ext4: fix warning in ext4_iomap_begin as race between bmap and write
authorYe Bin <yebin10@huawei.com>
Fri, 17 Jun 2022 01:39:35 +0000 (09:39 +0800)
committerTheodore Ts'o <tytso@mit.edu>
Wed, 3 Aug 2022 03:56:02 +0000 (23:56 -0400)
commit51ae846cff568c8c29921b1b28eb2dfbcd4ac12d
tree906a0cbaf34b1b0c5dfc9f18533ea1588aaffb6e
parentfd7e672ea98b95b9d4c9dae316639f03c16a749d
ext4: fix warning in ext4_iomap_begin as race between bmap and write

We got issue as follows:
------------[ cut here ]------------
WARNING: CPU: 3 PID: 9310 at fs/ext4/inode.c:3441 ext4_iomap_begin+0x182/0x5d0
RIP: 0010:ext4_iomap_begin+0x182/0x5d0
RSP: 0018:ffff88812460fa08 EFLAGS: 00010293
RAX: ffff88811f168000 RBX: 0000000000000000 RCX: ffffffff97793c12
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: ffff88812c669160 R08: ffff88811f168000 R09: ffffed10258cd20f
R10: ffff88812c669077 R11: ffffed10258cd20e R12: 0000000000000001
R13: 00000000000000a4 R14: 000000000000000c R15: ffff88812c6691ee
FS:  00007fd0d6ff3740(0000) GS:ffff8883af180000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fd0d6dda290 CR3: 0000000104a62000 CR4: 00000000000006e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 iomap_apply+0x119/0x570
 iomap_bmap+0x124/0x150
 ext4_bmap+0x14f/0x250
 bmap+0x55/0x80
 do_vfs_ioctl+0x952/0xbd0
 __x64_sys_ioctl+0xc6/0x170
 do_syscall_64+0x33/0x40
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Above issue may happen as follows:
          bmap                    write
bmap
  ext4_bmap
    iomap_bmap
      ext4_iomap_begin
                            ext4_file_write_iter
      ext4_buffered_write_iter
        generic_perform_write
  ext4_da_write_begin
    ext4_da_write_inline_data_begin
      ext4_prepare_inline_data
        ext4_create_inline_data
  ext4_set_inode_flag(inode,
EXT4_INODE_INLINE_DATA);
      if (WARN_ON_ONCE(ext4_has_inline_data(inode))) ->trigger bug_on

To solved above issue hold inode lock in ext4_bamp.

Signed-off-by: Ye Bin <yebin10@huawei.com>
Link: https://lore.kernel.org/r/20220617013935.397596-1-yebin10@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org
fs/ext4/inode.c