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don't let dirty blocks be evicted from cache!

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This commit is contained in:
Robert Morris 2011-10-14 10:23:23 -04:00
parent 38eee5bca7
commit 12abb1a561
4 changed files with 15 additions and 4 deletions
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4
bio.c
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@ -79,9 +79,9 @@ bget(uint dev, uint sector)
} }
} }
// Not cached; recycle some existing buffer. // Not cached; recycle some non-busy and clean buffer.
for(b = bcache.head.prev; b != &bcache.head; b = b->prev){ for(b = bcache.head.prev; b != &bcache.head; b = b->prev){
if((b->flags & B_BUSY) == 0){ if((b->flags & B_BUSY) == 0 && (b->flags & B_DIRTY) == 0){
b->dev = dev; b->dev = dev;
b->sector = sector; b->sector = sector;
b->flags = B_BUSY; b->flags = B_BUSY;

8
file.c
View file

@ -1,3 +1,7 @@
//
// File descriptors
//
#include "types.h" #include "types.h"
#include "defs.h" #include "defs.h"
#include "param.h" #include "param.h"
@ -87,7 +91,7 @@ filestat(struct file *f, struct stat *st)
return -1; return -1;
} }
// Read from file f. Addr is kernel address. // Read from file f.
int int
fileread(struct file *f, char *addr, int n) fileread(struct file *f, char *addr, int n)
{ {
@ -108,7 +112,7 @@ fileread(struct file *f, char *addr, int n)
} }
//PAGEBREAK! //PAGEBREAK!
// Write to file f. Addr is kernel address. // Write to file f.
int int
filewrite(struct file *f, char *addr, int n) filewrite(struct file *f, char *addr, int n)
{ {

1
log.c
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@ -177,6 +177,7 @@ log_write(struct buf *b)
brelse(lbuf); brelse(lbuf);
if (i == log.lh.n) if (i == log.lh.n)
log.lh.n++; log.lh.n++;
b->flags |= B_DIRTY; // XXX prevent eviction
} }
//PAGEBREAK! //PAGEBREAK!

6
sysfile.c
View file

@ -1,3 +1,9 @@
//
// File-system system calls.
// Mostly argument checking, since we don't trust
// user code, and calls into file.c and fs.c.
//
#include "types.h" #include "types.h"
#include "defs.h" #include "defs.h"
#include "param.h" #include "param.h"