diff options
| -rw-r--r-- | config/kernel-shrink.m4 | 39 | ||||
| -rw-r--r-- | config/kernel.m4 | 1 | ||||
| -rw-r--r-- | module/zfs/zpl_super.c | 4 |
3 files changed, 44 insertions, 0 deletions
diff --git a/config/kernel-shrink.m4 b/config/kernel-shrink.m4 index 479fb3a6e..1c211ed15 100644 --- a/config/kernel-shrink.m4 +++ b/config/kernel-shrink.m4 @@ -28,6 +28,45 @@ AC_DEFUN([ZFS_AC_KERNEL_SHRINK], [ ]) ]) +dnl # +dnl # 3.3 API change +dnl # The super_block structure was changed to use an hlist_node instead +dnl # of a list_head for the .s_instance linkage. +dnl # +dnl # This was done in part to resolve a race in the iterate_supers_type() +dnl # function which was introduced in Linux 3.0 kernel. The iterator +dnl # was supposed to provide a safe way to call an arbitrary function on +dnl # all super blocks of a specific type. Unfortunately, because a +dnl # list_head was used it was possible for iterate_supers_type() to +dnl # get stuck spinning a super block which was just deactivated. +dnl # +dnl # This can occur because when the list head is removed from the +dnl # fs_supers list it is reinitialized to point to itself. If the +dnl # iterate_supers_type() function happened to be processing the +dnl # removed list_head it will get stuck spinning on that list_head. +dnl # +dnl # To resolve the issue for existing 3.0 - 3.2 kernels we detect when +dnl # a list_head is used. Then to prevent the spinning from occurring +dnl # the .next pointer is set to the fs_supers list_head which ensures +dnl # the iterate_supers_type() function will always terminate. +dnl # +AC_DEFUN([ZFS_AC_KERNEL_S_INSTANCES_LIST_HEAD], [ + AC_MSG_CHECKING([whether super_block has s_instances list_head]) + ZFS_LINUX_TRY_COMPILE([ + #include <linux/fs.h> + ],[ + struct super_block sb __attribute__ ((unused)); + + INIT_LIST_HEAD(&sb.s_instances); + ],[ + AC_MSG_RESULT(yes) + AC_DEFINE(HAVE_S_INSTANCES_LIST_HEAD, 1, + [struct super_block has s_instances list_head]) + ],[ + AC_MSG_RESULT(no) + ]) +]) + AC_DEFUN([ZFS_AC_KERNEL_NR_CACHED_OBJECTS], [ AC_MSG_CHECKING([whether sops->nr_cached_objects() exists]) ZFS_LINUX_TRY_COMPILE([ diff --git a/config/kernel.m4 b/config/kernel.m4 index 46c0255b0..8742bc51f 100644 --- a/config/kernel.m4 +++ b/config/kernel.m4 @@ -72,6 +72,7 @@ AC_DEFUN([ZFS_AC_CONFIG_KERNEL], [ ZFS_AC_KERNEL_CALLBACK_SECURITY_INODE_INIT_SECURITY ZFS_AC_KERNEL_MOUNT_NODEV ZFS_AC_KERNEL_SHRINK + ZFS_AC_KERNEL_S_INSTANCES_LIST_HEAD ZFS_AC_KERNEL_S_D_OP ZFS_AC_KERNEL_BDI ZFS_AC_KERNEL_BDI_SETUP_AND_REGISTER diff --git a/module/zfs/zpl_super.c b/module/zfs/zpl_super.c index d4d4e1b67..eee4a50e0 100644 --- a/module/zfs/zpl_super.c +++ b/module/zfs/zpl_super.c @@ -240,6 +240,10 @@ zpl_kill_sb(struct super_block *sb) { zfs_preumount(sb); kill_anon_super(sb); + +#ifdef HAVE_S_INSTANCES_LIST_HEAD + sb->s_instances.next = &(zpl_fs_type.fs_supers); +#endif /* HAVE_S_INSTANCES_LIST_HEAD */ } #ifdef HAVE_SHRINK |