iomap: support direct I/O to inline data

Add support for reading from and writing to inline data to iomap_dio_rw.
This saves filesystems from having to implement fallback code for this
case.

The inline data is actually cached in the inode, so the I/O is only
direct in the sense that it doesn't go through the page cache.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

diff --git a/fs/iomap.c b/fs/iomap.c
index 4d8ff0f5ecc91c9f24903be9cb69c5759b187893..98a1fdd5c091bc397fdb30c6afaab3cc8b968e9c 100644 (file)
--- a/fs/iomap.c
+++ b/fs/iomap.c
@@ -1450,6 +1450,33 @@ iomap_dio_hole_actor(loff_t length, struct iomap_dio *dio)
        return length;
 }
 
+static loff_t
+iomap_dio_inline_actor(struct inode *inode, loff_t pos, loff_t length,
+               struct iomap_dio *dio, struct iomap *iomap)
+{
+       struct iov_iter *iter = dio->submit.iter;
+       size_t copied;
+
+       BUG_ON(pos + length > PAGE_SIZE - offset_in_page(iomap->inline_data));
+
+       if (dio->flags & IOMAP_DIO_WRITE) {
+               loff_t size = inode->i_size;
+
+               if (pos > size)
+                       memset(iomap->inline_data + size, 0, pos - size);
+               copied = copy_from_iter(iomap->inline_data + pos, length, iter);
+               if (copied) {
+                       if (pos + copied > size)
+                               i_size_write(inode, pos + copied);
+                       mark_inode_dirty(inode);
+               }
+       } else {
+               copied = copy_to_iter(iomap->inline_data + pos, length, iter);
+       }
+       dio->size += copied;
+       return copied;
+}
+
 static loff_t
 iomap_dio_actor(struct inode *inode, loff_t pos, loff_t length,
                void *data, struct iomap *iomap)
@@ -1467,6 +1494,8 @@ iomap_dio_actor(struct inode *inode, loff_t pos, loff_t length,
                return iomap_dio_bio_actor(inode, pos, length, dio, iomap);
        case IOMAP_MAPPED:
                return iomap_dio_bio_actor(inode, pos, length, dio, iomap);
+       case IOMAP_INLINE:
+               return iomap_dio_inline_actor(inode, pos, length, dio, iomap);
        default:
                WARN_ON_ONCE(1);
                return -EIO;