dm-verity needs to access data blocks by virtual address in three
different cases (zeroization, recheck, and forward error correction),
and one more case (shash support) is coming. Since it's guaranteed that
dm-verity data blocks never cross pages, and kmap_local_page and
kunmap_local are no-ops on modern platforms anyway, just unconditionally
"map" every data block's page and work with the virtual buffer directly.
This simplifies the code and eliminates unnecessary overhead.
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
commit df7b59ba92 ("dm verity: fix FEC for RS roots unaligned to
block size") introduced the possibility for misaligned roots IO
relative to the underlying device's logical block size. E.g. Android's
default RS roots=2 results in dm_bufio->block_size=1024, which causes
the following EIO if the logical block size of the device is 4096,
given v->data_dev_block_bits=12:
E sd 0 : 0:0:0: [sda] tag#30 request not aligned to the logical block size
E blk_update_request: I/O error, dev sda, sector 10368424 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0
E device-mapper: verity-fec: 254:8: FEC 9244672: parity read failed (block 18056): -5
Fix this by onlu using f->roots for dm_bufio blocksize IFF it is
aligned to v->data_dev_block_bits.
Fixes: df7b59ba92 ("dm verity: fix FEC for RS roots unaligned to block size")
Cc: stable@vger.kernel.org
Signed-off-by: Jaegeuk Kim <jaegeuk@google.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Based on 1 normalized pattern(s):
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-or-later
has been chosen to replace the boilerplate/reference in 3029 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Convert dm to embedded bio sets.
Acked-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
If the hash tree itself is sufficiently corrupt in addition to data blocks,
it's possible for error correction to end up in a deep recursive loop,
which eventually causes a kernel panic. This change limits the
recursion to a reasonable level during a single I/O operation.
Fixes: a739ff3f54 ("dm verity: add support for forward error correction")
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org # v4.5+
Add support for correcting corrupted blocks using Reed-Solomon.
This code uses RS(255, N) interleaved across data and hash
blocks. Each error-correcting block covers N bytes evenly
distributed across the combined total data, so that each byte is a
maximum distance away from the others. This makes it possible to
recover from several consecutive corrupted blocks with relatively
small space overhead.
In addition, using verity hashes to locate erasures nearly doubles
the effectiveness of error correction. Being able to detect
corrupted blocks also improves performance, because only corrupted
blocks need to corrected.
For a 2 GiB partition, RS(255, 253) (two parity bytes for each
253-byte block) can correct up to 16 MiB of consecutive corrupted
blocks if erasures can be located, and 8 MiB if they cannot, with
16 MiB space overhead.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
