[Fwd: [REISER4 PATCH] recover read performance]

[Hans Reiser <reiser@namesys.com>]

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Hello, Hans

This patch eliminates reiser4 read performance drop ffound by Elena.
Please send it to Andrew

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This patch recovers reiser4 read performance which was caused by incorrect using 
page_cache_readahead


 fs/reiser4/plugin/file/file.c            |    2 +-
 fs/reiser4/plugin/item/extent_file_ops.c |    8 +++++---
 2 files changed, 6 insertions(+), 4 deletions(-)

diff -puN fs/reiser4/plugin/file/file.c~reiser4-recover-read-performance fs/reiser4/plugin/file/file.c
--- linux-2.6.10-rc3-mm1/fs/reiser4/plugin/file/file.c~reiser4-recover-read-performance	2004-12-28 21:39:06.503209425 +0300
+++ linux-2.6.10-rc3-mm1-vs/fs/reiser4/plugin/file/file.c	2004-12-28 21:39:54.406304805 +0300
@@ -2929,7 +2929,7 @@ reiser4_internal ssize_t sendfile_common
 		index = *ppos >> PAGE_CACHE_SHIFT;
 		offset = *ppos & ~PAGE_CACHE_MASK;
 
-		page_cache_readahead(inode->i_mapping, &file->f_ra, file, offset, 0);
+		page_cache_readahead(inode->i_mapping, &file->f_ra, file, offset, (file_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT);
 
 		/* determine valid read request size. */
 		read_request_size = PAGE_CACHE_SIZE - offset;
diff -puN fs/reiser4/plugin/item/extent_file_ops.c~reiser4-recover-read-performance fs/reiser4/plugin/item/extent_file_ops.c
--- linux-2.6.10-rc3-mm1/fs/reiser4/plugin/item/extent_file_ops.c~reiser4-recover-read-performance	2004-12-28 21:39:16.473980410 +0300
+++ linux-2.6.10-rc3-mm1-vs/fs/reiser4/plugin/item/extent_file_ops.c	2004-12-28 21:39:54.410304312 +0300
@@ -1124,7 +1124,7 @@ read_readpages(struct address_space *map
 
 static void
 call_page_cache_readahead(struct address_space *mapping, struct file *file, unsigned long page_nr,
-			  const uf_coord_t *uf_coord)
+			  const uf_coord_t *uf_coord, unsigned long ra_pages)
 {
 	reiser4_file_fsdata *fsdata;
 	uf_coord_t ra_coord;
@@ -1135,7 +1135,7 @@ call_page_cache_readahead(struct address
 	fsdata->ra2.data = &ra_coord;
 	fsdata->ra2.readpages = read_readpages;
 
-	page_cache_readahead(mapping, &file->f_ra, file, page_nr, 0);
+	page_cache_readahead(mapping, &file->f_ra, file, page_nr, ra_pages);
 	fsdata->ra2.readpages = NULL;
 }
 
@@ -1171,6 +1171,7 @@ read_extent(struct file *file, flow_t *f
 	uf_coord_t *uf_coord;
 	coord_t *coord;
 	extent_coord_extension_t *ext_coord;
+	unsigned long ra_pages;
 
 	uf_coord = &hint->coord;
 	assert("vs-1318", coord_extension_is_ok(uf_coord));
@@ -1198,9 +1199,10 @@ read_extent(struct file *file, flow_t *f
 	page_off = (unsigned long)(file_off & (PAGE_CACHE_SIZE - 1));
 
 	count = PAGE_CACHE_SIZE - page_off;
+	ra_pages = (flow->length + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
 
 	do {
-		call_page_cache_readahead(inode->i_mapping, file, page_nr, uf_coord);
+		call_page_cache_readahead(inode->i_mapping, file, page_nr, uf_coord, ra_pages);
 
 		/* this will return page if it exists and is uptodate, otherwise it will allocate page and call
 		   extent_readpage to fill it */

_