There's a issue as follows:
Block Allocation Reservation Windows Map (ext2_try_to_allocate_with_rsv):
reservation window 0x000000006f105382 start: 0, end: 0
reservation window 0x000000008fd1a555 start: 1044, end: 1059
Window map complete.
kernel BUG at fs/ext2/balloc.c:1158!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
RIP: 0010:ext2_try_to_allocate_with_rsv.isra.0+0x15c4/0x1800
Call Trace:
<TASK>
ext2_new_blocks+0x935/0x1690
ext2_new_block+0x73/0xa0
ext2_xattr_set2+0x74f/0x1730
ext2_xattr_set+0x12b6/0x2260
ext2_xattr_user_set+0x9c/0x110
__vfs_setxattr+0x139/0x1d0
__vfs_setxattr_noperm+0xfc/0x370
__vfs_setxattr_locked+0x205/0x2c0
vfs_setxattr+0x19d/0x3b0
do_setxattr+0xff/0x220
setxattr+0x123/0x150
path_setxattr+0x193/0x1e0
__x64_sys_setxattr+0xc8/0x170
do_syscall_64+0x35/0x80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
Above issue may happens as follows:
setxattr write back
ext2_xattr_set
ext2_xattr_set2
ext2_new_block
ext2_new_blocks
ext2_try_to_allocate_with_rsv
alloc_new_reservation
--> group=0 [0, 1023] rsv [1016, 1023]
do_writepages
mpage_writepages
write_cache_pages
__mpage_writepage
ext2_get_block
ext2_get_blocks
ext2_alloc_branch
ext2_new_blocks
ext2_try_to_allocate_with_rsv
alloc_new_reservation
-->group=1 [1024, 2047] rsv [1044, 1059]
if ((my_rsv->rsv_start > group_last_block) ||
(my_rsv->rsv_end < group_first_block)
rsv_window_dump
BUG();
Now ext2 mkwrite delay allocate new blocks. So there maybe allocate blocks when
do write back. However, there is no concurrent protection between
ext2_xattr_set() and do_writepages().
To solve about issue hold '&ei->truncate_mutex' lock when new block for xattr.
Signed-off-by: Ye Bin <[email protected]>
---
fs/ext2/balloc.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/fs/ext2/balloc.c b/fs/ext2/balloc.c
index c8049c90323d..039f655febfd 100644
--- a/fs/ext2/balloc.c
+++ b/fs/ext2/balloc.c
@@ -1432,8 +1432,14 @@ ext2_fsblk_t ext2_new_blocks(struct inode *inode, ext2_fsblk_t goal,
ext2_fsblk_t ext2_new_block(struct inode *inode, unsigned long goal, int *errp)
{
unsigned long count = 1;
+ struct ext2_inode_info *ei = EXT2_I(inode);
+ ext2_fsblk_t ret;
+
+ mutex_lock(&ei->truncate_mutex);
+ ret = ext2_new_blocks(inode, goal, &count, errp);
+ mutex_unlock(&ei->truncate_mutex);
- return ext2_new_blocks(inode, goal, &count, errp);
+ return ret;
}
#ifdef EXT2FS_DEBUG
--
2.31.1
On Fri 11-08-23 11:38:56, Ye Bin wrote:
> There's a issue as follows:
> Block Allocation Reservation Windows Map (ext2_try_to_allocate_with_rsv):
> reservation window 0x000000006f105382 start: 0, end: 0
> reservation window 0x000000008fd1a555 start: 1044, end: 1059
> Window map complete.
> kernel BUG at fs/ext2/balloc.c:1158!
