From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sender-of-o58.zoho.eu (sender-of-o58.zoho.eu [136.143.169.58]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3A84C3955CD; Sat, 1 Aug 2026 22:56:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=pass smtp.client-ip=136.143.169.58 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785624997; cv=pass; b=fbKlGFcLr0DP87bYN7NgaQOGY7XkZc3uVCEqpZ/NppCrNImq/5Eoi3VxqryzQ7y/IW7UcPB3czODrdviTnCl/0i1OY0CIGAH3t3NzhbgTlvfjWaHXlwpSot6gmDUZmR0nqsA+BCxJTigbFx9EjwiE1GMUOIly0Yj3AWuLDRaByQ= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785624997; c=relaxed/simple; bh=6NYd6in0rzVfgUh8gjPpc/kYd9uu5M96agV9tYIQgcM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=AdefJBvwz8/S40CjbzxgynfhGaB8PD774ccPO1Q+O8EHIFPY8ua1ZdwXQdGLZFw0BIB+pI52UWKbiWEVy7HylZiJIPxgy1Sxek9Aft86sJsNtpcK+yqNoL/sRQnqYQHWepA+3sjC9HgD6sMPcr61KuRChs0Bzm0sHEevYDVHk7M= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=iusegentoo.com; spf=pass smtp.mailfrom=iusegentoo.com; dkim=pass (1024-bit key) header.d=iusegentoo.com header.i=ali@iusegentoo.com header.b=SBA37Rrx; arc=pass smtp.client-ip=136.143.169.58 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=iusegentoo.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=iusegentoo.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=iusegentoo.com header.i=ali@iusegentoo.com header.b="SBA37Rrx" ARC-Seal: i=1; a=rsa-sha256; t=1785624969; cv=none; d=zohomail.eu; s=zohoarc; b=R8N92I0M+ViE86cxahige+4EwK/EjPC4yApsIndD5VhvdvsLWTJ8wB69Jxb+98HxHCkqjWuYO/OaB7GR7JVWHq+4Eoh5DbgBcu4bctYfkhSblzkQluROuZ98CCjWwbEerEfGbKiHES4Oee7zK0p/r2G6KAyXf0h5L/Nb+Ma3hMY= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.eu; s=zohoarc; t=1785624969; h=Content-Transfer-Encoding:Cc:Cc:Date:Date:From:From:In-Reply-To:MIME-Version:Message-ID:Subject:Subject:To:To:Message-Id:Reply-To; bh=KJceAGSvicSHI55BXIH/luGROGrl7VGF+MQRV7iaMTM=; b=OvknFy9cD6ljgO90HnIGJVmRYxK5qmakrkolRCuz9+6tZBWvCap1XliTjEgYAqLW7+NI357/8frUHaWUGezROuuyglRyIchGSd35fO/GIs4Dkk9AppKLC9OAwDxQQHq2OcLAlJK4wRQsOT9YzznKFqwaf0O0raiXszL0qoKEkaE= ARC-Authentication-Results: i=1; mx.zohomail.eu; dkim=pass header.i=iusegentoo.com; spf=pass smtp.mailfrom=ali@iusegentoo.com; dmarc=pass header.from= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; t=1785624969; s=zmail; d=iusegentoo.com; i=ali@iusegentoo.com; h=From:From:To:To:Cc:Cc:Subject:Subject:Date:Date:Message-ID:In-Reply-To:MIME-Version:Content-Transfer-Encoding:Message-Id:Reply-To; bh=KJceAGSvicSHI55BXIH/luGROGrl7VGF+MQRV7iaMTM=; b=SBA37RrxmBlaXuFChukkvMl3N7eOufWGZZNntjS2n55cCjSfsFc+Cq2YhvJPA3ai UO5oILxWw4IZIxk8CyloqzIoc7xieT210Uh/+vgIUL0VV6Z8Twr5BRPtCP9bGZs1KF2 TnDK6+rmDdTZhAx1NZH5KkOtMkB+i+GRs7kccLPM= Received: by mx.zoho.eu with SMTPS id 1785624966606460.58651198992493; Sun, 2 Aug 2026 00:56:06 +0200 (CEST) From: Ali Ahmet Memis To: Alexander Viro , Christian Brauner Cc: Jan Kara , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 02/10] ufs: use i_size to detect fast symlinks Date: Sat, 1 Aug 2026 22:55:22 +0000 Message-ID: <20260801225530.148386-3-ali@iusegentoo.