But the directories are changed from /dev/loop/by-ref/ -> /dev/disk/by-loop-ref/
and /dev/loop/by-inode/ -> /dev/disk/by-loop-inode/.
As /dev/loop/ is used by losetup command for other purpose.
See issue #28475.
This effectively reverts commits 9915cc6086,
5022fab15f, and
c0d998248e.
We use usec_t for storing time value, which is 64bit.
However, usleep() takes useconds_t that is (typically?) 32bit.
Also, usleep() may only support the range [0, 1000000].
This introduce usleep_safe() which takes usec_t.
The kernel may be syncing a file system or doing something else that requires
more time. So make the delay a bit longer, but provide some feedback and also
grow the delay exponentially (though with a long exponent). If the kernel is
doing something else, no need to repeat so often. With 38 attempts, we get a
total of slightly above 5000 ms.
I wrote this when I thought that the the delay is not long enough. It turned
out that we were blocking the file system on the loop device, so waiting longer
wasn't helpful. But I think it's nicer to do it this way anyway.
On top of taking a directory file descriptor, we use xopenat() so
that the function can also be used to work on existing file
descriptors to image files including all the logic to use O_DIRECT
and fallback to O_RDONLY if needed.
-1 was used everywhere, but -EBADF or -EBADFD started being used in various
places. Let's make things consistent in the new style.
Note that there are two candidates:
EBADF 9 Bad file descriptor
EBADFD 77 File descriptor in bad state
Since we're initializating the fd, we're just assigning a value that means
"no fd yet", so it's just a bad file descriptor, and the first errno fits
better. If instead we had a valid file descriptor that became invalid because
of some operation or state change, the other errno would fit better.
In some places, initialization is dropped if unnecessary.
flock(2) works with file descriptors opened with O_RDONLY.
This affects SELinux systems where access to block devices is quite
restricted to avoid bypasses on filesystem objects.
Then, this makes loop_device_open_from_fd() or _from_path() be wrappers
of loop_device_open() with block_device_new_from_fd() or _from_path(),
respectively.
When LOOP_CONFIGURE fail, then it is not necessary to call it on any
later call of loop_configure(). Let's save the flag in a static variable
in the function.
This also fixes a leak of lock_fd, which introduced by
7f52206a2b, when fd is for a block device,
and size or offset is non-zero.
Fixes another issue in #24147.
This mirrors what we already do during allocation. We lock the control
device first, and then release the block device and then delete it.
This makes things substantially more robust as long all participants do
such locking: we won't attempt to delete a block device somebody else
already is using.
Back when I wrote this code I wasn't aware of BLKPG and what it can do.
Hence I came up with this hack to attach an empty file to delete all
partitions. But today we can do better with BLKPG: let's just explicitly
remove all partitions, and then try again.
Yu Watanabe
Daan De Meyer
Zbigniew Jędrzejewski-Szmek
Lennart Poettering
David Tardon
Christian Göttsche
Aidan Dang