2001-02-04 15:33:04

by Christoph Rohland

[permalink] [raw]
Subject: [patch] make tmpfs_statfs more user friendly

Hi Alan,

The following patch make shmem_statfs report some sensible size
estimates in the case that the user does not give a size limit.

This should make it more error prone when used as /tmp

Greetings
Christoph

diff -uNr 2.4.1-tmpfs/mm/shmem.c 2.4.1-tmpfs-fstat/mm/shmem.c
--- 2.4.1-tmpfs/mm/shmem.c Sun Feb 4 16:08:57 2001
+++ 2.4.1-tmpfs-fstat/mm/shmem.c Sun Feb 4 16:09:50 2001
@@ -696,13 +696,20 @@
buf->f_type = TMPFS_MAGIC;
buf->f_bsize = PAGE_CACHE_SIZE;
spin_lock (&sb->u.shmem_sb.stat_lock);
- if (sb->u.shmem_sb.max_blocks != ULONG_MAX ||
- sb->u.shmem_sb.max_inodes != ULONG_MAX) {
+ if (sb->u.shmem_sb.max_blocks == ULONG_MAX) {
+ /*
+ * This is only a guestimate and not honoured.
+ * We need it to make some programs happy which like to
+ * test the free space of a file system.
+ */
+ buf->f_bavail = buf->f_bfree = nr_free_pages() + nr_swap_pages + atomic_read(&buffermem_pages);
+ buf->f_blocks = buf->f_bfree + ULONG_MAX - sb->u.shmem_sb.free_blocks;
+ } else {
buf->f_blocks = sb->u.shmem_sb.max_blocks;
buf->f_bavail = buf->f_bfree = sb->u.shmem_sb.free_blocks;
- buf->f_files = sb->u.shmem_sb.max_inodes;
- buf->f_ffree = sb->u.shmem_sb.free_inodes;
}
+ buf->f_files = sb->u.shmem_sb.max_inodes;
+ buf->f_ffree = sb->u.shmem_sb.free_inodes;
spin_unlock (&sb->u.shmem_sb.stat_lock);
buf->f_namelen = 255;
return 0;


2001-02-05 07:00:51

by Christoph Rohland

[permalink] [raw]
Subject: Re: [patch] make tmpfs_statfs more user friendly

Christoph Rohland <[email protected]> writes:

> The following patch make shmem_statfs report some sensible size
> estimates in the case that the user does not give a size limit.
>
> This should make it more error prone when used as /tmp
^^^^
Oh well, Lars pointed out that I was apparently in outer space
when typing this mail ;-)

So: s/more/less/

Christoph

2001-02-05 18:34:58

by Andreas Dilger

[permalink] [raw]
Subject: Re: [patch] make tmpfs_statfs more user friendly

Christoph Rohland writes:
> The following patch make shmem_statfs report some sensible size
> estimates in the case that the user does not give a size limit.
>
> This should make it more error prone when used as /tmp
^^^^ less?

> diff -uNr 2.4.1-tmpfs/mm/shmem.c 2.4.1-tmpfs-fstat/mm/shmem.c
> --- 2.4.1-tmpfs/mm/shmem.c Sun Feb 4 16:08:57 2001
> +++ 2.4.1-tmpfs-fstat/mm/shmem.c Sun Feb 4 16:09:50 2001
> @@ -696,13 +696,20 @@
> buf->f_type = TMPFS_MAGIC;
> buf->f_bsize = PAGE_CACHE_SIZE;
> spin_lock (&sb->u.shmem_sb.stat_lock);
> - if (sb->u.shmem_sb.max_blocks != ULONG_MAX ||
> - sb->u.shmem_sb.max_inodes != ULONG_MAX) {
> + if (sb->u.shmem_sb.max_blocks == ULONG_MAX) {
> + /*
> + * This is only a guestimate and not honoured.
> + * We need it to make some programs happy which like to
> + * test the free space of a file system.
> + */
> + buf->f_bavail = buf->f_bfree = nr_free_pages() + nr_swap_pages + atomic_read(&buffermem_pages);

Should f_bavail be reduced by freepages.min or freepages.low?

> + buf->f_blocks = buf->f_bfree + ULONG_MAX - sb->u.shmem_sb.free_blocks;

It's not really clear what you are trying to calculate here... Since f_blocks
is a long, adding ULONG_MAX == subtracting 1. Maybe it should just hold
the total amount of VM in the system, (i.e. totalram_pages)?

Cheers, Andreas
--
Andreas Dilger \ "If a man ate a pound of pasta and a pound of antipasto,
\ would they cancel out, leaving him still hungry?"
http://www-mddsp.enel.ucalgary.ca/People/adilger/ -- Dogbert

2001-02-05 20:09:53

by Christoph Rohland

[permalink] [raw]
Subject: Re: [patch] make tmpfs_statfs more user friendly

Hi Andreas,

On Mon, 5 Feb 2001, Andreas Dilger wrote:
>> diff -uNr 2.4.1-tmpfs/mm/shmem.c 2.4.1-tmpfs-fstat/mm/shmem.c
>> --- 2.4.1-tmpfs/mm/shmem.c Sun Feb 4 16:08:57 2001
>> +++ 2.4.1-tmpfs-fstat/mm/shmem.c Sun Feb 4 16:09:50 2001
>> @@ -696,13 +696,20 @@
>> buf->f_type = TMPFS_MAGIC;
>> buf->f_bsize = PAGE_CACHE_SIZE;
>> spin_lock (&sb->u.shmem_sb.stat_lock);
>> - if (sb->u.shmem_sb.max_blocks != ULONG_MAX ||
>> - sb->u.shmem_sb.max_inodes != ULONG_MAX) {
>> + if (sb->u.shmem_sb.max_blocks == ULONG_MAX) {
>> + /*
>> + * This is only a guestimate and not honoured.
>> + * We need it to make some programs happy which like to
>> + * test the free space of a file system.
>> + */
>> + buf->f_bavail = buf->f_bfree = nr_free_pages() + nr_swap_pages + atomic_read(&buffermem_pages);
>
> Should f_bavail be reduced by freepages.min or freepages.low?

Is it still used? If yes, good idea.

>> + buf->f_blocks = buf->f_bfree + ULONG_MAX - sb->u.shmem_sb.free_blocks;
>
> It's not really clear what you are trying to calculate here...

(ULONG_MAX - sb->u.shmem_sb.free_blocks) is the number of occupied
blocks by this instance. So the size of the instance should be clearly
buf->f_bfree + ULONG_MAX - sb->u.shmem_sb.free_blocks

> Since f_blocks is a long, adding ULONG_MAX == subtracting 1. Maybe
> it should just hold the total amount of VM in the system,
> (i.e. totalram_pages)?

Nope, see above

Greetings
Christoph