(resend) reuse xxx_fifo_fops for xxx_pipe_fops

PATCH In review Denys Vlasenko 3 participants 8 messages Jul 1, 2008 VFS

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Denys Vlasenko

author

2008-07-01 07:02 UTC #0 lore raw

PATCH 1/1 (resend) reuse xxx_fifo_fops for xxx_pipe_fops

Hi Andrew, Al,

I posted this patch a few months ago, but it apparently fell thru cracks. Here we go again.

I noticed that read/write/rdwr_pipe_fops are (1) const and
(2) exactly identical to xxx_fifo_fops, which are also const.

Attached patch #defines xxx_pipe_fops as aliases to xxx_fifo_fops. Size difference:

# size linux-2.6.25-rc6*/*/pipe.o
   text    data     bss     dec     hex filename
   6534     144       0    6678    1a16 linux-2.6.25-rc6/fs/pipe.o
   5862     144       0    6006    1776 linux-2.6.25-rc6-pt/fs/pipe.o

Run-tested on 2.6.26-rc8. Please apply.

Signed-off-by Denys Vlasenko <[email protected]>

--
vda

fs/pipe.c +3 ~~-36~~

@@ -814,42 +814,9 @@
 	.fasync		= pipe_rdwr_fasync,
 };
 
-static const struct file_operations read_pipe_fops = {
-	.llseek		= no_llseek,
-	.read		= do_sync_read,
-	.aio_read	= pipe_read,
-	.write		= bad_pipe_w,
-	.poll		= pipe_poll,
-	.unlocked_ioctl	= pipe_ioctl,
-	.open		= pipe_read_open,
-	.release	= pipe_read_release,
-	.fasync		= pipe_read_fasync,
-};
-
-static const struct file_operations write_pipe_fops = {
-	.llseek		= no_llseek,
-	.read		= bad_pipe_r,
-	.write		= do_sync_write,
-	.aio_write	= pipe_write,
-	.poll		= pipe_poll,
-	.unlocked_ioctl	= pipe_ioctl,
-	.open		= pipe_write_open,
-	.release	= pipe_write_release,
-	.fasync		= pipe_write_fasync,
-};
-
-static const struct file_operations rdwr_pipe_fops = {
-	.llseek		= no_llseek,
-	.read		= do_sync_read,
-	.aio_read	= pipe_read,
-	.write		= do_sync_write,
-	.aio_write	= pipe_write,
-	.poll		= pipe_poll,
-	.unlocked_ioctl	= pipe_ioctl,
-	.open		= pipe_rdwr_open,
-	.release	= pipe_rdwr_release,
-	.fasync		= pipe_rdwr_fasync,
-};
+#define read_pipe_fops  read_fifo_fops
+#define write_pipe_fops write_fifo_fops
+#define rdwr_pipe_fops  rdwr_fifo_fops
 
 struct pipe_inode_info * alloc_pipe_info(struct inode *inode)
 {

Christoph Hellwig

2008-07-01 07:31 UTC #1 lore raw

Quoted 10 lines · Denys Vlasenko

Hi Andrew, Al,
I posted this patch a few months ago, but it apparently fell thru cracks. Here we go again.
I noticed that read/write/rdwr_pipe_fops are (1) const and
(2) exactly identical to xxx_fifo_fops, which are also const.
Attached patch #defines xxx_pipe_fops as aliases to xxx_fifo_fops. Size difference:

Why do you need the #defines? Just use the _fifo_ name directly.

Andrew Morton

2008-07-01 07:33 UTC #2 lore raw

In reply to Denys Vlasenko

Quoted 11 lines · On Tue, 1 Jul 2008 11:03:02 +0200 Denys Vlasenko <[email protected]>…

Hi Andrew, Al,
I posted this patch a few months ago, but it apparently fell thru cracks. Here we go again.
I noticed that read/write/rdwr_pipe_fops are (1) const and
(2) exactly identical to xxx_fifo_fops, which are also const.
Attached patch #defines xxx_pipe_fops as aliases to xxx_fifo_fops. Size difference:

Quoted 8 lines

# size linux-2.6.25-rc6*/*/pipe.o
   text    data     bss     dec     hex filename
   6534     144       0    6678    1a16 linux-2.6.25-rc6/fs/pipe.o
   5862     144       0    6006    1776 linux-2.6.25-rc6-pt/fs/pipe.o

Run-tested on 2.6.26-rc8. Please apply.

