From bd29109f1ac5be68f7f7c8bcb49e1b706fe899f0 Mon Sep 17 00:00:00 2001 From: Brian Behlendorf Date: Wed, 15 Jul 2015 10:54:26 -0700 Subject: [PATCH] Linux 4.2 compat: follow_link() / put_link() As of Linux 4.2 the kernel has completely retired the nameidata structure. One of the few remaining consumers of this interface were the follow_link() and put_link() callbacks. This patch adds the required checks to configure to detect the interface change and updates the functions accordingly. Migrating to the simple_follow_link() interface was considered but was decided against ironically due to the increased complexity. It also should be noted that the kernel follow_link() and put_link() interfaces changes several times after 4.1 and but before 4.2. This means there is a narrow range of kernel commits which never appear in an official tag of the Linux kernel which ZoL will not build. Signed-off-by: Brian Behlendorf Signed-off-by: Richard Yao Issue #3596 --- config/kernel-create-nameidata.m4 | 4 ++-- config/kernel-follow-link-nameidata.m4 | 24 +++++++++++++++++++ config/kernel-lookup-nameidata.m4 | 4 ++-- config/kernel-put-link-nameidata.m4 | 23 ++++++++++++++++++ config/kernel.m4 | 2 ++ module/zfs/zpl_inode.c | 33 ++++++++++++++++++++++---- 6 files changed, 81 insertions(+), 9 deletions(-) create mode 100644 config/kernel-follow-link-nameidata.m4 create mode 100644 config/kernel-put-link-nameidata.m4 diff --git a/config/kernel-create-nameidata.m4 b/config/kernel-create-nameidata.m4 index 9aad46fece..a71490a004 100644 --- a/config/kernel-create-nameidata.m4 +++ b/config/kernel-create-nameidata.m4 @@ -2,7 +2,7 @@ dnl # dnl # 3.6 API change dnl # AC_DEFUN([ZFS_AC_KERNEL_CREATE_NAMEIDATA], [ - AC_MSG_CHECKING([whether iops->create() takes struct nameidata]) + AC_MSG_CHECKING([whether iops->create() passes nameidata]) ZFS_LINUX_TRY_COMPILE([ #include @@ -22,7 +22,7 @@ AC_DEFUN([ZFS_AC_KERNEL_CREATE_NAMEIDATA], [ ],[ AC_MSG_RESULT(yes) AC_DEFINE(HAVE_CREATE_NAMEIDATA, 1, - [iops->create() operation takes nameidata]) + [iops->create() passes nameidata]) ],[ AC_MSG_RESULT(no) ]) diff --git a/config/kernel-follow-link-nameidata.m4 b/config/kernel-follow-link-nameidata.m4 new file mode 100644 index 0000000000..88c85accbe --- /dev/null +++ b/config/kernel-follow-link-nameidata.m4 @@ -0,0 +1,24 @@ +dnl # +dnl # 4.2 API change +dnl # This kernel retired the nameidata structure which forced the +dnl # restructuring of the follow_link() prototype and how it is called. +dnl # We check for the new interface rather than detecting the old one. +dnl # +AC_DEFUN([ZFS_AC_KERNEL_FOLLOW_LINK], [ + AC_MSG_CHECKING([whether iops->follow_link() passes nameidata]) + ZFS_LINUX_TRY_COMPILE([ + #include + const char *follow_link(struct dentry *de, void **cookie) + { return "symlink"; } + static struct inode_operations iops __attribute__ ((unused)) = { + .follow_link = follow_link, + }; + ],[ + ],[ + AC_MSG_RESULT(no) + ],[ + AC_MSG_RESULT(yes) + AC_DEFINE(HAVE_FOLLOW_LINK_NAMEIDATA, 1, + [iops->follow_link() nameidata]) + ]) +]) diff --git a/config/kernel-lookup-nameidata.m4 b/config/kernel-lookup-nameidata.m4 index 645560398c..43f5fb4cbc 100644 --- a/config/kernel-lookup-nameidata.m4 +++ b/config/kernel-lookup-nameidata.m4 @@ -2,7 +2,7 @@ dnl # dnl # 3.6 API change