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Date: Thu, 23 Apr 2020 21:13:43 +0800 From: Chao Yu <chao@...nel.org> To: Sayali Lokhande <sayalil@...eaurora.org>, jaegeuk@...nel.org, yuchao0@...wei.com, linux-f2fs-devel@...ts.sourceforge.net Cc: linux-kernel@...r.kernel.org Subject: Re: [f2fs-dev] [PATCH] f2fs: Avoid double lock for cp_rwsem Hi Sayali, On 2020-4-23 18:13, Sayali Lokhande wrote: > Call stack : > f2fs_write_checkpoint() > -> block_operations(sbi) > f2fs_lock_all(sbi); > down_write(&sbi->cp_rwsem); => write lock held > <> It looks the full race condition should be? Thread B - open() - igrab() - write() write inline data - unlink() > -> f2fs_sync_node_pages() > if (is_inline_node(page)) > flush_inline_data() ilookup() > page = f2fs_pagecache_get_page() > if (!page) > goto iput_out; > iput_out: - close() - iput() > iput(inode); > -> f2fs_evict_inode() > f2fs_truncate_blocks() > f2fs_lock_op() > down_read(&sbi->cp_rwsem); => read lock fail > > Signed-off-by: Sayali Lokhande <sayalil@...eaurora.org> > --- > fs/f2fs/checkpoint.c | 10 ++++------ > 1 file changed, 4 insertions(+), 6 deletions(-) > > diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c > index 5ba649e..5c504cf 100644 > --- a/fs/f2fs/checkpoint.c > +++ b/fs/f2fs/checkpoint.c > @@ -1219,21 +1219,19 @@ static int block_operations(struct f2fs_sb_info *sbi) > goto retry_flush_quotas; > } > > -retry_flush_nodes: > down_write(&sbi->node_write); > > if (get_pages(sbi, F2FS_DIRTY_NODES)) { > up_write(&sbi->node_write); Call up_write(&sbi->node_change) here could wake up threads earlier who hang on this lock, how do you think? Thanks, > + f2fs_unlock_all(sbi); > atomic_inc(&sbi->wb_sync_req[NODE]); > err = f2fs_sync_node_pages(sbi, &wbc, false, FS_CP_NODE_IO); > atomic_dec(&sbi->wb_sync_req[NODE]); > - if (err) { > - up_write(&sbi->node_change); > - f2fs_unlock_all(sbi); > + up_write(&sbi->node_change); > + if (err) > goto out; > - } > cond_resched(); > - goto retry_flush_nodes; > + goto retry_flush_quotas; > } > > /* >
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