nvme-discover: Re-check generation counter after log page transfer

The log page transfer might have been split up in several chunks, so
it might happen that the generation counter changed inbetween these
transfer. Hence we need to re-fetch the header again to figure out
if there had been changes to the generation counter; if so we need
to fetch the entire page again.

Signed-off-by: Hannes Reinecke <hare@suse.com>

diff --git a/fabrics.c b/fabrics.c
index 83eeb00eaa5d9409eb95e01f678431462e9da4f2..1c25ccb0af6c65471b34f92b599309a56c34844e 100644 (file)
--- a/fabrics.c
+++ b/fabrics.c
@@ -282,7 +282,7 @@ static int nvmf_get_log_page_discovery(const char *dev_path,
                struct nvmf_disc_rsp_page_hdr **logp, int *numrec)
 {
        struct nvmf_disc_rsp_page_hdr *log;
-       unsigned int log_size = 0;
+       unsigned int hdr_size;
        unsigned long genctr;
        int error, fd, max_retries = MAX_DISC_RETRIES, retries = 0;
 
@@ -297,26 +297,28 @@ static int nvmf_get_log_page_discovery(const char *dev_path,
        /* first get_log_page we just need numrec entry from discovery hdr.
         * host supplies its desired bytes via dwords, per NVMe spec.
         */
-       log_size = round_up((offsetof(struct nvmf_disc_rsp_page_hdr, numrec) +
+       hdr_size = round_up((offsetof(struct nvmf_disc_rsp_page_hdr, numrec) +
                            sizeof(log->numrec)), sizeof(__u32));
 
        /*
         * Issue first get log page w/numdl small enough to retrieve numrec.
         * We just want to know how many records to retrieve.
         */
-       log = calloc(1, log_size);
+       log = calloc(1, hdr_size);
        if (!log) {
                error = -ENOMEM;
                goto out_close;
        }
 
-       error = nvme_discovery_log(fd, log, log_size);
+       error = nvme_discovery_log(fd, log, hdr_size);
        if (error) {
                error = DISC_GET_NUMRECS;
                goto out_free_log;
        }
 
        do {
+               unsigned int log_size;
+
                /* check numrec limits */
                *numrec = le64_to_cpu(log->numrec);
                genctr = le64_to_cpu(log->genctr);
@@ -352,6 +354,18 @@ static int nvmf_get_log_page_discovery(const char *dev_path,
                        goto out_free_log;
                }
 
+               /*
+                * The above call to nvme_discovery_log() might result
+                * in several calls (with different offsets), so we need
+                * to fetch the header again to have the most up-to-date
+                * value for the generation counter
+                */
+               genctr = le64_to_cpu(log->genctr);
+               error = nvme_discovery_log(fd, log, hdr_size);
+               if (error) {
+                       error = DISC_GET_LOG;
+                       goto out_free_log;
+               }
        } while (genctr != le64_to_cpu(log->genctr) &&
                 ++retries < max_retries);