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>

2 files changed, 28 insertions, 15 deletions

diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index 10cbee9dc3d1..8510c5ed402e 100644
--- 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 d009cdfd2679..271a61c25601 100644
--- 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
  */