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SubjectRe: [-mm patch] relayfs: add read() support
On Thu, Aug 04 2005, Tom Zanussi wrote:
> At the kernel summit, there was some discussion of relayfs and the
> consensus was that it didn't make sense for relayfs to not implement
> read(). So here's a read implementation...

It needs a few fixes to actually compile without errors. This works for
me, just tested with the block tracing stuff, works a charm!


diff -urp -X /home/axboe/cdrom/exclude /opt/kernel/linux-2.6.13-rc4-mm1/fs/relayfs/inode.c linux-2.6.13-rc4-mm1/fs/relayfs/inode.c
--- /opt/kernel/linux-2.6.13-rc4-mm1/fs/relayfs/inode.c 2005-08-05 16:47:57.000000000 +0200
+++ linux-2.6.13-rc4-mm1/fs/relayfs/inode.c 2005-08-05 16:45:38.000000000 +0200
@@ -33,6 +33,8 @@ static struct backing_dev_info relayfs_
.capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
};

+struct file_operations relayfs_file_operations;
+
static struct inode *relayfs_get_inode(struct super_block *sb, int mode,
struct rchan *chan)
{
@@ -370,7 +372,7 @@ static inline unsigned int relayfs_read_
*
*/
static inline unsigned int relayfs_read_avail(struct rchan_buf *buf,
- unsigned int *start_subbuf)
+ size_t *start_subbuf)
{
unsigned int avail, complete_subbufs, cur_subbuf, buf_offset;
unsigned int subbuf_size = buf->chan->subbuf_size;
@@ -378,12 +380,12 @@ static inline unsigned int relayfs_read_

buf_offset = buf->offset > subbuf_size ? subbuf_size : buf->offset;

- if (buf->subbufs_produced >= n_subbufs) {
+ if (atomic_read(&buf->subbufs_produced) >= n_subbufs) {
complete_subbufs = n_subbufs - 1;
cur_subbuf = (buf->data - buf->start) / subbuf_size;
*start_subbuf = (cur_subbuf + 1) % n_subbufs;
} else {
- complete_subbufs = buf->subbufs_produced;
+ complete_subbufs = atomic_read(&buf->subbufs_produced);
*start_subbuf = 0;
}

@@ -416,8 +418,8 @@ static ssize_t relayfs_read(struct file
{
struct inode *inode = filp->f_dentry->d_inode;
struct rchan_buf *buf = RELAYFS_I(inode)->buf;
- unsigned int read_start, read_end, avail, start_subbuf;
- unsigned int buf_size = buf->chan->subbuf_size * buf->chan->n_subbufs;
+ size_t read_start, read_end, avail, start_subbuf;
+ size_t buf_size = buf->chan->subbuf_size * buf->chan->n_subbufs;
void *from;

avail = relayfs_read_avail(buf, &start_subbuf);
diff -urp -X /home/axboe/cdrom/exclude /opt/kernel/linux-2.6.13-rc4-mm1/include/linux/relayfs_fs.h linux-2.6.13-rc4-mm1/include/linux/relayfs_fs.h
--- /opt/kernel/linux-2.6.13-rc4-mm1/include/linux/relayfs_fs.h 2005-08-05 16:47:44.000000000 +0200
+++ linux-2.6.13-rc4-mm1/include/linux/relayfs_fs.h 2005-08-05 16:45:47.000000000 +0200
@@ -253,15 +253,5 @@ static inline void *relay_reserve(struct
return reserved;
}

-/*
- * exported relayfs file operations, fs/relayfs/inode.c
- */
-
-extern struct file_operations relayfs_file_operations;
-extern int relayfs_open(struct inode *inode, struct file *filp);
-extern unsigned int relayfs_poll(struct file *filp, poll_table *wait);
-extern int relayfs_mmap(struct file *filp, struct vm_area_struct *vma);
-extern int relayfs_release(struct inode *inode, struct file *filp);
-
#endif /* _LINUX_RELAYFS_FS_H */


--
Jens Axboe

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