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When adding a device to the devices file with --adddev, lvm
by default chooses the best device ID type for the new device.
The new --deviceidtype option allows the user to override the
built in preference. This is useful if there's a problem with
the default type, or if a secondary type is preferrable.
If the specified deviceidtype does not produce a device ID,
then lvm falls back to the preference it would otherwise use.
error reading dev and no pvid on dev were both
returning 0. make it easier for callers to
know which, if they care.
return 1 if the device could be read, regardless
of whether a pvid was found or not.
set has_pvid=1 if a pvid is found and 0 if no
pvid is found.
This case happens when i.e. we convert LV to another type,
when we change existing LV into a different type - so change
to debug level and avoid confusing users with message about
Device path not match.
We may eventually enhnace caching code to drop cached info
after taking lock and reading VG.
With commit b44db5d1a7
needs to check allocated pointer for failed malloc().
Existing check was actually no checking anything so failing
malloc here would result in segfault (although with very
low chance to ever happen).
Use different 'hint' size for dm_hash_create() call - so
when debug info about hash is printed we can recognize which
hash was in use.
This patch doesn't change actual used size since that is always
rounded to be power of 2 and >=16 - so as such is only a
help to developer.
We could eventually use 'name' arg, but since this would have changed
API and this patchset will be routed to libdm & stable - we will
just use this small trick.
Use 'C' for alphasort - there is no need to use localized and slower
sorting for internal directory scanning.
Ensure on all code paths allocated dirent entries are released.
Optimize full path construction.
The LVM devices file lists devices that lvm can use. The default
file is /etc/lvm/devices/system.devices, and the lvmdevices(8)
command is used to add or remove device entries. If the file
does not exist, or if lvm.conf includes use_devicesfile=0, then
lvm will not use a devices file. When the devices file is in use,
the regex filter is not used, and the filter settings in lvm.conf
or on the command line are ignored.
LVM records devices in the devices file using hardware-specific
IDs, such as the WWID, and attempts to use subsystem-specific
IDs for virtual device types. These device IDs are also written
in the VG metadata. When no hardware or virtual ID is available,
lvm falls back using the unstable device name as the device ID.
When devnames are used, lvm performs extra scanning to find
devices if their devname changes, e.g. after reboot.
When proper device IDs are used, an lvm command will not look
at devices outside the devices file, but when devnames are used
as a fallback, lvm will scan devices outside the devices file
to locate PVs on renamed devices. A config setting
search_for_devnames can be used to control the scanning for
renamed devname entries.
Related to the devices file, the new command option
--devices <devnames> allows a list of devices to be specified for
the command to use, overriding the devices file. The listed
devices act as a sort of devices file in terms of limiting which
devices lvm will see and use. Devices that are not listed will
appear to be missing to the lvm command.
Multiple devices files can be kept in /etc/lvm/devices, which
allows lvm to be used with different sets of devices, e.g.
system devices do not need to be exposed to a specific application,
and the application can use lvm on its own set of devices that are
not exposed to the system. The option --devicesfile <filename> is
used to select the devices file to use with the command. Without
the option set, the default system devices file is used.
Setting --devicesfile "" causes lvm to not use a devices file.
An existing, empty devices file means lvm will see no devices.
The new command vgimportdevices adds PVs from a VG to the devices
file and updates the VG metadata to include the device IDs.
vgimportdevices -a will import all VGs into the system devices file.
LVM commands run by dmeventd not use a devices file by default,
and will look at all devices on the system. A devices file can
be created for dmeventd (/etc/lvm/devices/dmeventd.devices) If
this file exists, lvm commands run by dmeventd will use it.
Internal implementaion:
- device_ids_read - read the devices file
. add struct dev_use (du) to cmd->use_devices for each devices file entry
- dev_cache_scan - get /dev entries
. add struct device (dev) to dev_cache for each device on the system
- device_ids_match - match devices file entries to /dev entries
. match each du on cmd->use_devices to a dev in dev_cache, using device ID
. on match, set du->dev, dev->id, dev->flags MATCHED_USE_ID
- label_scan - read lvm headers and metadata from devices
. filters are applied, those that do not need data from the device
. filter-deviceid skips devs without MATCHED_USE_ID, i.e.
skips /dev entries that are not listed in the devices file
. read lvm label from dev
. filters are applied, those that use data from the device
. read lvm metadata from dev
. add info/vginfo structs for PVs/VGs (info is "lvmcache")
- device_ids_find_renamed_devs - handle devices with unstable devname ID
where devname changed
. this step only needed when devs do not have proper device IDs,
and their dev names change, e.g. after reboot sdb becomes sdc.
