f2fs: remove redundant lock_page calls

In get_node_page, we do not need to call lock_page all the time.

If the node page is cached as uptodate,

1. grab_cache_page locks the page,
2. read_node_page unlocks the page, and
3. lock_page is called for further process.

Let's avoid this.

Reviewed-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index 10cbee9..8510c5e 100644 (file)
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -847,6 +847,12 @@ fail:
        return ERR_PTR(err);
 }
 
+/*
+ * Caller should do after getting the following values.
+ * 0: f2fs_put_page(page, 0)
+ * LOCKED_PAGE: f2fs_put_page(page, 1)
+ * error: nothing
+ */
 static int read_node_page(struct page *page, int type)
 {
        struct f2fs_sb_info *sbi = F2FS_SB(page->mapping->host->i_sb);
@@ -859,10 +865,8 @@ static int read_node_page(struct page *page, int type)
                return -ENOENT;
        }
 
-       if (PageUptodate(page)) {
-               unlock_page(page);
-               return 0;
-       }
+       if (PageUptodate(page))
+               return LOCKED_PAGE;
 
        return f2fs_readpage(sbi, page, ni.blk_addr, type);
 }
@@ -874,6 +878,7 @@ void ra_node_page(struct f2fs_sb_info *sbi, nid_t nid)
 {
        struct address_space *mapping = sbi->node_inode->i_mapping;
        struct page *apage;
+       int err;
 
        apage = find_get_page(mapping, nid);
        if (apage && PageUptodate(apage)) {
@@ -886,30 +891,36 @@ void ra_node_page(struct f2fs_sb_info *sbi, nid_t nid)
        if (!apage)
                return;
 
-       if (read_node_page(apage, READA) == 0)
+       err = read_node_page(apage, READA);
+       if (err == 0)
                f2fs_put_page(apage, 0);
+       else if (err == LOCKED_PAGE)
+               f2fs_put_page(apage, 1);
        return;
 }
 
 struct page *get_node_page(struct f2fs_sb_info *sbi, pgoff_t nid)
 {
-       int err;
-       struct page *page;
        struct address_space *mapping = sbi->node_inode->i_mapping;
+       struct page *page;
+       int err;
 
        page = grab_cache_page(mapping, nid);
        if (!page)
                return ERR_PTR(-ENOMEM);
 
        err = read_node_page(page, READ_SYNC);
-       if (err)
+       if (err < 0)
                return ERR_PTR(err);
+       else if (err == LOCKED_PAGE)
+               goto got_it;
 
        lock_page(page);
        if (!PageUptodate(page)) {
                f2fs_put_page(page, 1);
                return ERR_PTR(-EIO);
        }
+got_it:
        BUG_ON(nid != nid_of_node(page));
        mark_page_accessed(page);
        return page;
@@ -923,10 +934,9 @@ struct page *get_node_page_ra(struct page *parent, int start)
 {
        struct f2fs_sb_info *sbi = F2FS_SB(parent->mapping->host->i_sb);
        struct address_space *mapping = sbi->node_inode->i_mapping;
-       int i, end;
-       int err = 0;
-       nid_t nid;
        struct page *page;
+       int err, i, end;
+       nid_t nid;
 
        /* First, try getting the desired direct node. */
        nid = get_nid(parent, start, false);
@@ -936,12 +946,12 @@ struct page *get_node_page_ra(struct page *parent, int start)
        page = grab_cache_page(mapping, nid);
        if (!page)
                return ERR_PTR(-ENOMEM);
-       else if (PageUptodate(page))
-               goto page_hit;
 
        err = read_node_page(page, READ_SYNC);
-       if (err)
+       if (err < 0)
                return ERR_PTR(err);
+       else if (err == LOCKED_PAGE)
+               goto page_hit;
 
        /* Then, try readahead for siblings of the desired node */
        end = start + MAX_RA_NODE;
@@ -956,7 +966,7 @@ struct page *get_node_page_ra(struct page *parent, int start)
        lock_page(page);
 
 page_hit:
-       if (PageError(page)) {
+       if (!PageUptodate(page)) {
                f2fs_put_page(page, 1);
                return ERR_PTR(-EIO);
        }

diff --git a/fs/f2fs/node.h b/fs/f2fs/node.h
index d009cdf..271a61c 100644 (file)
--- a/fs/f2fs/node.h
+++ b/fs/f2fs/node.h
@@ -29,6 +29,9 @@
 /* vector size for gang look-up from nat cache that consists of radix tree */
 #define NATVEC_SIZE    64
 
+/* return value for read_node_page */
+#define LOCKED_PAGE    1
+
 /*
  * For node information
  */