When we mount device w/ gc_merge mount option, we may suffer below
potential deadlock:
Kworker GC trehad
Truncator
- f2fs_write_cache_pages
- f2fs_write_single_data_page
- f2fs_do_write_data_page
- folio_start_writeback --- set writeback flag on folio
- f2fs_outplace_write_data
: cached folio in internal bio cache
- f2fs_balance_fs
- wake_up(gc_thread)
: wake up gc thread to run foreground GC
- finish_wait(fggc_wq)
: wait on the waitqueue --- wait on GC thread to finish the work
-
truncate_inode_pages_range
-
__filemap_get_folio(, FGP_LOCK) --- lock folio
-
truncate_inode_partial_folio
-
folio_wait_writeback --- wait on writeback being cleared
- do_garbage_collect
- move_data_page
- f2fs_get_lock_data_folio
- lock on folio --- blocked on
folio's lock
In order to avoid such deadlock, let's call below functions to commit
cached bios in GC_MERGE path of f2fs_balance_fs() as the same as we did
in NOGC_MERGE path.
- f2fs_submit_merged_write(sbi, DATA);
- f2fs_submit_all_merged_ipu_writes(sbi);
Cc: [email protected]
Fixes: 351df4b20115 ("f2fs: add segment operations")
Cc: Ruipeng Qi <[email protected]>
Reported: Sandeep Dhavale <[email protected]>
Signed-off-by: Chao Yu <[email protected]>
Signed-off-by: Chao Yu <[email protected]>
---
fs/f2fs/segment.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 7c8ac62b1b0d..1ef4edb77078 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -445,6 +445,13 @@ void f2fs_balance_fs(struct f2fs_sb_info *sbi, bool need)
if (has_enough_free_secs(sbi, 0, 0))
return;
+ /*
+ * Submit all cached OPU/IPU DATA bios before triggering
+ * foreground GC to avoid potential deadlocks.
+ */
+ f2fs_submit_merged_write(sbi, DATA);
+ f2fs_submit_all_merged_ipu_writes(sbi);
+
if (test_opt(sbi, GC_MERGE) && sbi->gc_thread &&
sbi->gc_thread->f2fs_gc_task) {
DEFINE_WAIT(wait);
@@ -464,13 +471,6 @@ void f2fs_balance_fs(struct f2fs_sb_info *sbi, bool need)
.err_gc_skipped = false,
.nr_free_secs = 1 };
- /*
- * Submit all cached OPU/IPU DATA bios before triggering
- * foreground GC to avoid potential deadlocks.
- */
- f2fs_submit_merged_write(sbi, DATA);
- f2fs_submit_all_merged_ipu_writes(sbi);
-
f2fs_down_write_trace(&sbi->gc_lock, &gc_control.lc);
stat_inc_gc_call_count(sbi, FOREGROUND);
f2fs_gc(sbi, &gc_control);
--
2.49.0
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