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SubjectRe: [PATCH 13/16] show-pipesize-in-stat.diff
On Sun, 1 Apr 2007 20:17:24 +0200 (MEST)
Jan Engelhardt <jengelh@linux01.gwdg.de> wrote:

>
> Show the fill status of a pipe (in bytes) when stat'ing one.
>
> Signed-off-by: Jan Engelhardt <jengelh@gmx.de>
>
> fs/stat.c | 31 ++++++++++++++++++++++++++++++-
> include/linux/un.h | 2 ++
> include/net/af_unix.h | 3 +++
> net/unix/af_unix.c | 10 ++++++++++
> 4 files changed, 45 insertions(+), 1 deletion(-)

Please dont do that, adding uggly tests in generic_fillattr()

The following patch does the right thing for pipes, I let you doing the same for sockets...

[PATCH] : fill the size of pipes

Instead of reporting 0 in size when stating() a pipe, we give the number of queued bytes. This might avoid using ioctl(FIONREAD) to get this information.

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
---
--- linux-2.6.21-rc5-mm3/fs/pipe.c
+++ linux-2.6.21-rc5-mm3/fs/pipe.c
@@ -570,27 +570,34 @@ bad_pipe_w(struct file *filp, const char
return -EBADF;
}

+static int pipe_size(struct inode *inode)
+{
+ struct pipe_inode_info *pipe;
+ int count, buf, nrbufs;
+
+ mutex_lock(&inode->i_mutex);
+ pipe = inode->i_pipe;
+ count = 0;
+ buf = pipe->curbuf;
+ nrbufs = pipe->nrbufs;
+ while (--nrbufs >= 0) {
+ count += pipe->bufs[buf].len;
+ buf = (buf+1) & (PIPE_BUFFERS-1);
+ }
+ mutex_unlock(&inode->i_mutex);
+ return count;
+}
+
static int
pipe_ioctl(struct inode *pino, struct file *filp,
unsigned int cmd, unsigned long arg)
{
struct inode *inode = filp->f_path.dentry->d_inode;
- struct pipe_inode_info *pipe;
- int count, buf, nrbufs;
+ int count;

switch (cmd) {
case FIONREAD:
- mutex_lock(&inode->i_mutex);
- pipe = inode->i_pipe;
- count = 0;
- buf = pipe->curbuf;
- nrbufs = pipe->nrbufs;
- while (--nrbufs >= 0) {
- count += pipe->bufs[buf].len;
- buf = (buf+1) & (PIPE_BUFFERS-1);
- }
- mutex_unlock(&inode->i_mutex);
-
+ count = pipe_size(inode);
return put_user(count, (int __user *)arg);
default:
return -EINVAL;
@@ -908,6 +915,20 @@ static struct dentry_operations pipefs_d
.d_dname = pipefs_dname,
};

+int pipe_getattr(struct vfsmount *mnt, struct dentry *dentry,
+ struct kstat *stat)
+{
+ struct inode *inode = dentry->d_inode;
+
+ generic_fillattr(inode, stat);
+ stat->size = pipe_size(inode);
+ return 0;
+}
+
+const struct inode_operations pipe_inode_operations = {
+ .getattr = pipe_getattr,
+};
+
static struct inode * get_pipe_inode(void)
{
struct inode *inode = new_inode(pipe_mnt->mnt_sb);
@@ -921,6 +942,7 @@ static struct inode * get_pipe_inode(voi
goto fail_iput;
inode->i_pipe = pipe;

+ inode->i_op = &pipe_inode_operations;
pipe->readers = pipe->writers = 1;
inode->i_fop = &rdwr_pipe_fops;

-
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