3.16.47-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Eric Biggers <ebiggers@xxxxxxxxxx> commit 7b4cc9787fe35b3ee2dfb1c35e22eafc32e00c33 upstream. Currently the case of writing via mmap to a file with inline data is not handled. This is maybe a rare case since it requires a writable memory map of a very small file, but it is trivial to trigger with on inline_data filesystem, and it causes the 'BUG_ON(ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA));' in ext4_writepages() to be hit: mkfs.ext4 -O inline_data /dev/vdb mount /dev/vdb /mnt xfs_io -f /mnt/file \ -c 'pwrite 0 1' \ -c 'mmap -w 0 1m' \ -c 'mwrite 0 1' \ -c 'fsync' kernel BUG at fs/ext4/inode.c:2723! invalid opcode: 0000 [#1] SMP CPU: 1 PID: 2532 Comm: xfs_io Not tainted 4.11.0-rc1-xfstests-00301-g071d9acf3d1f #633 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-20170228_101828-anatol 04/01/2014 task: ffff88003d3a8040 task.stack: ffffc90000300000 RIP: 0010:ext4_writepages+0xc89/0xf8a RSP: 0018:ffffc90000303ca0 EFLAGS: 00010283 RAX: 0000028410000000 RBX: ffff8800383fa3b0 RCX: ffffffff812afcdc RDX: 00000a9d00000246 RSI: ffffffff81e660e0 RDI: 0000000000000246 RBP: ffffc90000303dc0 R08: 0000000000000002 R09: 869618e8f99b4fa5 R10: 00000000852287a2 R11: 00000000a03b49f4 R12: ffff88003808e698 R13: 0000000000000000 R14: 7fffffffffffffff R15: 7fffffffffffffff FS: 00007fd3e53094c0(0000) GS:ffff88003e400000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fd3e4c51000 CR3: 000000003d554000 CR4: 00000000003406e0 Call Trace: ? _raw_spin_unlock+0x27/0x2a ? kvm_clock_read+0x1e/0x20 do_writepages+0x23/0x2c ? do_writepages+0x23/0x2c __filemap_fdatawrite_range+0x80/0x87 filemap_write_and_wait_range+0x67/0x8c ext4_sync_file+0x20e/0x472 vfs_fsync_range+0x8e/0x9f ? syscall_trace_enter+0x25b/0x2d0 vfs_fsync+0x1c/0x1e do_fsync+0x31/0x4a SyS_fsync+0x10/0x14 do_syscall_64+0x69/0x131 entry_SYSCALL64_slow_path+0x25/0x25 We could try to be smart and keep the inline data in this case, or at least support delayed allocation when allocating the block, but these solutions would be more complicated and don't seem worthwhile given how rare this case seems to be. So just fix the bug by calling ext4_convert_inline_data() when we're asked to make a page writable, so that any inline data gets evicted, with the block allocated immediately. Reported-by: Nick Alcock <nick.alcock@xxxxxxxxxx> Reviewed-by: Andreas Dilger <adilger@xxxxxxxxx> Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx> Signed-off-by: Theodore Ts'o <tytso@xxxxxxx> [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx> --- fs/ext4/inode.c | 5 +++++ 1 file changed, 5 insertions(+) --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -5273,6 +5273,11 @@ int ext4_page_mkwrite(struct vm_area_str sb_start_pagefault(inode->i_sb); file_update_time(vma->vm_file); + + ret = ext4_convert_inline_data(inode); + if (ret) + goto out_ret; + /* Delalloc case is easy... */ if (test_opt(inode->i_sb, DELALLOC) && !ext4_should_journal_data(inode) &&