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Date: Fri, 20 May 2022 11:31:05 +0200 From: Jan Kara <jack@...e.cz> To: Zhang Yi <yi.zhang@...wei.com> Cc: linux-ext4@...r.kernel.org, tytso@....edu, adilger.kernel@...ger.ca, jack@...e.cz, ritesh.list@...il.com, yukuai3@...wei.com Subject: Re: [PATCH v2] ext4: fix warning when submitting superblock in ext4_commit_super() On Fri 20-05-22 10:32:16, Zhang Yi wrote: > We have already check the io_error and uptodate flag before submitting > the superblock buffer, and re-set the uptodate flag if it has been > failed to write out. But it was lockless and could be raced by another > ext4_commit_super(), and finally trigger '!uptodate' WARNING when > marking buffer dirty. Fix it by submit buffer directly. > > Reported-by: Hulk Robot <hulkci@...wei.com> > Signed-off-by: Zhang Yi <yi.zhang@...wei.com> Looks good. Feel free to add: Reviewed-by: Jan Kara <jack@...e.cz> Honza > --- > v2->v1: > - Add clear_buffer_dirty() before submit_bh(). > > fs/ext4/super.c | 22 ++++++++++++++++------ > 1 file changed, 16 insertions(+), 6 deletions(-) > > diff --git a/fs/ext4/super.c b/fs/ext4/super.c > index 1466fbdbc8e3..9f6892665be4 100644 > --- a/fs/ext4/super.c > +++ b/fs/ext4/super.c > @@ -6002,7 +6002,6 @@ static void ext4_update_super(struct super_block *sb) > static int ext4_commit_super(struct super_block *sb) > { > struct buffer_head *sbh = EXT4_SB(sb)->s_sbh; > - int error = 0; > > if (!sbh) > return -EINVAL; > @@ -6011,6 +6010,13 @@ static int ext4_commit_super(struct super_block *sb) > > ext4_update_super(sb); > > + lock_buffer(sbh); > + /* Buffer got discarded which means block device got invalidated */ > + if (!buffer_mapped(sbh)) { > + unlock_buffer(sbh); > + return -EIO; > + } > + > if (buffer_write_io_error(sbh) || !buffer_uptodate(sbh)) { > /* > * Oh, dear. A previous attempt to write the > @@ -6025,17 +6031,21 @@ static int ext4_commit_super(struct super_block *sb) > clear_buffer_write_io_error(sbh); > set_buffer_uptodate(sbh); > } > - BUFFER_TRACE(sbh, "marking dirty"); > - mark_buffer_dirty(sbh); > - error = __sync_dirty_buffer(sbh, > - REQ_SYNC | (test_opt(sb, BARRIER) ? REQ_FUA : 0)); > + get_bh(sbh); > + /* Clear potential dirty bit if it was journalled update */ > + clear_buffer_dirty(sbh); > + sbh->b_end_io = end_buffer_write_sync; > + submit_bh(REQ_OP_WRITE, > + REQ_SYNC | (test_opt(sb, BARRIER) ? REQ_FUA : 0), sbh); > + wait_on_buffer(sbh); > if (buffer_write_io_error(sbh)) { > ext4_msg(sb, KERN_ERR, "I/O error while writing " > "superblock"); > clear_buffer_write_io_error(sbh); > set_buffer_uptodate(sbh); > + return -EIO; > } > - return error; > + return 0; > } > > /* > -- > 2.31.1 > -- Jan Kara <jack@...e.com> SUSE Labs, CR
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