[RFC] block: remove never-modified global variable

[RFC] block: remove never-modified global variable

[Brian Norris]

AFAICT, 'warn_no_part' never takes (and never has? at least, not in the
git history) taken a value besides 1. It also has a disgruntled warning
comment next to it, suggesting it shouldn't be there at all.

Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Boaz Harrosh <boaz@plexistor.com>
Cc: Jens Axboe <axboe@fb.com>
---
Only compile tested for now, as it's trivial. Just an RFC, since I don't really
understand the context of why this (or the comment) is here in the first place.
I just ran across this in code reading.

 block/partitions/amiga.c | 10 ++++------
 block/partitions/check.c |  7 ++-----
 block/partitions/check.h |  2 --
 3 files changed, 6 insertions(+), 13 deletions(-)

diff --git a/block/partitions/amiga.c b/block/partitions/amiga.c
index 2b13533d60a2..9dbf1cec7152 100644
--- a/block/partitions/amiga.c
+++ b/block/partitions/amiga.c
@@ -41,9 +41,8 @@ int amiga_partition(struct parsed_partitions *state)
 			goto rdb_done;
 		data = read_part_sector(state, blk, &sect);
 		if (!data) {
-			if (warn_no_part)
-				pr_err("Dev %s: unable to read RDB block %d\n",
-				       bdevname(state->bdev, b), blk);
+			pr_err("Dev %s: unable to read RDB block %d\n",
+			       bdevname(state->bdev, b), blk);
 			res = -1;
 			goto rdb_done;
 		}
@@ -84,9 +83,8 @@ int amiga_partition(struct parsed_partitions *state)
 		blk *= blksize;	/* Read in terms partition table understands */
 		data = read_part_sector(state, blk, &sect);
 		if (!data) {
-			if (warn_no_part)
-				pr_err("Dev %s: unable to read partition block %d\n",
-				       bdevname(state->bdev, b), blk);
+			pr_err("Dev %s: unable to read partition block %d\n",
+			       bdevname(state->bdev, b), blk);
 			res = -1;
 			goto rdb_done;
 		}
diff --git a/block/partitions/check.c b/block/partitions/check.c
index 16118d11dbfc..513c601b7874 100644
--- a/block/partitions/check.c
+++ b/block/partitions/check.c
@@ -36,8 +36,6 @@
 #include "sysv68.h"
 #include "cmdline.h"
 
-int warn_no_part = 1; /*This is ugly: should make genhd removable media aware*/
-
 static int (*check_part[])(struct parsed_partitions *) = {
 	/*
 	 * Probe partition formats with tables at disk address 0
@@ -185,9 +183,8 @@ check_partition(struct gendisk *hd, struct block_device *bdev)
 	/* The partition is unrecognized. So report I/O errors if there were any */
 		res = err;
 	if (res) {
-		if (warn_no_part)
-			strlcat(state->pp_buf,
-				" unable to read partition table\n", PAGE_SIZE);
+		strlcat(state->pp_buf,
+			" unable to read partition table\n", PAGE_SIZE);
 		printk(KERN_INFO "%s", state->pp_buf);
 	}
 
diff --git a/block/partitions/check.h b/block/partitions/check.h
index eade17ea910b..e09fac216adc 100644
--- a/block/partitions/check.h
+++ b/block/partitions/check.h
@@ -50,5 +50,3 @@ put_partition(struct parsed_partitions *p, int n, sector_t from, sector_t size)
 	}
 }
 
-extern int warn_no_part;
-
-- 
1.9.1

Re: [RFC] block: remove never-modified global variable

[Boaz Harrosh]

On 05/19/2015 02:08 AM, Brian Norris wrote:
> AFAICT, 'warn_no_part' never takes (and never has? at least, not in the
> git history) taken a value besides 1. It also has a disgruntled warning
> comment next to it, suggesting it shouldn't be there at all.
> 
> Signed-off-by: Brian Norris <computersforpeace@gmail.com>
> Cc: Christoph Hellwig <hch@infradead.org>
> Cc: Boaz Harrosh <boaz@plexistor.com>

Reviewed-by: Boaz Harrosh <boaz@plexistor.com>

I have also tested it by returning error from read of sector zero.
And the print prints. Of course. No one ever turns it off.

