Minor Description
Move rename is_subdir check (mdo_is_subdir) from MDD to MDT to avoid duplicate lu object find for the same fid, which might cause lu_obect_find() hang.
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This is not urgent, but probably need it for final racer pass. Please only work on it if you have extra time. Thanks
hmm, seems for old fid as well
mold = mdt_object_find(info->mti_env, info->mti_mdt, old_fid);
if (IS_ERR(mold))
GOTO(out_unlock_parents, rc = PTR_ERR(mold));
/* Check if @mtgtdir is subdir of @mold, before locking child
* to avoid reverse locking. */
rc = mdt_is_subdir(info, mtgtdir, old_fid);
if (rc)
GOTO(out_put_old, rc);
oh, mostly this is because mdt_is_subdir is being called multiple times during rename, which can be avoided if we move subdir check to MDT. And also
mnew = mdt_object_find(info->mti_env, info->mti_mdt, new_fid);
if (IS_ERR(mnew))
GOTO(out_put_old, rc = PTR_ERR(mnew));
/* Before locking the target dir, check we do not replace
* a dir with a non-dir, otherwise it may deadlock with
* link op which tries to create a link in this dir
* back to this non-dir. */
if (S_ISDIR(lu_object_attr(&mnew->mot_obj)) &&
!S_ISDIR(lu_object_attr(&mold->mot_obj)))
GOTO(out_put_new, rc = -EISDIR);
lh_oldp = &info->mti_lh[MDT_LH_OLD];
mdt_lock_reg_init(lh_oldp, LCK_EX);
rc = mdt_object_lock(info, mold, lh_oldp, MDS_INODELOCK_LOOKUP |
MDS_INODELOCK_XATTR);
if (rc != 0)
GOTO(out_put_new, rc);
/* Check if @msrcdir is subdir of @mnew, before locking child
* to avoid reverse locking. */
rc = mdt_is_subdir(info, msrcdir, new_fid); <---- new obj might be found again here.
if (rc)
GOTO(out_unlock_old, rc);
well, if _is_subdir() is called with LDLM lock held and we checked the passed object does exists, then how deadlock is possible - all "parents" must exist by definition?