nvmet: add ns revalidation support

Add support for detecting capacity changes on nvmet blockdev and file
backed namespaces. This allows for emulating and testing online resizing
of nvme devices and filesystems on top.
Signed-off-by: Anthony Iliopoulos <ailiop@suse.com>
[chaitanya: Fix comments posted on V1]
Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
[hch: reuse code a bit more]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/nvme/target/admin-cmd.c

@@ -486,6 +486,11 @@ static void nvmet_execute_identify_ns(struct nvmet_req *req)
 	if (!ns)
 		goto done;
 
+	if (ns->bdev)
+		nvmet_bdev_ns_revalidate(ns);
+	else
+		nvmet_file_ns_revalidate(ns);
+
 	/*
 	 * nuse = ncap = nsze isn't always true, but we have no way to find
 	 * that out from the underlying device.

drivers/nvme/target/io-cmd-bdev.c

@@ -75,6 +75,11 @@ void nvmet_bdev_ns_disable(struct nvmet_ns *ns)
 	}
 }
 
+void nvmet_bdev_ns_revalidate(struct nvmet_ns *ns)
+{
+	ns->size = i_size_read(ns->bdev->bd_inode);
+}
+
 static u16 blk_to_nvme_status(struct nvmet_req *req, blk_status_t blk_sts)
 {
 	u16 status = NVME_SC_SUCCESS;

drivers/nvme/target/io-cmd-file.c

@@ -13,6 +13,18 @@
 #define NVMET_MAX_MPOOL_BVEC		16
 #define NVMET_MIN_MPOOL_OBJ		16
 
+int nvmet_file_ns_revalidate(struct nvmet_ns *ns)
+{
+	struct kstat stat;
+	int ret;
+
+	ret = vfs_getattr(&ns->file->f_path, &stat, STATX_SIZE,
+			  AT_STATX_FORCE_SYNC);
+	if (!ret)
+		ns->size = stat.size;
+	return ret;
+}
+
 void nvmet_file_ns_disable(struct nvmet_ns *ns)
 {
 	if (ns->file) {
@@ -30,7 +42,6 @@ void nvmet_file_ns_disable(struct nvmet_ns *ns)
 int nvmet_file_ns_enable(struct nvmet_ns *ns)
 {
 	int flags = O_RDWR | O_LARGEFILE;
-	struct kstat stat;
 	int ret;
 
 	if (!ns->buffered_io)
@@ -43,12 +54,10 @@ int nvmet_file_ns_enable(struct nvmet_ns *ns)
 		return PTR_ERR(ns->file);
 	}
 
-	ret = vfs_getattr(&ns->file->f_path,
-			&stat, STATX_SIZE, AT_STATX_FORCE_SYNC);
+	ret = nvmet_file_ns_revalidate(ns);
 	if (ret)
 		goto err;
 
-	ns->size = stat.size;
 	/*
 	 * i_blkbits can be greater than the universally accepted upper bound,
 	 * so make sure we export a sane namespace lba_shift.

drivers/nvme/target/nvmet.h

@@ -498,6 +498,8 @@ void nvmet_file_ns_disable(struct nvmet_ns *ns);
 u16 nvmet_bdev_flush(struct nvmet_req *req);
 u16 nvmet_file_flush(struct nvmet_req *req);
 void nvmet_ns_changed(struct nvmet_subsys *subsys, u32 nsid);
+void nvmet_bdev_ns_revalidate(struct nvmet_ns *ns);
+int nvmet_file_ns_revalidate(struct nvmet_ns *ns);
 
 static inline u32 nvmet_rw_len(struct nvmet_req *req)
 {