scanning: open devs rw when rescanning for write

When vg_read rescans devices with the intention of
writing the VG, the label rescan can open the devs
RW so they do not need to be closed and reopened
RW in dev_write_bytes.

diff --git a/lib/cache/lvmcache.c b/lib/cache/lvmcache.c
index 1d92e0198d974be0b1499dc87b0f3fe4a0664373..e2d19e8996a13c8b77786c718316deae693a68e8 100644 (file)
--- a/lib/cache/lvmcache.c
+++ b/lib/cache/lvmcache.c
@@ -772,7 +772,7 @@ next:
  * to that VG after a scan.
  */
 
-int lvmcache_label_rescan_vg(struct cmd_context *cmd, const char *vgname, const char *vgid)
+static int _label_rescan_vg(struct cmd_context *cmd, const char *vgname, const char *vgid, int rw)
 {
        struct dm_list devs;
        struct device_list *devl, *devl2;
@@ -804,7 +804,10 @@ int lvmcache_label_rescan_vg(struct cmd_context *cmd, const char *vgname, const
        /* FIXME: should we also rescan unused_duplicate_devs for devs
           being rescanned here and then repeat resolving the duplicates? */
 
-       label_scan_devs(cmd, cmd->filter, &devs);
+       if (rw)
+               label_scan_devs_rw(cmd, cmd->filter, &devs);
+       else
+               label_scan_devs(cmd, cmd->filter, &devs);
 
        dm_list_iterate_items_safe(devl, devl2, &devs) {
                dm_list_del(&devl->list);
@@ -819,6 +822,16 @@ int lvmcache_label_rescan_vg(struct cmd_context *cmd, const char *vgname, const
        return 1;
 }
 
+int lvmcache_label_rescan_vg(struct cmd_context *cmd, const char *vgname, const char *vgid)
+{
+       return _label_rescan_vg(cmd, vgname, vgid, 0);
+}
+
+int lvmcache_label_rescan_vg_rw(struct cmd_context *cmd, const char *vgname, const char *vgid)
+{
+       return _label_rescan_vg(cmd, vgname, vgid, 1);
+}
+
 /*
  * Uses label_scan to populate lvmcache with 'vginfo' struct for each VG
  * and associated 'info' structs for those VGs.  Only VG summary information

diff --git a/lib/cache/lvmcache.h b/lib/cache/lvmcache.h
index 5b78d7afb2271bcc2b832a9843c4f19e122a97f9..e2d967c625a2d6cfdf198006af847a5afcc313fe 100644 (file)
--- a/lib/cache/lvmcache.h
+++ b/lib/cache/lvmcache.h
@@ -71,6 +71,7 @@ void lvmcache_destroy(struct cmd_context *cmd, int retain_orphans, int reset);
 
 int lvmcache_label_scan(struct cmd_context *cmd);
 int lvmcache_label_rescan_vg(struct cmd_context *cmd, const char *vgname, const char *vgid);
+int lvmcache_label_rescan_vg_rw(struct cmd_context *cmd, const char *vgname, const char *vgid);
 
 /* Add/delete a device */
 struct lvmcache_info *lvmcache_add(struct labeller *labeller, const char *pvid,

diff --git a/lib/label/label.c b/lib/label/label.c
index a8d87ec16ce4d1915c873a3f4a1a3b05b7c3980f..185e51b0c33ac5d929179bc3283809d68c18b00d 100644 (file)
--- a/lib/label/label.c
+++ b/lib/label/label.c
@@ -1118,7 +1118,37 @@ int label_scan_devs(struct cmd_context *cmd, struct dev_filter *f, struct dm_lis
 
        _scan_list(cmd, f, devs, NULL);
 
