LU-8855 llite: return small device numbers for compat stat()

The compat_sys_*stat*() syscalls will fail unless the devices majors
and minors are both less than 256. So in ll_getattr_it(), if we are in
32 bit compat mode then coerce the device numbers in to the expected
format.

Signed-off-by: John L. Hammond <john.hammond@intel.com>
Change-Id: I1bf13258902e13c76b9ebf3476fd1767712de0b3
Reviewed-on: https://review.whamcloud.com/23877
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>

diff --git a/lustre/llite/file.c b/lustre/llite/file.c
index 6f2fe92..95d1598 100644 (file)
--- a/lustre/llite/file.c
+++ b/lustre/llite/file.c
@@ -3557,6 +3557,18 @@ ll_inode_revalidate(struct dentry *dentry, __u64 ibits)
        RETURN(rc);
 }
 
+static inline dev_t ll_compat_encode_dev(dev_t dev)
+{
+       /* The compat_sys_*stat*() syscalls will fail unless the
+        * device majors and minors are both less than 256. Note that
+        * the value returned here will be passed through
+        * old_encode_dev() in cp_compat_stat(). And so we are not
+        * trying to return a valid compat (u16) device number, just
+        * one that will pass the old_valid_dev() check. */
+
+       return MKDEV(MAJOR(dev) & 0xff, MINOR(dev) & 0xff);
+}
+
 int ll_getattr(struct vfsmount *mnt, struct dentry *de, struct kstat *stat)
 {
         struct inode *inode = de->d_inode;
@@ -3573,15 +3585,19 @@ int ll_getattr(struct vfsmount *mnt, struct dentry *de, struct kstat *stat)
 
        OBD_FAIL_TIMEOUT(OBD_FAIL_GETATTR_DELAY, 30);
 
-       stat->dev = inode->i_sb->s_dev;
-       if (ll_need_32bit_api(sbi))
+       if (ll_need_32bit_api(sbi)) {
                stat->ino = cl_fid_build_ino(&lli->lli_fid, 1);
-       else
+               stat->dev = ll_compat_encode_dev(inode->i_sb->s_dev);
+               stat->rdev = ll_compat_encode_dev(inode->i_rdev);
+       } else {
                stat->ino = inode->i_ino;
+               stat->dev = inode->i_sb->s_dev;
+               stat->rdev = inode->i_rdev;
+       }
+
        stat->mode = inode->i_mode;
        stat->uid = inode->i_uid;
        stat->gid = inode->i_gid;
-       stat->rdev = inode->i_rdev;
        stat->atime = inode->i_atime;
        stat->mtime = inode->i_mtime;
        stat->ctime = inode->i_ctime;