Some comments

> Cc: Jens Axboe <axboe@fb.com>
> ---
> Only compile tested for now, as it's trivial. Just an RFC, since I don't really
> understand the context of why this (or the comment) is here in the first place.
> I just ran across this in code reading.
> 
>  block/partitions/amiga.c | 10 ++++------
>  block/partitions/check.c |  7 ++-----
>  block/partitions/check.h |  2 --
>  3 files changed, 6 insertions(+), 13 deletions(-)
> 
> diff --git a/block/partitions/amiga.c b/block/partitions/amiga.c
> index 2b13533d60a2..9dbf1cec7152 100644
> --- a/block/partitions/amiga.c
> +++ b/block/partitions/amiga.c
> @@ -41,9 +41,8 @@ int amiga_partition(struct parsed_partitions *state)
>  			goto rdb_done;
>  		data = read_part_sector(state, blk, &sect);
>  		if (!data) {
> -			if (warn_no_part)
> -				pr_err("Dev %s: unable to read RDB block %d\n",
> -				       bdevname(state->bdev, b), blk);
> +			pr_err("Dev %s: unable to read RDB block %d\n",
> +			       bdevname(state->bdev, b), blk);
>  			res = -1;
>  			goto rdb_done;
>  		}
> @@ -84,9 +83,8 @@ int amiga_partition(struct parsed_partitions *state)
>  		blk *= blksize;	/* Read in terms partition table understands */
>  		data = read_part_sector(state, blk, &sect);
>  		if (!data) {
> -			if (warn_no_part)
> -				pr_err("Dev %s: unable to read partition block %d\n",
> -				       bdevname(state->bdev, b), blk);
> +			pr_err("Dev %s: unable to read partition block %d\n",
> +			       bdevname(state->bdev, b), blk);
>  			res = -1;
>  			goto rdb_done;
>  		}
> diff --git a/block/partitions/check.c b/block/partitions/check.c
> index 16118d11dbfc..513c601b7874 100644
> --- a/block/partitions/check.c
> +++ b/block/partitions/check.c
> @@ -36,8 +36,6 @@
>  #include "sysv68.h"
>  #include "cmdline.h"
>  
> -int warn_no_part = 1; /*This is ugly: should make genhd removable media aware*/
> -
>  static int (*check_part[])(struct parsed_partitions *) = {
>  	/*
>  	 * Probe partition formats with tables at disk address 0
> @@ -185,9 +183,8 @@ check_partition(struct gendisk *hd, struct block_device *bdev)
>  	/* The partition is unrecognized. So report I/O errors if there were any */
>  		res = err;
>  	if (res) {
> -		if (warn_no_part)
> -			strlcat(state->pp_buf,
> -				" unable to read partition table\n", PAGE_SIZE);
> +		strlcat(state->pp_buf,
> +			" unable to read partition table\n", PAGE_SIZE);

OK I admit this was kind of very dumb before, If theoretically warn_no_part
would be false then the system would print "disk_name:\n" and nothing
else.

But specially now that you are unconditionally printing it. It is better
to just combine the two statements. See suggested patch below:

>  		printk(KERN_INFO "%s", state->pp_buf);
>  	}
>  
> diff --git a/block/partitions/check.h b/block/partitions/check.h
> index eade17ea910b..e09fac216adc 100644
> --- a/block/partitions/check.h
> +++ b/block/partitions/check.h
> @@ -50,5 +50,3 @@ put_partition(struct parsed_partitions *p, int n, sector_t from, sector_t size)
>  	}
>  }
>  
> -extern int warn_no_part;
> -
> 

diff --git a/block/partitions/check.c b/block/partitions/check.c
index 513c601..5fd2b7e 100644
--- a/block/partitions/check.c
+++ b/block/partitions/check.c
@@ -182,11 +182,9 @@ check_partition(struct gendisk *hd, struct block_device *bdev)
 	if (err)
 	/* The partition is unrecognized. So report I/O errors if there were any */
 		res = err;
-	if (res) {
-		strlcat(state->pp_buf,
-			" unable to read partition table\n", PAGE_SIZE);
-		printk(KERN_INFO "%s", state->pp_buf);
-	}
+	if (res)
+		printk(KERN_INFO "%s unable to read partition table\n",
+		       state->pp_buf);
 
 	free_page((unsigned long)state->pp_buf);
 	free_partitions(state);

Thanks
Boaz

Re: [RFC] block: remove never-modified global variable

[Boaz Harrosh]

On 05/19/2015 10:19 AM, Boaz Harrosh wrote:
<>
> But specially now that you are unconditionally printing it. It is better
> to just combine the two statements. See suggested patch below:
> 

Actually we can even do better:

diff --git a/block/partitions/check.c b/block/partitions/check.c
index 513c601..9bea23d 100644
--- a/block/partitions/check.c
+++ b/block/partitions/check.c
@@ -160,35 +160,31 @@ check_partition(struct gendisk *hd, struct block_device *bdev)
 
 	i = res = err = 0;
 	while (!res && check_part[i]) {
 		memset(state->parts, 0, state->limit * sizeof(state->parts[0]));
 		res = check_part[i++](state);
 		if (res < 0) {
 			/* We have hit an I/O error which we don't report now.
 		 	* But record it, and let the others do their job.
 		 	*/
 			err = res;
 			res = 0;
 		}
 
