From bcb15891ab394e11615eee08bba1fd85ac32e158 Mon Sep 17 00:00:00 2001 From: Yuxuan Shui Date: Thu, 11 Oct 2012 22:41:33 +0800 Subject: [PATCH] Linux 3.6 compat, kern_path_locked() added The kern_path_parent() function was removed from Linux 3.6 because it was observed that all the callers just want the parent dentry. The simpler kern_path_locked() function replaces kern_path_parent() and does the lookup while holding the ->i_mutex lock. This is good news for the vn implementation because it removes the need for us to handle the locking. However, it makes it harder to implement a single readable vn_remove()/vn_rename() function which is usually what we prefer. Therefore, we implement a new version of vn_remove()/vn_rename() for Linux 3.6 and newer kernels. This allows us to leave the existing working implementation untouched, and to add a simpler version for newer kernels. Long term I would very much like to see all of the vn code removed since what this code enabled is generally frowned upon in the kernel. But that can't happen util we either abondon the zpool.cache file or implement alternate infrastructure to update is correctly in user space. Signed-off-by: Yuxuan Shui Signed-off-by: Richard Yao Signed-off-by: Brian Behlendorf Closes #154 --- config/spl-build.m4 | 16 +++++ include/linux/file_compat.h | 6 ++ module/spl/spl-vnode.c | 136 ++++++++++++++++++++++++++++++++++++ 3 files changed, 158 insertions(+) diff --git a/config/spl-build.m4 b/config/spl-build.m4 index 0c7a03c..eb644a1 100644 --- a/config/spl-build.m4 +++ b/config/spl-build.m4 @@ -86,6 +86,7 @@ AC_DEFUN([SPL_AC_CONFIG_KERNEL], [ SPL_AC_SHRINK_ICACHE_MEMORY SPL_AC_KERN_PATH_PARENT_HEADER SPL_AC_KERN_PATH_PARENT_SYMBOL + SPL_AC_KERN_PATH_LOCKED SPL_AC_2ARGS_ZLIB_DEFLATE_WORKSPACESIZE SPL_AC_SHRINK_CONTROL_STRUCT SPL_AC_RWSEM_SPINLOCK_IS_RAW @@ -2187,6 +2188,21 @@ AC_DEFUN([SPL_AC_KERN_PATH_PARENT_SYMBOL], ]) ]) +dnl # +dnl # 3.6 API compat, +dnl # The kern_path_parent() function was replaced by the kern_path_locked() +dnl # function to eliminate all struct nameidata usage outside fs/namei.c. +dnl # +AC_DEFUN([SPL_AC_KERN_PATH_LOCKED], [ + SPL_CHECK_SYMBOL_HEADER( + [kern_path_locked], + [struct dentry \*kern_path_locked(const char \*, struct path \*)], + [include/linux/namei.h], + [AC_DEFINE(HAVE_KERN_PATH_LOCKED, 1, + [kern_path_locked() is available])], + []) +]) + dnl # dnl # 2.6.39 API compat, dnl # The function zlib_deflate_workspacesize() now take 2 arguments. diff --git a/include/linux/file_compat.h b/include/linux/file_compat.h index 2b5b7d2..27819d5 100644 --- a/include/linux/file_compat.h +++ b/include/linux/file_compat.h @@ -83,6 +83,12 @@ extern kern_path_parent_t kern_path_parent_fn; # define spl_kern_path_parent(path, nd) path_lookup(path, LOOKUP_PARENT, nd) #endif /* HAVE_KERN_PATH_PARENT_HEADER */ +#ifdef HAVE_KERN_PATH_LOCKED +typedef struct dentry * (*kern_path_locked_t)(const char *, struct path *); +extern kern_path_locked_t kern_path_locked_fn; +# define spl_kern_path_locked(name, path) kern_path_locked_fn(name, path) +#endif /* HAVE_KERN_PATH_LOCKED */ + #ifndef HAVE_CLEAR_CLOSE_ON_EXEC #define __clear_close_on_exec(fd, fdt) FD_CLR(fd, fdt->close_on_exec) #endif diff --git a/module/spl/spl-vnode.c b/module/spl/spl-vnode.c index f5fc65d..a0fed32 100644 --- a/module/spl/spl-vnode.c +++ b/module/spl/spl-vnode.c @@ -50,6 +50,10 @@ EXPORT_SYMBOL(kern_path_parent_fn); #endif /* HAVE_KERN_PATH_PARENT_SYMBOL */ #endif /* HAVE_KERN_PATH_PARENT_HEADER */ +#ifdef HAVE_KERN_PATH_LOCKED +kern_path_locked_t kern_path_locked_fn = SYMBOL_POISON; +#endif /* HAVE_KERN_PATH_LOCKED */ + vtype_t vn_mode_to_vtype(mode_t mode) { @@ -298,6 +302,128 @@ vn_seek(vnode_t *vp, offset_t ooff, offset_t *noffp, void *ct) } EXPORT_SYMBOL(vn_seek); +#ifdef HAVE_KERN_PATH_LOCKED +/* Based on do_unlinkat() from linux/fs/namei.c */ +int +vn_remove(const char *path, uio_seg_t seg, int flags) +{ + struct dentry *dentry; + struct path parent; + struct inode *inode = NULL; + int rc = 0; + SENTRY; + + ASSERT(seg == UIO_SYSSPACE); + ASSERT(flags == RMFILE); + + dentry = spl_kern_path_locked(path, &parent); + rc = PTR_ERR(dentry); + if (!IS_ERR(dentry)) { + if (parent.dentry->d_name.name[parent.dentry->d_name.len]) + SGOTO(slashes, rc = 0); + + inode = dentry->d_inode; + if (!inode) + SGOTO(slashes, rc = 0); + + if (inode) + ihold(inode); + + rc = vfs_unlink(parent.dentry->d_inode, dentry); +exit1: + dput(dentry); + } + + spl_inode_unlock(parent.dentry->d_inode); + if (inode) + iput(inode); /* truncate the inode here */ + + path_put(&parent); + SRETURN(-rc); + +slashes: + rc = !dentry->d_inode ? -ENOENT : + S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; + SGOTO(exit1, rc); +} /* vn_remove() */ +EXPORT_SYMBOL(vn_remove); + +/* Based on do_rename() from linux/fs/namei.c */ +int +vn_rename(const char *oldname, const char *newname, int x1) +{ + struct dentry *old_dir, *new_dir; + struct dentry *old_dentry, *new_dentry; + struct dentry *trap; + struct path old_parent, new_parent; + int rc = 0; + SENTRY; + + old_dentry = spl_kern_path_locked(oldname, &old_parent); + if (IS_ERR(old_dentry)) + SGOTO(exit, rc = PTR_ERR(old_dentry)); + + spl_inode_unlock(old_parent.dentry->d_inode); + + new_dentry = spl_kern_path_locked(newname, &new_parent); + if (IS_ERR(new_dentry)) + SGOTO(exit2, rc = PTR_ERR(new_dentry)); + + spl_inode_unlock(new_parent.dentry->d_inode); + + rc = -EXDEV; + if (old_parent.mnt != new_parent.mnt) + SGOTO(exit3, rc); + + old_dir = old_parent.dentry; + new_dir = new_parent.dentry; + trap = lock_rename(new_dir, old_dir); + + /* source should not be ancestor of target */ + rc = -EINVAL; + if (old_dentry == trap) + SGOTO(exit4, rc); + + /* target should not be an ancestor of source */ + rc = -ENOTEMPTY; + if (new_dentry == trap) + SGOTO(exit4, rc); + + /* source must exist */ + rc = -ENOENT; + if (!old_dentry->d_inode) + SGOTO(exit4, rc); + + /* unless the source is a directory trailing slashes give -ENOTDIR */ + if (!S_ISDIR(old_dentry->d_inode->i_mode)) { + rc = -ENOTDIR; + if (old_dentry->d_name.name[old_dentry->d_name.len]) + SGOTO(exit4, rc); + if (new_dentry->d_name.name[new_dentry->d_name.len]) + SGOTO(exit4, rc); + } + +#ifdef HAVE_4ARGS_VFS_RENAME + rc = vfs_rename(old_dir->d_inode, old_dentry, + new_dir->d_inode, new_dentry); +#else + rc = vfs_rename(old_dir->d_inode, old_dentry, oldnd.nd_mnt, + new_dir->d_inode, new_dentry, newnd.nd_mnt); +#endif /* HAVE_4ARGS_VFS_RENAME */ +exit4: + unlock_rename(new_dir, old_dir); +exit3: + dput(new_dentry); + path_put(&new_parent); +exit2: + dput(old_dentry); + path_put(&old_parent); +exit: + SRETURN(-rc); +} +EXPORT_SYMBOL(vn_rename); + +#else static struct dentry * vn_lookup_hash(struct nameidata *nd) { @@ -458,6 +584,7 @@ exit: SRETURN(-rc); } EXPORT_SYMBOL(vn_rename); +#endif /* HAVE_KERN_PATH_LOCKED */ int vn_getattr(vnode_t *vp, vattr_t *vap, int flags, void *x3, void *x4) @@ -862,6 +989,15 @@ int spl_vn_init_kallsyms_lookup(void) #endif /* HAVE_KERN_PATH_PARENT_SYMBOL */ #endif /* HAVE_KERN_PATH_PARENT_HEADER */ +#ifdef HAVE_KERN_PATH_LOCKED + kern_path_locked_fn = (kern_path_locked_t) + spl_kallsyms_lookup_name("kern_path_locked"); + if (!kern_path_locked_fn) { + printk(KERN_ERR "Error: Unknown symbol kern_path_locked\n"); + return -EFAULT; + } +#endif + return (0); } -- 2.40.0