* bcachefs xattr
@ 2015-08-13 7:39 Ming Lin
2015-08-13 7:41 ` Kent Overstreet
0 siblings, 1 reply; 4+ messages in thread
From: Ming Lin @ 2015-08-13 7:39 UTC (permalink / raw)
To: linux-bcache; +Cc: Kent Overstreet
Hi Kent,
Seems the max length of xattr name+value is only 2004 bytes.
Why the limit of U8_MAX below?
root@bee:~# dd if=/dev/zero bs=1 count=1996 2>/dev/null | attr -s "long_attr" /mnt/test/attr.txt
attr_set: Numerical result out of range
Could not set "long_attr" for /mnt/test/attr.txt
183 int bch_xattr_set(struct inode *inode, const char *name,
...
230 if (value) {
231 struct keylist keys;
232 struct bkey_i_xattr *xattr;
233 unsigned u64s = BKEY_U64s +
234 DIV_ROUND_UP(sizeof(struct bch_xattr) +
235 qname.len + size,
236 sizeof(u64));
237
238 if (u64s > U8_MAX) {
239 ret = -ERANGE;
240 break;
241 }
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: bcachefs xattr
2015-08-13 7:39 bcachefs xattr Ming Lin
@ 2015-08-13 7:41 ` Kent Overstreet
2015-08-13 7:49 ` Ming Lin
0 siblings, 1 reply; 4+ messages in thread
From: Kent Overstreet @ 2015-08-13 7:41 UTC (permalink / raw)
To: Ming Lin; +Cc: linux-bcache
On Thu, Aug 13, 2015 at 12:39:07AM -0700, Ming Lin wrote:
> Hi Kent,
>
> Seems the max length of xattr name+value is only 2004 bytes.
> Why the limit of U8_MAX below?
The size of the key and value is stored as a u8 in units of u64s - the u64s
field of struct bkey.
>
> root@bee:~# dd if=/dev/zero bs=1 count=1996 2>/dev/null | attr -s "long_attr" /mnt/test/attr.txt
> attr_set: Numerical result out of range
> Could not set "long_attr" for /mnt/test/attr.txt
>
> 183 int bch_xattr_set(struct inode *inode, const char *name,
> ...
>
> 230 if (value) {
> 231 struct keylist keys;
> 232 struct bkey_i_xattr *xattr;
> 233 unsigned u64s = BKEY_U64s +
> 234 DIV_ROUND_UP(sizeof(struct bch_xattr) +
> 235 qname.len + size,
> 236 sizeof(u64));
> 237
> 238 if (u64s > U8_MAX) {
> 239 ret = -ERANGE;
> 240 break;
> 241 }
>
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: bcachefs xattr
2015-08-13 7:41 ` Kent Overstreet
@ 2015-08-13 7:49 ` Ming Lin
2015-08-13 7:50 ` Kent Overstreet
0 siblings, 1 reply; 4+ messages in thread
From: Ming Lin @ 2015-08-13 7:49 UTC (permalink / raw)
To: Kent Overstreet; +Cc: linux-bcache
On Wed, 2015-08-12 at 23:41 -0800, Kent Overstreet wrote:
> On Thu, Aug 13, 2015 at 12:39:07AM -0700, Ming Lin wrote:
> > Hi Kent,
> >
> > Seems the max length of xattr name+value is only 2004 bytes.
> > Why the limit of U8_MAX below?
>
> The size of the key and value is stored as a u8 in units of u64s - the u64s
> field of struct bkey.
xfstests/generic/020 failed.
Got it now.
xfs supports 64KB values.
In order to support larger size of value, does it make sense to store
the value in "extent"?
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: bcachefs xattr
2015-08-13 7:49 ` Ming Lin
@ 2015-08-13 7:50 ` Kent Overstreet
0 siblings, 0 replies; 4+ messages in thread
From: Kent Overstreet @ 2015-08-13 7:50 UTC (permalink / raw)
To: Ming Lin; +Cc: linux-bcache
On Thu, Aug 13, 2015 at 12:49:13AM -0700, Ming Lin wrote:
> On Wed, 2015-08-12 at 23:41 -0800, Kent Overstreet wrote:
> > On Thu, Aug 13, 2015 at 12:39:07AM -0700, Ming Lin wrote:
> > > Hi Kent,
> > >
> > > Seems the max length of xattr name+value is only 2004 bytes.
> > > Why the limit of U8_MAX below?
> >
> > The size of the key and value is stored as a u8 in units of u64s - the u64s
> > field of struct bkey.
>
> xfstests/generic/020 failed.
> Got it now.
>
> xfs supports 64KB values.
> In order to support larger size of value, does it make sense to store
> the value in "extent"?
Perhaps, but let's leave that for now and add it if there's demand for it.
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2015-08-13 7:50 UTC | newest]
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2015-08-13 7:39 bcachefs xattr Ming Lin
2015-08-13 7:41 ` Kent Overstreet
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