Commit fde2b400 authored by Kirill Smelkov's avatar Kirill Smelkov

.

parent 0052dc9a
......@@ -46,7 +46,7 @@
// Wcfs client implements pins handling in so-called "pinner" thread(+). The
// pinner thread receives pin requests from wcfs server via watchlink handle
// opened through wcfs/head/watch. For every pin request the pinner finds
// corresponding Mappings and injects wcfs/@revX/f parts into the Mappings
// corresponding Mappings and injects wcfs/@revX/f parts via Mapping._remmapblk
// appropriately.
//
// The same watchlink handle is used to send client-originated requests to wcfs
......@@ -74,10 +74,10 @@
//
// Integration with wendelin.core virtmem layer
//
// Wcfs client integrates with virtmem layer to support virtmem to handle
// Wcfs client integrates with virtmem layer to support virtmem handle
// dirtying pages of read-only base-layer that wcfs client provides via
// isolated Mapping. For wcfs-backed bigfiles every VMA is interlinked with
// Mapping:
// isolated Mapping. For wcfs-backed bigfiles every virtmem VMA is interlinked
// with Mapping:
//
// VMA -> BigFileH -> ZBigFile -----> Z
// ↑↓ O
......@@ -88,13 +88,15 @@
// there, and marks that page as read-write.
//
// Upon receiving pin message, the pinner consults virtmem, whether
// corresponding page was already dirtied in virtmem's BigFileH, and if it was,
// the pinner does not remmap Mapping part to wcfs/@revX/f and just leaves
// dirty page in its place, remembering pin information in fileh._pinned.
// corresponding page was already dirtied in virtmem's BigFileH (call to
// __fileh_page_isdirty), and if it was, the pinner does not remmap Mapping
// part to wcfs/@revX/f and just leaves dirty page in its place, remembering
// pin information in fileh._pinned.
//
// Once dirty pages are no longer needed (either after discard/abort or
// writeout/commit), virtmem asks wcfs client to remmap corresponding regions
// of Mapping in its place again.
// of Mapping in its place again via calls to Mapping.remmap_blk for previously
// dirtied blocks.
//
// The scheme outlined above does not need to split Mapping upon dirtying an
// inner page.
......
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