From: Qu Wenruo wqu@suse.com
commit 917ac77846b907dfdbd878688a9a61236ad6c51e upstream.
[BUG] Test case btrfs/027 would crash with subpage (64K page size, 4K sectorsize) with the following dying messages:
debug: map_length=16384 length=65536 type=metadata|raid6(0x104) assertion failed: map_length >= length, in fs/btrfs/volumes.c:8093 ------------[ cut here ]------------ kernel BUG at fs/btrfs/messages.c:259! Hardware name: QEMU KVM Virtual Machine, BIOS 0.0.0 02/06/2015 Call trace: btrfs_assertfail+0x28/0x2c [btrfs] btrfs_map_repair_block+0x150/0x2b8 [btrfs] btrfs_repair_io_failure+0xd4/0x31c [btrfs] btrfs_read_extent_buffer+0x150/0x16c [btrfs] read_tree_block+0x38/0xbc [btrfs] read_tree_root_path+0xfc/0x1bc [btrfs] btrfs_get_root_ref.part.0+0xd4/0x3a8 [btrfs] open_ctree+0xa30/0x172c [btrfs] btrfs_mount_root+0x3c4/0x4a4 [btrfs] legacy_get_tree+0x30/0x60 vfs_get_tree+0x28/0xec vfs_kern_mount.part.0+0x90/0xd4 vfs_kern_mount+0x14/0x28 btrfs_mount+0x114/0x418 [btrfs] legacy_get_tree+0x30/0x60 vfs_get_tree+0x28/0xec path_mount+0x3e0/0xb64 __arm64_sys_mount+0x200/0x2d8 invoke_syscall+0x48/0x114 el0_svc_common.constprop.0+0x60/0x11c do_el0_svc+0x38/0x98 el0_svc+0x40/0xa8 el0t_64_sync_handler+0xf4/0x120 el0t_64_sync+0x190/0x194 Code: aa0403e2 b0fff060 91010000 959c2024 (d4210000)
[CAUSE] In btrfs/027 we test RAID6 with missing devices, in this particular case, we're repairing a metadata at the end of a data stripe.
But at btrfs_repair_io_failure(), we always pass a full PAGE for repair, and for subpage case this can cross stripe boundary and lead to the above BUG_ON().
This metadata repair code is always there, since the introduction of subpage support, but this can trigger BUG_ON() after the bio split ability at btrfs_map_bio().
[FIX] Instead of passing the old PAGE_SIZE, we calculate the correct length based on the eb size and page size for both regular and subpage cases.
CC: stable@vger.kernel.org # 6.3+ Reviewed-by: Christoph Hellwig hch@lst.de Signed-off-by: Qu Wenruo wqu@suse.com Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/btrfs/disk-io.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 2b1b227505f3..88e6d1072a35 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -242,7 +242,6 @@ static int btrfs_repair_eb_io_failure(const struct extent_buffer *eb, int mirror_num) { struct btrfs_fs_info *fs_info = eb->fs_info; - u64 start = eb->start; int i, num_pages = num_extent_pages(eb); int ret = 0;
@@ -251,12 +250,14 @@ static int btrfs_repair_eb_io_failure(const struct extent_buffer *eb,
for (i = 0; i < num_pages; i++) { struct page *p = eb->pages[i]; + u64 start = max_t(u64, eb->start, page_offset(p)); + u64 end = min_t(u64, eb->start + eb->len, page_offset(p) + PAGE_SIZE); + u32 len = end - start;
- ret = btrfs_repair_io_failure(fs_info, 0, start, PAGE_SIZE, - start, p, start - page_offset(p), mirror_num); + ret = btrfs_repair_io_failure(fs_info, 0, start, len, + start, p, offset_in_page(start), mirror_num); if (ret) break; - start += PAGE_SIZE; }
return ret;