-       /* FIXME: this function should probably fail if any devs couldn't be scanned */
+       return 1;
+}
+
+/*
+ * This function is used when the caller plans to write to the devs, so opening
+ * them RW during rescan avoids needing to close and reopen with WRITE in
+ * dev_write_bytes.
+ */
+
+int label_scan_devs_rw(struct cmd_context *cmd, struct dev_filter *f, struct dm_list *devs)
+{
+       struct device_list *devl;
+
+       if (!scan_bcache) {
+               if (!_setup_bcache(0))
+                       return 0;
+       }
+
+       dm_list_iterate_items(devl, devs) {
+               if (_in_bcache(devl->dev)) {
+                       bcache_invalidate_fd(scan_bcache, devl->dev->bcache_fd);
+                       _scan_dev_close(devl->dev);
+               }
+               /*
+                * With this flag set, _scan_dev_open() done by
+                * _scan_list() will do open RW
+                */
+               devl->dev->flags |= DEV_BCACHE_WRITE;
+       }
+
+       _scan_list(cmd, f, devs, NULL);
 
        return 1;
 }

diff --git a/lib/label/label.h b/lib/label/label.h
index 07bb77d884492e66f545eb0fc493ce6fd9e3d56e..f06b7df6398f825c156afc1ba1a88ec1377ddf2f 100644 (file)
--- a/lib/label/label.h
+++ b/lib/label/label.h
@@ -104,6 +104,7 @@ extern struct bcache *scan_bcache;
 
 int label_scan(struct cmd_context *cmd);
 int label_scan_devs(struct cmd_context *cmd, struct dev_filter *f, struct dm_list *devs);
+int label_scan_devs_rw(struct cmd_context *cmd, struct dev_filter *f, struct dm_list *devs);
 int label_scan_devs_excl(struct dm_list *devs);
 void label_scan_invalidate(struct device *dev);
 void label_scan_invalidate_lv(struct cmd_context *cmd, struct logical_volume *lv);

diff --git a/lib/metadata/metadata-exported.h b/lib/metadata/metadata-exported.h
index 9029d3f64020e2f2a54e0722baf963a9b34ac81d..966c88f95ec418dbe65d12ba84a1c21e3211d050 100644 (file)
--- a/lib/metadata/metadata-exported.h
+++ b/lib/metadata/metadata-exported.h
@@ -184,8 +184,9 @@
 #define READ_ALLOW_EXPORTED    0x00020000U
 #define READ_OK_NOTFOUND       0x00040000U
 #define READ_WARN_INCONSISTENT 0x00080000U
-#define READ_FOR_UPDATE                0x00100000U /* A meta-flag, useful with toollib for_each_* functions. */
-#define PROCESS_SKIP_SCAN       0x00200000U /* skip lvmcache_label_scan in process_each_pv */
+#define READ_FOR_UPDATE                0x00100000U /* command tells vg_read it plans to write the vg */
+#define PROCESS_SKIP_SCAN      0x00200000U /* skip lvmcache_label_scan in process_each_pv */
+#define READ_FOR_ACTIVATE      0x00400000U /* command tells vg_read it plans to activate the vg */
 
 /* vg_read returns these in error_flags */
 #define FAILED_NOT_ENABLED     0x00000001U

