cifs: Avoid calling unlock_page() twice in cifs_readpage() when using fscache

[~andy/linux] / fs / cifs / file.c

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index d044b35ce228194c667c75f236b765aa9f97ad36..eb955b525e55307a18c1b534e95e5bfbe8462764 100644 (file)
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -3379,6 +3379,9 @@ static int cifs_readpages(struct file *file, struct address_space *mapping,
        return rc;
 }
 
+/*
+ * cifs_readpage_worker must be called with the page pinned
+ */
 static int cifs_readpage_worker(struct file *file, struct page *page,
        loff_t *poffset)
 {
@@ -3390,7 +3393,6 @@ static int cifs_readpage_worker(struct file *file, struct page *page,
        if (rc == 0)
                goto read_complete;
 
-       page_cache_get(page);
        read_data = kmap(page);
        /* for reads over a certain size could initiate async read ahead */
 
@@ -3417,7 +3419,7 @@ static int cifs_readpage_worker(struct file *file, struct page *page,
 
 io_error:
        kunmap(page);
-       page_cache_release(page);
+       unlock_page(page);
 
 read_complete:
        return rc;
@@ -3442,8 +3444,6 @@ static int cifs_readpage(struct file *file, struct page *page)
 
        rc = cifs_readpage_worker(file, page, &offset);
 
-       unlock_page(page);
-
        free_xid(xid);
        return rc;
 }
@@ -3497,6 +3497,7 @@ static int cifs_write_begin(struct file *file, struct address_space *mapping,
                        loff_t pos, unsigned len, unsigned flags,
                        struct page **pagep, void **fsdata)
 {
+       int oncethru = 0;
        pgoff_t index = pos >> PAGE_CACHE_SHIFT;
        loff_t offset = pos & (PAGE_CACHE_SIZE - 1);
        loff_t page_start = pos & PAGE_MASK;
@@ -3506,6 +3507,7 @@ static int cifs_write_begin(struct file *file, struct address_space *mapping,
 
        cifs_dbg(FYI, "write_begin from %lld len %d\n", (long long)pos, len);
 
+start:
        page = grab_cache_page_write_begin(mapping, index, flags);
        if (!page) {
                rc = -ENOMEM;
@@ -3547,13 +3549,16 @@ static int cifs_write_begin(struct file *file, struct address_space *mapping,
                }
        }
 
-       if ((file->f_flags & O_ACCMODE) != O_WRONLY) {
+       if ((file->f_flags & O_ACCMODE) != O_WRONLY && !oncethru) {
                /*
                 * might as well read a page, it is fast enough. If we get
                 * an error, we don't need to return it. cifs_write_end will
                 * do a sync write instead since PG_uptodate isn't set.
                 */
                cifs_readpage_worker(file, page, &page_start);
+               page_cache_release(page);
+               oncethru = 1;
+               goto start;
        } else {
                /* we could try using another file handle if there is one -
                   but how would we lock it to prevent close of that handle