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>
diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
index 99ed8a5..78288c5 100644
--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -370,6 +370,10 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
if (sec_usage_check(sbi, secno))
goto next;
+ /* Don't touch checkpointed data */
+ if (unlikely(is_sbi_flag_set(sbi, SBI_CP_DISABLED) &&
+ get_ckpt_valid_blocks(sbi, segno)))
+ goto next;
if (gc_type == BG_GC && test_bit(secno, dirty_i->victim_secmap))
goto next;
@@ -1189,7 +1193,8 @@ int f2fs_gc(struct f2fs_sb_info *sbi, bool sync,
* threshold, we can make them free by checkpoint. Then, we
* secure free segments which doesn't need fggc any more.
*/
- if (prefree_segments(sbi)) {
+ if (prefree_segments(sbi) &&
+ !is_sbi_flag_set(sbi, SBI_CP_DISABLED)) {
ret = f2fs_write_checkpoint(sbi, &cpc);
if (ret)
goto stop;
@@ -1241,7 +1246,7 @@ int f2fs_gc(struct f2fs_sb_info *sbi, bool sync,
segno = NULL_SEGNO;
goto gc_more;
}
- if (gc_type == FG_GC)
+ if (gc_type == FG_GC && !is_sbi_flag_set(sbi, SBI_CP_DISABLED))
ret = f2fs_write_checkpoint(sbi, &cpc);
}
stop: