Hi Jaegeuk,
I found a space leak problem in f2fs. This problem could lead to
ENOSPC error during stress tests, e.g. ltp.
<<<test_output>>>
growfiles(gf15): 11656 growfiles.c/2249: 16920 tlibio.c/739 write(6, buf, 1352) ret:-1, errno=28 No space left on device
gf15 1 TFAIL : growfiles.c:132: Test failed
...
And can be reproduced by these steps whether background_gc is on
or not:
1) format a 4GB f2fs partition
2) dd a 3G file,
3) unlink it.
Do these steps again and again. Soon, after one unlink operation,
you can see the space of the 3G file is not free.
Fs-Server:/mnt/f2fs # df .
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sdd3 4193280 301064 3854328 8% /mnt/f2fs
Fs-Server:/mnt/f2fs # dd if=/dev/zero of=./test bs=1M count=3072
3072+0 records in
3072+0 records out
3221225472 bytes (3.2 GB) copied, 3.1892 s, 1.0 GB/s
Fs-Server:/mnt/f2fs # unlink ./test
Fs-Server:/mnt/f2fs # dd if=/dev/zero of=./test bs=1M count=3072
3072+0 records in
3072+0 records out
3221225472 bytes (3.2 GB) copied, 3.44288 s, 936 MB/s
Fs-Server:/mnt/f2fs # unlink ./test
Fs-Server:/mnt/f2fs # df .
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sdd3 4193280 3449888 705504 84% /mnt/f2fs
Fs-Server:/mnt/f2fs # ls
Fs-Server:/mnt/f2fs # ls
Fs-Server:/mnt/f2fs # df .
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sdd3 4193280 3449888 705504 84% /mnt/f2fs
Fs-Server:/mnt/f2fs # dd if=/dev/zero of=./test bs=1M count=3072
dd: writing `./test': No space left on device
689+0 records in
688+0 records out
721719296 bytes (722 MB) copied, 0.618972 s, 1.2 GB/s
Fs-Server:/mnt/f2fs # df .
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sdd3 4193280 4155392 0 100% /mnt/f2fs
Fs-Server:/mnt/f2fs # ls -l test
-rw-r--r-- 1 root root 721719296 May 13 14:52 test
We can reuse the leaking space after a sync call:
Fs-Server:/mnt/f2fs # df .
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sdd3 4193280 4155392 0 100% /mnt/f2fs
Fs-Server:/mnt/f2fs # sync
Fs-Server:/mnt/f2fs # df .
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sdd3 4193280 1006568 3148824 25% /mnt/f2fs
I found this may caused by .drop_inode in f2fs. see f2fs_drop_inode()
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 19438f2..7646d2a 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -424,15 +424,6 @@ static struct inode *f2fs_alloc_inode(struct super_block *sb)
static int f2fs_drop_inode(struct inode *inode)
{
- /*
- * This is to avoid a deadlock condition like below.
- * writeback_single_inode(inode)
- * - f2fs_write_data_page
- * - f2fs_gc -> iput -> evict
- * - inode_wait_for_writeback(inode)
- */
- if (!inode_unhashed(inode) && inode->i_state & I_SYNC)
- return 0;
return generic_drop_inode(inode);
}
After removing these code, this problem is fixed. But this function is
introduced by commit 531ad7d58c6476c5856653448b4c7d26427502b4 to fix
a deadlock problem.
I wish you and other developers in this list could help me to fix this
problem in a correct way.
Thanks,
Hu
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