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Recent kernels allow messages to respond with a string.
Add dm_task_get_message_response() to libdevmapper to perform some
basic sanity checks and return this.
Have 'dmsetup message' display any response.
DM statistics will make extensive use of this.
(From Mikulas.)
On each ioctl return, the device UUID is decoded from \xNN format.
If the UUID of the device being *removed* is malformed (e.g. it
hasn't been corrected before), just remove it without any error
as the UUID is not needed anymore - the device is gone anyway.
Otherwise a misleading error message would be issued just after
the removal:
# dmsetup remove test
The UUID "a b" should be mangled but it contains blacklisted characters.
Command failed
Just like we already have existing mangling support for
device-mapper names, we need exactly the same for device-mapper
UUIDs as their character whitelist is wider than what udev supports.
In case udev is used to create entries in /dev based on UUIDs
and these UUIDs contain characters not supported by udev,
we'll end up with incorrect /dev content for such devices.
So we need to mangle them to a form that is supported by udev.
The mangling used for UUIDs follows the mangling used for names
(that is already supported and used throughout). That means,
setting the name mangling mode via dm_set_name_mangling_mode
affects mangling used for UUIDs in exactly the same manner.
It would be useless to add a new and separate
dm_set_uuid_mangling_mode fn, we'll reuse existing interface.
(un)mangle_name -> (un)mangle_string
check_multiple_mangled_name_allowed -> check_multiple_mangled_string_allowed
Just for clarity as the same functions will be reused to (un)mangle dm UUIDs.
Auto mode can't deal with multiple mangled names. We can do that while working
in hex mode, but in auto mode, this would lead to device name ambiguity.
Be more strict when unmangling names on ioctl return - require the name to be
properly mangled in 'auto' and 'hex' mode. There really should not be any
blacklisted character since the names should be renamed already (by means of
renaming it directly or running 'dmsetup mangle' for automatic rename).
Since lvm seems to call driver_version(NULL, 0) this would lead
to crash. Though the combination of the code is probably very hard to hit.
If the user doesn't supply version buffer, just skip printing to buffer.
Device-mapper in kernel uses '\' as escape character so it's better
to double it to avoid any confusion when using existing device names
with '\' in the table specification.
For example:
dmsetup create x --table "0 8 linear /dev/mapper/a\x20b 0"
should pass just fine now without a need to explicitly escape the '\' char
like this:
dmsetup create x --table "0 8 linear /dev/mapper/a\\x20b 0"
If dm_task_get_name or dm_task_get_names gets called, these will return
unmangled form of the names so the name mangling stays totally transparent
to any libdevmapper user (unless DM_STRING_MANGLING_NONE is used in which
case the name is not touched and it is is returned as it is in kernel).
For example:
dmsetup create "a b" - will create a\x20b device in kernel and so udev will
create /dev/mapper/a\x20b
dm_task_get_name/names will still return "a b"
In AUTO mode, the libdevmapper user can still query the device by using
the mangled ("a\x20b") or unmangled form of the name when calling dm_task_set_name.
If mangled name is provided, it's detected and the name is kept as it is.
If unmangled name is provided, it will be mangled. IOW in AUTO mode it's
totally transparent and it should not require any changes in the code
using libdevmapper.
However, any libdevmapper user must be aware of the fact that the mangled form
of the name appears in /dev/mapper (udev just can't deal with those blacklisted
characters).
Use the DEV_NAME macro to use the mangled form of the name if present,
use normal name otherwise (we store both forms - mangled and unmangled in
struct dm_task). Mangled form should be always preferred over unmangled
with the exception of the situations where we divide one task into several
others (like "create and load") - we need to avoid mangling the name twice
(because of multiple dm_task_set_name calls)!
If dm_task_set_name/newname is called, the name provided will be
automatically translated to correct encoded form with the hex enconding
so any character not on udev whitelist will be mangled with \xNN
format where NN is hex value of the character used.
By default, the name mangling mode used is the one set during
configure with the '--with-default-name-mangling' option.
Since the function dm_get_next_target() returns NULL as 'next' pointer
so it's not a 'real' error - set 0 to all parameters when NULL is
returned because of missing head.
i.e. one of use case::
do {
next = dm_get_next_target(dmt, next, &start, &length,
&target_type, ¶ms);
size += length;
} while (next);
If we know major:minor number of device (which is known after resume) we will
try to use sysfs to set/get read ahead parameters of device.
This avoid potential problem of blocking commands like 'dmsetup info' awaiting
for device being usable for open/close - i.e. overfilled thin pool may block
such command.
RAID is not like traditional LVM mirroring. LVM mirroring required failed
devices to be removed or the logical volume would simply hang. RAID arrays can
keep on running with failed devices. In fact, for RAID types other than RAID1,
removing a device would mean substituting an error target or converting to a
lower level RAID (e.g. RAID6 -> RAID5, or RAID4/5 to RAID0). Therefore, rather
than removing a failed device unconditionally and potentially allocating a
replacement, RAID allows the user to "replace" a device with a new one. This
approach is a 1-step solution vs the current 2-step solution.
example> lvconvert --replace <dev_to_remove> vg/lv [possible_replacement_PVs]
'--replace' can be specified more than once.
example> lvconvert --replace /dev/sdb1 --replace /dev/sdc1 vg/lv
Avoid creation of target type name when it's longer then
DM_MAX_TYPE_NAME (noticed by static analyzer where the
sp.target_type might be missing '\0' at the end.)
Before patch:
$> dmsetup create long
0 1000 looooooooooooooooooooooooooong
^D
device-mapper: reload ioctl failed: Invalid argument
After patch:
$> dmsetup create xxx
0 1000 looooooooooooooooooooooooooong
Target type name looooooooooooooooooooooooooong is too long.
Command failed
Certain errno codes could be expected in some situations thus
add experimental support for them.
When expected errno is set after ioctl error - function skips error
printing and exits succefully.
Currently only useful for thin pool messages.
This is a workaround for long-lasting problem with using the WATCH udev
rule. When trying to remove a DM device, this one can still be opened
while processing the event in parallel (generated based on the WATCH
udev rule).
Let's use this until we have a proper solution.
