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authorNick Piggin <npiggin@kernel.dk>2011-01-07 17:49:32 +1100
committerNick Piggin <npiggin@kernel.dk>2011-01-07 17:50:21 +1100
commitb7ab39f631f505edc2bbdb86620d5493f995c9da (patch)
tree62be97ebc7fc69ceb601f23312d335ebb8038ee7 /include/linux/dcache.h
parent2304450783dfde7b0b94ae234edd0dbffa865073 (diff)
downloadop-kernel-dev-b7ab39f631f505edc2bbdb86620d5493f995c9da.zip
op-kernel-dev-b7ab39f631f505edc2bbdb86620d5493f995c9da.tar.gz
fs: dcache scale dentry refcount
Make d_count non-atomic and protect it with d_lock. This allows us to ensure a 0 refcount dentry remains 0 without dcache_lock. It is also fairly natural when we start protecting many other dentry members with d_lock. Signed-off-by: Nick Piggin <npiggin@kernel.dk>
Diffstat (limited to 'include/linux/dcache.h')
-rw-r--r--include/linux/dcache.h29
1 files changed, 15 insertions, 14 deletions
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index 2feb624..b0ade2d 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -87,7 +87,7 @@ full_name_hash(const unsigned char *name, unsigned int len)
#endif
struct dentry {
- atomic_t d_count;
+ unsigned int d_count; /* protected by d_lock */
unsigned int d_flags; /* protected by d_lock */
spinlock_t d_lock; /* per dentry lock */
int d_mounted;
@@ -297,17 +297,28 @@ extern char *dentry_path(struct dentry *, char *, int);
* needs and they take necessary precautions) you should hold dcache_lock
* and call dget_locked() instead of dget().
*/
-
+static inline struct dentry *dget_dlock(struct dentry *dentry)
+{
+ if (dentry) {
+ BUG_ON(!dentry->d_count);
+ dentry->d_count++;
+ }
+ return dentry;
+}
static inline struct dentry *dget(struct dentry *dentry)
{
if (dentry) {
- BUG_ON(!atomic_read(&dentry->d_count));
- atomic_inc(&dentry->d_count);
+ spin_lock(&dentry->d_lock);
+ dget_dlock(dentry);
+ spin_unlock(&dentry->d_lock);
}
return dentry;
}
extern struct dentry * dget_locked(struct dentry *);
+extern struct dentry * dget_locked_dlock(struct dentry *);
+
+extern struct dentry *dget_parent(struct dentry *dentry);
/**
* d_unhashed - is dentry hashed
@@ -338,16 +349,6 @@ static inline void dont_mount(struct dentry *dentry)
spin_unlock(&dentry->d_lock);
}
-static inline struct dentry *dget_parent(struct dentry *dentry)
-{
- struct dentry *ret;
-
- spin_lock(&dentry->d_lock);
- ret = dget(dentry->d_parent);
- spin_unlock(&dentry->d_lock);
- return ret;
-}
-
extern void dput(struct dentry *);
static inline int d_mountpoint(struct dentry *dentry)
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