 	}

boaz> When we exit the loop res can only be (res >= 0)

 	if (res > 0) {
 		printk(KERN_INFO "%s", state->pp_buf);
 
 		free_page((unsigned long)state->pp_buf);
 		return state;

boaz> When bigger we exit here

 	}
 	if (state->access_beyond_eod)
 		err = -ENOSPC;

boaz> So by this stage res can only be == 0. So we should just do:

 	if (err)
	/* The partition is unrecognized. So report I/O errors if there were any */
-		res = err;
-	if (res) {
-		strlcat(state->pp_buf,
-			" unable to read partition table\n", PAGE_SIZE);
-		printk(KERN_INFO "%s", state->pp_buf);
-	}
+		printk(KERN_INFO "%s unable to read partition table\n",
+		       state->pp_buf);
 
 	free_page((unsigned long)state->pp_buf);
 	free_partitions(state);
 	return ERR_PTR(res);
 }

----
Here is a proper diff:
----
diff --git a/block/partitions/check.c b/block/partitions/check.c
index 513c601..9bea23d 100644
--- a/block/partitions/check.c
+++ b/block/partitions/check.c
@@ -181,12 +181,8 @@ check_partition(struct gendisk *hd, struct block_device *bdev)
 		err = -ENOSPC;
 	if (err)
 	/* The partition is unrecognized. So report I/O errors if there were any */
-		res = err;
-	if (res) {
-		strlcat(state->pp_buf,
-			" unable to read partition table\n", PAGE_SIZE);
-		printk(KERN_INFO "%s", state->pp_buf);
-	}
+		printk(KERN_INFO "%s unable to read partition table\n",
+		       state->pp_buf);
 
 	free_page((unsigned long)state->pp_buf);
 	free_partitions(state);

Thanks
Boaz

Re: [RFC] block: remove never-modified global variable

[Brian Norris]

On Tue, May 19, 2015 at 10:34:56AM +0300, Boaz Harrosh wrote:
> On 05/19/2015 10:19 AM, Boaz Harrosh wrote:
> <>
> > But specially now that you are unconditionally printing it. It is better
> > to just combine the two statements. See suggested patch below:
> > 
> 
> Actually we can even do better:
> 
> diff --git a/block/partitions/check.c b/block/partitions/check.c
> index 513c601..9bea23d 100644
> --- a/block/partitions/check.c
> +++ b/block/partitions/check.c
> @@ -160,35 +160,31 @@ check_partition(struct gendisk *hd, struct block_device *bdev)
>  
>  	i = res = err = 0;
>  	while (!res && check_part[i]) {
>  		memset(state->parts, 0, state->limit * sizeof(state->parts[0]));
>  		res = check_part[i++](state);
>  		if (res < 0) {
>  			/* We have hit an I/O error which we don't report now.
>  		 	* But record it, and let the others do their job.
>  		 	*/
>  			err = res;
>  			res = 0;
>  		}
>  
>  	}
> 
> boaz> When we exit the loop res can only be (res >= 0)
> 
>  	if (res > 0) {
>  		printk(KERN_INFO "%s", state->pp_buf);
>  
>  		free_page((unsigned long)state->pp_buf);
>  		return state;
> 
> boaz> When bigger we exit here
> 
>  	}
>  	if (state->access_beyond_eod)
>  		err = -ENOSPC;
> 
> boaz> So by this stage res can only be == 0. So we should just do:
> 
>  	if (err)
> 	/* The partition is unrecognized. So report I/O errors if there were any */
> -		res = err;

^^ You don't want to kill this line, since we still return ERR_PRT(res).
But otherwise, I think you're right.

> -	if (res) {
> -		strlcat(state->pp_buf,
> -			" unable to read partition table\n", PAGE_SIZE);
> -		printk(KERN_INFO "%s", state->pp_buf);
> -	}
> +		printk(KERN_INFO "%s unable to read partition table\n",
> +		       state->pp_buf);
>  
>  	free_page((unsigned long)state->pp_buf);
>  	free_partitions(state);
>  	return ERR_PTR(res);
>  }
> 
> ----
> Here is a proper diff:

I can send out a full patch, squashing my original + your fixup + my
fixup, if that sounds OK.

