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bhyve: [snapshot] Do not flush readonly device at blockif_pause()
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Authored by gusev.vitaliy_gmail.com on Mar 2 2023, 6:08 PM.
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Details

Summary

Part of Capsicum integration for snapshots.

Eliminates error:

blockif_pause: [WARN] failed to flush backing file.

Sponsored by: vStack

Test Plan

Compile, run VM, suspend/resume.

Diff Detail

Repository
rG FreeBSD src repository
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Event Timeline

markj added inline comments.
usr.sbin/bhyve/block_if.c
1012

BTW, the BOP_FLUSH handler does not check whether the device is read-only before calling blockif_flush_bc(). Perhaps it should be a no-op in that situation?

This revision is now accepted and ready to land.Mar 2 2023, 9:55 PM
gusev.vitaliy_gmail.com added inline comments.
usr.sbin/bhyve/block_if.c
1012

BOP_FLUSH() is called when emulated device directly calls blockif_flush(). Look at ahci_handle_flush() and nvme_opc_flush()) or pci_vtblk_proc().
In all cases it is just handle of guest's requests. So guest is aware about readonly device and shouldn't call flush commands.