[PATCH 4/9] xfs: convert log flags to an operational state field

Dave Chinner
2021-07-14T03:20:06Z

From: Dave Chinner <dchinner@redhat.com>

log->l_flags doesn't actually contain "flags" as such, it contains
operational state information that can change at runtime. For the
shutdown state, this at least should be an atomic bit because
it is read without holding locks in many places and so using atomic
bitops for the state field modifications makes sense.

This allows us to use things like test_and_set_bit() on state
changes (e.g. setting XLOG_TAIL_WARN) to avoid races in setting the
state when we aren't holding locks.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
---
fs/xfs/xfs_log.c | 58 ++++++++++++++++------------------------
fs/xfs/xfs_log.h | 1 -
fs/xfs/xfs_log_priv.h | 34 +++++++++++++++--------
fs/xfs/xfs_log_recover.c | 6 ++---
fs/xfs/xfs_super.c | 2 +-
5 files changed, 50 insertions(+), 51 deletions(-)

diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index 6760608642cc..54fff0d41fd0 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -299,7 +299,7 @@ xlog_grant_head_check(
int free_bytes;
int error = 0;

- ASSERT(!(log->l_flags & XLOG_ACTIVE_RECOVERY));
+ ASSERT(!xlog_in_recovery(log));

/*
* If there are other waiters on the queue then give them a chance at
@@ -552,6 +552,7 @@ xfs_log_mount(
xfs_daddr_t blk_offset,
int num_bblks)
{
+ struct xlog *log;
bool fatal = xfs_sb_version_hascrc(&mp->m_sb);
int error = 0;
int min_logfsbs;
@@ -566,11 +567,12 @@ xfs_log_mount(
ASSERT(mp->m_flags & XFS_MOUNT_RDONLY);
}

- mp->m_log = xlog_alloc_log(mp, log_target, blk_offset, num_bblks);
- if (IS_ERR(mp->m_log)) {
- error = PTR_ERR(mp->m_log);
+ log = xlog_alloc_log(mp, log_target, blk_offset, num_bblks);
+ if (IS_ERR(log)) {
+ error = PTR_ERR(log);
goto out;
}
+ mp->m_log = log;

/*
* Validate the given log space and drop a critical message via syslog
@@ -635,7 +637,7 @@ xfs_log_mount(
xfs_warn(mp, "AIL initialisation failed: error %d", error);
goto out_free_log;
}
- mp->m_log->l_ailp = mp->m_ail;
+ log->l_ailp = mp->m_ail;

/*
* skip log recovery on a norecovery mount. pretend it all
@@ -647,39 +649,39 @@ xfs_log_mount(
if (readonly)
mp->m_flags &= ~XFS_MOUNT_RDONLY;

- error = xlog_recover(mp->m_log);
+ error = xlog_recover(log);

if (readonly)
mp->m_flags |= XFS_MOUNT_RDONLY;
if (error) {
xfs_warn(mp, "log mount/recovery failed: error %d",
error);
- xlog_recover_cancel(mp->m_log);
+ xlog_recover_cancel(log);
goto out_destroy_ail;
}
}

- error = xfs_sysfs_init(&mp->m_log->l_kobj, &xfs_log_ktype, &mp->m_kobj,
+ error = xfs_sysfs_init(&log->l_kobj, &xfs_log_ktype, &mp->m_kobj,
"log");
if (error)
goto out_destroy_ail;

/* Normal transactions can now occur */
- mp->m_log->l_flags &= ~XLOG_ACTIVE_RECOVERY;
+ clear_bit(XLOG_ACTIVE_RECOVERY, &log->l_opstate);

/*
* Now the log has been fully initialised and we know were our
* space grant counters are, we can initialise the permanent ticket
* needed for delayed logging to work.
*/
- xlog_cil_init_post_recovery(mp->m_log);
+ xlog_cil_init_post_recovery(log);

return 0;

out_destroy_ail:
xfs_trans_ail_destroy(mp);
out_free_log:
- xlog_dealloc_log(mp->m_log);
+ xlog_dealloc_log(log);
out:
return error;
}
@@ -731,7 +733,7 @@ xfs_log_mount_finish(
* mount failure occurs.
*/
mp->m_super->s_flags |= SB_ACTIVE;
- if (log->l_flags & XLOG_RECOVERY_NEEDED)
+ if (xlog_recovery_needed(log))
error = xlog_recover_finish(log);
if (!error)
xfs_log_work_queue(mp);
@@ -747,7 +749,7 @@ xfs_log_mount_finish(
* Don't push in the error case because the AIL may have pending intents
* that aren't removed until recovery is cancelled.
*/
- if (log->l_flags & XLOG_RECOVERY_NEEDED) {
+ if (xlog_recovery_needed(log)) {
if (!error) {
xfs_log_force(mp, XFS_LOG_SYNC);
xfs_ail_push_all_sync(mp->m_ail);
@@ -759,7 +761,7 @@ xfs_log_mount_finish(
}
xfs_buftarg_drain(mp->m_ddev_targp);

