[PATCH 1/4] page_cache_readahead: unneeded prev_page assignments

[PATCH 1/4] page_cache_readahead: unneeded prev_page assignments

[Oleg Nesterov]

There is no point in setting ra->prev_page before 'goto out',
it will be overwritten anyway.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>

--- 2.6.11-rc2/mm/readahead.c~	Wed Jan 12 11:44:55 2005
+++ 2.6.11-rc2/mm/readahead.c	Mon Jan 24 20:19:38 2005
@@ -432,7 +432,6 @@ page_cache_readahead(struct address_spac
 
 	if (newsize == 0 || (ra->flags & RA_FLAG_INCACHE)) {
 		newsize = 1;
-		ra->prev_page = offset;
 		goto out;	/* No readahead or file already in cache */
 	}
 	/*
@@ -443,7 +442,6 @@ page_cache_readahead(struct address_spac
 	if ((ra->size == 0 && offset == 0)	/* first io and start of file */
 	    || (ra->size == -1 && ra->prev_page == offset - 1)) {
 		/* First sequential */
-		ra->prev_page  = offset + newsize - 1;
 		ra->size = get_init_ra_size(newsize, max);
 		ra->start = offset;
 		if (!blockable_page_cache_readahead(mapping, filp, offset,
@@ -475,7 +473,6 @@ page_cache_readahead(struct address_spac
 	 */
 	if ((offset != (ra->prev_page+1) || (ra->size == 0))) {
 		ra_off(ra);
-		ra->prev_page  = offset + newsize - 1;
 		blockable_page_cache_readahead(mapping, filp, offset,
 				 newsize, ra, 1);
 		goto out;
@@ -545,7 +542,7 @@ page_cache_readahead(struct address_spac
 
 out:
 	ra->prev_page = offset + newsize - 1;
-	return(newsize);
+	return newsize;
 }
 
 /*

Re: [PATCH 1/4] page_cache_readahead: unneeded prev_page assignments

[Steven Pratt]

Looks fine, thought we had some reason for it in the past, but it will 
definitly be overwritten.

Signed-off-by: Steven Pratt <slpratt@austin.ibm.com>

Oleg Nesterov wrote:

>There is no point in setting ra->prev_page before 'goto out',
>it will be overwritten anyway.
>
>Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
>
>--- 2.6.11-rc2/mm/readahead.c~	Wed Jan 12 11:44:55 2005
>+++ 2.6.11-rc2/mm/readahead.c	Mon Jan 24 20:19:38 2005
>@@ -432,7 +432,6 @@ page_cache_readahead(struct address_spac
> 
> 	if (newsize == 0 || (ra->flags & RA_FLAG_INCACHE)) {
> 		newsize = 1;
>-		ra->prev_page = offset;
> 		goto out;	/* No readahead or file already in cache */
> 	}
> 	/*
>@@ -443,7 +442,6 @@ page_cache_readahead(struct address_spac
> 	if ((ra->size == 0 && offset == 0)	/* first io and start of file */
> 	    || (ra->size == -1 && ra->prev_page == offset - 1)) {
> 		/* First sequential */
>-		ra->prev_page  = offset + newsize - 1;
> 		ra->size = get_init_ra_size(newsize, max);
> 		ra->start = offset;
> 		if (!blockable_page_cache_readahead(mapping, filp, offset,
>@@ -475,7 +473,6 @@ page_cache_readahead(struct address_spac
> 	 */
> 	if ((offset != (ra->prev_page+1) || (ra->size == 0))) {
> 		ra_off(ra);
>-		ra->prev_page  = offset + newsize - 1;
> 		blockable_page_cache_readahead(mapping, filp, offset,
> 				 newsize, ra, 1);
> 		goto out;
>@@ -545,7 +542,7 @@ page_cache_readahead(struct address_spac
> 
> out:
> 	ra->prev_page = offset + newsize - 1;
>-	return(newsize);
>+	return newsize;
> }
> 
> /*
>  
>