Signed-off-by Denys Vlasenko <[email protected]>

<argh, an attachment. save-as, read, edit..>

--- linux-2.6.25-rc6.src/fs/pipe.c Sat Mar 22 23:00:34 2008

Quoted 37 lines

+++ linux-2.6.25-rc6.pipe/fs/pipe.c Fri Mar 28 15:52:00 2008

fs/pipe.c +0 ~~-32~~

@@ -814,42 +814,9 @@
 	.fasync		= pipe_rdwr_fasync,
 };
 
-static const struct file_operations read_pipe_fops = {
-	.llseek		= no_llseek,
-	.read		= do_sync_read,
-	.aio_read	= pipe_read,
-	.write		= bad_pipe_w,
-	.poll		= pipe_poll,
-	.unlocked_ioctl	= pipe_ioctl,
-	.open		= pipe_read_open,
-	.release	= pipe_read_release,
-	.fasync		= pipe_read_fasync,
-};
-
-static const struct file_operations write_pipe_fops = {
-	.llseek		= no_llseek,
-	.read		= bad_pipe_r,
-	.write		= do_sync_write,
-	.aio_write	= pipe_write,
-	.poll		= pipe_poll,
-	.unlocked_ioctl	= pipe_ioctl,
-	.open		= pipe_write_open,
-	.release	= pipe_write_release,
-	.fasync		= pipe_write_fasync,
-};
-
-static const struct file_operations rdwr_pipe_fops = {
-	.llseek		= no_llseek,
-	.read		= do_sync_read,
-	.aio_read	= pipe_read,
-	.write		= do_sync_write,
-	.aio_write	= pipe_write,
-	.poll		= pipe_poll,
-	.unlocked_ioctl	= pipe_ioctl,

fs/pipe.c line 822

Quoted 10 lines

fs/pipe.c +3 -4

-	.open		= pipe_rdwr_open,
-	.release	= pipe_rdwr_release,
-	.fasync		= pipe_rdwr_fasync,
-};
+#define read_pipe_fops  read_fifo_fops
+#define write_pipe_fops write_fifo_fops
+#define rdwr_pipe_fops  rdwr_fifo_fops
 
 struct pipe_inode_info * alloc_pipe_info(struct inode *inode)
 {

Well OK. But there's a risk that someone will go and modify read_fifo_fops without realising that they're also modifying read_pipe_fops.

So it'd be better to rename read_fifo_fops to (say) shared_read_fops then do

#define read_pipe_fops shared_read_fops
#define read_fifo_fops shared_read_fops

no?

Denys Vlasenko

author

2008-07-01 08:03 UTC #3 lore raw

Quoted 11 lines · Andrew Morton

Quoted 11 lines
I noticed that read/write/rdwr_pipe_fops are (1) const and
(2) exactly identical to xxx_fifo_fops, which are also const.
Attached patch #defines xxx_pipe_fops as aliases to xxx_fifo_fops. Size difference:
# size linux-2.6.25-rc6*/*/pipe.o
   text    data     bss     dec     hex filename
   6534     144       0    6678    1a16 linux-2.6.25-rc6/fs/pipe.o
   5862     144       0    6006    1776 linux-2.6.25-rc6-pt/fs/pipe.o

Quoted 5 lines

Quoted 3 lines
Run-tested on 2.6.26-rc8. Please apply.
Signed-off-by Denys Vlasenko <[email protected]>
<argh, an attachment. save-as, read, edit..>

Let's see how KMail will cope with inline cut-n-paste...

Quoted 11 lines

(quoted diff) +0 ~~-11~~

-static const struct file_operations rdwr_pipe_fops = {
-	.llseek		= no_llseek,
-	.read		= do_sync_read,
-	.aio_read	= pipe_read,
-	.write		= do_sync_write,
-	.aio_write	= pipe_write,
-	.poll		= pipe_poll,
-	.unlocked_ioctl	= pipe_ioctl,
-	.open		= pipe_rdwr_open,
-	.release	= pipe_rdwr_release,
-	.fasync		= pipe_rdwr_fasync,

Quoted 8 lines

Review
Quoted 4 lines
(quoted diff) +3 -1
-};
+#define read_pipe_fops  read_fifo_fops
+#define write_pipe_fops write_fifo_fops
+#define rdwr_pipe_fops  rdwr_fifo_fops
Well OK. But there's a risk that someone will go and modify read_fifo_fops without realising that they're also modifying read_pipe_fops.

Yes, it is possible.

Quoted 5 lines

So it'd be better to rename read_fifo_fops to (say) shared_read_fops then do
#define read_pipe_fops shared_read_fops
#define read_fifo_fops shared_read_fops

I think since XXX_pipe_fops are only used in this file, just explaining this in the comment would be enough.

Please take a look at the version below.