diff --git a/lib/metadata/metadata.c b/lib/metadata/metadata.c
index 039a7d690d15c1d216b12f718d5a26c55da9ec5a..7b0d6ce9239a4e9bb5dcec4be1a8427cd3deb654 100644 (file)
--- a/lib/metadata/metadata.c
+++ b/lib/metadata/metadata.c
@@ -4476,7 +4476,8 @@ void vg_write_commit_bad_mdas(struct cmd_context *cmd, struct volume_group *vg)
 static struct volume_group *_vg_read(struct cmd_context *cmd,
                                     const char *vgname,
                                     const char *vgid,
-                                    unsigned precommitted)
+                                    unsigned precommitted,
+                                    int writing)
 {
        const struct format_type *fmt = cmd->fmt;
        struct format_instance *fid = NULL;
@@ -4530,8 +4531,11 @@ static struct volume_group *_vg_read(struct cmd_context *cmd,
         * we can also skip the rescan in that case.
         */
        if (!cmd->can_use_one_scan || lvmcache_scan_mismatch(cmd, vgname, vgid)) {
-               log_debug_metadata("Rescanning devices for %s", vgname);
-               lvmcache_label_rescan_vg(cmd, vgname, vgid);
+               log_debug_metadata("Rescanning devices for %s %s", vgname, writing ? "rw" : "");
+               if (writing)
+                       lvmcache_label_rescan_vg_rw(cmd, vgname, vgid);
+               else
+                       lvmcache_label_rescan_vg(cmd, vgname, vgid);
        } else {
                log_debug_metadata("Skipped rescanning devices for %s", vgname);
        }
@@ -4752,6 +4756,7 @@ struct volume_group *vg_read(struct cmd_context *cmd, const char *vg_name, const
        int missing_pv_flag = 0;
        uint32_t failure = 0;
        int writing = (read_flags & READ_FOR_UPDATE);
+       int activating = (read_flags & READ_FOR_ACTIVATE);
 
        if (is_orphan_vg(vg_name)) {
                log_very_verbose("Reading orphan VG %s", vg_name);
@@ -4766,13 +4771,23 @@ struct volume_group *vg_read(struct cmd_context *cmd, const char *vg_name, const
                return NULL;
        }
 
-       if (!lock_vol(cmd, vg_name, writing ? LCK_VG_WRITE : LCK_VG_READ, NULL)) {
+       /*
+        * When a command is reading the VG with the intention of eventually
+        * writing it, it passes the READ_FOR_UPDATE flag.  This causes vg_read
+        * to acquire an exclusive VG lock, and causes vg_read to do some more
+        * checks, e.g. that the VG is writable and not exported.  It also
+        * means that when the label scan is repeated on the VG's devices, the
+        * VG's PVs can be reopened read-write when rescanning in anticipation
+        * of needing to write to them.
+        */
+
+       if (!lock_vol(cmd, vg_name, (writing || activating) ? LCK_VG_WRITE : LCK_VG_READ, NULL)) {
                log_error("Can't get lock for %s", vg_name);
                failure |= FAILED_LOCKING;
                goto_bad;
        }
 
-       if (!(vg = _vg_read(cmd, vg_name, vgid, 0))) {
+       if (!(vg = _vg_read(cmd, vg_name, vgid, 0, writing))) {
                /* Some callers don't care if the VG doesn't exist and don't want an error message. */
                if (!(read_flags & READ_OK_NOTFOUND))
                        log_error("Volume group \"%s\" not found", vg_name);
@@ -4883,29 +4898,36 @@ struct volume_group *vg_read(struct cmd_context *cmd, const char *vg_name, const
                goto_bad;
        }
 
-       if (writing && !(read_flags & READ_ALLOW_EXPORTED) && vg_is_exported(vg)) {
-               log_error("Volume group %s is exported", vg->name);
-               failure |= FAILED_EXPORTED;
-               goto_bad;
-       }
+       /*
+        * If the command intends to write or activate the VG, there are
+        * additional restrictions.  FIXME: These restrictions should
+        * probably be checked/applied after vg_read returns.
+        */
+       if (writing || activating) {
+               if (!(read_flags & READ_ALLOW_EXPORTED) && vg_is_exported(vg)) {
+                       log_error("Volume group %s is exported", vg->name);
+                       failure |= FAILED_EXPORTED;
+                       goto_bad;
+               }
 
-       if (writing && !(vg->status & LVM_WRITE)) {
-               log_error("Volume group %s is read-only", vg->name);
-               failure |= FAILED_READ_ONLY;
-               goto_bad;
-       }
+               if (!(vg->status & LVM_WRITE)) {
+                       log_error("Volume group %s is read-only", vg->name);
+                       failure |= FAILED_READ_ONLY;
+                       goto_bad;
+               }
 
