linux-kernel - Re: [f2fs-dev] [PATCH v2] f2fs: avoid sb_start

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Date:   Mon, 28 Feb 2022 20:48:37 -0800
From:   Jaegeuk Kim <jaegeuk@...nel.org>
To:     Chao Yu <chao@...nel.org>
Cc:     linux-kernel@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH v2] f2fs: avoid sb_start_intwrite during
 eviction

1. waiting for f2fs_evict_inode
[ 5560.043945]  __wait_on_freeing_inode+0xac/0xf0
[ 5560.045540]  ? var_wake_function+0x30/0x30
[ 5560.047036]  find_inode_fast+0x6d/0xc0
[ 5560.048473]  iget_locked+0x79/0x230
[ 5560.049933]  f2fs_iget+0x27/0x1200 [f2fs]
[ 5560.051496]  f2fs_lookup+0x18c/0x3e0 [f2fs]
[ 5560.053069]  __lookup_slow+0x84/0x150
[ 5560.054503]  walk_component+0x141/0x1b0
[ 5560.055938]  link_path_walk.part.0+0x23b/0x360
[ 5560.057541]  ? end_bio_bh_io_sync+0x37/0x50
[ 5560.059086]  path_parentat+0x3c/0x90
[ 5560.060492]  filename_parentat+0xd7/0x1e0
[ 5560.062002]  ? blk_mq_free_request+0x127/0x150
[ 5560.063576]  do_renameat2+0xc1/0x5b0
 --> sb_start_write(m->mnt_sb); ->  __sb_start_write(sb, SB_FREEZE_WRITE);

[ 5560.064999]  ? __check_object_size+0x13f/0x150
[ 5560.066559]  ? strncpy_from_user+0x44/0x150
[ 5560.068038]  ? getname_flags.part.0+0x4c/0x1b0
[ 5560.069617]  __x64_sys_renameat2+0x51/0x60

2. waiting for sb_start_intwrite -> __sb_start_write(sb, SB_FREEZE_FS);

[ 5560.152447]  percpu_rwsem_wait+0xaf/0x160
[ 5560.154000]  ? percpu_down_write+0xd0/0xd0
[ 5560.155498]  __percpu_down_read+0x4e/0x60
[ 5560.157000]  f2fs_evict_inode+0x5a3/0x610 [f2fs]
[ 5560.158648]  ? var_wake_function+0x30/0x30
[ 5560.160341]  evict+0xd2/0x180
[ 5560.161728]  prune_icache_sb+0x81/0xb0
 --> inode_lru_isolate() -> inode->i_state |= I_FREEING;

[ 5560.163179]  super_cache_scan+0x169/0x1f0
[ 5560.164675]  do_shrink_slab+0x145/0x2b0
[ 5560.166121]  shrink_slab+0x186/0x2d0
[ 5560.167481]  drop_slab_node+0x4a/0x90
[ 5560.168876]  drop_slab+0x3e/0x80
[ 5560.170178]  drop_caches_sysctl_handler+0x75/0x90
[ 5560.171761]  proc_sys_call_handler+0x149/0x280
[ 5560.173328]  proc_sys_write+0x13/0x20
[ 5560.174667]  new_sync_write+0x117/0x1b0
[ 5560.176120]  vfs_write+0x1d5/0x270
[ 5560.177409]  ksys_write+0x67/0xe0

Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
---
 Note, I found this call stack.

 fs/f2fs/inode.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c
index ab8e0c06c78c..882db4bd917b 100644
--- a/fs/f2fs/inode.c
+++ b/fs/f2fs/inode.c
@@ -778,7 +778,6 @@ void f2fs_evict_inode(struct inode *inode)
 	f2fs_remove_ino_entry(sbi, inode->i_ino, UPDATE_INO);
 	f2fs_remove_ino_entry(sbi, inode->i_ino, FLUSH_INO);
 
-	sb_start_intwrite(inode->i_sb);
 	set_inode_flag(inode, FI_NO_ALLOC);
 	i_size_write(inode, 0);
 retry:
@@ -809,7 +808,6 @@ void f2fs_evict_inode(struct inode *inode)
 		if (dquot_initialize_needed(inode))
 			set_sbi_flag(sbi, SBI_QUOTA_NEED_REPAIR);
 	}
-	sb_end_intwrite(inode->i_sb);
 no_delete:
 	dquot_drop(inode);
 
-- 
2.35.1.574.g5d30c73bfb-goog