[PATCH] shmem_populate: avoid an useless check, and some comments

[linux-2.6] / mm / shmem.c

diff --git a/mm/shmem.c b/mm/shmem.c
index e64fa726a790e0c4162fec88db0e1032dd8a5be0..08a3bc2fba61897dab763b687c926d44ca6fde0a 100644 (file)
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1195,6 +1195,7 @@ static int shmem_populate(struct vm_area_struct *vma,
                err = shmem_getpage(inode, pgoff, &page, sgp, NULL);
                if (err)
                        return err;
+               /* Page may still be null, but only if nonblock was set. */
                if (page) {
                        mark_page_accessed(page);
                        err = install_page(mm, vma, addr, page, prot);
@@ -1202,7 +1203,10 @@ static int shmem_populate(struct vm_area_struct *vma,
                                page_cache_release(page);
                                return err;
                        }
-               } else if (nonblock) {
+               } else {
+                       /* No page was found just because we can't read it in
+                        * now (being here implies nonblock != 0), but the page
+                        * may exist, so set the PTE to fault it in later. */
                        err = install_file_pte(mm, vma, addr, pgoff, prot);
                        if (err)
                                return err;
@@ -1773,32 +1777,27 @@ static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *s
        return 0;
 }
 
-static int shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd)
+static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd)
 {
        nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode));
-       return 0;
+       return NULL;
 }
 
-static int shmem_follow_link(struct dentry *dentry, struct nameidata *nd)
+static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd)
 {
        struct page *page = NULL;
        int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL);
        nd_set_link(nd, res ? ERR_PTR(res) : kmap(page));
-       return 0;
+       return page;
 }
 
-static void shmem_put_link(struct dentry *dentry, struct nameidata *nd)
+static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
 {
        if (!IS_ERR(nd_get_link(nd))) {
-               struct page *page;
-
-               page = find_get_page(dentry->d_inode->i_mapping, 0);
-               if (!page)
-                       BUG();
+               struct page *page = cookie;
                kunmap(page);
                mark_page_accessed(page);
                page_cache_release(page);
-               page_cache_release(page);
        }
 }