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authorNikolay Borisov <nborisov@suse.com>2020-01-27 12:59:26 +0300
committerDavid Sterba <dsterba@suse.com>2020-01-31 16:01:29 +0300
commit5750c37523a2c8cbb450b9ef31e21c2ba876b05e (patch)
tree4e23463e1ff13a95ab832e3d81d73af496d448a9 /fs/btrfs/tests/extent-io-tests.c
parent42ffb0bf584ae5b6b38f72259af1e0ee417ac77f (diff)
downloadlinux-5750c37523a2c8cbb450b9ef31e21c2ba876b05e.tar.xz
btrfs: Correctly handle empty trees in find_first_clear_extent_bit
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") CC: stable@vger.kernel.org # 5.2+ Signed-off-by: Nikolay Borisov <nborisov@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs/tests/extent-io-tests.c')
-rw-r--r--fs/btrfs/tests/extent-io-tests.c9
1 files changed, 9 insertions, 0 deletions
diff --git a/fs/btrfs/tests/extent-io-tests.c b/fs/btrfs/tests/extent-io-tests.c
index 123d9a614357..df7ce874a74b 100644
--- a/fs/btrfs/tests/extent-io-tests.c
+++ b/fs/btrfs/tests/extent-io-tests.c
@@ -441,8 +441,17 @@ static int test_find_first_clear_extent_bit(void)
int ret = -EINVAL;
test_msg("running find_first_clear_extent_bit test");
+
extent_io_tree_init(NULL, &tree, IO_TREE_SELFTEST, NULL);
+ /* Test correct handling of empty tree */
+ find_first_clear_extent_bit(&tree, 0, &start, &end, CHUNK_TRIMMED);
+ if (start != 0 || end != -1) {
+ test_err(
+ "error getting a range from completely empty tree: start %llu end %llu",
+ start, end);
+ goto out;
+ }
/*
* Set 1M-4M alloc/discard and 32M-64M thus leaving a hole between
* 4M-32M