| Message ID | 20170705163411.23546-1-romain.izard.pro@gmail.com |
|---|---|
| State | Changes Requested |
| Delegated to: | David Oberhollenzer |
| Headers | show |
If this change is done in userspace, it should also be done in the kernel, which also can "format" the media. I cannot remember now, but very small volumes were very problematic. May be it was very inprecise free space estimation. Or something like -ENOSPC when trying to remove a file. The point is, make sure to test the tiny volumes very thoroughly before this is merged. On Wed, 2017-07-05 at 18:34 +0200, Romain Izard wrote: > The minimum size for a UBIFS volume is 17 LEBs. As mkfs.ubifs counted > the reserved log and orphan blocks twice, the program did not allow > such a small volume. > > Fix the calculations to be able to build an image with 17 LEBs. With > this, the following command works: > > mkfs.ubifs -c 17 -l2 -m 2048 -e 124KiB -o small.ubifs > > Signed-off-by: Romain Izard <romain.izard.pro@gmail.com> > --- > ubifs-utils/mkfs.ubifs/mkfs.ubifs.c | 11 +++++++---- > 1 file changed, 7 insertions(+), 4 deletions(-) > > diff --git a/ubifs-utils/mkfs.ubifs/mkfs.ubifs.c b/ubifs- > utils/mkfs.ubifs/mkfs.ubifs.c > index 9e69a4f..ba0293c 100644 > --- a/ubifs-utils/mkfs.ubifs/mkfs.ubifs.c > +++ b/ubifs-utils/mkfs.ubifs/mkfs.ubifs.c > @@ -331,6 +331,9 @@ static long long add_space_overhead(long long > size) > return size / divisor; > } > > +#define UBIFS_MIN_LEB_NOLOG (UBIFS_MIN_LEB_CNT - > UBIFS_MIN_LOG_LEBS) > +#define UBIFS_MIN_LEB_NOORPH (UBIFS_MIN_LEB_CNT - > UBIFS_MIN_ORPH_LEBS) > + > static int validate_options(void) > { > int tmp; > @@ -372,15 +375,15 @@ static int validate_options(void) > if (c->log_lebs < UBIFS_MIN_LOG_LEBS) > return err_msg("too few log LEBs, minimum is %d", > UBIFS_MIN_LOG_LEBS); > - if (c->log_lebs >= c->max_leb_cnt - UBIFS_MIN_LEB_CNT) > + if (c->log_lebs > c->max_leb_cnt - UBIFS_MIN_LEB_NOLOG) > return err_msg("too many log LEBs, maximum is %d", > - c->max_leb_cnt - UBIFS_MIN_LEB_CNT); > + c->max_leb_cnt - > UBIFS_MIN_LEB_NOLOG); > if (c->orph_lebs < UBIFS_MIN_ORPH_LEBS) > return err_msg("too few orphan LEBs, minimum is %d", > UBIFS_MIN_ORPH_LEBS); > - if (c->orph_lebs >= c->max_leb_cnt - UBIFS_MIN_LEB_CNT) > + if (c->orph_lebs > c->max_leb_cnt - UBIFS_MIN_LEB_NOORPH) > return err_msg("too many orphan LEBs, maximum is > %d", > - c->max_leb_cnt - UBIFS_MIN_LEB_CNT); > + c->max_leb_cnt - > UBIFS_MIN_LEB_NOORPH); > tmp = UBIFS_SB_LEBS + UBIFS_MST_LEBS + c->log_lebs + c- > >lpt_lebs; > tmp += c->orph_lebs + 4; > if (tmp > c->max_leb_cnt)
2017-07-06 8:46 GMT+02:00 Artem Bityutskiy <dedekind1@gmail.com>: > > If this change is done in userspace, it should also be done in the > kernel, which also can "format" the media. > > I cannot remember now, but very small volumes were very problematic. > May be it was very inprecise free space estimation. Or something like > -ENOSPC when trying to remove a file. > > The point is, make sure to test the tiny volumes very thoroughly before > this is merged. > The algorithm used to determine the size of a UBIFS volume is not exactly the same in mkfs.ubifs and in the kernel. mkfs.ubifs lets the user tune more parameters, by specifying the number of log LEBs or orphan LEBs, whereas the kernel calculates all these values by itself. As a result, the kernel already accepts such small file systems, and creates them when trying to mount an empty UBI volume of 17 LEBs. If the empty volume has 16 or less LEBs, mounting fails with the following error message: [66897.450000] UBIFS error (ubi0:12 pid 12977): ubifs_mount: too few LEBs (16), min. is 17 I modified mkfs.ubifs to be able to generate offline an image matching the exact setup of an existing device. In this device, there is a small volume with a tiny 17 LEBs UBIFS. I did not notice anything special about it, but your comment worries me a little as I do not really have the means to test "very thoroughly" this configuration. Should I do something about it ? Best regards,
diff --git a/ubifs-utils/mkfs.ubifs/mkfs.ubifs.c b/ubifs-utils/mkfs.ubifs/mkfs.ubifs.c index 9e69a4f..ba0293c 100644 --- a/ubifs-utils/mkfs.ubifs/mkfs.ubifs.c +++ b/ubifs-utils/mkfs.ubifs/mkfs.ubifs.c @@ -331,6 +331,9 @@ static long long add_space_overhead(long long size) return size / divisor; } +#define UBIFS_MIN_LEB_NOLOG (UBIFS_MIN_LEB_CNT - UBIFS_MIN_LOG_LEBS) +#define UBIFS_MIN_LEB_NOORPH (UBIFS_MIN_LEB_CNT - UBIFS_MIN_ORPH_LEBS) + static int validate_options(void) { int tmp; @@ -372,15 +375,15 @@ static int validate_options(void) if (c->log_lebs < UBIFS_MIN_LOG_LEBS) return err_msg("too few log LEBs, minimum is %d", UBIFS_MIN_LOG_LEBS); - if (c->log_lebs >= c->max_leb_cnt - UBIFS_MIN_LEB_CNT) + if (c->log_lebs > c->max_leb_cnt - UBIFS_MIN_LEB_NOLOG) return err_msg("too many log LEBs, maximum is %d", - c->max_leb_cnt - UBIFS_MIN_LEB_CNT); + c->max_leb_cnt - UBIFS_MIN_LEB_NOLOG); if (c->orph_lebs < UBIFS_MIN_ORPH_LEBS) return err_msg("too few orphan LEBs, minimum is %d", UBIFS_MIN_ORPH_LEBS); - if (c->orph_lebs >= c->max_leb_cnt - UBIFS_MIN_LEB_CNT) + if (c->orph_lebs > c->max_leb_cnt - UBIFS_MIN_LEB_NOORPH) return err_msg("too many orphan LEBs, maximum is %d", - c->max_leb_cnt - UBIFS_MIN_LEB_CNT); + c->max_leb_cnt - UBIFS_MIN_LEB_NOORPH); tmp = UBIFS_SB_LEBS + UBIFS_MST_LEBS + c->log_lebs + c->lpt_lebs; tmp += c->orph_lebs + 4; if (tmp > c->max_leb_cnt)
The minimum size for a UBIFS volume is 17 LEBs. As mkfs.ubifs counted the reserved log and orphan blocks twice, the program did not allow such a small volume. Fix the calculations to be able to build an image with 17 LEBs. With this, the following command works: mkfs.ubifs -c 17 -l2 -m 2048 -e 124KiB -o small.ubifs Signed-off-by: Romain Izard <romain.izard.pro@gmail.com> --- ubifs-utils/mkfs.ubifs/mkfs.ubifs.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-)