Brian

Re: [RFC] block: remove never-modified global variable

[Brian Norris]

On Tue, May 19, 2015 at 10:55:32AM -0700, Brian Norris wrote:
> On Tue, May 19, 2015 at 10:34:56AM +0300, Boaz Harrosh wrote:
> > boaz> So by this stage res can only be == 0. So we should just do:
> > 
> >  	if (err)
> > 	/* The partition is unrecognized. So report I/O errors if there were any */
> > -		res = err;
> 
> ^^ You don't want to kill this line, since we still return ERR_PRT(res).
> But otherwise, I think you're right.
> 
> > -	if (res) {
> > -		strlcat(state->pp_buf,
> > -			" unable to read partition table\n", PAGE_SIZE);
> > -		printk(KERN_INFO "%s", state->pp_buf);
> > -	}
> > +		printk(KERN_INFO "%s unable to read partition table\n",
> > +		       state->pp_buf);
> >  
> >  	free_page((unsigned long)state->pp_buf);
> >  	free_partitions(state);
> >  	return ERR_PTR(res);

Or rather, just make the above line:

	return ERR_PTR(err);

> >  }

Brian

Re: [RFC] block: remove never-modified global variable

[Boaz Harrosh]

On 05/19/2015 08:58 PM, Brian Norris wrote:
> On Tue, May 19, 2015 at 10:55:32AM -0700, Brian Norris wrote:
<>
> 
> Or rather, just make the above line:
> 
> 	return ERR_PTR(err);
> 

Yes my thoughts too, thanks sorry about that.

Thanks
Boaz

>>>  }
> 
> Brian
> 

[PATCH v2] block: remove never-modified global variable

[Brian Norris]

AFAICT, 'warn_no_part' never takes (and never has? at least, not in the
git history) taken a value besides 1. It also has a disgruntled warning
comment next to it, suggesting it shouldn't be there at all.

While removing the 'warn_no_part' check, let's combine a pair of string
cat/print into a single print, and reduce the err/res logic to something
simpler.

Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Reviewed-by: Boaz Harrosh <boaz@plexistor.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Jens Axboe <axboe@fb.com>
---
v2:
  - combine the cat/print lines
  - simplify the err/res logic

 block/partitions/amiga.c | 10 ++++------
 block/partitions/check.c | 13 +++----------
 block/partitions/check.h |  2 --
 3 files changed, 7 insertions(+), 18 deletions(-)

diff --git a/block/partitions/amiga.c b/block/partitions/amiga.c
index 2b13533d60a2..9dbf1cec7152 100644
--- a/block/partitions/amiga.c
+++ b/block/partitions/amiga.c
@@ -41,9 +41,8 @@ int amiga_partition(struct parsed_partitions *state)
 			goto rdb_done;
 		data = read_part_sector(state, blk, &sect);
 		if (!data) {
-			if (warn_no_part)
-				pr_err("Dev %s: unable to read RDB block %d\n",
-				       bdevname(state->bdev, b), blk);
+			pr_err("Dev %s: unable to read RDB block %d\n",
+			       bdevname(state->bdev, b), blk);
 			res = -1;
 			goto rdb_done;
 		}
@@ -84,9 +83,8 @@ int amiga_partition(struct parsed_partitions *state)
 		blk *= blksize;	/* Read in terms partition table understands */
 		data = read_part_sector(state, blk, &sect);
 		if (!data) {
-			if (warn_no_part)
-				pr_err("Dev %s: unable to read partition block %d\n",
-				       bdevname(state->bdev, b), blk);
+			pr_err("Dev %s: unable to read partition block %d\n",
+			       bdevname(state->bdev, b), blk);
 			res = -1;
 			goto rdb_done;
 		}
diff --git a/block/partitions/check.c b/block/partitions/check.c
index 16118d11dbfc..2f83651692ef 100644
--- a/block/partitions/check.c
+++ b/block/partitions/check.c
@@ -36,8 +36,6 @@
 #include "sysv68.h"
 #include "cmdline.h"
 
-int warn_no_part = 1; /*This is ugly: should make genhd removable media aware*/
-
 static int (*check_part[])(struct parsed_partitions *) = {
 	/*
 	 * Probe partition formats with tables at disk address 0
@@ -183,15 +181,10 @@ check_partition(struct gendisk *hd, struct block_device *bdev)
 		err = -ENOSPC;
 	if (err)
 	/* The partition is unrecognized. So report I/O errors if there were any */
-		res = err;
-	if (res) {
-		if (warn_no_part)
-			strlcat(state->pp_buf,
-				" unable to read partition table\n", PAGE_SIZE);
-		printk(KERN_INFO "%s", state->pp_buf);
-	}
+		printk(KERN_INFO "%s unable to read partition table\n",
+		       state->pp_buf);
 
 	free_page((unsigned long)state->pp_buf);
 	free_partitions(state);
-	return ERR_PTR(res);
+	return ERR_PTR(err);
 }
diff --git a/block/partitions/check.h b/block/partitions/check.h
index eade17ea910b..e09fac216adc 100644
--- a/block/partitions/check.h
+++ b/block/partitions/check.h
@@ -50,5 +50,3 @@ put_partition(struct parsed_partitions *p, int n, sector_t from, sector_t size)
 	}
 }
 
-extern int warn_no_part;
-
-- 
1.9.1