[PATCH 5.10 518/545] ext4: fix warning in ext4_iomap_begin as race between bmap and write

Greg Kroah-Hartman
2022-08-19T16:49:15Z

From: Ye Bin <yebin10@huawei.com>

commit 51ae846cff568c8c29921b1b28eb2dfbcd4ac12d upstream.

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
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/ext4/inode.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)

--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3219,13 +3219,15 @@ static sector_t ext4_bmap(struct address
{
struct inode *inode = mapping->host;
journal_t *journal;
+ sector_t ret = 0;
int err;

+ inode_lock_shared(inode);
/*
* We can get here for an inline file via the FIBMAP ioctl
*/
if (ext4_has_inline_data(inode))
- return 0;
+ goto out;

if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY) &&
test_opt(inode->i_sb, DELALLOC)) {
@@ -3264,10 +3266,14 @@ static sector_t ext4_bmap(struct address
jbd2_journal_unlock_updates(journal);

if (err)
- return 0;
+ goto out;
}

- return iomap_bmap(mapping, block, &ext4_iomap_ops);
+ ret = iomap_bmap(mapping, block, &ext4_iomap_ops);
+
+out:
+ inode_unlock_shared(inode);
+ return ret;
}

static int ext4_readpage(struct file *file, struct page *page)