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Date: Wed, 7 Dec 2016 19:05:55 -0800
From: Jaegeuk Kim <jaegeuk@...nel.org>
To: linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
linux-f2fs-devel@...ts.sourceforge.net
Cc: Jaegeuk Kim <jaegeuk@...nel.org>
Subject: [PATCH] f2fs: fix to access nullified flush_cmd_control pointer
f2fs_sync_file() remount_ro
- f2fs_readonly
- destroy_flush_cmd_control
- f2fs_issue_flush
- no fcc pointer!
So, this patch doesn't free fcc in this case, but just stop its kernel thread
which sends flush commands.
Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
---
fs/f2fs/f2fs.h | 2 +-
fs/f2fs/segment.c | 33 +++++++++++++++++++++++++--------
fs/f2fs/super.c | 5 +++--
3 files changed, 29 insertions(+), 11 deletions(-)
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 35dbab157ec3..137bbf0ae4c6 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -2103,7 +2103,7 @@ void f2fs_balance_fs(struct f2fs_sb_info *, bool);
void f2fs_balance_fs_bg(struct f2fs_sb_info *);
int f2fs_issue_flush(struct f2fs_sb_info *);
int create_flush_cmd_control(struct f2fs_sb_info *);
-void destroy_flush_cmd_control(struct f2fs_sb_info *);
+void destroy_flush_cmd_control(struct f2fs_sb_info *, bool);
void invalidate_blocks(struct f2fs_sb_info *, block_t);
bool is_checkpointed_data(struct f2fs_sb_info *, block_t);
void refresh_sit_entry(struct f2fs_sb_info *, block_t, block_t);
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 8affc5621181..d7d5727fe8b2 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -489,8 +489,13 @@ int f2fs_issue_flush(struct f2fs_sb_info *sbi)
if (!fcc->dispatch_list)
wake_up(&fcc->flush_wait_queue);
- wait_for_completion(&cmd.wait);
- atomic_dec(&fcc->submit_flush);
+ if (fcc->f2fs_issue_flush) {
+ wait_for_completion(&cmd.wait);
+ atomic_dec(&fcc->submit_flush);
+ } else {
+ llist_del_all(&fcc->issue_list);
+ atomic_set(&fcc->submit_flush, 0);
+ }
return cmd.ret;
}
@@ -501,6 +506,11 @@ int create_flush_cmd_control(struct f2fs_sb_info *sbi)
struct flush_cmd_control *fcc;
int err = 0;
+ if (SM_I(sbi)->cmd_control_info) {
+ fcc = SM_I(sbi)->cmd_control_info;
+ goto init_thread;
+ }
+
fcc = kzalloc(sizeof(struct flush_cmd_control), GFP_KERNEL);
if (!fcc)
return -ENOMEM;
@@ -508,6 +518,7 @@ int create_flush_cmd_control(struct f2fs_sb_info *sbi)
init_waitqueue_head(&fcc->flush_wait_queue);
init_llist_head(&fcc->issue_list);
SM_I(sbi)->cmd_control_info = fcc;
+init_thread:
fcc->f2fs_issue_flush = kthread_run(issue_flush_thread, sbi,
"f2fs_flush-%u:%u", MAJOR(dev), MINOR(dev));
if (IS_ERR(fcc->f2fs_issue_flush)) {
@@ -520,14 +531,20 @@ int create_flush_cmd_control(struct f2fs_sb_info *sbi)
return err;
}
-void destroy_flush_cmd_control(struct f2fs_sb_info *sbi)
+void destroy_flush_cmd_control(struct f2fs_sb_info *sbi, bool free)
{
struct flush_cmd_control *fcc = SM_I(sbi)->cmd_control_info;
- if (fcc && fcc->f2fs_issue_flush)
- kthread_stop(fcc->f2fs_issue_flush);
- kfree(fcc);
- SM_I(sbi)->cmd_control_info = NULL;
+ if (fcc && fcc->f2fs_issue_flush) {
+ struct task_struct *flush_thread = fcc->f2fs_issue_flush;
+
+ fcc->f2fs_issue_flush = NULL;
+ kthread_stop(flush_thread);
+ }
+ if (free) {
+ kfree(fcc);
+ SM_I(sbi)->cmd_control_info = NULL;
+ }
}
static void __locate_dirty_segment(struct f2fs_sb_info *sbi, unsigned int segno,
@@ -2738,7 +2755,7 @@ void destroy_segment_manager(struct f2fs_sb_info *sbi)
if (!sm_info)
return;
- destroy_flush_cmd_control(sbi);
+ destroy_flush_cmd_control(sbi, true);
destroy_dirty_segmap(sbi);
destroy_curseg(sbi);
destroy_free_segmap(sbi);
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 1a526474b332..b62c10d28e06 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -1102,8 +1102,9 @@ static int f2fs_remount(struct super_block *sb, int *flags, char *data)
* or if flush_merge is not passed in mount option.
*/
if ((*flags & MS_RDONLY) || !test_opt(sbi, FLUSH_MERGE)) {
- destroy_flush_cmd_control(sbi);
- } else if (!SM_I(sbi)->cmd_control_info) {
+ clear_opt(sbi, FLUSH_MERGE);
+ destroy_flush_cmd_control(sbi, false);
+ } else {
err = create_flush_cmd_control(sbi);
if (err)
goto restore_gc;
--
2.11.0
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