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Mon, 26 Oct 2020 18:44:09 +0000 (UTC) Received: from dgilbert-t580.localhost (ovpn-112-208.ams2.redhat.com [10.36.112.208]) by smtp.corp.redhat.com (Postfix) with ESMTP id 779C15D9CA; Mon, 26 Oct 2020 18:44:08 +0000 (UTC) From: "Dr. David Alan Gilbert (git)" To: qemu-devel@nongnu.org, stefanha@redhat.com, mreitz@redhat.com, misono.tomohiro@jp.fujitsu.com Subject: [PULL 13/16] virtiofsd: Store every lo_inode's parent_dev Date: Mon, 26 Oct 2020 18:43:28 +0000 Message-Id: <20201026184331.272953-14-dgilbert@redhat.com> In-Reply-To: <20201026184331.272953-1-dgilbert@redhat.com> References: <20201026184331.272953-1-dgilbert@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dgilbert@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=63.128.21.124; envelope-from=dgilbert@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/10/25 21:03:19 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: virtio-fs@redhat.com, vgoyal@Redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" From: Max Reitz We want to detect mount points in the shared tree. We report them to the guest by setting the FUSE_ATTR_SUBMOUNT flag in fuse_attr.flags, but because the FUSE client will create a submount for every directory that has this flag set, we must do this only for the actual mount points. We can detect mount points by comparing a directory's st_dev with its parent's st_dev. To be able to do so, we need to store the parent's st_dev in the lo_inode object. Note that mount points need not necessarily be directories; a single file can be a mount point as well. However, for the sake of simplicity let us ignore any non-directory mount points for now. Signed-off-by: Max Reitz Message-Id: <20200909184028.262297-6-mreitz@redhat.com> Reviewed-by: Dr. David Alan Gilbert Signed-off-by: Dr. David Alan Gilbert --- tools/virtiofsd/passthrough_ll.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c index a0beb986f3..4188bf3ad2 100644 --- a/tools/virtiofsd/passthrough_ll.c +++ b/tools/virtiofsd/passthrough_ll.c @@ -125,6 +125,14 @@ struct lo_inode { GHashTable *posix_locks; /* protected by lo_inode->plock_mutex */ mode_t filetype; + + /* + * So we can detect crossmount roots + * (As such, this only needs to be valid for directories. Note + * that files can have multiple parents due to hard links, and so + * their parent_dev may fluctuate.) + */ + dev_t parent_dev; }; struct lo_cred { @@ -847,6 +855,7 @@ static int lo_do_lookup(fuse_req_t req, fuse_ino_t parent, const char *name, g_hash_table_insert(lo->inodes, &inode->key, inode); pthread_mutex_unlock(&lo->mutex); } + inode->parent_dev = dir->key.dev; e->ino = inode->fuse_ino; lo_inode_put(lo, &inode); lo_inode_put(lo, &dir); @@ -1073,6 +1082,14 @@ static void lo_link(fuse_req_t req, fuse_ino_t ino, fuse_ino_t parent, fuse_log(FUSE_LOG_DEBUG, " %lli/%s -> %lli\n", (unsigned long long)parent, name, (unsigned long long)e.ino); + /* + * No need to update inode->parent_dev, because + * (1) We cannot, the inode now has more than one parent, + * (2) Directories cannot have more than one parent, so link() + * does not work for them; but parent_dev only needs to be + * valid for directories. + */ + fuse_reply_entry(req, &e); lo_inode_put(lo, &parent_inode); lo_inode_put(lo, &inode);