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Message-Id: <20180620142522.27639-2-arnd@arndb.de>
Date: Wed, 20 Jun 2018 16:25:03 +0200
From: Arnd Bergmann <arnd@...db.de>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: y2038@...ts.linaro.org, Al Viro <viro@...iv.linux.org.uk>,
Jan Kara <jack@...e.cz>, Arnd Bergmann <arnd@...db.de>,
reiserfs-devel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 2/3] [v2] reiserfs: use monotonic time for j_trans_start_time
Using CLOCK_REALTIME time_t timestamps breaks on 32-bit systems
in 2038, and gives surprising results with a concurrent settimeofday().
This changes the reiserfs journal timestamps to use ktime_get_seconds()
instead, which makes it use a 64-bit CLOCK_MONOTONIC stamp.
In the procfs output, the monotonic timestamp needs to be converted
back to CLOCK_REALTIME to keep the existing ABI.
Reviewed-by: Jan Kara <jack@...e.cz>
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
v2: I split out the conversion from monotonic to real time into
a separate function for readability, though I decided against
making it a global function. I looked at almost all uses of
CLOCK_REALTIME in the kernel several times and don't remember
any other file that would benefit from making it a generic
helper, and it can be slightly inaccurate because of the double
rounding.
---
fs/reiserfs/journal.c | 22 +++++++++++-----------
fs/reiserfs/procfs.c | 11 +++++++++--
fs/reiserfs/reiserfs.h | 2 +-
3 files changed, 21 insertions(+), 14 deletions(-)
diff --git a/fs/reiserfs/journal.c b/fs/reiserfs/journal.c
index 1e7f733b2a12..e809da912c00 100644
--- a/fs/reiserfs/journal.c
+++ b/fs/reiserfs/journal.c
@@ -2381,7 +2381,7 @@ static int journal_read(struct super_block *sb)
struct reiserfs_journal_desc *desc;
unsigned int oldest_trans_id = 0;
unsigned int oldest_invalid_trans_id = 0;
- time_t start;
+ time64_t start;
unsigned long oldest_start = 0;
unsigned long cur_dblock = 0;
unsigned long newest_mount_id = 9;
@@ -2395,7 +2395,7 @@ static int journal_read(struct super_block *sb)
cur_dblock = SB_ONDISK_JOURNAL_1st_BLOCK(sb);
reiserfs_info(sb, "checking transaction log (%pg)\n",
journal->j_dev_bd);
- start = get_seconds();
+ start = ktime_get_seconds();
/*
* step 1, read in the journal header block. Check the transaction
@@ -2556,7 +2556,7 @@ static int journal_read(struct super_block *sb)
if (replay_count > 0) {
reiserfs_info(sb,
"replayed %d transactions in %lu seconds\n",
- replay_count, get_seconds() - start);
+ replay_count, ktime_get_seconds() - start);
}
/* needed to satisfy the locking in _update_journal_header_block */
reiserfs_write_lock(sb);
@@ -2914,7 +2914,7 @@ int journal_transaction_should_end(struct reiserfs_transaction_handle *th,
int new_alloc)
{
struct reiserfs_journal *journal = SB_JOURNAL(th->t_super);
- time_t now = get_seconds();
+ time64_t now = ktime_get_seconds();
/* cannot restart while nested */
BUG_ON(!th->t_trans_id);
if (th->t_refcount > 1)
@@ -3023,7 +3023,7 @@ static int do_journal_begin_r(struct reiserfs_transaction_handle *th,
struct super_block *sb, unsigned long nblocks,
int join)
{
- time_t now = get_seconds();
+ time64_t now = ktime_get_seconds();
unsigned int old_trans_id;
struct reiserfs_journal *journal = SB_JOURNAL(sb);
