[-mm patch] relayfs: add read() support

[-mm patch] relayfs: add read() support

[Tom Zanussi]

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...

Andrew, please apply.

Tom

Signed-off-by: Tom Zanussi <zanussi@us.ibm.com>

diff -urpN -X dontdiff linux-2.6.13-rc4-mm1/fs/relayfs/inode.c linux-2.6.13-rc4-mm1-cur/fs/relayfs/inode.c
--- linux-2.6.13-rc4-mm1/fs/relayfs/inode.c	2005-08-05 10:14:34.000000000 -0500
+++ linux-2.6.13-rc4-mm1-cur/fs/relayfs/inode.c	2005-08-05 10:17:47.000000000 -0500
@@ -232,7 +232,7 @@ int relayfs_remove_dir(struct dentry *de
  *
  *	Increments the channel buffer refcount.
  */
-int relayfs_open(struct inode *inode, struct file *filp)
+static int relayfs_open(struct inode *inode, struct file *filp)
 {
 	struct rchan_buf *buf = RELAYFS_I(inode)->buf;
 	kref_get(&buf->kref);
@@ -247,7 +247,7 @@ int relayfs_open(struct inode *inode, st
  *
  *	Calls upon relay_mmap_buf to map the file into user space.
  */
-int relayfs_mmap(struct file *filp, struct vm_area_struct *vma)
+static int relayfs_mmap(struct file *filp, struct vm_area_struct *vma)
 {
 	struct inode *inode = filp->f_dentry->d_inode;
 	return relay_mmap_buf(RELAYFS_I(inode)->buf, vma);
@@ -260,7 +260,7 @@ int relayfs_mmap(struct file *filp, stru
  *
  *	Poll implemention.
  */
-unsigned int relayfs_poll(struct file *filp, poll_table *wait)
+static unsigned int relayfs_poll(struct file *filp, poll_table *wait)
 {
 	unsigned int mask = 0;
 	struct inode *inode = filp->f_dentry->d_inode;
@@ -286,7 +286,7 @@ unsigned int relayfs_poll(struct file *f
  *	Decrements the channel refcount, as the filesystem is
  *	no longer using it.
  */
-int relayfs_release(struct inode *inode, struct file *filp)
+static int relayfs_release(struct inode *inode, struct file *filp)
 {
 	struct rchan_buf *buf = RELAYFS_I(inode)->buf;
 	kref_put(&buf->kref, relay_remove_buf);
@@ -295,6 +295,157 @@ int relayfs_release(struct inode *inode,
 }
 
