xfs: don't leak perag when growfs fails

Offering: HULK
hulk inclusion
category: bugfix
bugzilla: 188878, https://gitee.com/openeuler/kernel/issues/I76JSK

--------------------------------

During growfs, if new ag in memory has been initialized, however sb_agcount
has not been updated, if an error occurs at this time it will cause ag
leaks as follows, these new ags will not been freed during umount because
of sb_agcount is not been updated.

unreferenced object 0xffff88810751b000 (size 1024):
  comm "xfs_growfs", pid 123624, jiffies 4300733989 (age 124294.081s)
  hex dump (first 32 bytes):
    00 a0 38 16 81 88 ff ff 05 00 00 00 00 00 00 00  ..8.............
    00 00 00 01 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<00000000725c8ae4>] kmem_alloc+0x92/0x1d0 [xfs]
    [<000000005c32d74e>] xfs_initialize_perag+0x8d/0x3b0 [xfs]
    [<00000000830354cf>] xfs_growfs_data_private.isra.0+0x2af/0x610 [xfs]
    [<0000000038a29cb1>] xfs_growfs_data+0x228/0x300 [xfs]
    [<0000000004937dd2>] xfs_file_ioctl+0x8f3/0x10d0 [xfs]
    [<000000001a5d29a8>] __se_sys_ioctl+0xeb/0x120
    [<00000000cf30385a>] do_syscall_64+0x30/0x40
    [<00000000e4a6fd2f>] entry_SYSCALL_64_after_hwframe+0x61/0xc6

When growfs fails, use xfs_destroy_perag() to destroy newly initialized ag
in error handle path.
Signed-off-by: NLong Li <leo.lilong@huawei.com>
(cherry picked from commit 670cd2c8)

fs/xfs/xfs_fsops.c

@@ -72,7 +72,7 @@ xfs_growfs_data_private(
 	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_growdata,
 			XFS_GROWFS_SPACE_RES(mp), 0, XFS_TRANS_RESERVE, &tp);
 	if (error)
-		return error;
+		goto destroy_perag;
 
 	/*
 	 * Write new AG headers to disk. Non-transactional, but need to be
@@ -163,6 +163,9 @@ xfs_growfs_data_private(
 
 out_trans_cancel:
 	xfs_trans_cancel(tp);
+destroy_perag:
+	if (nagcount > oagcount)
+		xfs_destroy_perag(mp, oagcount, nagcount);
 	return error;
 }
 

fs/xfs/xfs_mount.h

@@ -564,6 +564,8 @@ extern void	xfs_uuid_table_free(void);
 extern int	xfs_log_sbcount(xfs_mount_t *);
 extern uint64_t xfs_default_resblks(xfs_mount_t *mp);
 extern int	xfs_mountfs(xfs_mount_t *mp);
+extern void	xfs_destroy_perag(xfs_mount_t *mp, xfs_agnumber_t agstart,
+				xfs_agnumber_t agend);
 extern int	xfs_initialize_perag(xfs_mount_t *mp, xfs_agnumber_t agcount,
 				     xfs_agnumber_t *maxagi);
 extern void	xfs_unmountfs(xfs_mount_t *);