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260801225530.148386-1-ali@iusegentoo.com> References: <20260801225530.148386-1-ali@iusegentoo.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-ZohoMailClient: External Whether a symlink stores its target inline is decided by testing i_blocks == 0. The on-disk criterion is i_size < fs_maxsymlinklen; FreeBSD's ufs_readlink() and ufs_symlink() both use it, and our own ufs_symlink() already checks s_maxsymlinklen on the write side. The two disagree on UFS2 inodes with extended attributes. ffs_alloc() adds every allocation to di_blocks, including the IO_EXT path, so a symlink carrying an extended attribute, an ACL or a MAC label has di_blocks != 0 while its target is still stored inline. Linux then takes it for a slow symlink. readlink() reads the target through ufs_getfrag_block(), treating the ASCII bytes of the target as block pointers. On a read-write mount unlinking it reaches ufs_truncate_blocks() from ufs_evict_inode(), which hands the same bytes to ufs_free_fragments() as block numbers. Values built from printable characters fall outside the device, so this ends in ufs_panic() with the inode already modified. Add ufs_is_fast_symlink() and use it in the read, write and evict paths. In ufs_evict_inode() it has to run before i_size is cleared. Flavours that leave s_maxsymlinklen at 0 keep the old i_blocks heuristic, so only 44BSD and UFS2 change behaviour. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Ali Ahmet Memis --- fs/ufs/inode.c | 54 +++++++++++++++++++++++++++++++------------------- 1 file changed, 34 insertions(+), 20 deletions(-) diff --git a/fs/ufs/inode.c b/fs/ufs/inode.c index 440d014cc5ed..802bc6e01db2 100644 --- a/fs/ufs/inode.c +++ b/fs/ufs/inode.c @@ -517,6 +517,17 @@ const struct address_space_operations ufs_aops = { .bmap = ufs_bmap }; +// on-disk criterion is i_size < fs_maxsymlinklen, not i_blocks +static bool ufs_is_fast_symlink(struct inode *inode) +{ + struct ufs_sb_private_info *uspi = UFS_SB(inode->i_sb)->s_uspi; + + if (uspi->s_maxsymlinklen) + return inode->i_size < uspi->s_maxsymlinklen; + + return inode->i_blocks == 0; +} + static void ufs_set_inode_ops(struct inode *inode) { if (S_ISREG(inode->i_mode)) { @@ -528,7 +539,7 @@ static void ufs_set_inode_ops(struct inode *inode) inode->i_fop = &ufs_dir_operations; inode->i_mapping->a_ops = &ufs_aops; } else if (S_ISLNK(inode->i_mode)) { - if (!inode->i_blocks) { + if (ufs_is_fast_symlink(inode)) { inode->i_link = (char *)UFS_I(inode)->i_u1.i_symlink; inode->i_op = &simple_symlink_inode_operations; } else { @@ -578,13 +589,13 @@ static int ufs1_read_inode(struct inode *inode, struct ufs_inode *ufs_inode) ufsi->i_oeftflag = fs32_to_cpu(sb, ufs_inode->ui_u3.ui_sun.ui_oeftflag); - if (S_ISCHR(mode) || S_ISBLK(mode) || inode->i_blocks) { - memcpy(ufsi->i_u1.i_data, &ufs_inode->ui_u2.ui_addr, - sizeof(ufs_inode->ui_u2.ui_addr)); - } else { + if (S_ISLNK(mode) && ufs_is_fast_symlink(inode)) { memcpy(ufsi->i_u1.i_symlink, ufs_inode->ui_u2.ui_symlink, sizeof(ufs_inode->ui_u2.ui_symlink) - 