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Fedora and LVMFedora and LVMPosted Nov 1, 2012 21:06 UTC (Thu) by agk (guest, #23332)In reply to: Fedora and LVM by mezcalero Parent article: Fedora and LVM
> The fact that the LVM/dm userspace bits heavily rely on stuff such as sysv semaphores
Semaphores are used only by the LVM/dm code for synchronisation with the udev rules that have to handle asynchronous uevents.
On a system using udev, after LVM/dm creates a device (or group of related devices) it needs to wait until udev has finished setting up those particular devices before it continues. This is done by having the last udev rule decrement a (per-transaction) semaphore to zero, which the blocked LVM/dm code waits for.
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Fedora and LVM Posted Nov 2, 2012 2:17 UTC (Fri) by mezcalero (subscriber, #45103) [Link]
There is no excuse for every using SysV semaphores, unless you are living in the 80s. There are a multitude of alternatives around. But SysV semphores, na, thank you.
Also, LVM could just subscribe to udev devices coming and going with libudev like everyvody else, and things would be good...
Fedora and LVM Posted Nov 2, 2012 3:58 UTC (Fri) by agk (guest, #23332) [Link]
> LVM could just subscribe to udev devices coming and going with libudev
If only! We had lengthy discussions with the udev developers which led to the existing synchronisation mechanism.
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