On Fri, Jan 26, 2018 at 09:44:29AM +0200, Amir Goldstein wrote:
> Commit 66f364649d870 ("xfs: remove if_rdev") moved storing of rdev
> value for special inodes to VFS inodes, but forgot to preserve the
> value of i_rdev when recycling a reclaimable xfs_inode.
>
> This was detected by xfstest overlay/017 with inodex=on mount option
> and xfs base fs. The test does a lookup of overlay chardev and blockdev
> right after drop caches.
>
> Overlayfs inodes hold a reference on underlying xfs inodes when mount
> option index=on is configured. If drop caches reclaim xfs inodes, before
> it relclaims overlayfs inodes, that can sometimes leave a reclaimable xfs
> inode and that test hits that case quite often.
>
> When that happens, the xfs inode cache remains broken (zere i_rdev)
> until the next cycle mount or drop caches.
>
> Fixes: 66f364649d870 ("xfs: remove if_rdev")
> Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
Looks ok,
Reviewed-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> ---
>
> Darrick,
>
> You may want to rush this last minute v4.15 regression fix.
>
> Thanks,
> Amir.
>
> fs/xfs/xfs_icache.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
> index 3861d61fb265..3ce946063ffe 100644
> --- a/fs/xfs/xfs_icache.c
> +++ b/fs/xfs/xfs_icache.c
> @@ -295,6 +295,7 @@ xfs_reinit_inode(
> uint32_t generation = inode->i_generation;
> uint64_t version = inode->i_version;
> umode_t mode = inode->i_mode;
> + dev_t dev = inode->i_rdev;
>
> error = inode_init_always(mp->m_super, inode);
>
> @@ -302,6 +303,7 @@ xfs_reinit_inode(
> inode->i_generation = generation;
> inode->i_version = version;
> inode->i_mode = mode;
> + inode->i_rdev = dev;
> return error;
> }
>
> --
> 2.7.4
>
> --
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