Signed-off-by Denys Vlasenko <[email protected]>

--
vda

fs/pipe.c renamed from fs/pipe.c.org +5 ~~-40~~

@@ -777,6 +777,8 @@
 /*
  * The file_operations structs are not static because they
  * are also used in linux/fs/fifo.c to do operations on FIFOs.
+ *
+ * Pipes reuse fifos' file_operations structs.
  */
 const struct file_operations read_fifo_fops = {
 	.llseek		= no_llseek,

@@ -815,43 +817,6 @@
 	.fasync		= pipe_rdwr_fasync,
 };
 
-static const struct file_operations read_pipe_fops = {
-	.llseek		= no_llseek,
-	.read		= do_sync_read,
-	.aio_read	= pipe_read,
-	.write		= bad_pipe_w,
-	.poll		= pipe_poll,
-	.unlocked_ioctl	= pipe_ioctl,
-	.open		= pipe_read_open,
-	.release	= pipe_read_release,
-	.fasync		= pipe_read_fasync,
-};
-
-static const struct file_operations write_pipe_fops = {
-	.llseek		= no_llseek,
-	.read		= bad_pipe_r,
-	.write		= do_sync_write,
-	.aio_write	= pipe_write,
-	.poll		= pipe_poll,
-	.unlocked_ioctl	= pipe_ioctl,
-	.open		= pipe_write_open,
-	.release	= pipe_write_release,
-	.fasync		= pipe_write_fasync,
-};
-
-static const struct file_operations rdwr_pipe_fops = {
-	.llseek		= no_llseek,
-	.read		= do_sync_read,
-	.aio_read	= pipe_read,
-	.write		= do_sync_write,
-	.aio_write	= pipe_write,
-	.poll		= pipe_poll,
-	.unlocked_ioctl	= pipe_ioctl,
-	.open		= pipe_rdwr_open,
-	.release	= pipe_rdwr_release,
-	.fasync		= pipe_rdwr_fasync,
-};
-
 struct pipe_inode_info * alloc_pipe_info(struct inode *inode)
 {
 	struct pipe_inode_info *pipe;

@@ -927,7 +892,7 @@
 	inode->i_pipe = pipe;
 
 	pipe->readers = pipe->writers = 1;
-	inode->i_fop = &rdwr_pipe_fops;
+	inode->i_fop = &rdwr_fifo_fops;
 
 	/*
 	 * Mark the inode dirty from the very beginning,

@@ -978,7 +943,7 @@
 	d_instantiate(dentry, inode);
 
 	err = -ENFILE;
-	f = alloc_file(pipe_mnt, dentry, FMODE_WRITE, &write_pipe_fops);
+	f = alloc_file(pipe_mnt, dentry, FMODE_WRITE, &write_fifo_fops);
 	if (!f)
 		goto err_dentry;
 	f->f_mapping = inode->i_mapping;

@@ -1021,7 +986,7 @@
 
 	f->f_pos = 0;
 	f->f_flags = O_RDONLY;
-	f->f_op = &read_pipe_fops;
+	f->f_op = &read_fifo_fops;
 	f->f_mode = FMODE_READ;
 	f->f_version = 0;

Andrew Morton

2008-07-01 08:10 UTC #4 lore raw

Quoted 2 lines · On Tue, 1 Jul 2008 12:03:50 +0200 Denys Vlasenko <[email protected]>…

I think since XXX_pipe_fops are only used in this file, just explaining this in the comment would be enough.

no, a comment is only needed when the code is unobvious. Make the code obvious and we don't need a comment.

As Christoph pointed out, open-coding shared_read_fops everywhere might make sense too. It'd make it harder to unshare them later on, but that's pretty improbable.

Christoph Hellwig

2008-07-01 08:15 UTC #5 lore raw

Quoted 11 lines · Andrew Morton

Quoted 2 lines · On Tue, 1 Jul 2008 12:03:50 +0200 Denys Vlasenko <[email protected]>…
I think since XXX_pipe_fops are only used in this file, just explaining this in the comment would be enough.
no, a comment is only needed when the code is unobvious. Make the code obvious and we don't need a comment.
As Christoph pointed out, open-coding shared_read_fops everywhere might make sense too. It'd make it harder to unshare them later on, but that's pretty improbable.

Deny's latest patch doesn't have the #defines anymore and looks quite reasonable to me. If you really insist on magic naming I think shared is a very bad choice because it doesn't have any useful meaning in this context. If you insist on magic naming do _pipefifo_, but I think the current version with the comment is much better.

Denys Vlasenko

author

2008-07-01 10:11 UTC #6 lore raw

In reply to Andrew Morton

Quoted 11 lines · Andrew Morton

Quoted 2 lines · On Tue, 1 Jul 2008 12:03:50 +0200 Denys Vlasenko <[email protected]>…
I think since XXX_pipe_fops are only used in this file, just explaining this in the comment would be enough.
no, a comment is only needed when the code is unobvious. Make the code obvious and we don't need a comment.
As Christoph pointed out, open-coding shared_read_fops everywhere might make sense too. It'd make it harder to unshare them later on, but that's pretty improbable.

