libzfs_sendrecv: Style pass on send_iterate_fs

* Capitalize and punctuate complete sentences in comments.
* Separate out a group of locals to add a comment on their purpose.
* Remove unnecessary line wrapping.
* Make it clear that dds_origin is a string by using explicit character
  comparison to check for an empty string, rather than implictly
  treating it as a boolean.
* Reorganize manipulation of props and holds nvlists to improve
  clarity.
* There's no need to initialize the snapname buffer with zeros, we're
  immediately overwriting it.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ryan Moeller <freqlabs@FreeBSD.org>
Closes #12967

diff --git a/lib/libzfs/libzfs_sendrecv.c b/lib/libzfs/libzfs_sendrecv.c
index d271db30311a33307afd5453d394ace345e2209d..78c04479bcb4833ac972bdcbde65ba1f81be07cb 100644 (file)
--- a/lib/libzfs/libzfs_sendrecv.c
+++ b/lib/libzfs/libzfs_sendrecv.c
@@ -460,7 +460,7 @@ get_snap_txg(libzfs_handle_t *hdl, const char *fs, const char *snap)
 }
 
 /*
- * recursively generate nvlists describing datasets.  See comment
+ * Recursively generate nvlists describing datasets.  See comment
  * for the data structure send_data_t above for description of contents
  * of the nvlist.
  */
@@ -471,14 +471,16 @@ send_iterate_fs(zfs_handle_t *zhp, void *arg)
        nvlist_t *nvfs = NULL, *nv = NULL;
        int rv = 0;
        uint64_t min_txg = 0, max_txg = 0;
-       uint64_t parent_fromsnap_guid_save = sd->parent_fromsnap_guid;
-       uint64_t fromsnap_txg_save = sd->fromsnap_txg;
-       uint64_t tosnap_txg_save = sd->tosnap_txg;
        uint64_t txg = zhp->zfs_dmustats.dds_creation_txg;
        uint64_t guid = zhp->zfs_dmustats.dds_guid;
        uint64_t fromsnap_txg, tosnap_txg;
        char guidstring[64];
 
+       /* These fields are restored on return from a recursive call. */
+       uint64_t parent_fromsnap_guid_save = sd->parent_fromsnap_guid;
+       uint64_t fromsnap_txg_save = sd->fromsnap_txg;
+       uint64_t tosnap_txg_save = sd->tosnap_txg;
+
        fromsnap_txg = get_snap_txg(zhp->zfs_hdl, zhp->zfs_name, sd->fromsnap);
        if (fromsnap_txg != 0)
                sd->fromsnap_txg = fromsnap_txg;
@@ -488,14 +490,14 @@ send_iterate_fs(zfs_handle_t *zhp, void *arg)
                sd->tosnap_txg = tosnap_txg;
 
        /*
-        * on the send side, if the current dataset does not have tosnap,
+        * On the send side, if the current dataset does not have tosnap,
         * perform two additional checks:
         *
-        * - skip sending the current dataset if it was created later than
-        *   the parent tosnap
-        * - return error if the current dataset was created earlier than
+        * - Skip sending the current dataset if it was created later than
+        *   the parent tosnap.
+        * - Return error if the current dataset was created earlier than
         *   the parent tosnap, unless --skip-missing specified. Then
-        *   just print a warning
+        *   just print a warning.
         */
        if (sd->tosnap != NULL && tosnap_txg == 0) {
                if (sd->tosnap_txg != 0 && txg > sd->tosnap_txg) {
@@ -522,10 +524,9 @@ send_iterate_fs(zfs_handle_t *zhp, void *arg)
 
        nvfs = fnvlist_alloc();
        fnvlist_add_string(nvfs, "name", zhp->zfs_name);
-       fnvlist_add_uint64(nvfs, "parentfromsnap",
-           sd->parent_fromsnap_guid);
+       fnvlist_add_uint64(nvfs, "parentfromsnap", sd->parent_fromsnap_guid);
 
-       if (zhp->zfs_dmustats.dds_origin[0]) {
+       if (zhp->zfs_dmustats.dds_origin[0] != '\0') {
                zfs_handle_t *origin = zfs_open(zhp->zfs_hdl,
                    zhp->zfs_dmustats.dds_origin, ZFS_TYPE_SNAPSHOT);
                if (origin == NULL) {
@@ -534,19 +535,19 @@ send_iterate_fs(zfs_handle_t *zhp, void *arg)
                }
                fnvlist_add_uint64(nvfs, "origin",
                    origin->zfs_dmustats.dds_guid);
-
                zfs_close(origin);
        }
 
