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blk_cache: don't try to sync 'zero' chunks

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Invalid cache entries called 'zero chunks' shouldn't be synced.

Fix #1249
This commit is contained in:
Stefan Kalkowski 2014-09-03 15:03:34 +02:00 committed by Norman Feske
parent 41b62e50bb
commit 53a7b4ca66
1 changed files with 11 additions and 2 deletions
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13
repos/os/src/server/blk_cache/chunk.h
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@ -52,6 +52,7 @@ namespace Cache {
offset_t const _base_offset; offset_t const _base_offset;
size_t _num_entries; /* corresponds to last used entry */ size_t _num_entries; /* corresponds to last used entry */
Chunk_base *_parent; Chunk_base *_parent;
bool const _zero; /* marks zero chunk */
/** /**
* Test if specified range lies within the chunk * Test if specified range lies within the chunk
@ -67,12 +68,14 @@ namespace Cache {
} }
Chunk_base(offset_t base_offset, Chunk_base *p) 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 * 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: public:
@ -86,6 +89,11 @@ namespace Cache {
*/ */
bool empty() const { return _num_entries == 0; } 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; virtual void free(size_t, offset_t) = 0;
}; };
@ -513,6 +521,7 @@ namespace Cache {
* Synchronize chunk when dirty * Synchronize chunk when dirty
*/ */
void sync(size_t len, offset_t seek_offset) const { void sync(size_t len, offset_t seek_offset) const {
if (zero()) return;
_range_op(*this, (char*)0, len, seek_offset, Sync_func()); } _range_op(*this, (char*)0, len, seek_offset, Sync_func()); }
/** /**