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Subject[PATCH v2 2/2] f2fs: fix to update mtime correctly
Date
From: Chao Yu <yuchao0@huawei.com>

If we change system time to the past, get_mtime() will return a
overflowed time, and SIT_I(sbi)->max_mtime will be udpated
incorrectly, this patch fixes the two issues.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
---
v2:
- fix to cover base time updating.
fs/f2fs/checkpoint.c | 2 +-
fs/f2fs/segment.c | 7 ++++---
fs/f2fs/segment.h | 16 +++++++++++++---
3 files changed, 18 insertions(+), 7 deletions(-)

diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
index 8eb184c3de84..40b39db317ea 100644
--- a/fs/f2fs/checkpoint.c
+++ b/fs/f2fs/checkpoint.c
@@ -1233,7 +1233,7 @@ static int do_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)
* modify checkpoint
* version number is already updated
*/
- ckpt->elapsed_time = cpu_to_le64(get_mtime(sbi));
+ ckpt->elapsed_time = cpu_to_le64(get_mtime(sbi, true));
ckpt->free_segment_count = cpu_to_le32(free_segments(sbi));
for (i = 0; i < NR_CURSEG_NODE_TYPE; i++) {
ckpt->cur_node_segno[i] =
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 66983acaad16..c1bd31da772d 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -1822,8 +1822,9 @@ static void update_sit_entry(struct f2fs_sb_info *sbi, block_t blkaddr, int del)
(new_vblocks > sbi->blocks_per_seg)));

se->valid_blocks = new_vblocks;
- se->mtime = get_mtime(sbi);
- SIT_I(sbi)->max_mtime = se->mtime;
+ se->mtime = get_mtime(sbi, false);
+ if (se->mtime > SIT_I(sbi)->max_mtime)
+ SIT_I(sbi)->max_mtime = se->mtime;

/* Update valid block bitmap */
if (del > 0) {
@@ -3879,7 +3880,7 @@ static void init_min_max_mtime(struct f2fs_sb_info *sbi)
if (sit_i->min_mtime > mtime)
sit_i->min_mtime = mtime;
}
- sit_i->max_mtime = get_mtime(sbi);
+ sit_i->max_mtime = get_mtime(sbi, false);
up_write(&sit_i->sentry_lock);
}

diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
index c574131ac7e1..11e62cd76269 100644
--- a/fs/f2fs/segment.h
+++ b/fs/f2fs/segment.h
@@ -745,12 +745,22 @@ static inline void set_to_next_sit(struct sit_info *sit_i, unsigned int start)
#endif
}

-static inline unsigned long long get_mtime(struct f2fs_sb_info *sbi)
+static inline unsigned long long get_mtime(struct f2fs_sb_info *sbi,
+ bool base_time)
{
struct sit_info *sit_i = SIT_I(sbi);
- time64_t now = ktime_get_real_seconds();
+ time64_t diff, now = ktime_get_real_seconds();

- return sit_i->elapsed_time + now - sit_i->mounted_time;
+ if (now >= sit_i->mounted_time)
+ return sit_i->elapsed_time + now - sit_i->mounted_time;
+
+ /* system time is set to the past */
+ if (!base_time) {
+ diff = sit_i->mounted_time - now;
+ if (sit_i->elapsed_time >= diff)
+ return sit_i->elapsed_time - diff;
+ }
+ return sit_i->elapsed_time;
}

static inline void set_summary(struct f2fs_summary *sum, nid_t nid,
--
2.16.2.17.g38e79b1fd
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