 /**
+ *	relayfs_read_start - find the first available byte to read
+ *
+ *	If the read_pos is in the middle of padding, return the
+ *	position of the first actually available byte, otherwise
+ *	return the original value.
+ */
+static inline unsigned int relayfs_read_start(unsigned int read_pos,
+					      unsigned int avail,
+					      unsigned int start_subbuf,
+					      struct rchan_buf *buf)
+{
+	unsigned int read_subbuf, adj_read_subbuf;
+	unsigned int padding, padding_start, padding_end;
+	unsigned int subbuf_size = buf->chan->subbuf_size;
+	unsigned int n_subbufs = buf->chan->n_subbufs;
+	
+	read_subbuf = read_pos / subbuf_size;
+	adj_read_subbuf = (read_subbuf + start_subbuf) % n_subbufs;
+	
+	if ((read_subbuf + 1) * subbuf_size <= avail) {
+		padding = buf->padding[adj_read_subbuf];
+		padding_start = (read_subbuf + 1) * subbuf_size - padding;
+		padding_end = (read_subbuf + 1) * subbuf_size;
+		if (read_pos >= padding_start && read_pos < padding_end) {
+			read_subbuf = (read_subbuf + 1) % n_subbufs;
+			read_pos = read_subbuf * subbuf_size;
+		}
+	}
+
+	return read_pos;
+}
+
+/**
+ *	relayfs_read_end - return the end of available bytes to read
+ *
+ *	If the read_pos is in the middle of a full sub-buffer, return
+ *	the padding-adjusted end of that sub-buffer, otherwise return
+ *	the position after the last byte written to the buffer.  At
+ *	most, 1 sub-buffer can be read at a time.
+ *	
+ */
+static inline unsigned int relayfs_read_end(unsigned int read_pos,
+					    unsigned int avail,
+					    unsigned int start_subbuf,
+					    struct rchan_buf *buf)
+{
+	unsigned int padding, read_endpos, buf_offset;
+	unsigned int read_subbuf, adj_read_subbuf;
+	unsigned int subbuf_size = buf->chan->subbuf_size;
+	unsigned int n_subbufs = buf->chan->n_subbufs;
+
+	buf_offset = buf->offset > subbuf_size ? subbuf_size : buf->offset;
+	read_subbuf = read_pos / subbuf_size;
+	adj_read_subbuf = (read_subbuf + start_subbuf) % n_subbufs;
+
+	if ((read_subbuf + 1) * subbuf_size <= avail) {
+		padding = buf->padding[adj_read_subbuf];
+		read_endpos = (read_subbuf + 1) * subbuf_size - padding;
+	} else
+		read_endpos = read_subbuf * subbuf_size + buf_offset;
+
+	return read_endpos;
+}
+
+/**
+ *	relayfs_read_avail - return total available along with buffer start
+ *
+ *	Because buffers are circular, the 'beginning' of the buffer
+ *	depends on where the buffer was last written.  If the writer
+ *	has cycled around the buffer, the beginning is defined to be
+ *	the beginning of the sub-buffer following the last sub-buffer
+ *	written to, otherwise it's the beginning of sub-buffer 0.
+ *	
+ */
+static inline unsigned int relayfs_read_avail(struct rchan_buf *buf,
+					      unsigned int *start_subbuf)
+{
+	unsigned int avail, complete_subbufs, cur_subbuf, buf_offset;
+	unsigned int subbuf_size = buf->chan->subbuf_size;
+	unsigned int n_subbufs = buf->chan->n_subbufs;
+
+	buf_offset = buf->offset > subbuf_size ? subbuf_size : buf->offset;
+	
+	if (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;
+		*start_subbuf = 0;
+	}
+	
+	avail = complete_subbufs * subbuf_size + buf_offset;
+
+	return avail;
+}
+
+/**
+ *	relayfs_read - read file op for relayfs files
+ *	@filp: the file
+ *	@buffer: the userspace buffer
+ *	@count: number of bytes to read
+ *	@ppos: position to read from
+ *
+ *	Reads count bytes or the number of bytes available in the
+ *	current sub-buffer being read, whichever is smaller.
+ *	
+ *	NOTE: The results of reading a relayfs file which is currently
+ *	being written to are undefined.  This is because the buffer is
+ *	circular and an active writer in the kernel could be
+ *	overwriting the data currently being read.  Therefore read()
+ *	is mainly useful for reading the contents of a buffer after
+ *	logging has completed.
+ */
+static ssize_t relayfs_read(struct file *filp,
+			    char __user *buffer,
+			    size_t count,
+			    loff_t *ppos)
+{
+	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;
+	void *from;
+
+	avail = relayfs_read_avail(buf, &start_subbuf);
+	if (*ppos >= avail)
+		return 0;
+
+	read_start = relayfs_read_start(*ppos, avail, start_subbuf, buf);
+	if (read_start == 0 && *ppos)
+		return 0;
+	
+	read_end = relayfs_read_end(read_start, avail, start_subbuf, buf);
+	if (read_end == read_start)
+		return 0;
+	
+	from = buf->start + start_subbuf * buf->chan->subbuf_size + read_start;
+	if (from >= buf->start + buf_size)
+		from -= buf_size;
+
+	count = min(count, read_end - read_start);
+	if (copy_to_user(buffer, from, count))
+		return -EFAULT;
+
+	*ppos = read_start + count;
+	
+	return count;
+}
+
+/**
  *	relayfs alloc_inode() implementation
  */
 static struct inode *relayfs_alloc_inode(struct super_block *sb)
@@ -329,6 +480,7 @@ struct file_operations relayfs_file_oper
 	.open		= relayfs_open,
 	.poll		= relayfs_poll,
 	.mmap		= relayfs_mmap,
+	.read		= relayfs_read,
 	.release	= relayfs_release,
 };
 
