[PATCH 1/3] btrfs: Set qgroup inherit size limit to SZ_4K instead of page size

[Qu Wenruo]

Change btrfs_qgroup_inherit maximum size from PAGE_SIZE to SZ_4K to make
it consistent across different architectures.

Although in theory this could lead to incompatibility, but considering
how rare btrfs_qgroup_inherit is used, it's still not too late to change
it without impacting a large user base.

Signed-off-by: Qu Wenruo <w...@suse.com>
---
 fs/btrfs/ioctl.c           | 2 +-
 include/uapi/linux/btrfs.h | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 63600dc2ac4c..5db8680b40a9 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1811,7 +1811,7 @@ static noinline int btrfs_ioctl_snap_create_v2(struct 
file *file,
        if (vol_args->flags & BTRFS_SUBVOL_RDONLY)
                readonly = true;
        if (vol_args->flags & BTRFS_SUBVOL_QGROUP_INHERIT) {
-               if (vol_args->size > PAGE_SIZE) {
+               if (vol_args->size > BTRFS_QGROUP_INHERIT_MAX_SIZE) {
                        ret = -EINVAL;
                        goto free_args;
                }
diff --git a/include/uapi/linux/btrfs.h b/include/uapi/linux/btrfs.h
index 5ca1d21fc4a7..311edb65567c 100644
--- a/include/uapi/linux/btrfs.h
+++ b/include/uapi/linux/btrfs.h
@@ -82,6 +82,7 @@ struct btrfs_qgroup_limit {
  */
 #define BTRFS_QGROUP_INHERIT_SET_LIMITS        (1ULL << 0)
 
+#define BTRFS_QGROUP_INHERIT_MAX_SIZE  (SZ_4K)
 struct btrfs_qgroup_inherit {
        __u64   flags;
        __u64   num_qgroups;
-- 
2.18.0