UBUNTU: SAUCE: ceph: make sure all the files successfully put before …

…unmounting

BugLink: https://bugs.launchpad.net/bugs/2032959

When close a file it will be deferred to call the fput(), which
will hold the inode's i_count. And when unmounting the mountpoint
the evict_inodes() may skip evicting some inodes.

If encrypt is enabled the kernel generate a warning when removing
the encrypt keys when the skipped inodes still hold the keyring:

WARNING: CPU: 4 PID: 168846 at fs/crypto/keyring.c:242 fscrypt_destroy_keyring+0x7e/0xd0
CPU: 4 PID: 168846 Comm: umount Tainted: G S  6.1.0-rc5-ceph-g72ead199864c #1
Hardware name: Supermicro SYS-5018R-WR/X10SRW-F, BIOS 2.0 12/17/2015
RIP: 0010:fscrypt_destroy_keyring+0x7e/0xd0
RSP: 0018:ffffc9000b277e28 EFLAGS: 00010202
RAX: 0000000000000002 RBX: ffff88810d52ac00 RCX: ffff88810b56aa00
RDX: 0000000080000000 RSI: ffffffff822f3a09 RDI: ffff888108f59000
RBP: ffff8881d394fb88 R08: 0000000000000028 R09: 0000000000000000
R10: 0000000000000001 R11: 11ff4fe6834fcd91 R12: ffff8881d394fc40
R13: ffff888108f59000 R14: ffff8881d394f800 R15: 0000000000000000
FS:  00007fd83f6f1080(0000) GS:ffff88885fd00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f918d417000 CR3: 000000017f89a005 CR4: 00000000003706e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
generic_shutdown_super+0x47/0x120
kill_anon_super+0x14/0x30
ceph_kill_sb+0x36/0x90 [ceph]
deactivate_locked_super+0x29/0x60
cleanup_mnt+0xb8/0x140
task_work_run+0x67/0xb0
exit_to_user_mode_prepare+0x23d/0x240
syscall_exit_to_user_mode+0x25/0x60
do_syscall_64+0x40/0x80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fd83dc39e9b

URL: https://tracker.ceph.com/issues/58126
Signed-off-by: Xiubo Li <xiubli@redhat.com>
(cherry picked from https://github.com/ceph/ceph-client.git)
Signed-off-by: Andrea Righi <andrea.righi@canonical.com>

fs/crypto/keyring.c

@@ -237,7 +237,11 @@ void fscrypt_destroy_keyring(struct super_block *sb)
 			 * with ->mk_secret.  There should be no structural refs
 			 * beyond the one associated with the active ref.
 			 */
-			WARN_ON_ONCE(refcount_read(&mk->mk_active_refs) != 1);
+			if (refcount_read(&mk->mk_active_refs) != 1) {
+				printk("fscrypt_destroy_keyring: mk_active_refs = %d\n",
+				       refcount_read(&mk->mk_active_refs));
+				WARN_ON_ONCE(refcount_read(&mk->mk_active_refs) != 1);
+			}
 			WARN_ON_ONCE(refcount_read(&mk->mk_struct_refs) != 1);
 			WARN_ON_ONCE(!is_master_key_secret_present(&mk->mk_secret));
 			wipe_master_key_secret(&mk->mk_secret);

fs/inode.c

@@ -716,8 +716,11 @@ void evict_inodes(struct super_block *sb)
 again:
 	spin_lock(&sb->s_inode_list_lock);
 	list_for_each_entry_safe(inode, next, &sb->s_inodes, i_sb_list) {
-		if (atomic_read(&inode->i_count))
+		if (atomic_read(&inode->i_count)) {
+			printk("evict_inodes inode %p, i_count = %d, was skipped!\n",
+			       inode, atomic_read(&inode->i_count));
 			continue;
+		}
 
 		spin_lock(&inode->i_lock);
 		if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) {