-       /* iterate over props */
+       /* Iterate over props. */
        if (sd->props || sd->backup || sd->recursive) {
                nv = fnvlist_alloc();
                send_iterate_prop(zhp, sd->backup, nv);
+               fnvlist_add_nvlist(nvfs, "props", nv);
        }
        if (zfs_prop_get_int(zhp, ZFS_PROP_ENCRYPTION) != ZIO_CRYPT_OFF) {
                boolean_t encroot;
 
-               /* determine if this dataset is an encryption root */
+               /* Determine if this dataset is an encryption root. */
                if (zfs_crypto_get_encryption_root(zhp, &encroot, NULL) != 0) {
                        rv = -1;
                        goto out;
@@ -572,22 +573,19 @@ send_iterate_fs(zfs_handle_t *zhp, void *arg)
 
        }
 
-       if (nv != NULL)
-               fnvlist_add_nvlist(nvfs, "props", nv);
-
-       /* iterate over snaps, and set sd->parent_fromsnap_guid */
-       sd->parent_fromsnap_guid = 0;
-       sd->parent_snaps = fnvlist_alloc();
-       sd->snapprops = fnvlist_alloc();
-       if (sd->holds)
-               sd->snapholds = fnvlist_alloc();
-
        /*
+        * Iterate over snaps, and set sd->parent_fromsnap_guid.
+        *
         * If this is a "doall" send, a replicate send or we're just trying
         * to gather a list of previous snapshots, iterate through all the
         * snaps in the txg range. Otherwise just look at the one we're
         * interested in.
         */
+       sd->parent_fromsnap_guid = 0;
+       sd->parent_snaps = fnvlist_alloc();
+       sd->snapprops = fnvlist_alloc();
+       if (sd->holds)
+               sd->snapholds = fnvlist_alloc();
        if (sd->doall || sd->replicate || sd->tosnap == NULL) {
                if (!sd->replicate && fromsnap_txg != 0)
                        min_txg = fromsnap_txg;
@@ -596,26 +594,26 @@ send_iterate_fs(zfs_handle_t *zhp, void *arg)
                (void) zfs_iter_snapshots_sorted(zhp, send_iterate_snap, sd,
                    min_txg, max_txg);
        } else {
-               char snapname[MAXPATHLEN] = { 0 };
+               char snapname[MAXPATHLEN];
                zfs_handle_t *snap;
 
                (void) snprintf(snapname, sizeof (snapname), "%s@%s",
                    zhp->zfs_name, sd->tosnap);
                if (sd->fromsnap != NULL)
                        sd->seenfrom = B_TRUE;
-               snap = zfs_open(zhp->zfs_hdl, snapname,
-                   ZFS_TYPE_SNAPSHOT);
+               snap = zfs_open(zhp->zfs_hdl, snapname, ZFS_TYPE_SNAPSHOT);
                if (snap != NULL)
                        (void) send_iterate_snap(snap, sd);
        }
 
        fnvlist_add_nvlist(nvfs, "snaps", sd->parent_snaps);
-       fnvlist_add_nvlist(nvfs, "snapprops", sd->snapprops);
-       if (sd->holds)
-               fnvlist_add_nvlist(nvfs, "snapholds", sd->snapholds);
        fnvlist_free(sd->parent_snaps);
+       fnvlist_add_nvlist(nvfs, "snapprops", sd->snapprops);
        fnvlist_free(sd->snapprops);
-       fnvlist_free(sd->snapholds);
+       if (sd->holds) {
+               fnvlist_add_nvlist(nvfs, "snapholds", sd->snapholds);
+               fnvlist_free(sd->snapholds);
+       }
 
        /* Do not allow the size of the properties list to exceed the limit */
        if ((fnvlist_size(nvfs) + fnvlist_size(sd->fss)) >
@@ -629,19 +627,21 @@ send_iterate_fs(zfs_handle_t *zhp, void *arg)
                rv = EZFS_NOSPC;
                goto out;
        }
-       /* add this fs to nvlist */
+       /* Add this fs to nvlist. */
        (void) snprintf(guidstring, sizeof (guidstring),
            "0x%llx", (longlong_t)guid);
        fnvlist_add_nvlist(sd->fss, guidstring, nvfs);
 
-       /* iterate over children */
+       /* Iterate over children. */
        if (sd->recursive)
                rv = zfs_iter_filesystems(zhp, send_iterate_fs, sd);
 
 out:
+       /* Restore saved fields. */
        sd->parent_fromsnap_guid = parent_fromsnap_guid_save;
        sd->fromsnap_txg = fromsnap_txg_save;
        sd->tosnap_txg = tosnap_txg_save;
+
        fnvlist_free(nv);
        fnvlist_free(nvfs);