VFS: delay the dentry name generation on sockets and pipes
1) Introduces a new method in 'struct dentry_operations'. This method
called d_dname() might be called from d_path() to build a pathname for
special filesystems. It is called without locks.
Future patches (if we succeed in having one common dentry for all
pipes/sockets) may need to change prototype of this method, but we now
use : char *d_dname(struct dentry *dentry, char *buffer, int buflen);
2) Adds a dynamic_dname() helper function that eases d_dname() implementations
3) Defines d_dname method for sockets : No more sprintf() at socket
creation. This is delayed up to the moment someone does an access to
/proc/pid/fd/...
4) Defines d_dname method for pipes : No more sprintf() at pipe
creation. This is delayed up to the moment someone does an access to
/proc/pid/fd/...
A benchmark consisting of 1.000.000 calls to pipe()/close()/close() gives a
*nice* speedup on my Pentium(M) 1.6 Ghz :
3.090 s instead of 3.450 s
Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Acked-by: Christoph Hellwig <hch@infradead.org>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index 63f64a9..aab53df 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -133,6 +133,7 @@
int (*d_delete)(struct dentry *);
void (*d_release)(struct dentry *);
void (*d_iput)(struct dentry *, struct inode *);
+ char *(*d_dname)(struct dentry *, char *, int);
};
/* the dentry parameter passed to d_hash and d_compare is the parent
@@ -293,6 +294,11 @@
/* validate "insecure" dentry pointer */
extern int d_validate(struct dentry *, struct dentry *);
+/*
+ * helper function for dentry_operations.d_dname() members
+ */
+extern char *dynamic_dname(struct dentry *, char *, int, const char *, ...);
+
extern char * d_path(struct dentry *, struct vfsmount *, char *, int);
/* Allocation counts.. */