| Message ID | 20201006091912.1139071-1-u.kleine-koenig@pengutronix.de |
|---|---|
| State | RFC |
| Headers | show |
| Series | [mtd-utils,RFC] Add an ubifs mount helper | expand |
Hello, On Tue, Oct 06, 2020 at 11:19:13AM +0200, Uwe Kleine-König wrote: > This abstracts away attaching of the right ubi and then selecting the right > ubi device and volume to mount. > > As described in the comment at the top this allows to mount ubifs volumes > directly from /etc/fstab without having to use hardcoded numbers (which > depend on mount order and so are unreliable) and extra magic to care for > attaching. > > Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> > --- > Hello, > > this is a nice script that helps attaching ubis and mounting ubifs'. I > already discussed this a bit with Richard on irc and the idea was > welcome in principle. > > A concern was that the entry in /etc/fstab is too magic and there should > be an indication that this relies on the mount helper. Something like > using ubifs.autoattach as file system type (fs_vfstype) or requiring > "autoattach" in the fourth field (fs_mntops). > > Having thought a bit I'm not convinced we need this indication. Yes > there is magic but nothing out of the ordinary as mount helpers are a > known concept and the fs_spec already looks interesting enough to make > it obvious there is something going on. And once people are used to the > magic it is annoying to have to always write this indication in your > fstab. Additionally it complicates the implementation. > > Also "autoattach" doesn't completely cover the script as it does a > translation from mtd name to mtd number, too. "autoattach,mtdtranslate" > seems a bit excessive. I didn't hear any feedback here. Is reviewing this patch still on somebody's todo list? Best regards Uwe
On 11/16/20 10:39 AM, Uwe Kleine-König wrote: > > I didn't hear any feedback here. Is reviewing this patch still on > somebody's todo list? > I compared this version against the one you linked to on IRC earlier, where the idea itself seemed to be approved quite well. I don't see any issue with this patch, but I was still waiting out for maybe *somebody* else posting some kind comment or remark, if not outright spotting an issue we missed when discussing it on IRC. As there seem to be no objects, I applied it to mtd-utils.git master. Greetings, David
diff --git a/ubifs-utils/Makemodule.am b/ubifs-utils/Makemodule.am index 59109ccd613c..5c5d99f7572b 100644 --- a/ubifs-utils/Makemodule.am +++ b/ubifs-utils/Makemodule.am @@ -47,4 +47,6 @@ UBIFS_EXTRA = \ EXTRA_DIST += $(UBIFS_HEADER) $(UBIFS_EXTRA) +dist_sbin_SCRIPTS = ubifs-utils/mount.ubifs + sbin_PROGRAMS += $(UBIFS_BINS) diff --git a/ubifs-utils/mount.ubifs b/ubifs-utils/mount.ubifs new file mode 100755 index 000000000000..b94ddc5649f4 --- /dev/null +++ b/ubifs-utils/mount.ubifs @@ -0,0 +1,101 @@ +#!/bin/sh + +# This script should be installed as /sbin/mount.ubifs. The benefit is that an +# fstab entry like: +# +# mtd=mtddev:home /home ubifs defaults 0 0 +# +# results in the ubi contained in the mtd named "mtddev" to be attached (if not +# already done) and then the volume named "home" being mounted to /home. + +# This is called by mount with the following options: +# /sbin/mount.ubifs spec dir [-sfnv] [-N namespace] [-o options] [-t type.subtype] + +spec="$1" +shift + +mtdname2num() { + local name + + name="$1" + + for d in $(find /sys/class/mtd/ -regex '.*/mtd[0-9]*'); do + case "$d" in + *ro) + continue + ;; + esac + + if test "$name" = "$(cat "$d/name")"; then + local dev mtdnum + + dev="$(basename "$d")" + mtdnum="${dev#mtd}" + echo "$mtdnum" + return + fi + done + + return 1 +} + +mtdnum2ubi() { + local mtdnum + + mtdnum="$1" + + for d in $(find /sys/class/ubi/ -regex '.*/ubi[0-9]*'); do + case "$d" in + *_[0-9]*) + continue + ;; + esac + + if test "$mtdnum" = "$(cat "$d/mtd_num")"; then + local ubi + + ubi="$(basename "$d")" + echo "$ubi" + return; + fi + done + + return 1 +} + +mtdnum2ubi_autoattach() { + local mtdnum ubi + + mtdnum="$1" + + ubi="$(mtdnum2ubi "$mtdnum")" && { echo "$ubi"; return; } + + # ubiattach might fail with "mtdX is already attached to ubiY" if there + # is more than one mount to do in the same mtd partition. So ignore errors. + ubiattach -m "$mtdnum" >&2 || true + + mtdnum2ubi "$mtdnum" +} + +case "$spec" in + mtd=*:*) + spec="${spec#mtd=}" + mtd="${spec%:*}" + rspec="${spec#*:}" + + mtdnum="$(mtdname2num "$mtd")" || { + echo "Failed to find mtdnum for mtd \"$mtd\"" + exit 1 + } + + ubi="$(mtdnum2ubi_autoattach "$mtdnum")" || { + echo "Failed to find ubi for mtd \"$mtd\"" + exit 1 + } + + spec="$ubi:$rspec" + + ;; +esac + +/bin/mount -i -t ubifs "$spec" "$@"
This abstracts away attaching of the right ubi and then selecting the right ubi device and volume to mount. As described in the comment at the top this allows to mount ubifs volumes directly from /etc/fstab without having to use hardcoded numbers (which depend on mount order and so are unreliable) and extra magic to care for attaching. Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> --- Hello, this is a nice script that helps attaching ubis and mounting ubifs'. I already discussed this a bit with Richard on irc and the idea was welcome in principle. A concern was that the entry in /etc/fstab is too magic and there should be an indication that this relies on the mount helper. Something like using ubifs.autoattach as file system type (fs_vfstype) or requiring "autoattach" in the fourth field (fs_mntops). Having thought a bit I'm not convinced we need this indication. Yes there is magic but nothing out of the ordinary as mount helpers are a known concept and the fs_spec already looks interesting enough to make it obvious there is something going on. And once people are used to the magic it is annoying to have to always write this indication in your fstab. Additionally it complicates the implementation. Also "autoattach" doesn't completely cover the script as it does a translation from mtd name to mtd number, too. "autoattach,mtdtranslate" seems a bit excessive. Best regards Uwe ubifs-utils/Makemodule.am | 2 + ubifs-utils/mount.ubifs | 101 ++++++++++++++++++++++++++++++++++++++ 2 files changed, 103 insertions(+) create mode 100755 ubifs-utils/mount.ubifs