From 53a7b4ca6664cd8dfb1218d73e00d0ec047adf29 Mon Sep 17 00:00:00 2001 From: Stefan Kalkowski Date: Wed, 3 Sep 2014 15:03:34 +0200 Subject: [PATCH] blk_cache: don't try to sync 'zero' chunks Invalid cache entries called 'zero chunks' shouldn't be synced. Fix #1249 --- repos/os/src/server/blk_cache/chunk.h | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/repos/os/src/server/blk_cache/chunk.h b/repos/os/src/server/blk_cache/chunk.h index 251e55d20b..e85b436a13 100644 --- a/repos/os/src/server/blk_cache/chunk.h +++ b/repos/os/src/server/blk_cache/chunk.h @@ -52,6 +52,7 @@ namespace Cache { offset_t const _base_offset; size_t _num_entries; /* corresponds to last used entry */ Chunk_base *_parent; + bool const _zero; /* marks zero chunk */ /** * Test if specified range lies within the chunk @@ -67,12 +68,14 @@ namespace Cache { } Chunk_base(offset_t base_offset, Chunk_base *p) - : _base_offset(base_offset), _num_entries(0), _parent(p) { } + : _base_offset(base_offset), _num_entries(0), _parent(p), + _zero(false) { } /** * Construct zero chunk */ - Chunk_base() : _base_offset(0), _num_entries(0), _parent(0) { } + Chunk_base() + : _base_offset(0), _num_entries(0), _parent(0), _zero(true) { } public: @@ -86,6 +89,11 @@ namespace Cache { */ bool empty() const { return _num_entries == 0; } + /** + * Return true if this is an unused 'zero' chunk + */ + bool zero() const { return _zero; } + virtual void free(size_t, offset_t) = 0; }; @@ -513,6 +521,7 @@ namespace Cache { * Synchronize chunk when dirty */ void sync(size_t len, offset_t seek_offset) const { + if (zero()) return; _range_op(*this, (char*)0, len, seek_offset, Sync_func()); } /**