. detect incorrect match because PVID in the devices file entry
does not match the PVID found when the device was read above
. undo incorrect match between du and dev above
. search system devices for new location of PVID
. update devices file with new devnames for PVIDs on renamed devices
. label_scan the renamed devs
- continue with command processing
Since lvm2 normally block signals during protected
phase where it does not want to be interrupted.
Support interruptible processing when allowed
in section between sigint_allow() ... sigint_restore())
and let the 'io_getenvents()' finish with EINTR.
When bcache tries to write data to a faulty device,
it may get out of caching blocks and then just busy-loops
on a CPU - so this check protects this by checking
if there is already max_io (~64) errored blocks.
Call _wait_all() which does check whether there is still
some pending IO before sleep. Otherwise it may happen
our submitted IO operations have been already dispatched
and this call then endlessly waits for IO which are all done.
This can be reproduced when device returns quickly errors
on write requests.
Add a "device index" (di) for each device, and use this
in the bcache api to the rest of lvm. This replaces the
file descriptor (fd) in the api. The rest of lvm uses
new functions bcache_set_fd(), bcache_clear_fd(), and
bcache_change_fd() to control which fd bcache uses for
io to a particular device.
. lvm opens a dev and gets and fd.
fd = open(dev);
. lvm passes fd to the bcache layer and gets a di
to use in the bcache api for the dev.
di = bcache_set_fd(fd);
. lvm uses bcache functions, passing di for the dev.
bcache_write_bytes(di, ...), etc.
. bcache translates di to fd to do io.
. lvm closes the device and clears the di/fd bcache state.
close(fd);
bcache_clear_fd(di);
In the bcache layer, a di-to-fd translation table
(int *_fd_table) is added. When bcache needs to
perform io on a di, it uses _fd_table[di].
In the following commit, lvm will make use of the new
bcache_change_fd() function to change the fd that
bcache uses for the dev, without dropping cached blocks.
Switch remaining zero sized struct to flexible arrays to be C99
complient.
These simple rules should apply:
- The incomplete array type must be the last element within the structure.
- There cannot be an array of structures that contain a flexible array member.
- Structures that contain a flexible array member cannot be used as a member of another structure.
- The structure must contain at least one named member in addition to the flexible array member.
Although some of the code pieces should be still improved.
When initiated larger write request, it may have happened, bcache
got out of free chunks - fix the loop, that is supposed to wait
until next free chunk becomes avain available.
It's possible for a dev-cache entry to remain after all
paths for it have been removed, and other parts of the
code expect that a dev always has a name. A better fix
may be to remove a device from dev-cache after all paths
to it have been removed.
dm-integrity stores checksums of the data written to an
LV, and returns an error if data read from the LV does
not match the previously saved checksum. When used on
raid images, dm-raid will correct the error by reading
the block from another image, and the device user sees
no error. The integrity metadata (checksums) are stored
on an internal LV allocated by lvm for each linear image.
The internal LV is allocated on the same PV as the image.
Create a raid LV with an integrity layer over each
raid image (for raid levels 1,4,5,6,10):
lvcreate --type raidN --raidintegrity y [options]
Add an integrity layer to images of an existing raid LV:
lvconvert --raidintegrity y LV
Remove the integrity layer from images of a raid LV:
lvconvert --raidintegrity n LV
Settings
Use --raidintegritymode journal|bitmap (journal is default)
to configure the method used by dm-integrity to ensure
crash consistency.
Initialization
When integrity is added to an LV, the kernel needs to
initialize the integrity metadata/checksums for all blocks
in the LV. The data corruption checking performed by
dm-integrity will only operate on areas of the LV that
are already initialized. The progress of integrity
initialization is reported by the "syncpercent" LV
reporting field (and under the Cpy%Sync lvs column.)
