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lib/nvme: prevent creating existing cuse device

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This patch attempts to solve naming conflict between
CUSE devices created by different SPDK instances.

Each NVMe device is enumerated by SPDK process from 0
up to 127. When process attempts to start cuse device
tries to set exclusive lock on temporary file
"/tmp/spdk_nvme_cuse_lock_<index>" and keep it until
device will be stopped.
If setting lock fails, index is incremented.

It prevents to use the same controller index from
few SPDK instances.

Change-Id: If744ac23f813bd992efb80ae2b61a1acefb5054c
Signed-off-by: Tomasz Kulasek <tomaszx.kulasek@intel.com>
Reviewed-on: https://review.gerrithub.io/c/spdk/spdk/+/474829
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Community-CI: Broadcom SPDK FC-NVMe CI <spdk-ci.pdl@broadcom.com>
Reviewed-by: Tomasz Zawadzki <tomasz.zawadzki@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>
This commit is contained in:
Tomasz Kulasek 2019-11-15 12:05:51 -05:00 committed by Tomasz Zawadzki
parent b7b45bc7bc
commit 46316bb5db
1 changed files with 78 additions and 4 deletions
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82
lib/nvme/nvme_cuse.c
View File

@ -45,6 +45,8 @@
struct cuse_device {
char dev_name[128];
uint32_t index;
int claim_fd;
char lock_name[64];
struct spdk_nvme_ctrlr *ctrlr; /**< NVMe controller */
uint32_t nsid; /**< NVMe name space id, or 0 */
@ -711,6 +713,68 @@ cuse_nvme_ns_start(struct cuse_device *ctrlr_device, uint32_t nsid, const char *
return 0;
}
static int
nvme_cuse_claim(struct cuse_device *ctrlr_device, uint32_t index)
{
int dev_fd;
int pid;
void *dev_map;
struct flock cusedev_lock = {
.l_type = F_WRLCK,
.l_whence = SEEK_SET,
.l_start = 0,
.l_len = 0,
};
snprintf(ctrlr_device->lock_name, sizeof(ctrlr_device->lock_name),
"/tmp/spdk_nvme_cuse_lock_%" PRIu32, index);
dev_fd = open(ctrlr_device->lock_name, O_RDWR | O_CREAT, S_IRUSR | S_IWUSR);
if (dev_fd == -1) {
fprintf(stderr, "could not open %s\n", ctrlr_device->lock_name);
return -errno;
}
if (ftruncate(dev_fd, sizeof(int)) != 0) {
fprintf(stderr, "could not truncate %s\n", ctrlr_device->lock_name);
close(dev_fd);
return -errno;
}
dev_map = mmap(NULL, sizeof(int), PROT_READ | PROT_WRITE,
MAP_SHARED, dev_fd, 0);
if (dev_map == MAP_FAILED) {
fprintf(stderr, "could not mmap dev %s (%d)\n", ctrlr_device->lock_name, errno);
close(dev_fd);
return -errno;
}
if (fcntl(dev_fd, F_SETLK, &cusedev_lock) != 0) {
pid = *(int *)dev_map;
fprintf(stderr, "Cannot create lock on device %s, probably"
" process %d has claimed it\n", ctrlr_device->lock_name, pid);
munmap(dev_map, sizeof(int));
close(dev_fd);
/* F_SETLK returns unspecified errnos, normalize them */
return -EACCES;
}
*(int *)dev_map = (int)getpid();
munmap(dev_map, sizeof(int));
ctrlr_device->claim_fd = dev_fd;
ctrlr_device->index = index;
/* Keep dev_fd open to maintain the lock. */
return 0;
}
static void
nvme_cuse_unclaim(struct cuse_device *ctrlr_device)
{
close(ctrlr_device->claim_fd);
ctrlr_device->claim_fd = -1;
unlink(ctrlr_device->lock_name);
}
static void
cuse_nvme_ctrlr_stop(struct cuse_device *ctrlr_device)
{
@ -730,6 +794,7 @@ cuse_nvme_ctrlr_stop(struct cuse_device *ctrlr_device)
if (spdk_bit_array_count_set(g_ctrlr_started) == 0) {
spdk_bit_array_free(&g_ctrlr_started);
}
nvme_cuse_unclaim(ctrlr_device);
free(ctrlr_device);
}
@ -760,10 +825,19 @@ nvme_cuse_start(struct spdk_nvme_ctrlr *ctrlr)
TAILQ_INIT(&ctrlr_device->ns_devices);
ctrlr_device->ctrlr = ctrlr;
ctrlr_device->index = spdk_bit_array_find_first_clear(g_ctrlr_started, 0);
if (ctrlr_device->index == UINT32_MAX) {
SPDK_ERRLOG("Too many registered controllers\n");
goto err2;
/* Check if device already exists, if not increment index until success */
ctrlr_device->index = 0;
while (1) {
ctrlr_device->index = spdk_bit_array_find_first_clear(g_ctrlr_started, ctrlr_device->index);
if (ctrlr_device->index == UINT32_MAX) {
SPDK_ERRLOG("Too many registered controllers\n");
goto err2;
}
if (nvme_cuse_claim(ctrlr_device, ctrlr_device->index) == 0) {
break;
}
ctrlr_device->index++;
}
spdk_bit_array_set(g_ctrlr_started, ctrlr_device->index);
snprintf(ctrlr_device->dev_name, sizeof(ctrlr_device->dev_name), "spdk/nvme%d",