ext4: inline jbd2_journal_[un]register_shrinker()
The function jbd2_journal_unregister_shrinker() was getting called
twice when the file system was getting unmounted. On Power and ARM
platforms this was causing kernel crash when unmounting the file
system, when a percpu_counter was destroyed twice.
Fix this by removing jbd2_journal_[un]register_shrinker() functions,
and inlining the shrinker setup and teardown into
journal_init_common() and jbd2_journal_destroy(). This means that
ext4 and ocfs2 now no longer need to know about registering and
unregistering jbd2's shrinker.
Also, while we're at it, rename the percpu counter from
j_jh_shrink_count to j_checkpoint_jh_count, since this makes it
clearer what this counter is intended to track.
Link: https://lore.kernel.org/r/20210705145025.3363130-1-tytso@mit.edu
Fixes: 4ba3fcdde7e3 ("jbd2,ext4: add a shrinker to release checkpointed buffers")
Reported-by: Jon Hunter <jonathanh@nvidia.com>
Reported-by: Sachin Sant <sachinp@linux.vnet.ibm.com>
Tested-by: Sachin Sant <sachinp@linux.vnet.ibm.com>
Tested-by: Jon Hunter <jonathanh@nvidia.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index 152880c..35302bc 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -1283,6 +1283,48 @@ static int jbd2_min_tag_size(void)
return sizeof(journal_block_tag_t) - 4;
}
+/**
+ * jbd2_journal_shrink_scan()
+ *
+ * Scan the checkpointed buffer on the checkpoint list and release the
+ * journal_head.
+ */
+static unsigned long jbd2_journal_shrink_scan(struct shrinker *shrink,
+ struct shrink_control *sc)
+{
+ journal_t *journal = container_of(shrink, journal_t, j_shrinker);
+ unsigned long nr_to_scan = sc->nr_to_scan;
+ unsigned long nr_shrunk;
+ unsigned long count;
+
+ count = percpu_counter_read_positive(&journal->j_checkpoint_jh_count);
+ trace_jbd2_shrink_scan_enter(journal, sc->nr_to_scan, count);
+
+ nr_shrunk = jbd2_journal_shrink_checkpoint_list(journal, &nr_to_scan);
+
+ count = percpu_counter_read_positive(&journal->j_checkpoint_jh_count);
+ trace_jbd2_shrink_scan_exit(journal, nr_to_scan, nr_shrunk, count);
+
+ return nr_shrunk;
+}
+
+/**
+ * jbd2_journal_shrink_count()
+ *
+ * Count the number of checkpoint buffers on the checkpoint list.
+ */
+static unsigned long jbd2_journal_shrink_count(struct shrinker *shrink,
+ struct shrink_control *sc)
+{
+ journal_t *journal = container_of(shrink, journal_t, j_shrinker);
+ unsigned long count;
+
+ count = percpu_counter_read_positive(&journal->j_checkpoint_jh_count);
+ trace_jbd2_shrink_count(journal, sc->nr_to_scan, count);
+
+ return count;
+}
+
/*
* Management for journal control blocks: functions to create and
* destroy journal_t structures, and to initialise and read existing
@@ -1361,9 +1403,23 @@ static journal_t *journal_init_common(struct block_device *bdev,
journal->j_sb_buffer = bh;
journal->j_superblock = (journal_superblock_t *)bh->b_data;
+ journal->j_shrink_transaction = NULL;
+ journal->j_shrinker.scan_objects = jbd2_journal_shrink_scan;
+ journal->j_shrinker.count_objects = jbd2_journal_shrink_count;
+ journal->j_shrinker.seeks = DEFAULT_SEEKS;
+ journal->j_shrinker.batch = journal->j_max_transaction_buffers;
+
+ if (percpu_counter_init(&journal->j_checkpoint_jh_count, 0, GFP_KERNEL))
+ goto err_cleanup;
+
+ if (register_shrinker(&journal->j_shrinker)) {
+ percpu_counter_destroy(&journal->j_checkpoint_jh_count);
+ goto err_cleanup;
+ }
return journal;
err_cleanup:
+ brelse(journal->j_sb_buffer);
kfree(journal->j_wbuf);
jbd2_journal_destroy_revoke(journal);
kfree(journal);
@@ -2051,93 +2107,6 @@ int jbd2_journal_load(journal_t *journal)
}
/**
- * jbd2_journal_shrink_scan()
- *
- * Scan the checkpointed buffer on the checkpoint list and release the
- * journal_head.