struct reiserfs_transaction_handle myth;
@@ -3056,7 +3056,7 @@ static int do_journal_begin_r(struct reiserfs_transaction_handle *th,
PROC_INFO_INC(sb, journal.journal_relock_writers);
goto relock;
}
- now = get_seconds();
+ now = ktime_get_seconds();
/*
* if there is no room in the journal OR
@@ -3119,7 +3119,7 @@ static int do_journal_begin_r(struct reiserfs_transaction_handle *th,
}
/* we are the first writer, set trans_id */
if (journal->j_trans_start_time == 0) {
- journal->j_trans_start_time = get_seconds();
+ journal->j_trans_start_time = ktime_get_seconds();
}
atomic_inc(&journal->j_wcount);
journal->j_len_alloc += nblocks;
@@ -3559,11 +3559,11 @@ static void flush_async_commits(struct work_struct *work)
*/
void reiserfs_flush_old_commits(struct super_block *sb)
{
- time_t now;
+ time64_t now;
struct reiserfs_transaction_handle th;
struct reiserfs_journal *journal = SB_JOURNAL(sb);
- now = get_seconds();
+ now = ktime_get_seconds();
/*
* safety check so we don't flush while we are replaying the log during
* mount
@@ -3613,7 +3613,7 @@ void reiserfs_flush_old_commits(struct super_block *sb)
static int check_journal_end(struct reiserfs_transaction_handle *th, int flags)
{
- time_t now;
+ time64_t now;
int flush = flags & FLUSH_ALL;
int commit_now = flags & COMMIT_NOW;
int wait_on_commit = flags & WAIT;
@@ -3694,7 +3694,7 @@ static int check_journal_end(struct reiserfs_transaction_handle *th, int flags)
}
/* deal with old transactions where we are the last writers */
- now = get_seconds();
+ now = ktime_get_seconds();
if ((now - journal->j_trans_start_time) > journal->j_max_trans_age) {
commit_now = 1;
journal->j_next_async_flush = 1;
diff --git a/fs/reiserfs/procfs.c b/fs/reiserfs/procfs.c
index e39b3910d24d..f2cf3441fdfc 100644
--- a/fs/reiserfs/procfs.c
+++ b/fs/reiserfs/procfs.c
@@ -297,6 +297,13 @@ static int show_oidmap(struct seq_file *m, void *unused)
return 0;
}
+static time64_t ktime_mono_to_real_seconds(time64_t mono)
+{
+ ktime_t kt = ktime_set(mono, NSEC_PER_SEC/2);
+
+ return ktime_divns(ktime_mono_to_real(kt), NSEC_PER_SEC);
+}
+
static int show_journal(struct seq_file *m, void *unused)
{
struct super_block *sb = m->private;
@@ -325,7 +332,7 @@ static int show_journal(struct seq_file *m, void *unused)
"j_bcount: \t%lu\n"
"j_first_unflushed_offset: \t%lu\n"
"j_last_flush_trans_id: \t%u\n"
- "j_trans_start_time: \t%li\n"
+ "j_trans_start_time: \t%lli\n"
"j_list_bitmap_index: \t%i\n"
"j_must_wait: \t%i\n"
"j_next_full_flush: \t%i\n"
@@ -366,7 +373,7 @@ static int show_journal(struct seq_file *m, void *unused)
JF(j_bcount),
JF(j_first_unflushed_offset),
JF(j_last_flush_trans_id),
- JF(j_trans_start_time),
+ ktime_mono_to_real_seconds(JF(j_trans_start_time)),
JF(j_list_bitmap_index),
JF(j_must_wait),
JF(j_next_full_flush),
diff --git a/fs/reiserfs/reiserfs.h b/fs/reiserfs/reiserfs.h
index 1536ebbaf6ab..d0fc829bd760 100644
--- a/fs/reiserfs/reiserfs.h
+++ b/fs/reiserfs/reiserfs.h
@@ -330,7 +330,7 @@ struct reiserfs_journal {
struct buffer_head *j_header_bh;
- time_t j_trans_start_time; /* time this transaction started */
+ time64_t j_trans_start_time; /* time this transaction started */
struct mutex j_mutex;
struct mutex j_flush_mutex;
--
2.9.0
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