ext4: Enable extent format for symlinks.

This patch enables extent-formatted normal symlinks.  Using extents
format allows a symlink to refer to a block number larger than 2^32
on large filesystems.  We still don't enable extent format for fast
symlinks, which are contained in the inode itself.
Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: NMingming Cao <cmm@us.ibm.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

fs/ext4/ialloc.c

@@ -750,8 +750,8 @@ struct inode *ext4_new_inode(handle_t *handle, struct inode * dir, int mode)
 		goto fail_free_drop;
 	}
 	if (test_opt(sb, EXTENTS)) {
-		/* set extent flag only for directory and file */
-		if (S_ISDIR(mode) || S_ISREG(mode)) {
+		/* set extent flag only for diretory, file and normal symlink*/
+		if (S_ISDIR(mode) || S_ISREG(mode) || S_ISLNK(mode)) {
 			EXT4_I(inode)->i_flags |= EXT4_EXTENTS_FL;
 			ext4_ext_tree_init(handle, inode);
 			err = ext4_update_incompat_feature(handle, sb,

fs/ext4/namei.c

@@ -2217,6 +2217,8 @@ static int ext4_symlink (struct inode * dir,
 			goto out_stop;
 		}
 	} else {
+		/* clear the extent format for fast symlink */
+		EXT4_I(inode)->i_flags &= ~EXT4_EXTENTS_FL;
 		inode->i_op = &ext4_fast_symlink_inode_operations;
 		memcpy((char*)&EXT4_I(inode)->i_data,symname,l);
 		inode->i_size = l-1;