Date: Tue, 30 Jun 2015 19:26:12 +0530 From: Prasad Joshi <prasadjoshi.linux@gmail.com> To: soc-status@freebsd.org Cc: Xin LI <d@delphij.net> Subject: Re: [gsoc15] dynamically discover bes Message-ID: <CALJbWerDVXCi0K4nv7%2BZNUbUQ=GmgOag9mbk0dBTU8nV3XaMBA@mail.gmail.com> In-Reply-To: <CALJbWert-6-0fa6_%2BdK0N8zcU053GyRSQ8hRoQ5DGfBxeGGu4g@mail.gmail.com> References: <CALJbWeobZj9BqDoYW5Si9NWFFxd2q=w1EsBPVOxcNML-vZF3aQ@mail.gmail.com> <CALJbWerHWL8=P-hJ57V8SfZTyJ5uV9g-=a2x%2B3epGLuit0vn3w@mail.gmail.com> <CALJbWert-6-0fa6_%2BdK0N8zcU053GyRSQ8hRoQ5DGfBxeGGu4g@mail.gmail.com>
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Week 5 Update - I did not work on GSoC for 3 days in this week. Had to attend full day sessions in the University. - Last week I was faced with a problem with booting alternate (non-active) BE. Plan in this week was to locate the problem. It seems like, during bootup zfsloader needs to initialize libzfs library. The libzfs library initialization fails because '/dev/zfs' cannot be opened. I verified the zfs kernel modules, which create the device are loaded. I think, and as suggested by mentor, I will have to set vfs.root.mountfrom environment variable during bootup. Thanks and Regards, Prasad On Mon, Jun 22, 2015 at 11:42 PM, Prasad Joshi <prasadjoshi.linux@gmail.com> wrote: > Week 4 update > > - I have been able to discover BEs on console. I could detect active BE. > Created list of BEs. Code to sort BEs on object number, name, or timestamp > is added. > > - I am able to boot from nonactive BE to some extent. At the moment, code > requires me to enter BE number to boot from. > > Tasks next week > 1. Identify a problem with be bootup. > 2. Pass mount point info through env variable to loader. > 3. Start with console based menu. > > Thanks and Regards, > Prasad > > On Jun 15, 2015 7:48 PM, "Prasad Joshi" <prasadjoshi.linux@gmail.com> wrote: >> >> Week 3 status >> ========== >> After understanding on disk representation of snapshots and clones, I >> have been able to find names of the BEs created using beadm command. I >> could print the BE names on console. >> >> The next task would be to convert BE names to object numbers, create >> list of BEs. >> >> Thanks and Regards, >> Prasad >> >> On Tue, Jun 9, 2015 at 6:36 AM, Prasad Joshi >> <prasadjoshi.linux@gmail.com> wrote: >> > Last week I mostly worked on understanding beadm and gptzfsboot code >> > >> > beadm create prepares new BE by creating a snapshot and clone of that >> > snapshot. beadm activate command sets bootfs property of the POOL. >> > bootfs property contains object number of active dataset object. >> > During bootup gptzfsboot probes all the disks, creating SPA for any >> > valid pool. gptzfsboot assumes the first pool it finds as a primary >> > pool, it then reads meta object set, then tries to find object nunber >> > of active dataset object either through >> > a. bootfs - it would be set if BE was already created >> > b. mos->properties_zap->root_dataset->dd_head_dataset_obj (through >> > root_datasets bonus buffer) >> > Once the object number is obtaind gptzfsboot mounts the dataset. >> > >> > After mounting, few files are looked up like /boot/config or >> > /boot.config for presense of boot command (did not went into details >> > of this). Then (if keyboard is not hit), gptzfsboot execs >> > /boot/zfsloader. If gptzfsboot is interrupted by keyboard, then it >> > displays default BE or POOL it is trying to boot from (using >> > zfs_rlookup() to map active dataset object to string BE name). Though >> > I haven't checked this but through serial console user would be >> > allowed to enter other pool or BE to boot from. >> > >> > I could not go into details of how gptzfsboot reads /boot/zfsloader from >> > disk. >> > >> > Pending Tasks >> > ============= >> > 1. Understand upon keyboard interruption, how user entered zfs paths >> > (format [zfs:pool/filesystem:][/path/to/loader]) are converted in >> > object numbers? >> > 2. Learn ZFS on disk format in more details so as to identify active >> > dataset object numbers of all BEs. Once the object numbers are >> > available, I can use zfs_rlookup() function to map object number to >> > printable pool name. >> > 3. Prepare library for console based menu. >> > >> > Plan for next week >> > ================== >> > Pending task 2 above
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