Hi all,
I make a prototype for exporting info from btrfs via sysfs.
Under /sys/btrfs were created two directories, named "fs" and "devices".
/sys/btrfs/fs/<fs-uuid>/
label -> filesystem label
num_devices -> total number of devices
open_devices -> number of opened devices
[...]
/sys/btrfs/devices/<dev-uuid>/
devid -> btrfs device number
fsid -> filesystem uuid (fs-uuid)
major, minor -> major minor
name -> device name
writeable -> is the device writeable
where <fs-uuid> is the filesystem uuid, and <dev-uuid> is the device uuid. The
link between devices and filesystem is the <fsid> parameter of a device.
I create these structure because we should handle the case were the devices
are present (like after a "btrfs device scan") but the filesystem aren't
mounted.
In this case the devices/ subdirectory is populated. Instead the fs/
subdirectory is empty.
I don't attach a patch because the code is very ugly.
Comments ? Thoughts ?
Below an example of use.
$ /sbin/blkid img*
img0.img: UUID="099ea4b7-96dd-41fc-91df-0d1ab0066e05"
UUID_SUB="1103c4e9-2dba-4b58-82ea-7c7c633fe04a" TYPE="btrfs"
img1.img: UUID="099ea4b7-96dd-41fc-91df-0d1ab0066e05"
UUID_SUB="d677e338-5eb0-4373-a540-78b9e7938987" TYPE="btrfs"
img2.img: UUID="099ea4b7-96dd-41fc-91df-0d1ab0066e05"
UUID_SUB="de5e3fbf-2400-438c-95b5-e4c876d96bed" TYPE="btrfs"
img3.img: UUID="099ea4b7-96dd-41fc-91df-0d1ab0066e05" UUID_SUB="019b1657-
edad-488e-ad72-ccd2ea92e3ac" TYPE="btrfs"
$ (cd /sys/fs/btrfs/; for i in */*/*; do echo -e "$i:\t$(cat $i)"; done )
devices/019b1657-edad-488e-ad72-ccd2ea92e3ac/devid: 4
devices/019b1657-edad-488e-ad72-ccd2ea92e3ac/fsid:
099ea4b7-96dd-41fc-91df-0d1ab0066e05
devices/019b1657-edad-488e-ad72-ccd2ea92e3ac/major: 98
devices/019b1657-edad-488e-ad72-ccd2ea92e3ac/minor: 64
devices/019b1657-edad-488e-ad72-ccd2ea92e3ac/name: /dev/ubde
devices/019b1657-edad-488e-ad72-ccd2ea92e3ac/writeable: 1
devices/1103c4e9-2dba-4b58-82ea-7c7c633fe04a/devid: 1
devices/1103c4e9-2dba-4b58-82ea-7c7c633fe04a/fsid:
099ea4b7-96dd-41fc-91df-0d1ab0066e05
devices/1103c4e9-2dba-4b58-82ea-7c7c633fe04a/major: 98
devices/1103c4e9-2dba-4b58-82ea-7c7c633fe04a/minor: 16
devices/1103c4e9-2dba-4b58-82ea-7c7c633fe04a/name: /dev/ubdb
devices/1103c4e9-2dba-4b58-82ea-7c7c633fe04a/writeable: 1
devices/d677e338-5eb0-4373-a540-78b9e7938987/devid: 2
devices/d677e338-5eb0-4373-a540-78b9e7938987/fsid:
099ea4b7-96dd-41fc-91df-0d1ab0066e05
devices/d677e338-5eb0-4373-a540-78b9e7938987/major: 98
devices/d677e338-5eb0-4373-a540-78b9e7938987/minor: 32
devices/d677e338-5eb0-4373-a540-78b9e7938987/name: /dev/ubdc
devices/d677e338-5eb0-4373-a540-78b9e7938987/writeable: 1
devices/de5e3fbf-2400-438c-95b5-e4c876d96bed/devid: 3
devices/de5e3fbf-2400-438c-95b5-e4c876d96bed/fsid:
099ea4b7-96dd-41fc-91df-0d1ab0066e05
devices/de5e3fbf-2400-438c-95b5-e4c876d96bed/major: 98
devices/de5e3fbf-2400-438c-95b5-e4c876d96bed/minor: 48
devices/de5e3fbf-2400-438c-95b5-e4c876d96bed/name: /dev/ubdd
devices/de5e3fbf-2400-438c-95b5-e4c876d96bed/writeable: 1
fs/099ea4b7-96dd-41fc-91df-0d1ab0066e05/blocks_used: 32768
fs/099ea4b7-96dd-41fc-91df-0d1ab0066e05/blocksize: 4096
fs/099ea4b7-96dd-41fc-91df-0d1ab0066e05/label:
fs/099ea4b7-96dd-41fc-91df-0d1ab0066e05/num_devices: 4
fs/099ea4b7-96dd-41fc-91df-0d1ab0066e05/open_devices: 4
fs/099ea4b7-96dd-41fc-91df-0d1ab0066e05/rw_devices: 4
fs/099ea4b7-96dd-41fc-91df-0d1ab0066e05/total_blocks: 2222981120
fs/099ea4b7-96dd-41fc-91df-0d1ab0066e05/total_devices: 4
On Saturday, 30 October, 2010, you (Goffredo Baroncelli) wrote:
> On Saturday, 30 October, 2010, Hugo Mills wrote:
> > These two patches give a degree of control over balance operations.
> > The first makes it possible to get an idea of how much work remains to
> > do, by tracking the number of block groups (chunks) that need to be
> > moved/rewritten. The second patch allows a running balance operation
> > to be cancelled when the current block group has been moved.
> >
> > One fundamental question, though -- is the progress monitor
> > function best implemented as an ioctl, as I've done here, or should it
> > be two or three sysfs files? I'm thinking of /proc/mdstat...
> > Obviously, /proc/mdstat would never get into /sys, but exposing the
> > "expected" and "remaining" values as files has an attractive
> > simplicity to it.
>
>
> I like the idea that these info should be put under sysfs. Something like
>
> /sys/btrfs/<filesystem-uuid>/
> balance -> info on balancing
> devices -> list of device (a directory of
> links or a file which contains
> the list of devices)
> subvolumes/ -> info on subvolume(s)
> label -> label of the filesystem
> <other btrfs filesystem related knoba>
>
>
>
>
> Obviously we need another btrfs command to extract an uuid from a btrfs
> filesystem like:
>
> # btrfs filesystem get-uuid /path/to/a/btrfs/filesystem
> f9b9c413-0dc8-4e3f-94f2-86faa702f519
>
> >
> > The user-space side of things are in a separate patch series, to
> > follow.
> >
> > Please be gentle with me, this is my first (serious, non-trivial)
> > kernel patch. :)
> >
> > Hugo.
> >
> >
> > --
> > === Hugo Mills: hugo@... carfax.org.uk | darksatanic.net | lug.org.uk ===
> > PGP key: 515C238D from wwwkeys.eu.pgp.net or http://www.carfax.org.uk
> > --- "No! My collection of rare, incurable diseases! Violated!" ---
> >
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
> > the body of a message to majordomo@xxxxxxxxxxxxxxx
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> >
>
>
> --
> gpg key@ keyserver.linux.it: Goffredo Baroncelli (ghigo)
<kreijack@xxxxxxxxx>
> Key fingerprint = 4769 7E51 5293 D36C 814E C054 BF04 F161 3DC5 0512
>
>
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