@@ -404,10 +556,6 @@ static void __exit exit_relayfs_fs(void)
 module_init(init_relayfs_fs)
 module_exit(exit_relayfs_fs)
 
-EXPORT_SYMBOL_GPL(relayfs_open);
-EXPORT_SYMBOL_GPL(relayfs_poll);
-EXPORT_SYMBOL_GPL(relayfs_mmap);
-EXPORT_SYMBOL_GPL(relayfs_release);
 EXPORT_SYMBOL_GPL(relayfs_file_operations);
 EXPORT_SYMBOL_GPL(relayfs_create_dir);
 EXPORT_SYMBOL_GPL(relayfs_remove_dir);

Re: [-mm patch] relayfs: add read() support

[Andrew Morton]

Tom Zanussi <zanussi@us.ibm.com> wrote:
>
> +static ssize_t relayfs_read(struct file *filp,
>  +			    char __user *buffer,
>  +			    size_t count,
>  +			    loff_t *ppos)
>  +{
>  +	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;
>  +	void *from;
>  +
>  +	avail = relayfs_read_avail(buf, &start_subbuf);
>  +	if (*ppos >= avail)
>  +		return 0;
>  +
>  +	read_start = relayfs_read_start(*ppos, avail, start_subbuf, buf);
>  +	if (read_start == 0 && *ppos)
>  +		return 0;
>  +	
>  +	read_end = relayfs_read_end(read_start, avail, start_subbuf, buf);
>  +	if (read_end == read_start)
>  +		return 0;
>  +	
>  +	from = buf->start + start_subbuf * buf->chan->subbuf_size + read_start;
>  +	if (from >= buf->start + buf_size)
>  +		from -= buf_size;
>  +
>  +	count = min(count, read_end - read_start);
>  +	if (copy_to_user(buffer, from, count))
>  +		return -EFAULT;
>  +
>  +	*ppos = read_start + count;
>  +	
>  +	return count;
>  +}

The use of `unsigned int' in here will cause >4G reads to fail on 64-bit
platforms.  I think you want size_t throughout.

Re: [-mm patch] relayfs: add read() support

[Tom Zanussi]

Andrew Morton writes:
 > 
 > The use of `unsigned int' in here will cause >4G reads to fail on 64-bit
 > platforms.  I think you want size_t throughout.

OK, here's a patch that does that.  It also switches to size_t for the
buffer-related sizes elsewhere in relayfs.

This applies on top of the previous patches.

Tom

Signed-off-by: Tom Zanussi <zanussi@us.ibm.com>

diff -urpN -X dontdiff linux-2.6.13-rc4-mm1-cur-prev/fs/relayfs/buffers.c linux-2.6.13-rc4-mm1-cur/fs/relayfs/buffers.c
--- linux-2.6.13-rc4-mm1-cur-prev/fs/relayfs/buffers.c	2005-08-05 10:17:30.000000000 -0500
+++ linux-2.6.13-rc4-mm1-cur/fs/relayfs/buffers.c	2005-08-06 11:33:56.000000000 -0500
@@ -137,7 +137,7 @@ struct rchan_buf *relay_create_buf(struc
 	if (!buf)
 		return NULL;
 
-	buf->padding = kmalloc(chan->n_subbufs * sizeof(unsigned *), GFP_KERNEL);
+	buf->padding = kmalloc(chan->n_subbufs * sizeof(size_t *), GFP_KERNEL);
 	if (!buf->padding)
 		goto free_buf;
 
diff -urpN -X dontdiff linux-2.6.13-rc4-mm1-cur-prev/fs/relayfs/inode.c linux-2.6.13-rc4-mm1-cur/fs/relayfs/inode.c
--- linux-2.6.13-rc4-mm1-cur-prev/fs/relayfs/inode.c	2005-08-05 10:17:47.000000000 -0500
+++ linux-2.6.13-rc4-mm1-cur/fs/relayfs/inode.c	2005-08-06 11:36:02.000000000 -0500
@@ -301,15 +301,15 @@ static int relayfs_release(struct inode 
  *	position of the first actually available byte, otherwise
  *	return the original value.
  */
-static inline unsigned int relayfs_read_start(unsigned int read_pos,
-					      unsigned int avail,
-					      unsigned int start_subbuf,
-					      struct rchan_buf *buf)
-{
-	unsigned int read_subbuf, adj_read_subbuf;
-	unsigned int padding, padding_start, padding_end;
-	unsigned int subbuf_size = buf->chan->subbuf_size;
-	unsigned int n_subbufs = buf->chan->n_subbufs;
+static inline size_t relayfs_read_start(size_t read_pos,
+					size_t avail,
+					size_t start_subbuf,
+					struct rchan_buf *buf)
+{
+	size_t read_subbuf, adj_read_subbuf;
+	size_t padding, padding_start, padding_end;
+	size_t subbuf_size = buf->chan->subbuf_size;
+	size_t n_subbufs = buf->chan->n_subbufs;
 	