dnl # AC_DEFUN([ZFS_AC_KERNEL_LOOKUP_NAMEIDATA], [ - AC_MSG_CHECKING([whether iops->lookup() takes struct nameidata]) + AC_MSG_CHECKING([whether iops->lookup() passes nameidata]) ZFS_LINUX_TRY_COMPILE([ #include @@ -18,7 +18,7 @@ AC_DEFUN([ZFS_AC_KERNEL_LOOKUP_NAMEIDATA], [ ],[ AC_MSG_RESULT(yes) AC_DEFINE(HAVE_LOOKUP_NAMEIDATA, 1, - [iops->lookup() operation takes nameidata]) + [iops->lookup() passes nameidata]) ],[ AC_MSG_RESULT(no) ]) diff --git a/config/kernel-put-link-nameidata.m4 b/config/kernel-put-link-nameidata.m4 new file mode 100644 index 0000000000..0181ae515a --- /dev/null +++ b/config/kernel-put-link-nameidata.m4 @@ -0,0 +1,23 @@ +dnl # +dnl # 4.2 API change +dnl # This kernel retired the nameidata structure which forced the +dnl # restructuring of the put_link() prototype and how it is called. +dnl # We check for the new interface rather than detecting the old one. +dnl # +AC_DEFUN([ZFS_AC_KERNEL_PUT_LINK], [ + AC_MSG_CHECKING([whether iops->put_link() passes nameidata]) + ZFS_LINUX_TRY_COMPILE([ + #include + void put_link(struct inode *ip, void *cookie) { return; } + static struct inode_operations iops __attribute__ ((unused)) = { + .put_link = put_link, + }; + ],[ + ],[ + AC_MSG_RESULT(no) + ],[ + AC_MSG_RESULT(yes) + AC_DEFINE(HAVE_PUT_LINK_NAMEIDATA, 1, + [iops->put_link() nameidata]) + ]) +]) diff --git a/config/kernel.m4 b/config/kernel.m4 index 806c5747ae..5c97659c7b 100644 --- a/config/kernel.m4 +++ b/config/kernel.m4 @@ -70,6 +70,8 @@ AC_DEFUN([ZFS_AC_CONFIG_KERNEL], [ ZFS_AC_KERNEL_MKDIR_UMODE_T ZFS_AC_KERNEL_LOOKUP_NAMEIDATA ZFS_AC_KERNEL_CREATE_NAMEIDATA + ZFS_AC_KERNEL_FOLLOW_LINK + ZFS_AC_KERNEL_PUT_LINK ZFS_AC_KERNEL_TRUNCATE_RANGE ZFS_AC_KERNEL_AUTOMOUNT ZFS_AC_KERNEL_ENCODE_FH_WITH_INODE diff --git a/module/zfs/zpl_inode.c b/module/zfs/zpl_inode.c index 31251e7305..70b5e12399 100644 --- a/module/zfs/zpl_inode.c +++ b/module/zfs/zpl_inode.c @@ -348,8 +348,13 @@ zpl_symlink(struct inode *dir, struct dentry *dentry, const char *name) return (error); } +#ifdef HAVE_FOLLOW_LINK_NAMEIDATA static void * zpl_follow_link(struct dentry *dentry, struct nameidata *nd) +#else +const char * +zpl_follow_link(struct dentry *dentry, void **symlink_cookie) +#endif { cred_t *cr = CRED(); struct inode *ip = dentry->d_inode; @@ -372,17 +377,28 @@ zpl_follow_link(struct dentry *dentry, struct nameidata *nd) cookie = spl_fstrans_mark(); error = -zfs_readlink(ip, &uio, cr); spl_fstrans_unmark(cookie); - if (error) { + + if (error) kmem_free(link, MAXPATHLEN); - nd_set_link(nd, ERR_PTR(error)); - } else { - nd_set_link(nd, link); - } crfree(cr); + +#ifdef HAVE_FOLLOW_LINK_NAMEIDATA + if (error) + nd_set_link(nd, ERR_PTR(error)); + else + nd_set_link(nd, link); + return (NULL); +#else + if (error) + return (ERR_PTR(error)); + else + return (*symlink_cookie = link); +#endif } +#ifdef HAVE_PUT_LINK_NAMEIDATA static void zpl_put_link(struct dentry *dentry, struct nameidata *nd, void *ptr) { @@ -391,6 +407,13 @@ zpl_put_link(struct dentry *dentry, struct nameidata *nd, void *ptr) if (!IS_ERR(link)) kmem_free(link, MAXPATHLEN); } +#else +static void +zpl_put_link(struct inode *unused, void *symlink_cookie) +{ + kmem_free(symlink_cookie, MAXPATHLEN); +} +#endif static int zpl_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)