Messages in this thread | ![/](/images/icornerl.gif) | | Date | Wed, 11 May 2022 10:58:37 +0200 | From | Karel Zak <> | Subject | Re: [RFC PATCH] getting misc stats/attributes via xattr API |
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On Wed, May 11, 2022 at 09:25:52AM +1000, Dave Chinner wrote: > > I'd love something like: > > > > ssize_t sz; > > fsinfo_query query[] = { > > { .request = FSINFO_MOUNT_PATH }, > > { .request = FSINFO_PROPAGATION }, > > { .request = FSINFO_CHILDREN_IDS }, > > }; > > > > sz = fsinfo(dfd, "", AT_EMPTY_PATH, > > &query, ARRAY_SIZE(query), > > buf, sizeof(buf)); > > > > for (p = buf; p < buf + sz; ) { > > { > > fsinfo_entry *e = (struct fsinfo_entry) p; > > char *data = p + sizeof(struct fsinfo_entry); > > > > switch(e->request) { > > case FSINFO_MOUNT_PATH: > > printf("mountpoint %s\n", data); > > break; > > case FSINFO_PROPAGATION: > > printf("propagation %x\n", (uintptr_t) data); > > break; > > case FSINFO_CHILDREN_IDS: > > fsinfo_child *x = (fsinfo_child *) data; > > for (i = 0; i < e->count; i++) { > > printf("child: %d\n", x[i].mnt_id); > > } > > break; > > ... > > } > > > > p += sizeof(struct fsinfo_entry) + e->len; > > } > > That's pretty much what a multi-xattr get operation looks like. > It's a bit more more intricate in the setup of the request/return > buffer, but otherwise the structure of the code is the same. > > I just don't see why we need special purpose interfaces like this > for key/value information when small tweaks to the existing > generic key/value interfaces can provide exactly the same > functionality....
I don't say we need a new interface ;-) I'd be happy with whatever as long as:
* minimal strings parsing (wish than a requirement) * one syscall returns multiple key/value * can address mount table entries by ID * can ask for list of children (submounts) * extensible
if this will be possible with xattr (listxattr2(), or so) when great.
Karel
-- Karel Zak <kzak@redhat.com> http://karelzak.blogspot.com
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