From mboxrd@z Thu Jan 1 00:00:00 1970 From: Miklos Szeredi Date: Wed, 01 Apr 2020 13:34:31 +0000 Subject: Re: Upcoming: Notifications, FS notifications and fsinfo() Message-Id: MIME-Version: 1 Content-Type: multipart/mixed; boundary="0000000000002e407205a23abf26" List-Id: References: <20200330211700.g7evnuvvjenq3fzm@wittgenstein> <1445647.1585576702@warthog.procyon.org.uk> <2418286.1585691572@warthog.procyon.org.uk> <20200401090445.6t73dt7gz36bv4rh@ws.net.home> In-Reply-To: <20200401090445.6t73dt7gz36bv4rh@ws.net.home> To: Karel Zak Cc: David Howells , Christian Brauner , Linus Torvalds , Al Viro , dray@redhat.com, Miklos Szeredi , Steven Whitehouse , Jeff Layton , Ian Kent , andres@anarazel.de, keyrings@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Lennart Poettering , Aleksa Sarai --0000000000002e407205a23abf26 Content-Type: text/plain; charset="UTF-8" On Wed, Apr 1, 2020 at 11:05 AM Karel Zak wrote: > > On Tue, Mar 31, 2020 at 10:52:52PM +0100, David Howells wrote: > > Christian Brauner wrote: > > > > > querying all properties of a mount atomically all-at-once, > > > > I don't actually offer that, per se. > > > > Having an atomic all-at-once query for a single mount is actually quite a > > burden on the system. There's potentially a lot of state involved, much of > > which you don't necessarily need. > > If all means "all possible attributes" than it is unnecessary, for > example ext4 timestamps or volume uuid/label are rarely necessary. > We usually need together (as consistent set): > > source > mountpoint > FS type > FS root (FSINFO_ATTR_MOUNT_PATH) > FS options (FSINFO_ATTR_CONFIGURATION) > VFS attributes > VFS propagation flags > mount ID > parent ID > devno (or maj:min) This is trivial with mountfs (reuse format of /proc/PID/mountinfo): # cat /mnt/30/info 30 20 0:14 / /mnt rw,relatime - mountfs none rw Attached patch applies against readfile patch. We might want something more generic, and it won't get any simpler: mount.h | 1 + mountfs/super.c | 12 +++++++++++- proc_namespace.c | 2 +- 3 files changed, 13 insertions(+), 2 deletions(-) Thanks, Miklos --0000000000002e407205a23abf26 Content-Type: text/x-patch; charset="US-ASCII"; name="mountfs-info.patch" Content-Disposition: attachment; filename="mountfs-info.patch" Content-Transfer-Encoding: base64 Content-ID: X-Attachment-Id: f_k8hdan1o0 LS0tCiBmcy9tb3VudC5oICAgICAgICAgIHwgICAgMSArCiBmcy9tb3VudGZzL3N1cGVyLmMgIHwg