[PATCH] f2fs: should use GFP_NOFS for directory inodes

[PATCH] f2fs: should use GFP_NOFS for directory inodes

[Jaegeuk Kim]

We use inline_dentry which requires to allocate dentry page when adding a link.
If we allow to reclaim memory from filesystem, we do down_read(&sbi->cp_rwsem)
twice by f2fs_lock_op(). I think this should be okay, but how about stopping
the lockdep complaint [1]?

f2fs_create()
 - f2fs_lock_op()
 - f2fs_do_add_link()
  - __f2fs_find_entry
   - f2fs_get_read_data_page()
   -> kswapd
    - shrink_node
     - f2fs_evict_inode
      - f2fs_lock_op()

[1]

fs_reclaim
){+.+.}-{0:0}
:
kswapd0:        lock_acquire+0x114/0x394
kswapd0:        __fs_reclaim_acquire+0x40/0x50
kswapd0:        prepare_alloc_pages+0x94/0x1ec
kswapd0:        __alloc_pages_nodemask+0x78/0x1b0
kswapd0:        pagecache_get_page+0x2e0/0x57c
kswapd0:        f2fs_get_read_data_page+0xc0/0x394
kswapd0:        f2fs_find_data_page+0xa4/0x23c
kswapd0:        find_in_level+0x1a8/0x36c
kswapd0:        __f2fs_find_entry+0x70/0x100
kswapd0:        f2fs_do_add_link+0x84/0x1ec
kswapd0:        f2fs_mkdir+0xe4/0x1e4
kswapd0:        vfs_mkdir+0x110/0x1c0
kswapd0:        do_mkdirat+0xa4/0x160
kswapd0:        __arm64_sys_mkdirat+0x24/0x34
kswapd0:        el0_svc_common.llvm.17258447499513131576+0xc4/0x1e8
kswapd0:        do_el0_svc+0x28/0xa0
kswapd0:        el0_svc+0x24/0x38
kswapd0:        el0_sync_handler+0x88/0xec
kswapd0:        el0_sync+0x1c0/0x200
kswapd0:
-> #1
(
&sbi->cp_rwsem
){++++}-{3:3}
:
kswapd0:        lock_acquire+0x114/0x394
kswapd0:        down_read+0x7c/0x98
kswapd0:        f2fs_do_truncate_blocks+0x78/0x3dc
kswapd0:        f2fs_truncate+0xc8/0x128
kswapd0:        f2fs_evict_inode+0x2b8/0x8b8
kswapd0:        evict+0xd4/0x2f8
kswapd0:        iput+0x1c0/0x258
kswapd0:        do_unlinkat+0x170/0x2a0
kswapd0:        __arm64_sys_unlinkat+0x4c/0x68
kswapd0:        el0_svc_common.llvm.17258447499513131576+0xc4/0x1e8
kswapd0:        do_el0_svc+0x28/0xa0
kswapd0:        el0_svc+0x24/0x38
kswapd0:        el0_sync_handler+0x88/0xec
kswapd0:        el0_sync+0x1c0/0x200

Fixes: bdbc90fa55af ("f2fs: don't put dentry page in pagecache into highmem")
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
---
 fs/f2fs/inode.c | 2 +-
 fs/f2fs/namei.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c
index 9141147b5bb0..1213f15ffd68 100644
--- a/fs/f2fs/inode.c
+++ b/fs/f2fs/inode.c
@@ -527,7 +527,7 @@ struct inode *f2fs_iget(struct super_block *sb, unsigned long ino)
 		inode->i_op = &f2fs_dir_inode_operations;
 		inode->i_fop = &f2fs_dir_operations;
 		inode->i_mapping->a_ops = &f2fs_dblock_aops;
-		inode_nohighmem(inode);
+		mapping_set_gfp_mask(inode->i_mapping, GFP_NOFS);
 	} else if (S_ISLNK(inode->i_mode)) {
 		if (file_is_encrypt(inode))
 			inode->i_op = &f2fs_encrypted_symlink_inode_operations;
diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c
index 9c528e583c9d..ae0838001480 100644
--- a/fs/f2fs/namei.c
+++ b/fs/f2fs/namei.c
@@ -757,7 +757,7 @@ static int f2fs_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
 	inode->i_op = &f2fs_dir_inode_operations;
 	inode->i_fop = &f2fs_dir_operations;
 	inode->i_mapping->a_ops = &f2fs_dblock_aops;
-	inode_nohighmem(inode);
+	mapping_set_gfp_mask(inode->i_mapping, GFP_NOFS);
 