- */
-static unsigned long jbd2_journal_shrink_scan(struct shrinker *shrink,
- struct shrink_control *sc)
-{
- journal_t *journal = container_of(shrink, journal_t, j_shrinker);
- unsigned long nr_to_scan = sc->nr_to_scan;
- unsigned long nr_shrunk;
- unsigned long count;
-
- count = percpu_counter_read_positive(&journal->j_jh_shrink_count);
- trace_jbd2_shrink_scan_enter(journal, sc->nr_to_scan, count);
-
- nr_shrunk = jbd2_journal_shrink_checkpoint_list(journal, &nr_to_scan);
-
- count = percpu_counter_read_positive(&journal->j_jh_shrink_count);
- trace_jbd2_shrink_scan_exit(journal, nr_to_scan, nr_shrunk, count);
-
- return nr_shrunk;
-}
-
-/**
- * jbd2_journal_shrink_count()
- *
- * Count the number of checkpoint buffers on the checkpoint list.
- */
-static unsigned long jbd2_journal_shrink_count(struct shrinker *shrink,
- struct shrink_control *sc)
-{
- journal_t *journal = container_of(shrink, journal_t, j_shrinker);
- unsigned long count;
-
- count = percpu_counter_read_positive(&journal->j_jh_shrink_count);
- trace_jbd2_shrink_count(journal, sc->nr_to_scan, count);
-
- return count;
-}
-
-/**
- * jbd2_journal_register_shrinker()
- * @journal: Journal to act on.
- *
- * Init a percpu counter to record the checkpointed buffers on the checkpoint
- * list and register a shrinker to release their journal_head.
- */
-int jbd2_journal_register_shrinker(journal_t *journal)
-{
- int err;
-
- journal->j_shrink_transaction = NULL;
-
- err = percpu_counter_init(&journal->j_jh_shrink_count, 0, GFP_KERNEL);
- if (err)
- return err;
-
- journal->j_shrinker.scan_objects = jbd2_journal_shrink_scan;
- journal->j_shrinker.count_objects = jbd2_journal_shrink_count;
- journal->j_shrinker.seeks = DEFAULT_SEEKS;
- journal->j_shrinker.batch = journal->j_max_transaction_buffers;
-
- err = register_shrinker(&journal->j_shrinker);
- if (err) {
- percpu_counter_destroy(&journal->j_jh_shrink_count);
- return err;
- }
-
- return 0;
-}
-EXPORT_SYMBOL(jbd2_journal_register_shrinker);
-
-/**
- * jbd2_journal_unregister_shrinker()
- * @journal: Journal to act on.
- *
- * Unregister the checkpointed buffer shrinker and destroy the percpu counter.
- */
-void jbd2_journal_unregister_shrinker(journal_t *journal)
-{
- percpu_counter_destroy(&journal->j_jh_shrink_count);
- unregister_shrinker(&journal->j_shrinker);
-}
-EXPORT_SYMBOL(jbd2_journal_unregister_shrinker);
-
-/**
* jbd2_journal_destroy() - Release a journal_t structure.
* @journal: Journal to act on.
*
@@ -2209,8 +2178,10 @@ int jbd2_journal_destroy(journal_t *journal)
brelse(journal->j_sb_buffer);
}
- jbd2_journal_unregister_shrinker(journal);
-
+ if (journal->j_shrinker.flags & SHRINKER_REGISTERED) {
+ percpu_counter_destroy(&journal->j_checkpoint_jh_count);
+ unregister_shrinker(&journal->j_shrinker);
+ }
if (journal->j_proc_entry)
jbd2_stats_proc_exit(journal);
iput(journal->j_inode);