1); ufsi->i_u1.i_symlink[sizeof(ufs_inode->ui_u2.ui_symlink) - 1] = 0; + } else { + memcpy(ufsi->i_u1.i_data, &ufs_inode->ui_u2.ui_addr, + sizeof(ufs_inode->ui_u2.ui_addr)); } return 0; } @@ -625,13 +636,13 @@ static int ufs2_read_inode(struct inode *inode, struct ufs2_inode *ufs2_inode) ufsi->i_oeftflag = fs32_to_cpu(sb, ufs_inode->ui_u3.ui_sun.ui_oeftflag); */ - if (S_ISCHR(mode) || S_ISBLK(mode) || inode->i_blocks) { - memcpy(ufsi->i_u1.u2_i_data, &ufs2_inode->ui_u2.ui_addr, - sizeof(ufs2_inode->ui_u2.ui_addr)); - } else { + if (S_ISLNK(mode) && ufs_is_fast_symlink(inode)) { memcpy(ufsi->i_u1.i_symlink, ufs2_inode->ui_u2.ui_symlink, sizeof(ufs2_inode->ui_u2.ui_symlink) - 1); ufsi->i_u1.i_symlink[sizeof(ufs2_inode->ui_u2.ui_symlink) - 1] = 0; + } else { + memcpy(ufsi->i_u1.u2_i_data, &ufs2_inode->ui_u2.ui_addr, + sizeof(ufs2_inode->ui_u2.ui_addr)); } return 0; } @@ -731,13 +742,12 @@ static void ufs1_update_inode(struct inode *inode, struct ufs_inode *ufs_inode) if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode)) { /* ufs_inode->ui_u2.ui_addr.ui_db[0] = cpu_to_fs32(sb, inode->i_rdev); */ ufs_inode->ui_u2.ui_addr.ui_db[0] = ufsi->i_u1.i_data[0]; - } else if (inode->i_blocks) { - memcpy(&ufs_inode->ui_u2.ui_addr, ufsi->i_u1.i_data, - sizeof(ufs_inode->ui_u2.ui_addr)); - } - else { + } else if (S_ISLNK(inode->i_mode) && ufs_is_fast_symlink(inode)) { memcpy(&ufs_inode->ui_u2.ui_symlink, ufsi->i_u1.i_symlink, sizeof(ufs_inode->ui_u2.ui_symlink)); + } else { + memcpy(&ufs_inode->ui_u2.ui_addr, ufsi->i_u1.i_data, + sizeof(ufs_inode->ui_u2.ui_addr)); } if (!inode->i_nlink) @@ -774,13 +784,13 @@ static void ufs2_update_inode(struct inode *inode, struct ufs2_inode *ufs_inode) if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode)) { /* ufs_inode->ui_u2.ui_addr.ui_db[0] = cpu_to_fs32(sb, inode->i_rdev); */ ufs_inode->ui_u2.ui_addr.ui_db[0] = ufsi->i_u1.u2_i_data[0]; - } else if (inode->i_blocks) { - memcpy(&ufs_inode->ui_u2.ui_addr, ufsi->i_u1.u2_i_data, - sizeof(ufs_inode->ui_u2.ui_addr)); - } else { + } else if (S_ISLNK(inode->i_mode) && ufs_is_fast_symlink(inode)) { memcpy(&ufs_inode->ui_u2.ui_symlink, ufsi->i_u1.i_symlink, sizeof(ufs_inode->ui_u2.ui_symlink)); - } + } else { + memcpy(&ufs_inode->ui_u2.ui_addr, ufsi->i_u1.u2_i_data, + sizeof(ufs_inode->ui_u2.ui_addr)); + } if (!inode->i_nlink) memset (ufs_inode, 0, sizeof(struct ufs2_inode)); @@ -839,14 +849,18 @@ int ufs_sync_inode (struct inode *inode) void ufs_evict_inode(struct inode * inode) { int want_delete = 0; + bool fast_symlink; if (!inode->i_nlink && !is_bad_inode(inode)) want_delete = 1; + // must be evaluated before i_size is cleared below + fast_symlink = S_ISLNK(inode->i_mode) && ufs_is_fast_symlink(inode); + truncate_inode_pages_final(&inode->i_data); if (want_delete) { inode->i_size = 0; - if (inode->i_blocks && + if (inode->i_blocks && !fast_symlink && (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode))) ufs_truncate_blocks(inode); -- 2.55.0