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9.4.14

940014

05-12-2023

[LU-6297] Move rename is_subdir check from MDD to MDT https://jira.whamcloud.com/browse/LU-6297 Lustre <p>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.</p> LU-6297

Move rename is_subdir check from MDD to MDT

Bug Minor Open Unresolved Lai Siyao Di Wang dne2 dne3 Thu, 26 Feb 2015 04:11:00 +0000 Tue, 18 Oct 2022 17:44:56 +0000 Lustre 2.8.0 0 2 <p>can you please describe the exact sequence?</p> <p>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</p> <div class="preformatted panel" style="border-width: 1px;"><div class="preformattedContent panelContent"> <pre> 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); </pre> </div></div> <p>hmm, seems for old fid as well</p> <div class="preformatted panel" style="border-width: 1px;"><div class="preformattedContent panelContent"> <pre> 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); </pre> </div></div> <p>This is not urgent, but probably need it for final racer pass. Please only work on it if you have extra time. Thanks</p> <p>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?</p> Related LU-11104 LU-3534 LU-6831 Development Rank 1|hzx767: Rank (Obsolete) 17632 Severity