 	read_subbuf = read_pos / subbuf_size;
 	adj_read_subbuf = (read_subbuf + start_subbuf) % n_subbufs;
@@ -336,15 +336,15 @@ static inline unsigned int relayfs_read_
  *	most, 1 sub-buffer can be read at a time.
  *	
  */
-static inline unsigned int relayfs_read_end(unsigned int read_pos,
-					    unsigned int avail,
-					    unsigned int start_subbuf,
-					    struct rchan_buf *buf)
-{
-	unsigned int padding, read_endpos, buf_offset;
-	unsigned int read_subbuf, adj_read_subbuf;
-	unsigned int subbuf_size = buf->chan->subbuf_size;
-	unsigned int n_subbufs = buf->chan->n_subbufs;
+static inline size_t relayfs_read_end(size_t read_pos,
+				      size_t avail,
+				      size_t start_subbuf,
+				      struct rchan_buf *buf)
+{
+	size_t padding, read_endpos, buf_offset;
+	size_t read_subbuf, adj_read_subbuf;
+	size_t subbuf_size = buf->chan->subbuf_size;
+	size_t n_subbufs = buf->chan->n_subbufs;
 
 	buf_offset = buf->offset > subbuf_size ? subbuf_size : buf->offset;
 	read_subbuf = read_pos / subbuf_size;
@@ -369,12 +369,12 @@ static inline unsigned int relayfs_read_
  *	written to, otherwise it's the beginning of sub-buffer 0.
  *	
  */
-static inline unsigned int relayfs_read_avail(struct rchan_buf *buf,
-					      unsigned int *start_subbuf)
+static inline size_t relayfs_read_avail(struct rchan_buf *buf,
+					size_t *start_subbuf)
 {
-	unsigned int avail, complete_subbufs, cur_subbuf, buf_offset;
-	unsigned int subbuf_size = buf->chan->subbuf_size;
-	unsigned int n_subbufs = buf->chan->n_subbufs;
+	size_t avail, complete_subbufs, cur_subbuf, buf_offset;
+	size_t subbuf_size = buf->chan->subbuf_size;
+	size_t n_subbufs = buf->chan->n_subbufs;
 
 	buf_offset = buf->offset > subbuf_size ? subbuf_size : buf->offset;
 	
@@ -416,8 +416,8 @@ 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 -urpN -X dontdiff linux-2.6.13-rc4-mm1-cur-prev/fs/relayfs/relay.c linux-2.6.13-rc4-mm1-cur/fs/relayfs/relay.c
--- linux-2.6.13-rc4-mm1-cur-prev/fs/relayfs/relay.c	2005-08-05 10:17:30.000000000 -0500
+++ linux-2.6.13-rc4-mm1-cur/fs/relayfs/relay.c	2005-08-06 11:20:10.000000000 -0500
@@ -37,7 +37,7 @@ int relay_buf_empty(struct rchan_buf *bu
  */
 int relay_buf_full(struct rchan_buf *buf)
 {
-	unsigned int ready = buf->subbufs_produced - buf->subbufs_consumed;
+	size_t ready = buf->subbufs_produced - buf->subbufs_consumed;
 	return (ready >= buf->chan->n_subbufs) ? 1 : 0;
 }
 
