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Date: Sun, 7 Apr 2013 15:29:03 -0600 From: Andreas Dilger <adilger@...ger.ca> To: Theodore Ts'o <tytso@....edu> Cc: "Dr. Tilmann Bubeck" <t.bubeck@...nform.de>, "linux-ext4@...r.kernel.org" <linux-ext4@...r.kernel.org> Subject: Re: [PATCH -v3] ext4: implementation of a new ioctl called EXT4_IOC_SWAP_BOOT On 2013-04-07, at 13:48, Theodore Ts'o <tytso@....edu> wrote: > On Sun, Apr 07, 2013 at 11:09:58AM -0600, Andreas Dilger wrote: >>> + if (inode_bl->i_nlink == 0) { >>> + /* this inode has never been used as a BOOT_LOADER */ >>> + set_nlink(inode_bl, 1); >>> + i_uid_write(inode_bl, 0); >>> + i_gid_write(inode_bl, 0); >>> + inode_bl->i_flags = 0; >>> + ei_bl->i_flags = 0; >>> + inode_bl->i_version = 1; >>> + i_size_write(inode_bl, 0); >>> + inode_bl->i_mode = S_IFREG; >>> + if (EXT4_HAS_INCOMPAT_FEATURE(sb, >>> + EXT4_FEATURE_INCOMPAT_EXTENTS)) { >>> + ext4_set_inode_flag(inode_bl, EXT4_INODE_EXTENTS); >>> + ext4_ext_tree_init(handle, inode_bl); >>> + } else >>> + memset(ei_bl->i_data, 0, sizeof(ei_bl->i_data)); >> >> I don't understand this. Wouldn't this clobber the block pointers if >> an existing boot inode and cause them to leak? This seems broken to me. > > If i_nlink is zero, then there is no existing boot loader inode. In > theory the rest of the inode is zero, but this is to make sure the > inode is initialized to something sane before we swap it into the > user-visible inode. Oh, my bad. I thought the else was for the nlink != 0 case, not the !extent case (the danger of reading email on my phone, I guess). Looks fine. > Cheers, Andreas-- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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