If an image file is actually a block device taking a lock on it doesn't
really make sense for us: it will interfere with udev's block device
probing logic, and it's not going to propagated across the network
anyway (which is what we are after here). Hence simply don't do it.
Follow-up for 2aaf565a2d
We currently call this ioctl even if we are backed by a regular file,
which is actually the common case. While this doesn't really hurt, it
does result in very confusing logs.
This adds support for dm integrity targets and an associated
/etc/integritytab file which is required as the dm integrity device
super block doesn't include all of the required metadata to bring up
the device correctly. See integritytab man page for details.
Let's define two helpers strdupa_safe() + strndupa_safe() which do the
same as their non-safe counterparts, except that they abort if called
with allocations larger than ALLOCA_MAX.
This should ensure that all our alloca() based allocations are subject
to this limit.
afaics glibc offers three alloca() based APIs: alloca() itself,
strndupa() + strdupa(). With this we have now replacements for all of
them, that take the limit into account.
This is like alloca(), but does two things:
1. Verifies the allocation is smaller than ALLOCA_MAX
2. Ensures we allocate at least one byte
This was previously done manually in all invocations. This adds a handy
helper that does that implicitly.
