Hi Richard, On Fri, Apr 20, 2018 at 11:37:07AM +0200, Richard Weinberger wrote: > Quentin, > > Am Freitag, 20. April 2018, 10:52:41 CEST schrieb Quentin Schulz: > > There's already ECC on NAND pages so there may be no need for one to > > check the CRC of a UBI volume. > > > > Let's introduce a ubi.nocheck parameter that let one skip the CRC check > > when attaching a UBI volume. > > > > This also drastically speeds kernel boot by removing a potentially > > useless check, e.g. I gained 3.2s on boot time of a SPEAr600-based board > > for a ~20MB UBI volume used as rootfs. > > You mean at *open* time of a *static* UBI volume? > So I guess the use case is having a read-only filesystem on top of ubiblock? >
Turns out I forgot some important information and poorly worded my commit log :) Yes sorry, I have a squashfs (read-only by design) as the image of one static UBI volume. And yes, I meant when opening a static UBI volume. Quentin > > Signed-off-by: Quentin Schulz <[email protected]> > > --- > > drivers/mtd/ubi/kapi.c | 70 +++++++++++++++++++++++++++++++++++++++++++- > > drivers/mtd/ubi/ubi.h | 6 ++++- > > drivers/mtd/ubi/vtbl.c | 24 ++++++++++++++- > > 3 files changed, 99 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/mtd/ubi/kapi.c b/drivers/mtd/ubi/kapi.c > > index d4b2e87..d604cd5 100644 > > --- a/drivers/mtd/ubi/kapi.c > > +++ b/drivers/mtd/ubi/kapi.c > > @@ -28,6 +28,9 @@ > > #include <asm/div64.h> > > #include "ubi.h" > > > > +struct ubivol_param ubinocheck_param[UBIVOL_MAX_DEVICES]; > > +int ubinocheck_devs; > > + > > /** > > * ubi_do_get_device_info - get information about UBI device. > > * @ubi: UBI device description object > > @@ -865,3 +868,70 @@ int ubi_unregister_volume_notifier(struct > > notifier_block *nb) > > return blocking_notifier_chain_unregister(&ubi_notifiers, nb); > > } > > EXPORT_SYMBOL_GPL(ubi_unregister_volume_notifier); > > + > > +static int __init ubinocheckvol_set_param(const char *val, > > + const struct kernel_param *kp) > > +{ > > + int i, ret; > > + size_t len; > > + struct ubivol_param *param; > > + char buf[UBIVOL_PARAM_LEN]; > > + char *pbuf = &buf[0]; > > + char *tokens[UBIVOL_PARAM_COUNT]; > > + > > + if (!val) > > + return -EINVAL; > > + > > + len = strnlen(val, UBIVOL_PARAM_LEN); > > + if (len == 0) { > > + pr_warn("UBI: nocheck: empty 'nocheck=' parameter - ignored\n"); > > + return 0; > > + } > > + > > + if (len == UBIVOL_PARAM_LEN) { > > + pr_err("UBI: nocheck: parameter \"%s\" is too long, max. is > > %d\n", > > + val, UBIVOL_PARAM_LEN); > > + return -EINVAL; > > + } > > + > > + strcpy(buf, val); > > + > > + /* Get rid of the final newline */ > > + if (buf[len - 1] == '\n') > > + buf[len - 1] = '\0'; > > + > > + for (i = 0; i < UBIVOL_PARAM_COUNT; i++) > > + tokens[i] = strsep(&pbuf, ","); > > + > > + param = &ubinocheck_param[ubinocheck_devs]; > > + if (tokens[1]) { > > + /* Two parameters: can be 'ubi, vol_id' or 'ubi, vol_name' */ > > + ret = kstrtoint(tokens[0], 10, ¶m->ubi_num); > > + if (ret < 0) > > + return -EINVAL; > > + > > + /* Second param can be a number or a name */ > > + ret = kstrtoint(tokens[1], 10, ¶m->vol_id); > > + if (ret < 0) { > > + param->vol_id = -1; > > + strcpy(param->name, tokens[1]); > > + } > > + } > > > > Do we really need this per volume? If your flash is trustworthy, it should > not matter. > Having it per UBI instance instead of volume would make the code less > complicated. > > > + ubinocheck_devs++; > > + > > + return 0; > > +} > > + > > +static const struct kernel_param_ops ubinocheckvol_param_ops = { > > + .set = ubinocheckvol_set_param, > > +}; > > +module_param_cb(nocheck, &ubinocheckvol_param_ops, NULL, 0); > > +MODULE_PARM_DESC(nocheck, > > + "Disable CRC check for UBI volumes. Parameter format: > > nocheck=dev,[num|name]>.\n" > > + "Multiple \"nocheck\" parameters may be specified.\n" > > + "Examples\n" > > + "Using the UBI device, and the volume name:\n" > > + "ubi.nocheck=0,rootfs\n" > > + "Using both UBI device number and UBI volume number:\n" > > + "ubi.nocheck=0,0\n"); > > diff --git a/drivers/mtd/ubi/ubi.h b/drivers/mtd/ubi/ubi.h > > index 4cc6ec9..2bd89b4 100644 > > --- a/drivers/mtd/ubi/ubi.h > > +++ b/drivers/mtd/ubi/ubi.h > > @@ -825,6 +825,12 @@ struct ubivol_param { > > char name[UBIVOL_PARAM_LEN + 1]; > > }; > > > > +/* Numbers of elements set in the @ubinocheck_param array */ > > +extern int ubinocheck_devs; > > + > > +/* MTD devices specification parameters */ > > +extern struct ubivol_param ubinocheck_param[UBIVOL_MAX_DEVICES]; > > + > > #include "debug.h" > > > > extern struct kmem_cache *ubi_wl_entry_slab; > > diff --git a/drivers/mtd/ubi/vtbl.c b/drivers/mtd/ubi/vtbl.c > > index 263743e..06b6cfd 100644 > > --- a/drivers/mtd/ubi/vtbl.c > > +++ b/drivers/mtd/ubi/vtbl.c > > @@ -534,9 +534,10 @@ static int init_volumes(struct ubi_device *ubi, > > const struct ubi_attach_info *ai, > > const struct ubi_vtbl_record *vtbl) > > { > > - int i, reserved_pebs = 0; > > + int i, j, reserved_pebs = 0; > > struct ubi_ainf_volume *av; > > struct ubi_volume *vol; > > + struct ubivol_param *param; > > > > for (i = 0; i < ubi->vtbl_slots; i++) { > > cond_resched(); > > @@ -620,6 +621,27 @@ static int init_volumes(struct ubi_device *ubi, > > (long long)(vol->used_ebs - 1) * vol->usable_leb_size; > > vol->used_bytes += av->last_data_size; > > vol->last_eb_bytes = av->last_data_size; > > + > > + for (j = 0; j < ubinocheck_devs; j++) { > > + param = &ubinocheck_param[j]; > > + > > + if (vol->ubi->ubi_num != param->ubi_num) > > + continue; > > + if (vol->vol_id == param->vol_id) { > > + ubi_msg(vol->ubi, > > + "skipping CRC check for volume %d", > > + vol->vol_id); > > + vol->checked = true; > > Please don't abuse the checked flag. > A new one a la "skip_check" does not hurt. > But again, I don't think we need it per volume. > > Also don't forget to add the nocheck parameter to the ioctl() interface, such > that > you can specify it also with ubiattach... > > Thanks, > //richard
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