4.15-stable review patch. If anyone has any objections, please let me know.
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From: Amir Goldstein amir73il@gmail.com
commit a5a927a7c82e28ea76599dee4019c41e372c911f upstream.
The optimization in ovl_cache_get_impure() that tries to remove an unneeded "impure" xattr needs to take mnt_want_write() on upper fs.
Fixes: 4edb83bb1041 ("ovl: constant d_ino for non-merge dirs") Signed-off-by: Amir Goldstein amir73il@gmail.com Signed-off-by: Miklos Szeredi mszeredi@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/overlayfs/readdir.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-)
--- a/fs/overlayfs/readdir.c +++ b/fs/overlayfs/readdir.c @@ -593,8 +593,15 @@ static struct ovl_dir_cache *ovl_cache_g return ERR_PTR(res); } if (list_empty(&cache->entries)) { - /* Good oportunity to get rid of an unnecessary "impure" flag */ - ovl_do_removexattr(ovl_dentry_upper(dentry), OVL_XATTR_IMPURE); + /* + * A good opportunity to get rid of an unneeded "impure" flag. + * Removing the "impure" xattr is best effort. + */ + if (!ovl_want_write(dentry)) { + ovl_do_removexattr(ovl_dentry_upper(dentry), + OVL_XATTR_IMPURE); + ovl_drop_write(dentry); + } ovl_clear_flag(OVL_IMPURE, d_inode(dentry)); kfree(cache); return NULL;