Fix a race between inline data destruction and block mapping.

The function ext4_destroy_inline_data_nolock() changes the inode data layout by clearing EXT4_INODE_INLINE_DATA and setting EXT4_INODE_EXTENTS. At the same time, another thread may execute ext4_map_blocks(), which tests EXT4_INODE_EXTENTS to decide whether to call ext4_ext_map_blocks() or ext4_ind_map_blocks().

Without i_data_sem protection, ext4_ind_map_blocks() may receive inode with EXT4_INODE_EXTENTS flag and triggering assert.

kernel BUG at fs/ext4/indirect.c:546! EXT4-fs (loop2): unmounting filesystem. invalid opcode: 0000 [#1] PREEMPT SMP KASAN NOPTI Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 RIP: 0010:ext4_ind_map_blocks.cold+0x2b/0x5a fs/ext4/indirect.c:546

Call Trace: <TASK> ext4_map_blocks+0xb9b/0x16f0 fs/ext4/inode.c:681 _ext4_get_block+0x242/0x590 fs/ext4/inode.c:822 ext4_block_write_begin+0x48b/0x12c0 fs/ext4/inode.c:1124 ext4_write_begin+0x598/0xef0 fs/ext4/inode.c:1255 ext4_da_write_begin+0x21e/0x9c0 fs/ext4/inode.c:3000 generic_perform_write+0x259/0x5d0 mm/filemap.c:3846 ext4_buffered_write_iter+0x15b/0x470 fs/ext4/file.c:285 ext4_file_write_iter+0x8e0/0x17f0 fs/ext4/file.c:679 call_write_iter include/linux/fs.h:2271 [inline] do_iter_readv_writev+0x212/0x3c0 fs/read_write.c:735 do_iter_write+0x186/0x710 fs/read_write.c:861 vfs_iter_write+0x70/0xa0 fs/read_write.c:902 iter_file_splice_write+0x73b/0xc90 fs/splice.c:685 do_splice_from fs/splice.c:763 [inline] direct_splice_actor+0x10f/0x170 fs/splice.c:950 splice_direct_to_actor+0x33a/0xa10 fs/splice.c:896 do_splice_direct+0x1a9/0x280 fs/splice.c:1002 do_sendfile+0xb13/0x12c0 fs/read_write.c:1255 __do_sys_sendfile64 fs/read_write.c:1323 [inline] __se_sys_sendfile64 fs/read_write.c:1309 [inline] __x64_sys_sendfile64+0x1cf/0x210 fs/read_write.c:1309 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x35/0x80 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x6e/0xd8

Fixes: c755e251357a ("ext4: fix deadlock between inline_data and ext4_expand_extra_isize_ea()") Cc: stable@vger.kernel.org # v4.11+ Signed-off-by: Alexey Nepomnyashih sdl@nppct.ru --- fs/ext4/inline.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c index 1b094a4f3866..ef7821f7fd26 100644 --- a/fs/ext4/inline.c +++ b/fs/ext4/inline.c @@ -446,9 +446,13 @@ static int ext4_destroy_inline_data_nolock(handle_t *handle, if (!ei->i_inline_off) return 0;

+ down_write(&ei->i_data_sem); + error = ext4_get_inode_loc(inode, &is.iloc); - if (error) + if (error) { + up_write(&ei->i_data_sem); return error; + }

error = ext4_xattr_ibody_find(inode, &i, &is); if (error) @@ -487,6 +491,7 @@ static int ext4_destroy_inline_data_nolock(handle_t *handle, brelse(is.iloc.bh); if (error == -ENODATA) error = 0; + up_write(&ei->i_data_sem); return error; }