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| author | Nick Piggin <npiggin@kernel.dk> | 2011-01-07 17:49:32 +1100 |
|---|---|---|
| committer | Nick Piggin <npiggin@kernel.dk> | 2011-01-07 17:50:21 +1100 |
| commit | b7ab39f631f505edc2bbdb86620d5493f995c9da (patch) | |
| tree | 62be97ebc7fc69ceb601f23312d335ebb8038ee7 /include | |
| parent | 2304450783dfde7b0b94ae234edd0dbffa865073 (diff) | |
| download | lwn-b7ab39f631f505edc2bbdb86620d5493f995c9da.tar.gz lwn-b7ab39f631f505edc2bbdb86620d5493f995c9da.zip | |
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')
| -rw-r--r-- | include/linux/dcache.h | 29 |
1 files changed, 15 insertions, 14 deletions
diff --git a/include/linux/dcache.h b/include/linux/dcache.h index 2feb624b67f1..b0ade2d46805 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) |