mm/filemap: rename generic_file_buffered_read to filemap_read

Rename generic_file_buffered_read to match the naming of filemap_fault,
also update the written parameter to a more descriptive name and improve
the kerneldoc comment.

Link: https://lkml.kernel.org/r/20210122160140.223228-18-willy@infradead.org
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Kent Overstreet <kent.overstreet@gmail.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index be9e390..bf2c51a 100644 (file)
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -3634,7 +3634,7 @@ static ssize_t btrfs_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
                        return ret;
        }
 
-       return generic_file_buffered_read(iocb, to, ret);
+       return filemap_read(iocb, to, ret);
 }
 
 const struct file_operations btrfs_file_operations = {

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 418b772..ec8f3dd 100644 (file)
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3080,8 +3080,8 @@ extern ssize_t generic_write_checks(struct kiocb *, struct iov_iter *);
 extern int generic_write_check_limits(struct file *file, loff_t pos,
                loff_t *count);
 extern int generic_file_rw_checks(struct file *file_in, struct file *file_out);
-extern ssize_t generic_file_buffered_read(struct kiocb *iocb,
-               struct iov_iter *to, ssize_t already_read);
+ssize_t filemap_read(struct kiocb *iocb, struct iov_iter *to,
+               ssize_t already_read);
 extern ssize_t generic_file_read_iter(struct kiocb *, struct iov_iter *);
 extern ssize_t __generic_file_write_iter(struct kiocb *, struct iov_iter *);
 extern ssize_t generic_file_write_iter(struct kiocb *, struct iov_iter *);

diff --git a/mm/filemap.c b/mm/filemap.c
index 1358cb0..28c290d 100644 (file)
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2394,23 +2394,20 @@ err:
 }
 
 /**
- * generic_file_buffered_read - generic file read routine
- * @iocb:      the iocb to read
- * @iter:      data destination
- * @written:   already copied
+ * filemap_read - Read data from the page cache.
+ * @iocb: The iocb to read.
+ * @iter: Destination for the data.
+ * @already_read: Number of bytes already read by the caller.
  *
- * This is a generic file read routine, and uses the
- * mapping->a_ops->readpage() function for the actual low-level stuff.
+ * Copies data from the page cache.  If the data is not currently present,
+ * uses the readahead and readpage address_space operations to fetch it.
  *
- * This is really ugly. But the goto's actually try to clarify some
- * of the logic when it comes to error handling etc.
- *
- * Return:
- * * total number of bytes copied, including those the were already @written
- * * negative error code if nothing was copied
+ * Return: Total number of bytes copied, including those already read by
+ * the caller.  If an error happens before any bytes are copied, returns
+ * a negative error number.
  */
-ssize_t generic_file_buffered_read(struct kiocb *iocb,
-               struct iov_iter *iter, ssize_t written)
+ssize_t filemap_read(struct kiocb *iocb, struct iov_iter *iter,
+               ssize_t already_read)
 {
        struct file *filp = iocb->ki_filp;
        struct file_ra_state *ra = &filp->f_ra;
@@ -2437,7 +2434,7 @@ ssize_t generic_file_buffered_read(struct kiocb *iocb,
                 * can no longer safely return -EIOCBQUEUED. Hence mark
                 * an async read NOWAIT at that point.
                 */
-               if ((iocb->ki_flags & IOCB_WAITQ) && written)
+               if ((iocb->ki_flags & IOCB_WAITQ) && already_read)
                        iocb->ki_flags |= IOCB_NOWAIT;
 
                error = filemap_get_pages(iocb, iter, &pvec);
@@ -2497,7 +2494,7 @@ ssize_t generic_file_buffered_read(struct kiocb *iocb,
 
                        copied = copy_page_to_iter(page, offset, bytes, iter);
 
-                       written += copied;
+                       already_read += copied;
                        iocb->ki_pos += copied;
                        ra->prev_pos = iocb->ki_pos;
 
@@ -2514,9 +2511,9 @@ put_pages:
 
        file_accessed(filp);
 
-       return written ? written : error;
+       return already_read ? already_read : error;
 }
-EXPORT_SYMBOL_GPL(generic_file_buffered_read);
+EXPORT_SYMBOL_GPL(filemap_read);
 
 /**
  * generic_file_read_iter - generic filesystem read routine
@@ -2591,7 +2588,7 @@ generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
                        goto out;
        }
 
-       retval = generic_file_buffered_read(iocb, iter, retval);
+       retval = filemap_read(iocb, iter, retval);
 out:
        return retval;
 }