ext4: fix warning in ext4_iomap_begin as race between bmap and write

In the Linux kernel, the following vulnerability has been resolved:

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.