> invalid opcode: 0000 [#1] PREEMPT SMP KASAN
> RIP: 0010:ext2_try_to_allocate_with_rsv.isra.0+0x15c4/0x1800
> Call Trace:
> <TASK>
> ext2_new_blocks+0x935/0x1690
> ext2_new_block+0x73/0xa0
> ext2_xattr_set2+0x74f/0x1730
> ext2_xattr_set+0x12b6/0x2260
> ext2_xattr_user_set+0x9c/0x110
> __vfs_setxattr+0x139/0x1d0
> __vfs_setxattr_noperm+0xfc/0x370
> __vfs_setxattr_locked+0x205/0x2c0
> vfs_setxattr+0x19d/0x3b0
> do_setxattr+0xff/0x220
> setxattr+0x123/0x150
> path_setxattr+0x193/0x1e0
> __x64_sys_setxattr+0xc8/0x170
> do_syscall_64+0x35/0x80
> entry_SYSCALL_64_after_hwframe+0x63/0xcd
>
> Above issue may happens as follows:
> setxattr write back
> ext2_xattr_set
> ext2_xattr_set2
> ext2_new_block
> ext2_new_blocks
> ext2_try_to_allocate_with_rsv
> alloc_new_reservation
> --> group=0 [0, 1023] rsv [1016, 1023]
> do_writepages
> mpage_writepages
> write_cache_pages
> __mpage_writepage
> ext2_get_block
> ext2_get_blocks
> ext2_alloc_branch
> ext2_new_blocks
> ext2_try_to_allocate_with_rsv
> alloc_new_reservation
> -->group=1 [1024, 2047] rsv [1044, 1059]
> if ((my_rsv->rsv_start > group_last_block) ||
> (my_rsv->rsv_end < group_first_block)
> rsv_window_dump
> BUG();
> Now ext2 mkwrite delay allocate new blocks. So there maybe allocate blocks when
> do write back. However, there is no concurrent protection between
> ext2_xattr_set() and do_writepages().
> To solve about issue hold '&ei->truncate_mutex' lock when new block for xattr.
>
> Signed-off-by: Ye Bin <[email protected]>
Thanks for the patch! I agree the handling of reservation window and its
use for block allocation needs to be protected by ei->i_truncate_mutex.
However in this particular case of xattr allocation where we want to
allocate just one block which is completely independent of file data, I'd
rather choose to make ext2_new_blocks() ignore the reservation window (set
my_rsv to NULL). There's already a logic at the beginning of
ext2_new_blocks() deciding whether to use the reservation window or not and
we could extend it - probably by adding flags argument to it a introducing
a NORESERVE flag.
Also as a preparatory patch, I'd just remove ext2_new_block() and opencode
it in the xattr code since it has only that one user anyway.
Honza
> ---
> fs/ext2/balloc.c | 8 +++++++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/fs/ext2/balloc.c b/fs/ext2/balloc.c
> index c8049c90323d..039f655febfd 100644
> --- a/fs/ext2/balloc.c
> +++ b/fs/ext2/balloc.c
> @@ -1432,8 +1432,14 @@ ext2_fsblk_t ext2_new_blocks(struct inode *inode, ext2_fsblk_t goal,
> ext2_fsblk_t ext2_new_block(struct inode *inode, unsigned long goal, int *errp)
> {
> unsigned long count = 1;
> + struct ext2_inode_info *ei = EXT2_I(inode);
> + ext2_fsblk_t ret;
> +
> + mutex_lock(&ei->truncate_mutex);
> + ret = ext2_new_blocks(inode, goal, &count, errp);
> + mutex_unlock(&ei->truncate_mutex);
>
> - return ext2_new_blocks(inode, goal, &count, errp);
> + return ret;
> }
>
> #ifdef EXT2FS_DEBUG
> --
> 2.31.1
>
--
Jan Kara <[email protected]>
SUSE Labs, CR
On 2023/8/14 20:46, Jan Kara wrote:
> On Fri 11-08-23 11:38:56, Ye Bin wrote:
>> There's a issue as follows:
>> Block Allocation Reservation Windows Map (ext2_try_to_allocate_with_rsv):
>> reservation window 0x000000006f105382 start: 0, end: 0
>> reservation window 0x000000008fd1a555 start: 1044, end: 1059
>> Window map complete.
>> kernel BUG at fs/ext2/balloc.c:1158!