-       if (!cmd->handles_missing_pvs && (missing_pv_dev || missing_pv_flag) && writing) {
-               log_error("Cannot change VG %s while PVs are missing.", vg->name);
-               log_error("See vgreduce --removemissing and vgextend --restoremissing.");
-               failure |= FAILED_NOT_ENABLED;
-               goto_bad;
-       }
+               if (!cmd->handles_missing_pvs && (missing_pv_dev || missing_pv_flag)) {
+                       log_error("Cannot change VG %s while PVs are missing.", vg->name);
+                       log_error("See vgreduce --removemissing and vgextend --restoremissing.");
+                       failure |= FAILED_NOT_ENABLED;
+                       goto_bad;
+               }
 
-       if (!cmd->handles_unknown_segments && vg_has_unknown_segments(vg) && writing) {
-               log_error("Cannot change VG %s with unknown segments in it!", vg->name);
-               failure |= FAILED_NOT_ENABLED; /* FIXME new failure code here? */
-               goto_bad;
+               if (!cmd->handles_unknown_segments && vg_has_unknown_segments(vg)) {
+                       log_error("Cannot change VG %s with unknown segments in it!", vg->name);
+                       failure |= FAILED_NOT_ENABLED; /* FIXME new failure code here? */
+                       goto_bad;
+               }
        }
 
        /*

diff --git a/tools/lvchange.c b/tools/lvchange.c
index 7bdf99742ab894d691bf85c83fc6a685ceeed18d..e7fb57d1d3db3d1213e29f5384c98a621eda427e 100644 (file)
--- a/tools/lvchange.c
+++ b/tools/lvchange.c
@@ -1435,7 +1435,7 @@ int lvchange_activate_cmd(struct cmd_context *cmd, int argc, char **argv)
        } else /* Component LVs might be active, support easy deactivation */
                cmd->process_component_lvs = 1;
 
-       ret = process_each_lv(cmd, argc, argv, NULL, NULL, READ_FOR_UPDATE,
+       ret = process_each_lv(cmd, argc, argv, NULL, NULL, READ_FOR_ACTIVATE,
                              NULL, &_lvchange_activate_check, &_lvchange_activate_single);
 
        if (ret != ECMD_PROCESSED)

diff --git a/tools/pvscan.c b/tools/pvscan.c
index d41345fac2a04b4bf2c233a0a03563ef6fcf011f..12711cb0aeaf754417f02b34a6264cc47e7ad456 100644 (file)
--- a/tools/pvscan.c
+++ b/tools/pvscan.c
@@ -900,7 +900,7 @@ static int _pvscan_aa(struct cmd_context *cmd, struct pvscan_aa_params *pp,
                return ECMD_PROCESSED;
        }
 
-       ret = process_each_vg(cmd, 0, NULL, NULL, vgnames, READ_FOR_UPDATE, 0, handle, _pvscan_aa_single);
+       ret = process_each_vg(cmd, 0, NULL, NULL, vgnames, READ_FOR_ACTIVATE, 0, handle, _pvscan_aa_single);
 
        destroy_processing_handle(cmd, handle);
 

diff --git a/tools/vgchange.c b/tools/vgchange.c
index a17f4566ff682c28f9f399dffa5d82d1d3014d96..aad6db32fbb980698dd9aaf3fb0899d28f6ae214 100644 (file)
--- a/tools/vgchange.c
+++ b/tools/vgchange.c
@@ -800,8 +800,10 @@ int vgchange(struct cmd_context *cmd, int argc, char **argv)
                        cmd->lockd_vg_enforce_sh = 1;
        }
 
-       if (update || arg_is_set(cmd, activate_ARG))
+       if (update)
                flags |= READ_FOR_UPDATE;
+       else if (arg_is_set(cmd, activate_ARG))
+               flags |= READ_FOR_ACTIVATE;
 
        if (!(handle = init_processing_handle(cmd, NULL))) {
                log_error("Failed to initialize processing handle.");