- log->l_flags &= ~XLOG_RECOVERY_NEEDED;
+ clear_bit(XLOG_RECOVERY_NEEDED, &log->l_opstate);
if (readonly)
mp->m_flags |= XFS_MOUNT_RDONLY;

@@ -1036,7 +1038,7 @@ xfs_log_space_wake(
return;

if (!list_empty_careful(&log->l_write_head.waiters)) {
- ASSERT(!(log->l_flags & XLOG_ACTIVE_RECOVERY));
+ ASSERT(!xlog_in_recovery(log));

spin_lock(&log->l_write_head.lock);
free_bytes = xlog_space_left(log, &log->l_write_head.grant);
@@ -1045,7 +1047,7 @@ xfs_log_space_wake(
}

if (!list_empty_careful(&log->l_reserve_head.waiters)) {
- ASSERT(!(log->l_flags & XLOG_ACTIVE_RECOVERY));
+ ASSERT(!xlog_in_recovery(log));

spin_lock(&log->l_reserve_head.lock);
free_bytes = xlog_space_left(log, &log->l_reserve_head.grant);
@@ -1400,7 +1402,7 @@ xlog_alloc_log(
log->l_logBBstart = blk_offset;
log->l_logBBsize = num_bblks;
log->l_covered_state = XLOG_STATE_COVER_IDLE;
- log->l_flags |= XLOG_ACTIVE_RECOVERY;
+ set_bit(XLOG_ACTIVE_RECOVERY, &log->l_opstate);
INIT_DELAYED_WORK(&log->l_work, xfs_log_worker);

log->l_prev_block = -1;
@@ -3527,17 +3529,15 @@ xlog_verify_grant_tail(
xlog_crack_atomic_lsn(&log->l_tail_lsn, &tail_cycle, &tail_blocks);
if (tail_cycle != cycle) {
if (cycle - 1 != tail_cycle &&
- !(log->l_flags & XLOG_TAIL_WARN)) {
+ !test_and_set_bit(XLOG_TAIL_WARN, &log->l_opstate)) {
xfs_alert_tag(log->l_mp, XFS_PTAG_LOGRES,
"%s: cycle - 1 != tail_cycle", __func__);
- log->l_flags |= XLOG_TAIL_WARN;
}

if (space > BBTOB(tail_blocks) &&
- !(log->l_flags & XLOG_TAIL_WARN)) {
+ !test_and_set_bit(XLOG_TAIL_WARN, &log->l_opstate)) {
xfs_alert_tag(log->l_mp, XFS_PTAG_LOGRES,
"%s: space > BBTOB(tail_blocks)", __func__);
- log->l_flags |= XLOG_TAIL_WARN;
}
}
}
@@ -3704,8 +3704,7 @@ xfs_log_force_umount(
* If this happens during log recovery, don't worry about
* locking; the log isn't open for business yet.
*/
- if (!log ||
- log->l_flags & XLOG_ACTIVE_RECOVERY) {
+ if (!log || xlog_in_recovery(log)) {
mp->m_flags |= XFS_MOUNT_FS_SHUTDOWN;
if (mp->m_sb_bp)
mp->m_sb_bp->b_flags |= XBF_DONE;
@@ -3742,10 +3741,8 @@ xfs_log_force_umount(
* Mark the log and the iclogs with IO error flags to prevent any
* further log IO from being issued or completed.
*/
- if (!(log->l_flags & XLOG_IO_ERROR)) {
- log->l_flags |= XLOG_IO_ERROR;
+ if (!test_and_set_bit(XLOG_IO_ERROR, &log->l_opstate))
retval = 1;
- }
spin_unlock(&log->l_icloglock);

/*
@@ -3832,12 +3829,3 @@ xfs_log_check_lsn(

return valid;
}
-
-bool
-xfs_log_in_recovery(
- struct xfs_mount *mp)
-{
- struct xlog *log = mp->m_log;
-
- return log->l_flags & XLOG_ACTIVE_RECOVERY;
-}
diff --git a/fs/xfs/xfs_log.h b/fs/xfs/xfs_log.h
index 813b972e9788..4c5c8a7db1d9 100644
--- a/fs/xfs/xfs_log.h
+++ b/fs/xfs/xfs_log.h
@@ -138,7 +138,6 @@ void xfs_log_work_queue(struct xfs_mount *mp);
int xfs_log_quiesce(struct xfs_mount *mp);
void xfs_log_clean(struct xfs_mount *mp);
bool xfs_log_check_lsn(struct xfs_mount *, xfs_lsn_t);
-bool xfs_log_in_recovery(struct xfs_mount *);

xfs_lsn_t xlog_grant_push_threshold(struct xlog *log, int need_bytes);

diff --git a/fs/xfs/xfs_log_priv.h b/fs/xfs/xfs_log_priv.h
index bf05763ba8df..6c2f88e06ac3 100644
--- a/fs/xfs/xfs_log_priv.h
+++ b/fs/xfs/xfs_log_priv.h
@@ -11,15 +11,6 @@ struct xlog;
struct xlog_ticket;
struct xfs_mount;

-/*
- * Flags for log structure
- */
-#define XLOG_ACTIVE_RECOVERY 0x2 /* in the middle of recovery */
-#define XLOG_RECOVERY_NEEDED 0x4 /* log was recovered */
-#define XLOG_IO_ERROR 0x8 /* log hit an I/O error, and being
- shutdown */
-#define XLOG_TAIL_WARN 0x10 /* log tail verify warning issued */
-
/*
* get client id from packed copy.
*
@@ -397,7 +388,7 @@ struct xlog {
struct xfs_buftarg *l_targ; /* buftarg of log */
struct workqueue_struct *l_ioend_workqueue; /* for I/O completions */
struct delayed_work l_work; /* background flush work */
- uint l_flags;
+ long l_opstate; /* operational state */
uint l_quotaoffs_flag; /* XFS_DQ_*, for QUOTAOFFs */
struct list_head *l_buf_cancel_table;
int l_iclog_hsize; /* size of iclog header */
@@ -451,10 +442,31 @@ struct xlog {
#define XLOG_BUF_CANCEL_BUCKET(log, blkno) \
((log)->l_buf_cancel_table + ((uint64_t)blkno % XLOG_BC_TABLE_SIZE))

+/*
+ * Bits for operational state
+ */
+#define XLOG_ACTIVE_RECOVERY 0 /* in the middle of recovery */
+#define XLOG_RECOVERY_NEEDED 1 /* log was recovered */
+#define XLOG_IO_ERROR 2 /* log hit an I/O error, and being
+ shutdown */
+#define XLOG_TAIL_WARN 3 /* log tail verify warning issued */
+
+static inline bool
+xlog_recovery_needed(struct xlog *log)
+{
+ return test_bit(XLOG_RECOVERY_NEEDED, &log->l_opstate);
+}
+
+static inline bool
+xlog_in_recovery(struct xlog *log)
+{
+ return test_bit(XLOG_ACTIVE_RECOVERY, &log->l_opstate);
+}
+
static inline bool
xlog_is_shutdown(struct xlog *log)
{
- return (log->l_flags & XLOG_IO_ERROR);
+ return test_bit(XLOG_IO_ERROR, &log->l_opstate);
}

/* common routines */
diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
index c384ecdd6389..5db3fb184fbe 100644
--- a/fs/xfs/xfs_log_recover.c
+++ b/fs/xfs/xfs_log_recover.c
@@ -3326,7 +3326,7 @@ xlog_do_recover(
xlog_recover_check_summary(log);

/* Normal transactions can now occur */
- log->l_flags &= ~XLOG_ACTIVE_RECOVERY;
+ clear_bit(XLOG_ACTIVE_RECOVERY, &log->l_opstate);
return 0;
}

@@ -3410,7 +3410,7 @@ xlog_recover(
: "internal");

error = xlog_do_recover(log, head_blk, tail_blk);
- log->l_flags |= XLOG_RECOVERY_NEEDED;
+ set_bit(XLOG_RECOVERY_NEEDED, &log->l_opstate);
}
return error;
}
@@ -3460,7 +3460,7 @@ void
xlog_recover_cancel(
struct xlog *log)
{
- if (log->l_flags & XLOG_RECOVERY_NEEDED)
+ if (xlog_recovery_needed(log))
xlog_recover_cancel_intents(log);
}

diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index 2c9e26a44546..29bec1f6476e 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -734,7 +734,7 @@ xfs_fs_drop_inode(
* that. See the comment for this inode flag.
*/
if (ip->i_flags & XFS_IRECOVERY) {
- ASSERT(ip->i_mount->m_log->l_flags & XLOG_RECOVERY_NEEDED);
+ ASSERT(xlog_recovery_needed(ip->i_mount->m_log));
return 0;
}

--
2.31.1