@@ -56,7 +56,7 @@ int relay_buf_full(struct rchan_buf *buf
 static int subbuf_start_default_callback (struct rchan_buf *buf,
 					  void *subbuf,
 					  void *prev_subbuf,
-					  unsigned int prev_padding)
+					  size_t prev_padding)
 {
 	return 1;
 }
@@ -107,7 +107,7 @@ static void wakeup_readers(void *private
  */
 static inline void __relay_reset(struct rchan_buf *buf, unsigned int init)
 {
-	unsigned int i;
+	size_t i;
 	
 	if (init) {
 		init_waitqueue_head(&buf->read_wait);
@@ -230,8 +230,8 @@ static inline void setup_callbacks(struc
  */
 struct rchan *relay_open(const char *base_filename,
 			 struct dentry *parent,
-			 unsigned int subbuf_size,
-			 unsigned int n_subbufs,
+			 size_t subbuf_size,
+			 size_t n_subbufs,
 			 struct rchan_callbacks *cb)
 {
 	unsigned int i;
@@ -292,10 +292,10 @@ free_chan:
  *	Performs sub-buffer-switch tasks such as invoking callbacks,
  *	updating padding counts, waking up readers, etc.
  */
-unsigned int relay_switch_subbuf(struct rchan_buf *buf, unsigned int length)
+size_t relay_switch_subbuf(struct rchan_buf *buf, size_t length)
 {
 	void *old, *new;
-	unsigned int old_subbuf, new_subbuf;
+	size_t old_subbuf, new_subbuf;
 
 	if (unlikely(length > buf->chan->subbuf_size))
 		goto toobig;
@@ -348,7 +348,7 @@ toobig:
  */
 void relay_subbufs_consumed(struct rchan *chan,
 			    unsigned int cpu,
-			    unsigned int subbufs_consumed)
+			    size_t subbufs_consumed)
 {
 	struct rchan_buf *buf;
 
diff -urpN -X dontdiff linux-2.6.13-rc4-mm1-cur-prev/include/linux/relayfs_fs.h linux-2.6.13-rc4-mm1-cur/include/linux/relayfs_fs.h
--- linux-2.6.13-rc4-mm1-cur-prev/include/linux/relayfs_fs.h	2005-08-05 10:17:30.000000000 -0500
+++ linux-2.6.13-rc4-mm1-cur/include/linux/relayfs_fs.h	2005-08-06 11:33:16.000000000 -0500
@@ -31,9 +31,9 @@ struct rchan_buf
 {
 	void *start;			/* start of channel buffer */
 	void *data;			/* start of current sub-buffer */
-	unsigned int offset;		/* current offset into sub-buffer */
-	unsigned int subbufs_produced;	/* count of sub-buffers produced */
-	unsigned int subbufs_consumed;	/* count of sub-buffers consumed */
+	size_t offset;			/* current offset into sub-buffer */
+	size_t subbufs_produced;	/* count of sub-buffers produced */
+	size_t subbufs_consumed;	/* count of sub-buffers consumed */
 	struct rchan *chan;		/* associated channel */
 	wait_queue_head_t read_wait;	/* reader wait queue */
 	struct work_struct wake_readers; /* reader wake-up work struct */
@@ -42,8 +42,8 @@ struct rchan_buf
 	struct page **page_array;	/* array of current buffer pages */
 	unsigned int page_count;	/* number of current buffer pages */
 	unsigned int finalized;		/* buffer has been finalized */
-	unsigned *padding;		/* padding counts per sub-buffer */
-	unsigned int prev_padding;	/* temporary variable */
+	size_t *padding;		/* padding counts per sub-buffer */
+	size_t prev_padding;		/* temporary variable */
 } ____cacheline_aligned;
 
 /*
@@ -52,9 +52,9 @@ struct rchan_buf
 struct rchan
 {
 	u32 version;			/* the version of this struct */
-	unsigned int subbuf_size;	/* sub-buffer size */
-	unsigned int n_subbufs;		/* number of sub-buffers per buffer */
-	unsigned int alloc_size;	/* total buffer size allocated */
+	size_t subbuf_size;		/* sub-buffer size */
+	size_t n_subbufs;		/* number of sub-buffers per buffer */
+	size_t alloc_size;		/* total buffer size allocated */
 	struct rchan_callbacks *cb;	/* client callbacks */
 	struct kref kref;		/* channel refcount */
 	void *private_data;		/* for user-defined data */
@@ -100,7 +100,7 @@ struct rchan_callbacks
 	int (*subbuf_start) (struct rchan_buf *buf,
 			     void *subbuf,
 			     void *prev_subbuf,
-			     unsigned int prev_padding);
+			     size_t prev_padding);
 
