#endif
#define CUnique 0x00001000 /* vc's uniquifier - latest unifiquier for fid */
#define CForeign 0x00002000 /* this is a non-afs vcache */
-#define CHasPages 0x00004000
#define CUnlinked 0x00010000
#define CBulkStat 0x00020000 /* loaded by a bulk stat, and not ref'd since */
#define CUnlinkedDel 0x00040000
#ifdef AFS_DARWIN_ENV
struct lock__bsd__ rwlock;
#endif
- afs_int32 parentVnode; /* Parent dir, if a file. */
+ afs_int32 parentVnode; /* Parent dir, if a file. */
afs_int32 parentUnique;
struct VenusFid *mvid; /* Either parent dir (if root) or root (if mt pt) */
char *linkData; /* Link data if a symlink. */
- afs_hyper_t flushDV; /* data version last flushed from text */
+ afs_hyper_t flushDV; /* data version last flushed from text */
afs_hyper_t mapDV; /* data version last flushed from map */
- afs_size_t truncPos; /* truncate file to this position at next store */
+ afs_size_t truncPos; /* truncate file to this position at next store */
struct server *callback; /* The callback host, if any */
- afs_uint32 cbExpires; /* time the callback expires */
+ afs_uint32 cbExpires; /* time the callback expires */
struct afs_q callsort; /* queue in expiry order, sort of */
struct axscache *Access; /* a list of cached access bits */
- afs_int32 anyAccess; /* System:AnyUser's access to this. */
- afs_int32 last_looker; /* pag/uid from last lookup here */
+ afs_int32 anyAccess; /* System:AnyUser's access to this. */
+ afs_int32 last_looker; /* pag/uid from last lookup here */
#if defined(AFS_SUN5_ENV)
afs_int32 activeV;
#endif /* defined(AFS_SUN5_ENV) */
/* struct dcache states bits */
#define DWriting 8 /* file being written (used for cache validation) */
-/* dcache flags */
-#define DFNextStarted 1 /* next chunk has been prefetched already */
-#define DFEntryMod 2 /* has entry itself been modified? */
-#define DFFetching 4 /* file is currently being fetched */
-#define DFWaiting 8 /* someone waiting for file */
+/* dcache data flags */
+#define DFEntryMod 0x02 /* has entry itself been modified? */
+#define DFFetching 0x04 /* file is currently being fetched */
+
+/* dcache meta flags */
+#define DFNextStarted 0x01 /* next chunk has been prefetched already */
#define DFFetchReq 0x10 /* someone is waiting for DFFetching to go on */
/* kept in memory */
struct dcache {
struct afs_q lruq; /* Free queue for in-memory images */
- afs_rwlock_t lock; /* XXX */
+ afs_rwlock_t lock; /* Protects validPos, some f */
+ afs_rwlock_t tlock; /* Atomizes updates to refCount */
+ afs_rwlock_t mflock; /* Atomizes accesses/updates to mflags */
afs_size_t validPos; /* number of valid bytes during fetch */
- afs_int32 index; /* The index in the CacheInfo file*/
+ afs_int32 index; /* The index in the CacheInfo file*/
short refCount; /* Associated reference count. */
- short flags; /* more flags bits */
+ char dflags; /* Data flags */
+ char mflags; /* Meta flags */
struct fcache f; /* disk image */
- afs_int32 stamp; /* used with vtodc struct for hints */
+ afs_int32 stamp; /* used with vtodc struct for hints */
+
+ /*
+ * Locking rules:
+ *
+ * dcache.lock protects the actual contents of the cache file (in
+ * f.inode), subfields of f except those noted below, dflags and
+ * validPos.
+ *
+ * dcache.tlock is used to make atomic updates to refCount. Zero
+ * refCount dcache entries are protected by afs_xdcache instead of
+ * tlock.
+ *
+ * dcache.mflock is used to access and update mflags. It cannot be
+ * held without holding the corresponding dcache.lock. Updating
+ * mflags requires holding dcache.lock(R) and dcache.mflock(W), and
+ * checking for mflags requires dcache.lock(R) and dcache.mflock(R).
+ * Note that dcache.lock(W) gives you the right to update mflags,
+ * as dcache.mflock(W) can only be held with dcache.lock(R).
+ *
+ * dcache.stamp is protected by the associated vcache lock, because
+ * it's only purpose is to establish correspondence between vcache
+ * and dcache entries.
+ *
+ * dcache.index, dcache.f.fid, dcache.f.chunk and dcache.f.inode are
+ * write-protected by afs_xdcache and read-protected by refCount.
+ * Once an entry is referenced, these values cannot change, and if
+ * it's on the free list (with refCount=0), it can be reused for a
+ * different file/chunk. These values can only be written while
+ * holding afs_xdcache(W) and allocating this dcache entry (thereby
+ * ensuring noone else has a refCount on it).
+ */
};
/* this is obsolete and should be removed */
#define ihint stamp
do { \
(x)->f.fid.Fid.Unique = 0; \
afs_indexUnique[(x)->index] = 0; \
- (x)->flags |= DFEntryMod; \
+ (x)->dflags |= DFEntryMod; \
} while(0)
-/*
- * Convenient release macro for use when afs_PutDCache would cause
- * deadlock on afs_xdcache lock
- */
-#define lockedPutDCache(ad) ((ad)->refCount--)
-
/* FakeOpen and Fake Close used to be real subroutines. They're only used in
* sun_subr and afs_vnodeops, and they're very frequently called, so I made
* them into macros. They do:
extern struct conn *afs_Conn();
extern struct conn *afs_ConnByHost();
extern struct conn *afs_ConnByMHosts();
-extern afs_int32 afs_NewCell();
+extern afs_int32 afs_NewCell();
extern struct dcache *afs_GetDCache();
extern struct dcache *afs_FindDCache();
extern struct dcache *afs_NewDCache();
git://git.openafs.org / openafs.git / blobdiff