ping ? On 8/20/2021 12:45 PM, Hou Tao wrote: > Now EXT4_FC_TAG_ADD_RANGE uses ext4_extent to track the > newly-added blocks, but the limit on the max value of > ee_len field is ignored, and it can lead to BUG_ON as > shown below when running command "fallocate -l 128M file" > on a fast_commit-enabled fs: > > kernel BUG at fs/ext4/ext4_extents.h:199! > invalid opcode: 0000 [#1] SMP PTI > CPU: 3 PID: 624 Comm: fallocate Not tainted 5.14.0-rc6+ #1 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996) > RIP: 0010:ext4_fc_write_inode_data+0x1f3/0x200 > Call Trace: > ? ext4_fc_write_inode+0xf2/0x150 > ext4_fc_commit+0x93b/0xa00 > ? ext4_fallocate+0x1ad/0x10d0 > ext4_sync_file+0x157/0x340 > ? ext4_sync_file+0x157/0x340 > vfs_fsync_range+0x49/0x80 > do_fsync+0x3d/0x70 > __x64_sys_fsync+0x14/0x20 > do_syscall_64+0x3b/0xc0 > entry_SYSCALL_64_after_hwframe+0x44/0xae > > Simply fixing it by limiting the number of blocks > in one EXT4_FC_TAG_ADD_RANGE TLV. > > Fixes: aa75f4d3daae ("ext4: main fast-commit commit path") > Signed-off-by: Hou Tao <houtao1@xxxxxxxxxx> > --- > fs/ext4/fast_commit.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/fs/ext4/fast_commit.c b/fs/ext4/fast_commit.c > index e8195229c252..782d05a3f97a 100644 > --- a/fs/ext4/fast_commit.c > +++ b/fs/ext4/fast_commit.c > @@ -893,6 +893,12 @@ static int ext4_fc_write_inode_data(struct inode *inode, u32 *crc) > sizeof(lrange), (u8 *)&lrange, crc)) > return -ENOSPC; > } else { > + unsigned int max = (map.m_flags & EXT4_MAP_UNWRITTEN) ? > + EXT_UNWRITTEN_MAX_LEN : EXT_INIT_MAX_LEN; > + > + /* Limit the number of blocks in one extent */ > + map.m_len = min(max, map.m_len); > + > fc_ext.fc_ino = cpu_to_le32(inode->i_ino); > ex = (struct ext4_extent *)&fc_ext.fc_ex; > ex->ee_block = cpu_to_le32(map.m_lblk);