master: read the writable-volumes cap from master.toml (#12009)

* master: read the writable-volumes cap from master.toml

-maxWritableVolumes becomes the master.max_writable_volumes config key,
so the new master limit is set the same way as other master options
instead of a flag wired into every command that embeds a master.

* master: name the writable cap master.max_writable_volumes_per_layout

The cap applies per volume layout (collection + replica placement + ttl +
disk type), so the key names its scope instead of reading as a global cap.

* master: keep an embedder's MaxWritableVolumes when the key is unset

NewMasterServer overwrote option.MaxWritableVolumes with the viper
value, which reads as 0 whenever master.toml omits the key, silently
dropping a cap a Go caller supplied through MasterOption. Seed the
default from the option instead so the field survives an absent key;
an explicit config entry still wins.

* master: drop stray nested-checkout gitlinks

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Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

---------

Co-authored-by: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

weed/command/master.go

@@ -57,7 +57,6 @@ type MasterOptions struct {
 	fileSizeLimitMB               *int
 	volumePreallocate             *bool
 	maxParallelVacuumPerServer    *int
-	maxWritableVolumes            *int
 	vacuumIntervalSeconds         *int
 	vacuumDeleteEmptyAfterSeconds *int
 	// pulseSeconds       *int
@@ -96,7 +95,6 @@ func init() {
 	m.fileSizeLimitMB = cmdMaster.Flag.Int("fileSizeLimitMB", 256, "limit the file size accepted by /submit, should match the volume servers' -fileSizeLimitMB (-volume.fileSizeLimitMB under weed server or weed mini, which set this for you)")
 	m.volumePreallocate = cmdMaster.Flag.Bool("volumePreallocate", false, "Preallocate disk space for volumes.")
 	m.maxParallelVacuumPerServer = cmdMaster.Flag.Int("maxParallelVacuumPerServer", 1, "maximum number of volumes to vacuum in parallel per volume server; 0 for no limit (deprecated, use master.vacuum.max_parallel_per_server in master.toml)")
-	m.maxWritableVolumes = cmdMaster.Flag.Int("maxWritableVolumes", 0, "maximum writable volumes in a volume layout (collection + replica placement + ttl + disk type) assignments are spread over, fullest picked first; 0 means no limit")
 	m.vacuumIntervalSeconds = cmdMaster.Flag.Int("vacuumIntervalSeconds", 840, "seconds between automatic vacuum sweeps")
 	m.vacuumDeleteEmptyAfterSeconds = cmdMaster.Flag.Int("vacuumDeleteEmptyAfterSeconds", 0, "automatic sweep deletes volume copies that stay empty this many seconds; 0 disables")
 	// m.pulseSeconds = cmdMaster.Flag.Int("pulseSeconds", 5, "number of seconds between heartbeats")
@@ -479,7 +477,6 @@ func (m *MasterOptions) toMasterOption(whiteList []string) *weed_server.MasterOp
 		FileSizeLimitMB:               *m.fileSizeLimitMB,
 		VolumePreallocate:             *m.volumePreallocate,
 		MaxParallelVacuumPerServer:    *m.maxParallelVacuumPerServer,
-		MaxWritableVolumes:            *m.maxWritableVolumes,
 		VacuumIntervalSeconds:         *m.vacuumIntervalSeconds,
 		VacuumDeleteEmptyAfterSeconds: *m.vacuumDeleteEmptyAfterSeconds,
 		// PulseSeconds:            *m.pulseSeconds,