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Date: Tue, 26 Apr 2022 22:06:58 +0800
From: Baokun Li <libaokun1@...wei.com>
To: <linux-ext4@...r.kernel.org>
CC: <tytso@....edu>, <adilger.kernel@...ger.ca>, <jack@...e.cz>,
<linux-kernel@...r.kernel.org>, <yi.zhang@...wei.com>,
<yebin10@...wei.com>, <yukuai3@...wei.com>, <libaokun1@...wei.com>,
<stable@...r.kernel.org>, Hulk Robot <hulkci@...wei.com>
Subject: [PATCH v2] ext4: fix race condition between ext4_write and ext4_convert_inline_data
Hulk Robot reported a BUG_ON:
==================================================================
EXT4-fs error (device loop3): ext4_mb_generate_buddy:805: group 0,
block bitmap and bg descriptor inconsistent: 25 vs 31513 free clusters
kernel BUG at fs/ext4/ext4_jbd2.c:53!
invalid opcode: 0000 [#1] SMP KASAN PTI
CPU: 0 PID: 25371 Comm: syz-executor.3 Not tainted 5.10.0+ #1
RIP: 0010:ext4_put_nojournal fs/ext4/ext4_jbd2.c:53 [inline]
RIP: 0010:__ext4_journal_stop+0x10e/0x110 fs/ext4/ext4_jbd2.c:116
[...]
Call Trace:
ext4_write_inline_data_end+0x59a/0x730 fs/ext4/inline.c:795
generic_perform_write+0x279/0x3c0 mm/filemap.c:3344
ext4_buffered_write_iter+0x2e3/0x3d0 fs/ext4/file.c:270
ext4_file_write_iter+0x30a/0x11c0 fs/ext4/file.c:520
do_iter_readv_writev+0x339/0x3c0 fs/read_write.c:732
do_iter_write+0x107/0x430 fs/read_write.c:861
vfs_writev fs/read_write.c:934 [inline]
do_pwritev+0x1e5/0x380 fs/read_write.c:1031
[...]
==================================================================
Above issue may happen as follows:
cpu1 cpu2
__________________________|__________________________
do_pwritev
vfs_writev
do_iter_write
ext4_file_write_iter
ext4_buffered_write_iter
generic_perform_write
ext4_da_write_begin
vfs_fallocate
ext4_fallocate
ext4_convert_inline_data
ext4_convert_inline_data_nolock
ext4_destroy_inline_data_nolock
clear EXT4_STATE_MAY_INLINE_DATA
ext4_map_blocks
ext4_ext_map_blocks
ext4_mb_new_blocks
ext4_mb_regular_allocator
ext4_mb_good_group_nolock
ext4_mb_init_group
ext4_mb_init_cache
ext4_mb_generate_buddy --> error
ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA)
ext4_restore_inline_data
set EXT4_STATE_MAY_INLINE_DATA
ext4_block_write_begin
ext4_da_write_end
ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA)
ext4_write_inline_data_end
handle=NULL
ext4_journal_stop(handle)
__ext4_journal_stop
ext4_put_nojournal(handle)
ref_cnt = (unsigned long)handle
BUG_ON(ref_cnt == 0) ---> BUG_ON
The lock held by ext4_convert_inline_data is xattr_sem, but the lock
held by generic_perform_write is i_rwsem. Therefore, the two locks can
be concurrent. To solve above issue, we just add inode_lock in
ext4_convert_inline_data.
Fixes: 0c8d414f163f ("ext4: let fallocate handle inline data correctly")
Cc: stable@...r.kernel.org
Reported-by: Hulk Robot <hulkci@...wei.com>
Signed-off-by: Baokun Li <libaokun1@...wei.com>
---
V1->V2:
Increase the range of the inode_lock.
fs/ext4/inline.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c
index 9c076262770d..0518edcfc0e1 100644
--- a/fs/ext4/inline.c
+++ b/fs/ext4/inline.c
@@ -2002,6 +2002,7 @@ int ext4_convert_inline_data(struct inode *inode)
handle_t *handle;
struct ext4_iloc iloc;
+ inode_lock(inode);
if (!ext4_has_inline_data(inode)) {
ext4_clear_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA);
return 0;
@@ -2024,6 +2025,7 @@ int ext4_convert_inline_data(struct inode *inode)
if (ext4_has_inline_data(inode))
error = ext4_convert_inline_data_nolock(handle, inode, &iloc);
ext4_write_unlock_xattr(inode, &no_expand);
+ inode_unlock(inode);
ext4_journal_stop(handle);
out_free:
brelse(iloc.bh);
--
2.31.1
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