[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.
References and derived from: http://lkml.org/lkml/2007/4/2/138
Cc: Eric Dumazet <[email protected]>
Signed-off-by: Jan Engelhardt <[email protected]>
---
fs/pipe.c | 49 ++++++++++++++++++++++++++++++++++++-------------
1 file changed, 36 insertions(+), 13 deletions(-)
Index: linux-2.6.23/fs/pipe.c
===================================================================
--- linux-2.6.23.orig/fs/pipe.c
+++ linux-2.6.23/fs/pipe.c
@@ -577,27 +577,35 @@ bad_pipe_w(struct file *filp, const char
return -EBADF;
}
+static unsigned int pipe_size(struct inode *inode)
+{
+ struct pipe_inode_info *pipe;
+ unsigned int count, buf;
+ int 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;
+ unsigned 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;
@@ -915,6 +923,20 @@ 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);
@@ -928,6 +950,7 @@ 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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