From mboxrd@z Thu Jan 1 00:00:00 1970 Content-Type: multipart/mixed; boundary="===============1366050397775033167==" MIME-Version: 1.0 From: Walker, Benjamin Subject: Re: [SPDK] Bdev claim and single writer semantics Date: Mon, 30 Apr 2018 17:24:00 +0000 Message-ID: <1525109039.2609.23.camel@intel.com> In-Reply-To: CANvN+ek6SG6XPdze4Rs2OaiFoFAuC=gDmVuwa9wZRdLPgXsMVw@mail.gmail.com List-ID: To: spdk@lists.01.org --===============1366050397775033167== Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable On Sat, 2018-04-28 at 21:30 +0000, Andrey Kuzmin wrote: > While adding support for the shared access semantics seems to be > pretty straightforward, I thought it reasonable to bring the issue up > here first, looking for insights, comments, and objections. Please let > me know if there are any or I can give a shot to a shared access > patch. On Sat, Apr 28, 2018, 02:06 Harris, James R wr= ote: > I=E2=80=99m wondering if we should just remove the safety check. The ori= ginal concern > was to prevent the overwriting of metadata. For example, an NVMe bdev > contains a logical volume store =E2=80=93 the lvol bdev module has claime= d the bdev, > opening and writing directly to the NVMe bdev could corrupt the metadata. > = > But I agree there are a lot of use cases where you may still want to allow > this for one reason or another. And the Linux kernel doesn=E2=80=99t try= to prevent > this =E2=80=93 you can put an LVM PV/VG on a block device and then write = zeroes to the > underlying block device. Same with using parted to put down a GPT and > creating a partition. Based on the behavior of other similar block stacks, I'm on board with just entirely removing the check. I vote we entirely decouple claiming (building= the block device dependency tree) from descriptors (read/write permission check= s). Thanks, Ben --===============1366050397775033167==--