 	set_inode_flag(inode, FI_INC_LINK);
 	f2fs_lock_op(sbi);
-- 
2.33.0.153.gba50c8fa24-goog

Re: [f2fs-dev] [PATCH] f2fs: should use GFP_NOFS for directory inodes

[Chao Yu]

On 2021/9/8 1:43, Jaegeuk Kim wrote:
> We use inline_dentry which requires to allocate dentry page when adding a link.
> If we allow to reclaim memory from filesystem, we do down_read(&sbi->cp_rwsem)
> twice by f2fs_lock_op(). I think this should be okay, but how about stopping
> the lockdep complaint [1]?
> 
> f2fs_create()
>   - f2fs_lock_op()
>   - f2fs_do_add_link()
>    - __f2fs_find_entry
>     - f2fs_get_read_data_page()
>     -> kswapd
>      - shrink_node
>       - f2fs_evict_inode
>        - f2fs_lock_op()
> 
> [1]
> 
> fs_reclaim
> ){+.+.}-{0:0}
> :
> kswapd0:        lock_acquire+0x114/0x394
> kswapd0:        __fs_reclaim_acquire+0x40/0x50
> kswapd0:        prepare_alloc_pages+0x94/0x1ec
> kswapd0:        __alloc_pages_nodemask+0x78/0x1b0
> kswapd0:        pagecache_get_page+0x2e0/0x57c
> kswapd0:        f2fs_get_read_data_page+0xc0/0x394
> kswapd0:        f2fs_find_data_page+0xa4/0x23c
> kswapd0:        find_in_level+0x1a8/0x36c
> kswapd0:        __f2fs_find_entry+0x70/0x100
> kswapd0:        f2fs_do_add_link+0x84/0x1ec
> kswapd0:        f2fs_mkdir+0xe4/0x1e4
> kswapd0:        vfs_mkdir+0x110/0x1c0
> kswapd0:        do_mkdirat+0xa4/0x160
> kswapd0:        __arm64_sys_mkdirat+0x24/0x34
> kswapd0:        el0_svc_common.llvm.17258447499513131576+0xc4/0x1e8
> kswapd0:        do_el0_svc+0x28/0xa0
> kswapd0:        el0_svc+0x24/0x38
> kswapd0:        el0_sync_handler+0x88/0xec
> kswapd0:        el0_sync+0x1c0/0x200
> kswapd0:
> -> #1
> (
> &sbi->cp_rwsem
> ){++++}-{3:3}
> :
> kswapd0:        lock_acquire+0x114/0x394
> kswapd0:        down_read+0x7c/0x98
> kswapd0:        f2fs_do_truncate_blocks+0x78/0x3dc
> kswapd0:        f2fs_truncate+0xc8/0x128
> kswapd0:        f2fs_evict_inode+0x2b8/0x8b8
> kswapd0:        evict+0xd4/0x2f8
> kswapd0:        iput+0x1c0/0x258
> kswapd0:        do_unlinkat+0x170/0x2a0
> kswapd0:        __arm64_sys_unlinkat+0x4c/0x68
> kswapd0:        el0_svc_common.llvm.17258447499513131576+0xc4/0x1e8
> kswapd0:        do_el0_svc+0x28/0xa0
> kswapd0:        el0_svc+0x24/0x38
> kswapd0:        el0_sync_handler+0x88/0xec
> kswapd0:        el0_sync+0x1c0/0x200
> 
> Fixes: bdbc90fa55af ("f2fs: don't put dentry page in pagecache into highmem")
> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

Reviewed-by: Chao Yu <chao@kernel.org>

Thanks,