freezer: unexport refrigerator() and update try_to_freeze() slightly

There is no reason to export two functions for entering the
refrigerator.  Calling refrigerator() instead of try_to_freeze()
doesn't save anything noticeable or removes any race condition.

* Rename refrigerator() to __refrigerator() and make it return bool
  indicating whether it scheduled out for freezing.

* Update try_to_freeze() to return bool and relay the return value of
  __refrigerator() if freezing().

* Convert all refrigerator() users to try_to_freeze().

* Update documentation accordingly.

* While at it, add might_sleep() to try_to_freeze().

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Samuel Ortiz <samuel@sortiz.org>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jan Kara <jack@suse.cz>
Cc: KONISHI Ryusuke <konishi.ryusuke@lab.ntt.co.jp>
Cc: Christoph Hellwig <hch@infradead.org>

11 files changed, 15 insertions, 20 deletions

diff --git a/fs/btrfs/async-thread.c b/fs/btrfs/async-thread.c
index 7ec14097fef1..98ab240072e5 100644
--- a/fs/btrfs/async-thread.c
+++ b/fs/btrfs/async-thread.c
@@ -340,7 +340,7 @@ again:
                 if (freezing(current)) {
                         worker->working = 0;
                         spin_unlock_irq(&worker->lock);
-                        refrigerator();
+                        try_to_freeze();
                 } else {
                         spin_unlock_irq(&worker->lock);
                         if (!kthread_should_stop()) {
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 62afe5c5694e..622654fe051f 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1579,9 +1579,7 @@ static int cleaner_kthread(void *arg)
                         btrfs_run_defrag_inodes(root->fs_info);
                 }
 
-                if (freezing(current)) {
-                        refrigerator();
-                } else {
+                if (!try_to_freeze()) {
                         set_current_state(TASK_INTERRUPTIBLE);
                         if (!kthread_should_stop())
                                 schedule();
@@ -1635,9 +1633,7 @@ sleep:
                 wake_up_process(root->fs_info->cleaner_kthread);
                 mutex_unlock(&root->fs_info->transaction_kthread_mutex);
 
-                if (freezing(current)) {
-                        refrigerator();
-                } else {
+                if (!try_to_freeze()) {
                         set_current_state(TASK_INTERRUPTIBLE);
                         if (!kthread_should_stop() &&
                             !btrfs_transaction_blocked(root->fs_info))
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 9953d80145ad..877350ef0253 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -2882,8 +2882,7 @@ cont_thread:
                 }
                 mutex_unlock(&eli->li_list_mtx);
 
-                if (freezing(current))
-                        refrigerator();
+                try_to_freeze();
 
                 cur = jiffies;
                 if ((time_after_eq(cur, next_wakeup)) ||
diff --git a/fs/gfs2/log.c b/fs/gfs2/log.c
index 598646434362..8154d42e4647 100644
--- a/fs/gfs2/log.c
+++ b/fs/gfs2/log.c
@@ -951,8 +951,8 @@ int gfs2_logd(void *data)
                         wake_up(&sdp->sd_log_waitq);
 
                 t = gfs2_tune_get(sdp, gt_logd_secs) * HZ;
-                if (freezing(current))
-                        refrigerator();
+
+                try_to_freeze();
 
                 do {
                         prepare_to_wait(&sdp->sd_logd_waitq, &wait,
diff --git a/fs/gfs2/quota.c b/fs/gfs2/quota.c
index 7e528dc14f85..d49669e92652 100644
--- a/fs/gfs2/quota.c
+++ b/fs/gfs2/quota.c
@@ -1427,8 +1427,8 @@ int gfs2_quotad(void *data)
                 /* Check for & recover partially truncated inodes */
                 quotad_check_trunc_list(sdp);
 
-                if (freezing(current))
-                        refrigerator();
+                try_to_freeze();
+
                 t = min(quotad_timeo, statfs_timeo);
 
                 prepare_to_wait(&sdp->sd_quota_wait, &wait, TASK_INTERRUPTIBLE);
diff --git a/fs/jbd/journal.c b/fs/jbd/journal.c
index fea8dd661d2b..a96cff0c5f1d 100644
--- a/fs/jbd/journal.c
+++ b/fs/jbd/journal.c
@@ -166,7 +166,7 @@ loop:
                  */
                 jbd_debug(1, "Now suspending kjournald\n");
                 spin_unlock(&journal->j_state_lock);
-                refrigerator();
+                try_to_freeze();
                 spin_lock(&journal->j_state_lock);
         } else {
                 /*
diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index 0fa0123151d3..c0a5f9f1b127 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -173,7 +173,7 @@ loop:
                  */
                 jbd_debug(1, "Now suspending kjournald2\n");
                 write_unlock(&journal->j_state_lock);
-                refrigerator();
+                try_to_freeze();
                 write_lock(&journal->j_state_lock);
         } else {
                 /*
diff --git a/fs/jfs/jfs_logmgr.c b/fs/jfs/jfs_logmgr.c
index cc5f811ed383..2eb952c41a69 100644
--- a/fs/jfs/jfs_logmgr.c
+++ b/fs/jfs/jfs_logmgr.c
@@ -2349,7 +2349,7 @@ int jfsIOWait(void *arg)
 
                 if (freezing(current)) {
                         spin_unlock_irq(&log_redrive_lock);
-                        refrigerator();
+                        try_to_freeze();
                 } else {
                         set_current_state(TASK_INTERRUPTIBLE);
                         spin_unlock_irq(&log_redrive_lock);
diff --git a/fs/jfs/jfs_txnmgr.c b/fs/jfs/jfs_txnmgr.c
index af9606057dde..bb8b661bcc50 100644
--- a/fs/jfs/jfs_txnmgr.c
+++ b/fs/jfs/jfs_txnmgr.c
@@ -2800,7 +2800,7 @@ int jfs_lazycommit(void *arg)
 
                 if (freezing(current)) {
                         LAZY_UNLOCK(flags);
-                        refrigerator();
+                        try_to_freeze();
                 } else {
                         DECLARE_WAITQUEUE(wq, current);
 
@@ -2994,7 +2994,7 @@ int jfs_sync(void *arg)
 
                 if (freezing(current)) {
                         TXN_UNLOCK();
-                        refrigerator();
+                        try_to_freeze();
                 } else {
                         set_current_state(TASK_INTERRUPTIBLE);
                         TXN_UNLOCK();
diff --git a/fs/nilfs2/segment.c b/fs/nilfs2/segment.c
index bb24ab6c282f..0e72ad6f22aa 100644
--- a/fs/nilfs2/segment.c
+++ b/fs/nilfs2/segment.c
@@ -2470,7 +2470,7 @@ static int nilfs_segctor_thread(void *arg)
 
         if (freezing(current)) {
                 spin_unlock(&sci->sc_state_lock);
-                refrigerator();
+                try_to_freeze();
                 spin_lock(&sci->sc_state_lock);
         } else {
                 DEFINE_WAIT(wait);
diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index cf0ac056815f..018829936d6d 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -1703,7 +1703,7 @@ xfsbufd(
 
                 if (unlikely(freezing(current))) {
                         set_bit(XBT_FORCE_SLEEP, &target->bt_flags);
-                        refrigerator();
+                        try_to_freeze();
                 } else {
                         clear_bit(XBT_FORCE_SLEEP, &target->bt_flags);
                 }