On Mon, Jan 27, 2020 at 11:59:26AM +0200, Nikolay Borisov wrote: > Raviu reported that running his regular fs_trim segfaulted with the > following backtrace: > > [ 237.525947] assertion failed: prev, in ../fs/btrfs/extent_io.c:1595 > [ 237.525984] ------------[ cut here ]------------ > [ 237.525985] kernel BUG at ../fs/btrfs/ctree.h:3117! > [ 237.525992] invalid opcode: 0000 [#1] SMP PTI > [ 237.525998] CPU: 4 PID: 4423 Comm: fstrim Tainted: G U OE 5.4.14-8-vanilla #1 > [ 237.526001] Hardware name: ASUSTeK COMPUTER INC. > [ 237.526044] RIP: 0010:assfail.constprop.58+0x18/0x1a [btrfs] > [ 237.526079] Call Trace: > [ 237.526120] find_first_clear_extent_bit+0x13d/0x150 [btrfs] > [ 237.526148] btrfs_trim_fs+0x211/0x3f0 [btrfs] > [ 237.526184] btrfs_ioctl_fitrim+0x103/0x170 [btrfs] > [ 237.526219] btrfs_ioctl+0x129a/0x2ed0 [btrfs] > [ 237.526227] ? filemap_map_pages+0x190/0x3d0 > [ 237.526232] ? do_filp_open+0xaf/0x110 > [ 237.526238] ? _copy_to_user+0x22/0x30 > [ 237.526242] ? cp_new_stat+0x150/0x180 > [ 237.526247] ? do_vfs_ioctl+0xa4/0x640 > [ 237.526278] ? btrfs_ioctl_get_supported_features+0x30/0x30 [btrfs] > [ 237.526283] do_vfs_ioctl+0xa4/0x640 > [ 237.526288] ? __do_sys_newfstat+0x3c/0x60 > [ 237.526292] ksys_ioctl+0x70/0x80 > [ 237.526297] __x64_sys_ioctl+0x16/0x20 > [ 237.526303] do_syscall_64+0x5a/0x1c0 > [ 237.526310] entry_SYSCALL_64_after_hwframe+0x49/0xbe > > That was due to btrfs_fs_device::aloc_tree being empty. Initially I > thought this wasn't possible and as a percaution have put the assert in > find_first_clear_extent_bit. Turns out this is indeed possible and could > happen when a file system with SINGLE data/metadata profile has a 2nd > device added. Until balance is run or a new chunk is allocated on this > device it will be completely empty. > > In this case find_first_clear_extent_bit should return the full range > [0, -1ULL] and let the caller handle this i.e for trim the end will be > capped at the size of actual device. > > Link: https://lore.kernel.org/linux-btrfs/izW2WNyvy1dEDweBICizKnd2KDwDiDyY2EYQr4YCwk7pkuIpthx-JRn65MPBde00ND6V0_Lh8mW0kZwzDiLDv25pUYWxkskWNJnVP0kgdMA=@protonmail.com/ > Fixes: 45bfcfc168f8 ("btrfs: Implement find_first_clear_extent_bit") > Signed-off-by: Nikolay Borisov <nborisov@xxxxxxxx> Added to misc-next with the goto fixed, thanks. > David can you try and squeeze this into 5.5? It only leads to an assertion > failure trigger (if assertion Yes, 2nd pull or some post rc1 pull.
