Nikolay Borisov 9e78c0e742 btrfs: Correctly handle empty trees in find_first_clear_extent_bit ... commit 5750c37523 upstream. 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: 45bfcfc168 ("btrfs: Implement find_first_clear_extent_bit") CC: stable@vger.kernel.org # 5.2+ Signed-off-by: Nikolay Borisov <nborisov@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2020-02-11 04:35:34 -08:00
..
btrfs-tests.c	Btrfs: fix race between adding and putting tree mod seq elements and nodes	2020-02-11 04:35:34 -08:00
btrfs-tests.h	btrfs: tests: add table of most common errors	2019-04-29 19:02:25 +02:00
extent-buffer-tests.c	btrfs: tests: use standard error message after path allocation failure	2019-04-29 19:02:26 +02:00
extent-io-tests.c	btrfs: Correctly handle empty trees in find_first_clear_extent_bit	2020-02-11 04:35:34 -08:00
extent-map-tests.c	btrfs: tests: add locks around add_extent_mapping	2019-07-01 13:35:03 +02:00
free-space-tests.c	btrfs: move basic block_group definitions to their own header	2019-09-09 14:59:03 +02:00
free-space-tree-tests.c	btrfs: return error pointer from alloc_test_extent_buffer	2019-12-31 16:41:57 +01:00
inode-tests.c	btrfs: stop clearing EXTENT_DIRTY in inode I/O tree	2019-09-09 14:59:17 +02:00
qgroup-tests.c	btrfs: return error pointer from alloc_test_extent_buffer	2019-12-31 16:41:57 +01:00