Ok.

Signed-off-by Denys Vlasenko <[email protected]>

--
vda

fs/fifo.c renamed from fs.org/fifo.c +4 -4

@@ -57,7 +57,7 @@
 	 *  POSIX.1 says that O_NONBLOCK means return with the FIFO
 	 *  opened, even when there is no process writing the FIFO.
 	 */
-		filp->f_op = &read_fifo_fops;
+		filp->f_op = &read_pipefifo_fops;
 		pipe->r_counter++;
 		if (pipe->readers++ == 0)
 			wake_up_partner(inode);

@@ -86,7 +86,7 @@
 		if ((filp->f_flags & O_NONBLOCK) && !pipe->readers)
 			goto err;
 
-		filp->f_op = &write_fifo_fops;
+		filp->f_op = &write_pipefifo_fops;
 		pipe->w_counter++;
 		if (!pipe->writers++)
 			wake_up_partner(inode);

@@ -105,7 +105,7 @@
 	 *  This implementation will NEVER block on a O_RDWR open, since
 	 *  the process can at least talk to itself.
 	 */
-		filp->f_op = &rdwr_fifo_fops;
+		filp->f_op = &rdwr_pipefifo_fops;
 
 		pipe->readers++;
 		pipe->writers++;

@@ -151,5 +151,5 @@
  * depending on the access mode of the file...
  */
 const struct file_operations def_fifo_fops = {
-	.open		= fifo_open,	/* will set read or write pipe_fops */
+	.open		= fifo_open,	/* will set read_ or write_pipefifo_fops */
 };

fs/pipe.c renamed from fs.org/pipe.c +8 ~~-43~~

94 lines not on this page · raw message

Denys Vlasenko

author

2008-07-01 10:16 UTC #7 lore raw

Quoted 6 lines · Denys Vlasenko

Quoted 5 lines · Andrew Morton
Quoted 2 lines · On Tue, 1 Jul 2008 12:03:50 +0200 Denys Vlasenko <[email protected]>…
I think since XXX_pipe_fops are only used in this file, just explaining this in the comment would be enough.

Quoted 8 lines

Quoted 6 lines
no, a comment is only needed when the code is unobvious. Make the code obvious and we don't need a comment.
As Christoph pointed out, open-coding shared_read_fops everywhere might make sense too. It'd make it harder to unshare them later on, but that's pretty improbable.
Ok.

And this one is even better [because it actually compiles :) ]. I forgot to change fs.h - XXX_pipefifo_fops live there.

Signed-off-by Denys Vlasenko <[email protected]>

--
vda

fs/fifo.c renamed from fs.org/fifo.c +4 -4

@@ -57,7 +57,7 @@
 	 *  POSIX.1 says that O_NONBLOCK means return with the FIFO
 	 *  opened, even when there is no process writing the FIFO.
 	 */
-		filp->f_op = &read_fifo_fops;
+		filp->f_op = &read_pipefifo_fops;
 		pipe->r_counter++;
 		if (pipe->readers++ == 0)
 			wake_up_partner(inode);

@@ -86,7 +86,7 @@
 		if ((filp->f_flags & O_NONBLOCK) && !pipe->readers)
 			goto err;
 
-		filp->f_op = &write_fifo_fops;
+		filp->f_op = &write_pipefifo_fops;
 		pipe->w_counter++;
 		if (!pipe->writers++)
 			wake_up_partner(inode);

@@ -105,7 +105,7 @@
 	 *  This implementation will NEVER block on a O_RDWR open, since
 	 *  the process can at least talk to itself.
 	 */
-		filp->f_op = &rdwr_fifo_fops;
+		filp->f_op = &rdwr_pipefifo_fops;
 
 		pipe->readers++;
 		pipe->writers++;

@@ -151,5 +151,5 @@
  * depending on the access mode of the file...
  */
 const struct file_operations def_fifo_fops = {
-	.open		= fifo_open,	/* will set read or write pipe_fops */
+	.open		= fifo_open,	/* will set read_ or write_pipefifo_fops */
 };

fs/pipe.c renamed from fs.org/pipe.c +8 ~~-43~~

94 lines not on this page · raw message

include/linux/fs.h renamed from include.org/linux/fs.h +3 -3

@@ -1687,9 +1687,9 @@
 extern void make_bad_inode(struct inode *);
 extern int is_bad_inode(struct inode *);
 
-extern const struct file_operations read_fifo_fops;
-extern const struct file_operations write_fifo_fops;
-extern const struct file_operations rdwr_fifo_fops;
+extern const struct file_operations read_pipefifo_fops;
+extern const struct file_operations write_pipefifo_fops;
+extern const struct file_operations rdwr_pipefifo_fops;
 
 extern int fs_may_remount_ro(struct super_block *);