 	/*
 	 * buf_mapped - relayfs buffer mmap notification
@@ -129,19 +129,19 @@ struct rchan_callbacks
 
 struct rchan *relay_open(const char *base_filename,
 			 struct dentry *parent,
-			 unsigned int subbuf_size,
-			 unsigned int n_subbufs,
+			 size_t subbuf_size,
+			 size_t n_subbufs,
 			 struct rchan_callbacks *cb);
 extern void relay_close(struct rchan *chan);
 extern void relay_flush(struct rchan *chan);
 extern void relay_subbufs_consumed(struct rchan *chan,
 				   unsigned int cpu,
-				   unsigned int consumed);
+				   size_t consumed);
 extern void relay_reset(struct rchan *chan);
 extern int relay_buf_full(struct rchan_buf *buf);
 
-extern unsigned int relay_switch_subbuf(struct rchan_buf *buf,
-					unsigned int length);
+extern size_t relay_switch_subbuf(struct rchan_buf *buf,
+				  size_t length);
 extern struct dentry *relayfs_create_dir(const char *name,
 					 struct dentry *parent);
 extern int relayfs_remove_dir(struct dentry *dentry);
@@ -161,7 +161,7 @@ extern int relayfs_remove_dir(struct den
  */
 static inline void relay_write(struct rchan *chan,
 			       const void *data,
-			       unsigned int length)
+			       size_t length)
 {
 	unsigned long flags;
 	struct rchan_buf *buf;
@@ -189,7 +189,7 @@ static inline void relay_write(struct rc
  */
 static inline void __relay_write(struct rchan *chan,
 				 const void *data,
-				 unsigned int length)
+				 size_t length)
 {
 	struct rchan_buf *buf;
 
@@ -212,7 +212,7 @@ static inline void __relay_write(struct 
  *	Does not protect the buffer at all - caller must provide
  *	appropriate synchronization.
  */
-static inline void *relay_reserve(struct rchan *chan, unsigned length)
+static inline void *relay_reserve(struct rchan *chan, size_t length)
 {
 	void *reserved;
 	struct rchan_buf *buf = chan->buf[smp_processor_id()];
@@ -237,7 +237,7 @@ static inline void *relay_reserve(struct
  *	a sub-buffer in the subbuf_start() callback.
  */
 static inline void subbuf_start_reserve(struct rchan_buf *buf,
-					unsigned int length)
+					size_t length)
 {
 	BUG_ON(length >= buf->chan->subbuf_size - 1);
 	buf->offset = length;

Re: [-mm patch] relayfs: add read() support

[Jens Axboe]

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

Re: [-mm patch] relayfs: add read() support

[Tom Zanussi]

Jens Axboe writes:
 > 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!

Great, glad to hear it!  I should have noted in the posting, though,
that you should first apply the 'API cleanup' patch, in which case you
shouldn't get the compile errors.

Tom

Re: [-mm patch] relayfs: add read() support

[Jens Axboe]

On Fri, Aug 05 2005, Tom Zanussi wrote:
> Jens Axboe writes:
>  > 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!
> 
> Great, glad to hear it!  I should have noted in the posting, though,
> that you should first apply the 'API cleanup' patch, in which case you
> shouldn't get the compile errors.

Ah, I see. The API is also much cleaner than what I looked at a few
months ago (even before the cleanup).

Andrew, can you merge it pretty please?

-- 
Jens Axboe

Re: [-mm patch] relayfs: add read() support

[Andrew Morton]

Jens Axboe <axboe@suse.de> wrote:
>
> On Fri, Aug 05 2005, Tom Zanussi wrote:
> > Jens Axboe writes:
> >  > 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!
> > 
> > Great, glad to hear it!  I should have noted in the posting, though,
> > that you should first apply the 'API cleanup' patch, in which case you
> > shouldn't get the compile errors.
> 
> Ah, I see. The API is also much cleaner than what I looked at a few
> months ago (even before the cleanup).
> 
> Andrew, can you merge it pretty please?

yup, we'll add relayfs to 2.6.14.