GitHub-Mirror/Star64_linux
2
0
Fork 0
mirror of https://github.com/Fishwaldo/Star64_linux.git synced 2025-06-24 15:42:32 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions

VFS: delay the dentry name generation on sockets and pipes

Browse source 
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>
This commit is contained in:
Eric Dumazet 2007-05-08 00:26:18 -07:00 • committed by Linus Torvalds
parent 2793274298
commit c23fbb6bcb
6 changed files with 86 additions and 14 deletions
Download patch file Download diff file Expand all files Collapse all files

31
fs/dcache.c
View file

@ -1853,6 +1853,16 @@ char * d_path(struct dentry *dentry, struct vfsmount *vfsmnt,
struct vfsmount *rootmnt;
struct dentry *root;
/*
* We have various synthetic filesystems that never get mounted. On
* these filesystems dentries are never used for lookup purposes, and
* thus don't need to be hashed. They also don't need a name until a
* user wants to identify the object in /proc/pid/fd/. The little hack
* below allows us to generate a name for these objects on demand:
*/
if (dentry->d_op && dentry->d_op->d_dname)
return dentry->d_op->d_dname(dentry, buf, buflen);
read_lock(&current->fs->lock);
rootmnt = mntget(current->fs->rootmnt);
root = dget(current->fs->root);
@ -1865,6 +1875,27 @@ char * d_path(struct dentry *dentry, struct vfsmount *vfsmnt,
return res;
}
/*
* Helper function for dentry_operations.d_dname() members
*/
char *dynamic_dname(struct dentry *dentry, char *buffer, int buflen,
const char *fmt, ...)
{
va_list args;
char temp[64];
int sz;
va_start(args, fmt);
sz = vsnprintf(temp, sizeof(temp), fmt, args) + 1;
va_end(args);
if (sz > sizeof(temp) || sz > buflen)
return ERR_PTR(-ENAMETOOLONG);
buffer += buflen - sz;
return memcpy(buffer, temp, sz);
}
/*
* NOTE! The user-level library version returns a
* character pointer. The kernel system call just