fs: Enable bmap() function to properly return errors
By now, bmap() will either return the physical block number related to
the requested file offset or 0 in case of error or the requested offset
maps into a hole.
This patch makes the needed changes to enable bmap() to proper return
errors, using the return value as an error return, and now, a pointer
must be passed to bmap() to be filled with the mapped physical block.
It will change the behavior of bmap() on return:
- negative value in case of error
- zero on success or map fell into a hole
In case of a hole, the *block will be zero too
Since this is a prep patch, by now, the only error return is -EINVAL if
->bmap doesn't exist.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/inode.c b/fs/inode.c
index 96d62d9..5dacfa1 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -1598,25 +1598,31 @@ void iput(struct inode *inode)
}
EXPORT_SYMBOL(iput);
+#ifdef CONFIG_BLOCK
/**
* bmap - find a block number in a file
- * @inode: inode of file
- * @block: block to find
+ * @inode: inode owning the block number being requested
+ * @block: pointer containing the block to find
*
- * Returns the block number on the device holding the inode that
- * is the disk block number for the block of the file requested.
- * That is, asked for block 4 of inode 1 the function will return the
- * disk block relative to the disk start that holds that block of the
- * file.
+ * Replaces the value in *block with the block number on the device holding
+ * corresponding to the requested block number in the file.
+ * That is, asked for block 4 of inode 1 the function will replace the
+ * 4 in *block, with disk block relative to the disk start that holds that
+ * block of the file.
+ *
+ * Returns -EINVAL in case of error, 0 otherwise. If mapping falls into a
+ * hole, returns 0 and *block is also set to 0.
*/
-sector_t bmap(struct inode *inode, sector_t block)
+int bmap(struct inode *inode, sector_t *block)
{
- sector_t res = 0;
- if (inode->i_mapping->a_ops->bmap)
- res = inode->i_mapping->a_ops->bmap(inode->i_mapping, block);
- return res;
+ if (!inode->i_mapping->a_ops->bmap)
+ return -EINVAL;
+
+ *block = inode->i_mapping->a_ops->bmap(inode->i_mapping, *block);
+ return 0;
}
EXPORT_SYMBOL(bmap);
+#endif
/*
* With relative atime, only update atime if the previous atime is
