Merge branch 'work.read_write' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

[linux-2.6-microblaze.git] / mm / filemap.c

diff --git a/mm/filemap.c b/mm/filemap.c
index 8c88e18..870971e 100644 (file)
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1917,9 +1917,8 @@ static void shrink_readahead_size_eio(struct file *filp,
 }
 
 /**
- * do_generic_file_read - generic file read routine
- * @filp:      the file to read
- * @ppos:      current file position
+ * generic_file_buffered_read - generic file read routine
+ * @iocb:      the iocb to read
  * @iter:      data destination
  * @written:   already copied
  *
@@ -1929,12 +1928,14 @@ static void shrink_readahead_size_eio(struct file *filp,
  * This is really ugly. But the goto's actually try to clarify some
  * of the logic when it comes to error handling etc.
  */
-static ssize_t do_generic_file_read(struct file *filp, loff_t *ppos,
+static ssize_t generic_file_buffered_read(struct kiocb *iocb,
                struct iov_iter *iter, ssize_t written)
 {
+       struct file *filp = iocb->ki_filp;
        struct address_space *mapping = filp->f_mapping;
        struct inode *inode = mapping->host;
        struct file_ra_state *ra = &filp->f_ra;
+       loff_t *ppos = &iocb->ki_pos;
        pgoff_t index;
        pgoff_t last_index;
        pgoff_t prev_index;
@@ -1967,6 +1968,8 @@ find_page:
 
                page = find_get_page(mapping, index);
                if (!page) {
+                       if (iocb->ki_flags & IOCB_NOWAIT)
+                               goto would_block;
                        page_cache_sync_readahead(mapping,
                                        ra, filp,
                                        index, last_index - index);
@@ -1980,6 +1983,11 @@ find_page:
                                        index, last_index - index);
                }
                if (!PageUptodate(page)) {
+                       if (iocb->ki_flags & IOCB_NOWAIT) {
+                               put_page(page);
+                               goto would_block;
+                       }
+
                        /*
                         * See comment in do_read_cache_page on why
                         * wait_on_page_locked is used to avoid unnecessarily
@@ -2161,6 +2169,8 @@ no_cached_page:
                goto readpage;
        }
 
+would_block:
+       error = -EAGAIN;
 out:
        ra->prev_pos = prev_index;
        ra->prev_pos <<= PAGE_SHIFT;
@@ -2182,14 +2192,14 @@ out:
 ssize_t
 generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
 {
-       struct file *file = iocb->ki_filp;
-       ssize_t retval = 0;
        size_t count = iov_iter_count(iter);
+       ssize_t retval = 0;
 
        if (!count)
                goto out; /* skip atime */
 
        if (iocb->ki_flags & IOCB_DIRECT) {
+               struct file *file = iocb->ki_filp;
                struct address_space *mapping = file->f_mapping;
                struct inode *inode = mapping->host;
                loff_t size;
@@ -2230,7 +2240,7 @@ generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
                        goto out;
        }
 
-       retval = do_generic_file_read(file, &iocb->ki_pos, iter, retval);
+       retval = generic_file_buffered_read(iocb, iter, retval);
 out:
        return retval;
 }