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Linux 3.6 compat, kern_path_locked() added

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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 <yshuiv7@gmail.com>
Signed-off-by: Richard Yao <ryao@cs.stonybrook.edu>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #154
This commit is contained in:
Yuxuan Shui 2012-10-11 22:41:33 +08:00 committed by Brian Behlendorf
parent dea3505dff
commit bcb15891ab
3 changed files with 158 additions and 0 deletions
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16
config/spl-build.m4
View File

@ -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.

6
include/linux/file_compat.h
View File

@ -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

136
module/spl/spl-vnode.c
View File

@ -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);
}