LU-6794 nfs: ASSERTION( atomic_read(&d->ld_ref) == 0 ) failed

ll_iget_for_nfs() can call unbalanced iput() causing memory
leaks. This patch removes this iput() call.

Also, avoid unhashing disconnected dentries in
d_lustre_invalidate(), which is another source of memory
leaks.

One of the symptoms of the leak is the following crash pattern:
<0>LustreError: 14812:0:(lu_object.c:1251:lu_device_fini())
ASSERTION( atomic_read(&d->ld_ref) == 0 ) failed: Refcount is 1
<0>LustreError: 14812:0:(lu_object.c:1251:lu_device_fini()) LBUG
<4>Pid: 14812, comm: umount
<4>
<4>Call Trace:
<4> [<ffffffffa11bc895>] libcfs_debug_dumpstack+0x55/0x80 [libcfs]
<4> [<ffffffffa11bce97>] lbug_with_loc+0x47/0xb0 [libcfs]
<4> [<ffffffffa1458a48>] lu_device_fini+0xb8/0xc0 [obdclass]
<4> [<ffffffffa08e9ab2>] lovsub_device_free+0x52/0x220 [lov]
<4> [<ffffffffa145c64e>] lu_stack_fini+0x7e/0xc0 [obdclass]
<4> [<ffffffffa146356e>] cl_stack_fini+0xe/0x10 [obdclass]
<4> [<ffffffffa08bc1a8>] lov_device_fini+0x58/0x120 [lov]
<4> [<ffffffffa145c619>] lu_stack_fini+0x49/0xc0 [obdclass]
<4> [<ffffffffa146356e>] cl_stack_fini+0xe/0x10 [obdclass]
<4> [<ffffffffa0e1279d>] cl_sb_fini+0x6d/0x190 [lustre]
<4> [<ffffffffa0dd34bc>] ll_put_super+0x1bc/0x11e0 [lustre]
<4> [<ffffffff811cd0f2>] ? fsnotify_clear_marks_by_inode+0x32/0xf0
<4> [<ffffffff811a59df>] ? destroy_inode+0x2f/0x60
<4> [<ffffffff811a5eac>] ? dispose_list+0xfc/0x120
<4> [<ffffffff811a62a6>] ? invalidate_inodes+0xf6/0x190
<4> [<ffffffff8118b35b>] generic_shutdown_super+0x5b/0xe0
<4> [<ffffffff8118b446>] kill_anon_super+0x16/0x60
<4> [<ffffffffa144e7ba>] lustre_kill_super+0x4a/0x60 [obdclass]
<4> [<ffffffff8118bbe7>] deactivate_super+0x57/0x80
<4> [<ffffffff811aabef>] mntput_no_expire+0xbf/0x110
<4> [<ffffffff811ab73b>] sys_umount+0x7b/0x3a0
<4> [<ffffffff8100b072>] system_call_fastpath+0x16/0x1b

Xyratex-bug-id: MRP-2414
Signed-off-by: Andrew Perepechko <andrew.perepechko@seagate.com>
Change-Id: Ie8bc428014f3897dc108568f55db9a9ed93c932b
Reviewed-on: http://review.whamcloud.com/15480
Tested-by: Jenkins
Reviewed-by: Lai Siyao <lai.siyao@intel.com>
Reviewed-by: Bobi Jam <bobijam@hotmail.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>

diff --git a/lustre/llite/llite_internal.h b/lustre/llite/llite_internal.h
index 3d06c68..c393a38 100644 (file)
--- a/lustre/llite/llite_internal.h
+++ b/lustre/llite/llite_internal.h
@@ -1462,7 +1462,15 @@ static inline void d_lustre_invalidate(struct dentry *dentry, int nested)
        spin_lock_nested(&dentry->d_lock,
                         nested ? DENTRY_D_LOCK_NESTED : DENTRY_D_LOCK_NORMAL);
        __d_lustre_invalidate(dentry);
-       if (ll_d_count(dentry) == 0)
+       /*
+        * We should be careful about dentries created by d_obtain_alias().
+        * These dentries are not put in the dentry tree, instead they are
+        * linked to sb->s_anon through dentry->d_hash.
+        * shrink_dcache_for_umount() shrinks the tree and sb->s_anon list.
+        * If we unhashed such a dentry, unmount would not be able to find
+        * it and busy inodes would be reported.
+        */
+       if (ll_d_count(dentry) == 0 && !(dentry->d_flags & DCACHE_DISCONNECTED))
                __d_drop(dentry);
        spin_unlock(&dentry->d_lock);
 }

diff --git a/lustre/llite/llite_nfs.c b/lustre/llite/llite_nfs.c
index 38e2726..9e19e78 100644 (file)
--- a/lustre/llite/llite_nfs.c
+++ b/lustre/llite/llite_nfs.c
@@ -135,13 +135,10 @@ ll_iget_for_nfs(struct super_block *sb, struct lu_fid *fid, struct lu_fid *paren
                 RETURN(ERR_PTR(-ESTALE));
         }
 
+       /* N.B. d_obtain_alias() drops inode ref on error */
        result = d_obtain_alias(inode);
-       if (IS_ERR(result)) {
-               iput(inode);
-               RETURN(result);
-       }
 
-        RETURN(result);
+       RETURN(result);
 }
 
 #ifndef FILEID_INVALID