>> invalid opcode: 0000 [#1] PREEMPT SMP KASAN
>> RIP: 0010:ext2_try_to_allocate_with_rsv.isra.0+0x15c4/0x1800
>> Call Trace:
>> <TASK>
>> ext2_new_blocks+0x935/0x1690
>> ext2_new_block+0x73/0xa0
>> ext2_xattr_set2+0x74f/0x1730
>> ext2_xattr_set+0x12b6/0x2260
>> ext2_xattr_user_set+0x9c/0x110
>> __vfs_setxattr+0x139/0x1d0
>> __vfs_setxattr_noperm+0xfc/0x370
>> __vfs_setxattr_locked+0x205/0x2c0
>> vfs_setxattr+0x19d/0x3b0
>> do_setxattr+0xff/0x220
>> setxattr+0x123/0x150
>> path_setxattr+0x193/0x1e0
>> __x64_sys_setxattr+0xc8/0x170
>> do_syscall_64+0x35/0x80
>> entry_SYSCALL_64_after_hwframe+0x63/0xcd
>>
>> Above issue may happens as follows:
>> setxattr write back
>> ext2_xattr_set
>> ext2_xattr_set2
>> ext2_new_block
>> ext2_new_blocks
>> ext2_try_to_allocate_with_rsv
>> alloc_new_reservation
>> --> group=0 [0, 1023] rsv [1016, 1023]
>> do_writepages
>> mpage_writepages
>> write_cache_pages
>> __mpage_writepage
>> ext2_get_block
>> ext2_get_blocks
>> ext2_alloc_branch
>> ext2_new_blocks
>> ext2_try_to_allocate_with_rsv
>> alloc_new_reservation
>> -->group=1 [1024, 2047] rsv [1044, 1059]
>> if ((my_rsv->rsv_start > group_last_block) ||
>> (my_rsv->rsv_end < group_first_block)
>> rsv_window_dump
>> BUG();
>> Now ext2 mkwrite delay allocate new blocks. So there maybe allocate blocks when
>> do write back. However, there is no concurrent protection between
>> ext2_xattr_set() and do_writepages().
>> To solve about issue hold '&ei->truncate_mutex' lock when new block for xattr.
>>
>> Signed-off-by: Ye Bin <[email protected]>
> Thanks for the patch! I agree the handling of reservation window and its
> use for block allocation needs to be protected by ei->i_truncate_mutex.
> However in this particular case of xattr allocation where we want to
> allocate just one block which is completely independent of file data, I'd
> rather choose to make ext2_new_blocks() ignore the reservation window (set
> my_rsv to NULL). There's already a logic at the beginning of
> ext2_new_blocks() deciding whether to use the reservation window or not and
> we could extend it - probably by adding flags argument to it a introducing
> a NORESERVE flag.
>
> Also as a preparatory patch, I'd just remove ext2_new_block() and opencode
> it in the xattr code since it has only that one user anyway.
>
> Honza
>
Thanks for your suggestion. I will send new version according to your
suggestion.
>
>> ---
>> fs/ext2/balloc.c | 8 +++++++-
>> 1 file changed, 7 insertions(+), 1 deletion(-)
>>
>> diff --git a/fs/ext2/balloc.c b/fs/ext2/balloc.c
>> index c8049c90323d..039f655febfd 100644
>> --- a/fs/ext2/balloc.c
>> +++ b/fs/ext2/balloc.c
>> @@ -1432,8 +1432,14 @@ ext2_fsblk_t ext2_new_blocks(struct inode *inode, ext2_fsblk_t goal,
>> ext2_fsblk_t ext2_new_block(struct inode *inode, unsigned long goal, int *errp)
>> {
>> unsigned long count = 1;
>> + struct ext2_inode_info *ei = EXT2_I(inode);
>> + ext2_fsblk_t ret;
>> +
>> + mutex_lock(&ei->truncate_mutex);
>> + ret = ext2_new_blocks(inode, goal, &count, errp);
>> + mutex_unlock(&ei->truncate_mutex);
>>
>> - return ext2_new_blocks(inode, goal, &count, errp);
>> + return ret;
>> }
>>
>> #ifdef EXT2FS_DEBUG
>> --
>> 2.31.1
>>