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| author | Ye Bin <yebin10@huawei.com> | 2023-08-15 13:26:11 +0200 |
|---|---|---|
| committer | Jan Kara <jack@suse.cz> | 2023-08-16 17:47:37 +0200 |
| commit | 83f99de1b7c0dcfa42b211e5e40334b7ad786b36 (patch) | |
| tree | ad5c3108ae0bdcb3a86743837f7c7959d84ed8a8 /fs/ext2/xattr.c | |
| parent | ext2: introduce new flags argument for ext2_new_blocks() (diff) | |
| download | linux-83f99de1b7c0dcfa42b211e5e40334b7ad786b36.tar.xz linux-83f99de1b7c0dcfa42b211e5e40334b7ad786b36.zip | |
ext2: fix race between setxattr and write back
There's an issue when allocating xattrs 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 doesn't allocate new blocks so for these cases we may
be allocating blocks during writeback. However, there is no protection
between ext2_xattr_set() and do_writepages() so these two functions can
conflict on handling the reservation window. To solve about issue don't
use the reservation window when allocating block for xattr.
Signed-off-by: Ye Bin <yebin10@huawei.com>
Message-Id: <20230815112612.221145-4-yebin10@huawei.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Diffstat (limited to '')
| -rw-r--r-- | fs/ext2/xattr.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/fs/ext2/xattr.c b/fs/ext2/xattr.c index 3b4ff6974ab8..b7c64fc1c008 100644 --- a/fs/ext2/xattr.c +++ b/fs/ext2/xattr.c @@ -744,7 +744,8 @@ ext2_xattr_set2(struct inode *inode, struct buffer_head *old_bh, EXT2_I(inode)->i_block_group); unsigned long count = 1; ext2_fsblk_t block = ext2_new_blocks(inode, goal, - &count, &error, 0); + &count, &error, + EXT2_ALLOC_NORESERVE); if (error) goto cleanup; ea_idebug(inode, "creating block %lu", block); |