linux-kernel - [PATCH] f2fs: avoid sb_start

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Message-Id: <20220215220039.1477906-1-jaegeuk@kernel.org>
Date:   Tue, 15 Feb 2022 14:00:39 -0800
From:   Jaegeuk Kim <jaegeuk@...nel.org>
To:     linux-kernel@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net
Cc:     Jaegeuk Kim <jaegeuk@...nel.org>
Subject: [PATCH] f2fs: avoid sb_start_intwrite during eviction

1. this thread is stuck in f2fs_evict_inode by #2:
[210757.653718]  __schedule+0x2e3/0x740
[210757.654811]  schedule+0x42/0xb0
[210757.655829]  rwsem_down_read_slowpath+0x16c/0x4a0
[210757.657161]  __down_read+0x6b/0x80
[210757.658254]  __percpu_down_read+0x54/0x80
[210757.659413]  __sb_start_write+0x79/0x80
[210757.660546]  f2fs_evict_inode+0x354/0x5c0 [f2fs]
[210757.661808]  ? var_wake_function+0x30/0x30
[210757.663016]  evict+0xd2/0x1b0
[210757.664007]  dispose_list+0x39/0x50
[210757.665083]  prune_icache_sb+0x5c/0x80
[210757.666226]  super_cache_scan+0x132/0x1b0
[210757.667373]  do_shrink_slab+0x150/0x2a0
[210757.668510]  shrink_slab+0x20c/0x2a0
[210757.669574]  drop_slab_node+0x33/0x60
[210757.670646]  drop_slab+0x3e/0x70
[210757.671633]  drop_caches_sysctl_handler+0x75/0x85
[210757.672904]  proc_sys_call_handler+0x1a2/0x1c0
[210757.674104]  proc_sys_write+0x14/0x20
[210757.675189]  __vfs_write+0x1b/0x40
[210757.676208]  vfs_write+0xb9/0x1a0
[210757.677219]  ksys_write+0x67/0xe0
[210757.678251]  __x64_sys_write+0x1a/0x20

2. another thread is waiting for #1:
[210757.754646]  schedule+0x42/0xb0
[210757.755680]  rwsem_down_write_slowpath+0x244/0x4d0
[210757.757016]  ? _cond_resched+0x19/0x30
[210757.758140]  down_write+0x41/0x50
[210757.759223]  prealloc_shrinker+0x6a/0x120
[210757.760397]  alloc_super+0x275/0x2d0
[210757.761500]  sget_fc+0x74/0x220
[210757.762547]  ? set_anon_super+0x20/0x20
[210757.763711]  ? shmem_create+0x20/0x20
[210757.764842]  vfs_get_super+0x3d/0x100
[210757.765925]  get_tree_nodev+0x16/0x20
[210757.767046]  shmem_get_tree+0x15/0x20
[210757.768165]  vfs_get_tree+0x2a/0xc0
[210757.769248]  ? ns_capable+0x10/0x20
[210757.770361]  do_mount+0x7b6/0x9c0
[210757.771423]  ksys_mount+0x82/0xd0
[210757.772469]  __x64_sys_mount+0x25/0x30
[210757.773592]  do_syscall_64+0x57/0x190

3. thaw_super is waiting for #2, resulting in xfstests/generic/068 being stuck.
[210757.695823]  __schedule+0x2e3/0x740
[210757.696897]  ? sched_clock+0x9/0x10
[210757.697959]  schedule+0x42/0xb0
[210757.698963]  rwsem_down_write_slowpath+0x244/0x4d0
[210757.700247]  down_write+0x41/0x50
[210757.701259]  thaw_super+0x17/0x30
[210757.702235]  do_vfs_ioctl+0x56f/0x670
[210757.703247]  ? do_user_addr_fault+0x216/0x450
[210757.704395]  ? _copy_to_user+0x2c/0x30
[210757.705443]  ksys_ioctl+0x67/0x90
[210757.706419]  __x64_sys_ioctl+0x1a/0x20
[210757.707437]  do_syscall_64+0x57/0x190

Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
---
 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);
 
-- 
2.35.1.265.g69c8d7142f-goog