_from_raw_sit(struct seg_entry *se,
 					struct f2fs_sit_entry *rs)
 {
@@ -576,6 +582,15 @@ static inline bool has_not_enough_free_secs(struct f2fs_sb_info *sbi,
 		reserved_sections(sbi) + needed);
 }
 
+static inline int f2fs_is_checkpoint_ready(struct f2fs_sb_info *sbi)
+{
+	if (likely(!is_sbi_flag_set(sbi, SBI_CP_DISABLED)))
+		return 0;
+	if (likely(!has_not_enough_free_secs(sbi, 0, 0)))
+		return 0;
+	return -ENOSPC;
+}
+
 static inline bool excess_prefree_segs(struct f2fs_sb_info *sbi)
 {
 	return prefree_segments(sbi) > SM_I(sbi)->rec_prefree_segments;