User can write 'remove' and 're-add' to trigger array reconfiguration
through sysfs, suspend array in this case so that io won't concurrent
with array reconfiguration.
And now that all the caller of add_bound_rdev() alread suspend the
array, remove mddev_suspend/resume() from add_bound_rdev() as well.
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20231010151958.145896-12-yukuai1@huaweicloud.com
The new helpers suspend the array first and then lock the array,
Prepare to refactor from:
mddev_lock/lock_nointr
mddev_suspend
...
mddev_resuem
mddev_lock
With:
mddev_suspend_and_lock/lock_nointr
...
mddev_unlock_and_resume
After all the use cases is refactored, mddev_suspend/resume() will be
removed.
And mddev_suspend_and_lock() will also replace mddev_lock() for the case
that the array will be reconfigured, in order to synchronize with io to
prevent problems in many corner cases.
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20231010151958.145896-6-yukuai1@huaweicloud.com
Advantages for new apis:
- reconfig_mutex is not required;
- the weird logical that suspend array hold 'reconfig_mutex' for
mddev_check_recovery() to update superblock is not needed;
- the specail handling, 'pers->prepare_suspend', for raid456 is not
needed;
- It's safe to be called at any time once mddev is allocated, and it's
designed to be used from slow path where array configuration is changed;
- the new helpers is designed to be called before mddev_lock(), hence
it support to be interrupted by user as well.
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20231010151958.145896-5-yukuai1@huaweicloud.com
Prepare to cleanup pers->prepare_suspend(), which is used to fix a
deadlock in raid456 by returning error for io that is waiting for
reshape to make progress in mddev_suspend().
This change will allow reshape to make progress while waiting for io to
be done in mddev_suspend() in following patches.
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20231010151958.145896-4-yukuai1@huaweicloud.com
Before this patch, the implementation is hacky and hard to understand:
1) md_seq_start set pos to 1;
2) md_seq_show found pos is 1, then print Personalities;
3) md_seq_next found pos is 1, then it update pos to the first mddev;
4) md_seq_show found pos is not 1 or 2, show mddev;
5) md_seq_next found pos is not 1 or 2, update pos to next mddev;
6) loop 4-5 until the last mddev, then md_seq_next update pos to 2;
7) md_seq_show found pos is 2, then print unused devices;
8) md_seq_next found pos is 2, stop;
This patch remove the magic value and use seq_list_start/next/stop()
directly, and move printing "Personalities" to md_seq_start(),
"unsed devices" to md_seq_stop():
1) md_seq_start print Personalities, and then set pos to first mddev;
2) md_seq_show show mddev;
3) md_seq_next update pos to next mddev;
4) loop 2-3 until the last mddev;
5) md_seq_stop print unsed devices;
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20230927061241.1552837-3-yukuai1@huaweicloud.com
`strncpy` is deprecated for use on NUL-terminated destination strings
[1] and as such we should prefer more robust and less ambiguous string
interfaces.
There are three such strncpy uses that this patch addresses:
The respective destination buffers are:
1) mddev->clevel
2) clevel
3) mddev->metadata_type
We expect mddev->clevel to be NUL-terminated due to its use with format
strings:
| ret = sprintf(page, "%s\n", mddev->clevel);
Furthermore, we can see that mddev->clevel is not expected to be
NUL-padded as `md_clean()` merely set's its first byte to NULL -- not
the entire buffer:
| static void md_clean(struct mddev *mddev)
| {
| mddev->array_sectors = 0;
| mddev->external_size = 0;
| ...
| mddev->level = LEVEL_NONE;
| mddev->clevel[0] = 0;
| ...
A suitable replacement for this instance is `memcpy` as we know the
number of bytes to copy and perform manual NUL-termination at a
specified offset. This really decays to just a byte copy from one buffer
to another. `strscpy` is also a considerable replacement but using
`slen` as the length argument would result in truncation of the last
byte unless something like `slen + 1` was provided which isn't the most
idiomatic strscpy usage.
For the next case, the destination buffer `clevel` is expected to be
NUL-terminated based on its usage within kstrtol() which expects
NUL-terminated strings. Note that, in context, this code removes a
trailing newline which is seemingly not required as kstrtol() can handle
trailing newlines implicitly. However, there exists further usage of
clevel (or buf) that would also like to have the newline removed. All in
all, with similar reasoning to the first case, let's just use memcpy as
this is just a byte copy and NUL-termination is handled manually.
The third and final case concerning `mddev->metadata_type` is more or
less the same as the other two. We expect that it be NUL-terminated
based on its usage with seq_printf:
| seq_printf(seq, " super external:%s",
| mddev->metadata_type);
... and we can surmise that NUL-padding isn't required either due to how
it is handled in md_clean():
| static void md_clean(struct mddev *mddev)
| {
| ...
| mddev->metadata_type[0] = 0;
| ...
So really, all these instances have precisely calculated lengths and
purposeful NUL-termination so we can just use memcpy to remove ambiguity
surrounding strncpy.
Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Link: https://github.com/KSPP/linux/issues/90
Cc: linux-hardening@vger.kernel.org
Signed-off-by: Justin Stitt <justinstitt@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20230925-strncpy-drivers-md-md-c-v1-1-2b0093b89c2b@google.com
'active_io' used to be initialized while the array is running, and
'mddev->pers' is set while the array is running as well. Hence caller
must hold 'reconfig_mutex' and guarantee 'mddev->pers' is set before
calling mddev_suspend().
Now that 'active_io' is initialized when mddev is allocated, such
restriction doesn't exist anymore. In the meantime, follow up patches
will refactor mddev_suspend(), hence add checking for 'mddev->pers' to
prevent null-ptr-deref.
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20230825030956.1527023-4-yukuai1@huaweicloud.com
