[PATCH] f2fs: fix to name f2fs GC task as per partition instead of per device

[Namjae Jeon <linkinjeon@gmail.com>]

From: Namjae Jeon <namjae.jeon@samsung.com>

After the commit 2184ad190a79ae2b40b5f5db1fbde5c22db6d310, it allowed
for naming GC threads based on the device.
i.e., if we have F2FS formatted partition in different devices - we will
have their GC thread names after the device. But, when we have a case like
2 or more partitions on the same device having F2FS filesystem.
In that case we are not able to differentiate between the GC threads.
So, to differentiate at all possible levels we can use the major/minor of
the device to have unique identification in the name.

Before patch:
root  9726  0.0  0.0  0  0 ?  S  14:32   0:00 [f2fs_gc-8:48]
root  9736  0.0  0.0  0  0 ?  S  14:32   0:00 [f2fs_gc-8:16]
root  9892  0.0  0.0  0  0 ?  S  14:33   0:00 [f2fs_gc-8:32]
root  9907  0.0  0.0  0  0 ?  S  14:34   0:00 [f2fs_gc-8:32]

After Patch:
root  16756  0.0  0.0  0  0 ?  S  14:57   0:00 [f2fs_gc-8:18]
root  16765  0.0  0.0  0  0 ?  S  14:57   0:00 [f2fs_gc-8:19]
root  16806  0.0  0.0  0  0 ?  S  14:58   0:00 [f2fs_gc-8:34]
root  16817  0.0  0.0  0  0 ?  S  14:58   0:00 [f2fs_gc-8:52]

Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Amit Sahrawat <a.sahrawat@samsung.com>
---
 fs/f2fs/gc.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
index 742135a..b0c1f8c 100644
--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -91,6 +91,7 @@ static int gc_thread_func(void *data)
 int start_gc_thread(struct f2fs_sb_info *sbi)
 {
 	struct f2fs_gc_kthread *gc_th;
+	dev_t dev = sbi->sb->s_bdev->bd_dev;
 
 	if (!test_opt(sbi, BG_GC))
 		return 0;
@@ -101,7 +102,7 @@ int start_gc_thread(struct f2fs_sb_info *sbi)
 	sbi->gc_thread = gc_th;
 	init_waitqueue_head(&sbi->gc_thread->gc_wait_queue_head);
 	sbi->gc_thread->f2fs_gc_task = kthread_run(gc_thread_func, sbi,
-				"f2fs_gc-%s", dev_name(sbi->sb->s_bdi->dev));
+				"f2fs_gc-%u:%u", MAJOR(dev), MINOR(dev));
 	if (IS_ERR(gc_th->f2fs_gc_task)) {
 		kfree(gc_th);
 		sbi->gc_thread = NULL;
-- 
1.7.9.5