On Thu, Nov 30, 2017 at 10:51:57PM +0100, Pavel Machek wrote: > Hi! > > > Proposed solution: > > > > Instead of fixing such semantics and trying to get all filesystems to do it > > right, we can easily do away with all freezing calls if the filesystem > > implements a proper freeze_fs() callback. The following 9 filesystems have > > freeze_fs() implemented as such we can let the kernel issue the callback upon > > suspend and thaw on resume automatically on our behalf. > > > > o xfs > > o reiserfs > > o nilfs2 > > o jfs > > o f2fs > > o ext4 > > o ext2 > > o btrfs > > > > Of these, the following have freezer helpers, which can then be removed > > after the kernel automaticaly calls freeze_fs for us on suspend: > > > > o xfs > > o nilfs2 > > o jfs > > o f2fs > > o ext4 > > > > I've tested this on a system with ext4 and XFS, and have let 0-day go at > > without issues. I have branches availabe for linux-next [3] and Linus' > > latest tree [4]. > > Was hibernation tested? uswsusp? I had not done a test before but I just did and it worked, in fact I was able to keep my ssh connection to my qemu guest after resume from hibernation with this. root@piggy:~# echo shutdown > /sys/power/disk; echo disk > /sys/power/state [ 87.930446] PM: hibernation entry [ 87.936294] firmware_class: device_cache_fw_images [ 87.936363] PM: Syncing filesystems ... [ 87.979960] PM: done. [ 87.980594] Freezing user space processes ... (elapsed 0.001 seconds) done. [ 87.983839] Freezing filesystems ... [ 87.983844] xfs (sdb1): freezing [ 88.013313] ext4 (sda1): freezing [ 88.057635] done. [ 88.058242] OOM killer disabled. ... [ 88.145364] Freezing remaining freezable tasks ... (elapsed 0.001 seconds) done. [ 88.221583] Disabling non-boot CPUs ... [ 88.241231] Unregister pv shared memory for cpu 1 [ 88.244139] smpboot: CPU 1 is now offline [ 88.273290] Unregister pv shared memory for cpu 2 [ 88.276170] smpboot: CPU 2 is now offline [ 88.297296] Unregister pv shared memory for cpu 3 [ 88.299991] smpboot: CPU 3 is now offline [ 88.302665] PM: Creating hibernation image: [ 88.305633] PM: Need to copy 107866 pages [ 88.305633] PM: Normal pages needed: 107866 + 1024, available pages: 940488 ... At this point my qemu session ends. I start it up again. 88.305633] Enabling non-boot CPUs ... [ 88.305633] x86: Booting SMP configuration: [ 88.305633] smpboot: Booting Node 0 Processor 1 APIC 0x1 [ 88.244097] kvm-clock: cpu 1, msr 1:3ffef041, secondary cpu clock [ 88.334899] KVM setup async PF for cpu 1 [ 88.335174] kvm-stealtime: cpu 1, msr 13fc8d9c0 ... [ 88.424852] sd 0:0:0:0: [sda] Starting disk [ 88.424893] sd 0:0:1:0: [sdb] Starting disk [ 88.424928] sd 1:0:0:0: [sdc] Starting disk [ 88.473888] PM: Basic memory bitmaps freed [ 88.473890] OOM killer enabled. [ 88.474876] ext4 (sda1): thawing [ 88.585233] ata2.01: NODEV after polling detection [ 88.587805] ata2.00: configured for MWDMA2 [ 88.589436] ata1.00: configured for MWDMA2 [ 88.592421] ata1.01: configured for MWDMA2 [ 88.601141] xfs (sdb1): thawing [ 88.602430] Restarting tasks ... done. [ 88.611055] PM: hibernation exit [ 90.492926] e1000: ens3 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: RX [ 98.780159] firmware_class: device_uncache_fw_images And ssh is working after this, without requiring to initiate another connection. Let me know if you'd like me to test something else. Luis
