Re: [PATCH v2] fs: clear writeback errors in inode_init_always

Jeff Layton
2018-05-22T10:14:29Z

On Mon, 2018-05-21 at 21:06 -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@oracle.com>
>
> In inode_init_always(), we clear the inode mapping flags, which clears
> any retained error (AS_EIO, AS_ENOSPC) bits. Unfortunately, we do not
> also clear wb_err, which means that old mapping errors can leak through
> to new inodes.
>
> This is crucial for the XFS inode allocation path because we recycle old
> in-core inodes and we do not want error state from an old file to leak
> into the new file. This bug was discovered by running generic/036 and
> generic/047 in a loop and noticing that the EIOs generated by the
> collision of direct and buffered writes in generic/036 would survive the
> remount between 036 and 047, and get reported to the fsyncs (on
> different files!) in generic/047.
>
> Since we're changing the semantics of inode_init_always, we must also
> change xfs_reinit_inode to retain the writeback error state when we go
> to recover an inode that has been torn down in the vfs but not yet
> disposed of by XFS.
>
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---
> v2: retain AS_EIO/AS_ENOSPC across xfs inode reinit
> ---
> fs/inode.c | 1 +
> fs/xfs/xfs_icache.c | 9 +++++++++
> 2 files changed, 10 insertions(+)
>
> diff --git a/fs/inode.c b/fs/inode.c
> index 13ceb98c3bd3..3b55391072f3 100644
> --- a/fs/inode.c
> +++ b/fs/inode.c
> @@ -178,6 +178,7 @@ int inode_init_always(struct super_block *sb, struct inode *inode)
> mapping->a_ops = &empty_aops;
> mapping->host = inode;
> mapping->flags = 0;
> + mapping->wb_err = 0;
> atomic_set(&mapping->i_mmap_writable, 0);
> mapping_set_gfp_mask(mapping, GFP_HIGHUSER_MOVABLE);
> mapping->private_data = NULL;
> diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
> index 164350d91efc..d01f9544ff01 100644
> --- a/fs/xfs/xfs_icache.c
> +++ b/fs/xfs/xfs_icache.c
> @@ -298,6 +298,10 @@ xfs_reinit_inode(
> uint64_t version = inode_peek_iversion(inode);
> umode_t mode = inode->i_mode;
> dev_t dev = inode->i_rdev;
> + errseq_t old_err = inode->i_mapping->wb_err;
> + bool as_eio = test_bit(AS_EIO, &inode->i_mapping->flags);
> + bool as_enospc = test_bit(AS_ENOSPC,
> + &inode->i_mapping->flags);
>
> error = inode_init_always(mp->m_super, inode);
>
> @@ -306,6 +310,11 @@ xfs_reinit_inode(
> inode_set_iversion_queried(inode, version);
> inode->i_mode = mode;
> inode->i_rdev = dev;
> + inode->i_mapping->wb_err = old_err;
> + if (as_eio)
> + set_bit(AS_EIO, &inode->i_mapping->flags);
> + if (as_enospc)
> + set_bit(AS_ENOSPC, &inode->i_mapping->flags);
> return error;
> }
>

Reviewed-by: Jeff Layton <jlayton@kernel.org>