Example: create a raid1 LV with integrity:
$ lvcreate --type raid1 -m1 --raidintegrity y -n rr -L1G foo
Creating integrity metadata LV rr_rimage_0_imeta with size 12.00 MiB.
Logical volume "rr_rimage_0_imeta" created.
Creating integrity metadata LV rr_rimage_1_imeta with size 12.00 MiB.
Logical volume "rr_rimage_1_imeta" created.
Logical volume "rr" created.
$ lvs -a foo
LV VG Attr LSize Origin Cpy%Sync
rr foo rwi-a-r--- 1.00g 4.93
[rr_rimage_0] foo gwi-aor--- 1.00g [rr_rimage_0_iorig] 41.02
[rr_rimage_0_imeta] foo ewi-ao---- 12.00m
[rr_rimage_0_iorig] foo -wi-ao---- 1.00g
[rr_rimage_1] foo gwi-aor--- 1.00g [rr_rimage_1_iorig] 39.45
[rr_rimage_1_imeta] foo ewi-ao---- 12.00m
[rr_rimage_1_iorig] foo -wi-ao---- 1.00g
[rr_rmeta_0] foo ewi-aor--- 4.00m
[rr_rmeta_1] foo ewi-aor--- 4.00m
Do this at two levels, although one would be enough to
fix the problem seen recently:
- Ignore any reported sector size other than 512 of 4096.
If either sector size (physical or logical) is reported
as 512, then use 512. If neither are reported as 512,
and one or the other is reported as 4096, then use 4096.
If neither is reported as either 512 or 4096, then use 512.
- When rounding up a limited write in bcache to be a multiple
of the sector size, check that the resulting write size is
not larger than the bcache block itself. (This shouldn't
happen if the sector size is 512 or 4096.)
An active md device with an end superblock causes lvm to
enable full md component detection. This was being done
within the filter loop instead of before, so the full
filtering of some devs could be missed.
Also incorporate the recently added config setting that
controls the md component detection.
If udev info is missing for a device, (which would indicate
if it's an MD component), then do an end-of-device read to
check if a PV is an MD component. (This is skipped when
using hints since we already know devs in hints are good.)
A new config setting md_component_checks can be used to
disable the additional end-of-device MD checks, or to
always enable end-of-device MD checks.
When both hints and udev info are disabled/unavailable,
the end of PVs will now be scanned by default. If md
devices with end-of-device superblocks are not being
used, the extra I/O overhead can be avoided by setting
md_component_checks="start".
udev_dev_is_md_component and udev_dev_is_mpath_component
are not used for obtaining the device list, but they still
use libudev for device info. When there are problems with
udev, these functions can get stuck. So, use the existing
obtain_device_list_from_udev config setting to also control
whether these "is component" functions are used, which gives
us a way to avoid using libudev entirely when it's causing
problems.
Save the list of PVs in /run/lvm/hints. These hints
are used to reduce scanning in a number of commands
to only the PVs on the system, or only the PVs in a
requested VG (rather than all devices on the system.)
Ensure configure.h is always 1st. included header.
Maybe we could eventually introduce gcc -include option, but for now
this better uses dependency tracking.
Also move _REENTRANT and _GNU_SOURCE into configure.h so it
doesn't need to be present in various source files.
This ensures consistent compilation of headers like stdio.h since
it may produce different declaration.
commit de28637
scan: use full md filter when md 1.0 devices are present
missed the fact that md superblock version 0.90 also puts
metadata at the end of the device, so the full md filter
needs to be used when either 0.90 or 1.0 is present.
fix lseek error check
fix read/write error checks
handle zero return from read and write
don't return an error for short io
fix partial read/write loop
io_setup() for aio may fail if a system has reached the
aio request limit. In this case, fall back to using
sync io. Also, lvm use of aio can be disabled entirely
with config setting global/use_aio=0.
The system limit for aio requests can be seen from
/proc/sys/fs/aio-max-nr
The current usage of aio requests can be seen from
/proc/sys/fs/aio-nr
The system limit for aio requests can be increased by
setting fs.aio-max-nr using sysctl.
Also add last-byte limit to the sync io code.
