f2fs: fix error handling in fill_super

In fill_super, if we fail to call f2fs_build_stats(), it needs to detach
from global f2fs shrink list, otherwise once system starts to shrink slab
cache, we will encounter below panic:

BUG: unable to handle kernel paging request at 00007d35
Oops: 0002 [#1] PREEMPT SMP
EIP: __lock_acquire+0x70/0x12c0
Call Trace:
 lock_acquire+0xae/0x220
 mutex_trylock+0xc5/0xf0
 f2fs_shrink_count+0x32/0xb0 [f2fs]
 shrink_slab+0xf1/0x5b0
 drop_slab_node+0x35/0x60
 drop_slab+0xf/0x20
 drop_caches_sysctl_handler+0x79/0xc0
 proc_sys_call_handler+0xa4/0xc0
 proc_sys_write+0x1f/0x30
 __vfs_write+0x24/0x150
 SyS_write+0x44/0x90
 do_fast_syscall_32+0xa1/0x1ca
 entry_SYSENTER_32+0x4c/0x7b

In addition, this patch relocates f2fs_join_shrinker in fill_super to
avoid unneeded error handling of it.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 2fabb131d385d105fefd364d8c57718ca9e0f066..f56230759b381c60c4deb347c46ff3078b4dcb12 100644 (file)
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -2615,18 +2615,16 @@ try_onemore:
                goto free_nm;
        }
 
-       f2fs_join_shrinker(sbi);
-
        err = f2fs_build_stats(sbi);
        if (err)
-               goto free_nm;
+               goto free_node_inode;
 
        /* read root inode and dentry */
        root = f2fs_iget(sb, F2FS_ROOT_INO(sbi));
        if (IS_ERR(root)) {
                f2fs_msg(sb, KERN_ERR, "Failed to read root inode");
                err = PTR_ERR(root);
-               goto free_node_inode;
+               goto free_stats;
        }
        if (!S_ISDIR(root->i_mode) || !root->i_blocks || !root->i_size) {
                iput(root);
@@ -2722,6 +2720,8 @@ skip_recovery:
                        sbi->valid_super_block ? 1 : 2, err);
        }
 
+       f2fs_join_shrinker(sbi);
+
        f2fs_msg(sbi->sb, KERN_NOTICE, "Mounted with checkpoint version = %llx",
                                cur_cp_version(F2FS_CKPT(sbi)));
        f2fs_update_time(sbi, CP_TIME);
@@ -2748,14 +2748,12 @@ free_sysfs:
 free_root_inode:
        dput(sb->s_root);
        sb->s_root = NULL;
+free_stats:
+       f2fs_destroy_stats(sbi);
 free_node_inode:
-       truncate_inode_pages_final(NODE_MAPPING(sbi));
-       mutex_lock(&sbi->umount_mutex);
        release_ino_entry(sbi, true);
-       f2fs_leave_shrinker(sbi);
+       truncate_inode_pages_final(NODE_MAPPING(sbi));
        iput(sbi->node_inode);
-       mutex_unlock(&sbi->umount_mutex);
-       f2fs_destroy_stats(sbi);
 free_nm:
        destroy_node_manager(sbi);
 free_sm: