Messages in this thread | | | From | John Ogness <> | Subject | Re: [RFC PATCH v2] fs/namespace: use percpu_rw_semaphore for writer holding | Date | Mon, 20 Jul 2020 17:41:01 +0206 |
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On 2020-07-19, Al Viro <viro@zeniv.linux.org.uk> wrote: >> The MNT_WRITE_HOLD flag is used to manually implement a rwsem. > > Could you show me where does it currently sleep? Your version does, > unless I'm misreading it...
You are reading it correctly. This patch introduces new possible sleeping for__mnt_want_write() when writers for a superblock are being held.
The RFCv1 [0] is a variant that does not introduce sleeping, but instead reverts back to per-cpu spinlocks.
Sebastian and I are requesting comments on these two possible solutions. Or perhaps you have an idea how to solve the potential live lock situation.
John Ogness
[0] https://lkml.kernel.org/r/20200617104058.14902-2-john.ogness@linutronix.de
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