1 files changed, 47 insertions, 4 deletions

diff --git a/sys/fs/ext2fs/ext2_subr.c b/sys/fs/ext2fs/ext2_subr.c
index df6e430..cd4a06b 100644
--- a/sys/fs/ext2fs/ext2_subr.c
+++ b/sys/fs/ext2fs/ext2_subr.c
@@ -50,10 +50,11 @@
 #include <fs/ext2fs/ext2_extern.h>
 #include <fs/ext2fs/ext2fs.h>
 #include <fs/ext2fs/fs.h>
-
-#ifdef KDB
+#include <fs/ext2fs/ext2_extents.h>
 #include <fs/ext2fs/ext2_mount.h>
+#include <fs/ext2fs/ext2_dinode.h>
 
+#ifdef KDB
 void	ext2_checkoverlap(struct buf *, struct inode *);
 #endif
 
@@ -70,21 +71,63 @@ ext2_blkatoff(struct vnode *vp, off_t offset, char **res, struct buf **bpp)
 	struct buf *bp;
 	e2fs_lbn_t lbn;
 	int bsize, error;
+	daddr_t newblk;
+	struct ext4_extent *ep;
+	struct ext4_extent_path path;
 
 	ip = VTOI(vp);
 	fs = ip->i_e2fs;
 	lbn = lblkno(fs, offset);
 	bsize = blksize(fs, ip, lbn);
-
 	*bpp = NULL;
-	if ((error = bread(vp, lbn, bsize, NOCRED, &bp)) != 0) {
+
+	/*
+	 * The EXT4_EXTENTS requires special treatment, otherwise we can
+	 * fall back to the normal path.
+	 */
+	if (!(ip->i_flags & EXT4_EXTENTS))
+		goto normal;
+
+	memset(&path, 0, sizeof(path));
+	if (ext4_ext_find_extent(fs, ip, lbn, &path) == NULL)
+		goto normal;
+	ep = path.ep_ext;
+	if (ep == NULL)
+		goto normal;
+
+	newblk = lbn - ep->e_blk +
+	    (ep->e_start_lo | (daddr_t)ep->e_start_hi << 32);
+
+	if (path.ep_bp != NULL) {
+		brelse(path.ep_bp);
+		path.ep_bp = NULL;
+	}
+	error = bread(ip->i_devvp, fsbtodb(fs, newblk), bsize, NOCRED, &bp);
+	if (error != 0) {
 		brelse(bp);
 		return (error);
 	}
 	if (res)
 		*res = (char *)bp->b_data + blkoff(fs, offset);
+	/*
+	 * If EXT4_EXTENTS is enabled we would get a wrong offset so
+	 * reset b_offset here.
+	 */
+	bp->b_offset = lbn * bsize;
 	*bpp = bp;
 	return (0);
+
+normal:
+	if (*bpp == NULL) {
+		if ((error = bread(vp, lbn, bsize, NOCRED, &bp)) != 0) {
+			brelse(bp);
+			return (error);
+		}
+		if (res)
+			*res = (char *)bp->b_data + blkoff(fs, offset);
+		*bpp = bp;
+	}
+	return (0);
 }
 
 #ifdef KDB