ICAxMiArKysrKysrKysrKy0KIGZzL3Byb2NfbmFtZXNwYWNlLmMgfCAgICAyICstCiAzIGZpbGVz IGNoYW5nZWQsIDEzIGluc2VydGlvbnMoKyksIDIgZGVsZXRpb25zKC0pCgotLS0gYS9mcy9tb3Vu dC5oCisrKyBiL2ZzL21vdW50LmgKQEAgLTE4NiwzICsxODYsNCBAQCB2b2lkIG1vdW50ZnNfY3Jl YXRlKHN0cnVjdCBtb3VudCAqbW50KTsKIGV4dGVybiB2b2lkIG1vdW50ZnNfcmVtb3ZlKHN0cnVj dCBtb3VudCAqbW50KTsKIGludCBtb3VudGZzX2xvb2t1cF9pbnRlcm5hbChzdHJ1Y3QgdmZzbW91 bnQgKm0sIHN0cnVjdCBwYXRoICpwYXRoKTsKIAoraW50IHNob3dfbW91bnRpbmZvKHN0cnVjdCBz ZXFfZmlsZSAqbSwgc3RydWN0IHZmc21vdW50ICptbnQpOwotLS0gYS9mcy9tb3VudGZzL3N1cGVy LmMKKysrIGIvZnMvbW91bnRmcy9zdXBlci5jCkBAIC0yMiw3ICsyMiw3IEBAIHN0cnVjdCBtb3Vu dGZzX2VudHJ5IHsKIAogc3RhdGljIGNvbnN0IGNoYXIgKm1vdW50ZnNfYXR0cnNbXSA9IHsKIAki cm9vdCIsICJtb3VudHBvaW50IiwgImlkIiwgInBhcmVudCIsICJvcHRpb25zIiwgImNoaWxkcmVu IiwKLQkiZ3JvdXAiLCAibWFzdGVyIiwgInByb3BhZ2F0ZV9mcm9tIiwgImNvdW50ZXIiCisJImdy b3VwIiwgIm1hc3RlciIsICJwcm9wYWdhdGVfZnJvbSIsICJjb3VudGVyIiwgImluZm8iCiB9Owog CiAjZGVmaW5lIE1PVU5URlNfSU5PKGlkKSAoKCh1bnNpZ25lZCBsb25nKSBpZCArIDEpICogXApA QCAtMTI2LDExICsxMjYsMjEgQEAgc3RhdGljIGludCBtb3VudGZzX2F0dHJfc2hvdyhzdHJ1Y3Qg c2VxXwogCQlpZiAoSVNfTU5UX1NMQVZFKG1udCkpIHsKIAkJCWdldF9mc19yb290KGN1cnJlbnQt PmZzLCAmcm9vdCk7CiAJCQl0bXAgPSBnZXRfZG9taW5hdGluZ19pZChtbnQsICZyb290KTsKKwkJ CXBhdGhfcHV0KCZyb290KTsKIAkJCWlmICh0bXApCiAJCQkJc2VxX3ByaW50ZihzZiwgIiVpXG4i LCB0bXApOwogCQl9CiAJfSBlbHNlIGlmIChzdHJjbXAobmFtZSwgImNvdW50ZXIiKSA9PSAwKSB7 CiAJCXNlcV9wcmludGYoc2YsICIldVxuIiwgYXRvbWljX3JlYWQoJm1udC0+bW50X3RvcG9sb2d5 X2NoYW5nZXMpKTsKKwl9IGVsc2UgaWYgKHN0cmNtcChuYW1lLCAiaW5mbyIpID09IDApIHsKKwkJ c3RydWN0IHByb2NfbW91bnRzIHAgPSB7fTsKKworCQlXQVJOX09OKHNmLT5wcml2YXRlKTsKKwkJ c2YtPnByaXZhdGUgPSAmcDsKKwkJZ2V0X2ZzX3Jvb3QoY3VycmVudC0+ZnMsICZwLnJvb3QpOwor CQllcnIgPSBzaG93X21vdW50aW5mbyhzZiwgbSk7CisJCXBhdGhfcHV0KCZwLnJvb3QpOworCQlz Zi0+cHJpdmF0ZSA9IE5VTEw7CiAJfSBlbHNlIHsKIAkJV0FSTl9PTigxKTsKIAkJZXJyID0gLUVJ TzsKLS0tIGEvZnMvcHJvY19uYW1lc3BhY2UuYworKysgYi9mcy9wcm9jX25hbWVzcGFjZS5jCkBA IC0xMTAsNyArMTEwLDcgQEAgc3RhdGljIGludCBzaG93X3Zmc21udChzdHJ1Y3Qgc2VxX2ZpbGUg KgogCXJldHVybiBlcnI7CiB9CiAKLXN0YXRpYyBpbnQgc2hvd19tb3VudGluZm8oc3RydWN0IHNl cV9maWxlICptLCBzdHJ1Y3QgdmZzbW91bnQgKm1udCkKK2ludCBzaG93X21vdW50aW5mbyhzdHJ1 Y3Qgc2VxX2ZpbGUgKm0sIHN0cnVjdCB2ZnNtb3VudCAqbW50KQogewogCXN0cnVjdCBwcm9jX21v dW50cyAqcCA9IG0tPnByaXZhdGU7CiAJc3RydWN0IG1vdW50ICpyID0gcmVhbF9tb3VudChtbnQp Owo= --0000000000002e407205a23abf26--