On Jun 21, 2007 11:54 +0200, Jan Kara wrote: > On Thu 21-06-07 03:33:43, Andreas Dilger wrote: > > > + if (LINUX_S_ISCHR(inode.i_mode) || LINUX_S_ISBLK(inode.i_mode) || > > > + (LINUX_S_ISLNK(inode.i_mode) && > > > + ext2fs_inode_data_blocks(fs, &inode) == 0)) > > > + return EXT2_ET_INVAL_INODE_TYPE; > > > > I would prefer that we NOT continue to make fast symlinks conditional upon > > the i_blocks count. That causes problems if e.g. an EA block is present > > (that would cause this blocks == 0 test to incorrectly fail), and may making > > the check (blocks - !!i_file_acl) can still fail for other reasons where a > > block is added to an inode (e.g. if we have larger EAs, etc). > > Note that ext2fs_inode_data_blocks() subtract number of EA blocks, so it > is equivalent to (blocks - !!i_file_acl). The function is supposed to > return the number of real data blocks so the test should be fine even in > future. This is where I disagree. We had a whole series of bugs in different places when SELinux patched ext2/3 to allow EAs on symlinks (also breaking ext2/3 compatibility in the process), because fast symlink checking was based on i_blocks and not i_size. Then we fixed those bugs, but we are open to a whole series of new bugs should any other blocks be assigned to an symlink. > > I'd prefer to make this check "i_size < sizeof(i_block)" or similar, which > > has always been true for fast symlinks, for every kernel that I have ever > > seen. > > Personally I don't mind much. If Ted finds this better, I'll change that. > Maybe introducing some macro LINUX_S_ISFASTLNK() would be fine. Ted, are you aware of any kernel that ever wrote a short symlink into an external block? Since it isn't possible to modify a symlink after it is created (except adding an EA ;-) it should never be possible that a "slow" symlink is shortened but left in the external block. Cheers, Andreas -- Andreas Dilger Principal Software Engineer Cluster File Systems, Inc. - To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
