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OpenCloudOS-Kernel
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VFS: Allow the filesystem to return a full file pointer on open intent 

This is needed by NFSv4 for atomicity reasons: our open command is in
 fact a lookup+open, so we need to be able to propagate open context
 information from lookup() into the resulting struct file's
 private_data field.

 Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
This commit is contained in:
Trond Myklebust 2005-10-18 14:20:16 -07:00
parent 039c4d7a82
commit 834f2a4a15
4 changed files with 165 additions and 27 deletions
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12
fs/exec.c
View File

@ -126,8 +126,7 @@ asmlinkage long sys_uselib(const char __user * library)
struct nameidata nd;
int error;
nd.intent.open.flags = FMODE_READ;
error = __user_walk(library, LOOKUP_FOLLOW|LOOKUP_OPEN, &nd);
error = __user_path_lookup_open(library, LOOKUP_FOLLOW, &nd, FMODE_READ);
if (error)
goto out;
@ -139,7 +138,7 @@ asmlinkage long sys_uselib(const char __user * library)
if (error)
goto exit;
file = dentry_open(nd.dentry, nd.mnt, O_RDONLY);
file = nameidata_to_filp(&nd, O_RDONLY);
error = PTR_ERR(file);
if (IS_ERR(file))
goto out;
@ -167,6 +166,7 @@ asmlinkage long sys_uselib(const char __user * library)
out:
return error;
exit:
release_open_intent(&nd);
path_release(&nd);
goto out;
}
@ -490,8 +490,7 @@ struct file *open_exec(const char *name)
int err;
struct file *file;
nd.intent.open.flags = FMODE_READ;
err = path_lookup(name, LOOKUP_FOLLOW|LOOKUP_OPEN, &nd);
err = path_lookup_open(name, LOOKUP_FOLLOW, &nd, FMODE_READ);
file = ERR_PTR(err);
if (!err) {
@ -504,7 +503,7 @@ struct file *open_exec(const char *name)
err = -EACCES;
file = ERR_PTR(err);
if (!err) {
file = dentry_open(nd.dentry, nd.mnt, O_RDONLY);
file = nameidata_to_filp(&nd, O_RDONLY);
if (!IS_ERR(file)) {
err = deny_write_access(file);
if (err) {
@ -516,6 +515,7 @@ out:
return file;
}
}
release_open_intent(&nd);
path_release(&nd);
}
goto out;

93
fs/namei.c
View File

@ -28,6 +28,7 @@
#include <linux/syscalls.h>
#include <linux/mount.h>
#include <linux/audit.h>
#include <linux/file.h>
#include <asm/namei.h>
#include <asm/uaccess.h>
@ -317,6 +318,18 @@ void path_release_on_umount(struct nameidata *nd)
mntput_no_expire(nd->mnt);
}
/**
* release_open_intent - free up open intent resources
* @nd: pointer to nameidata
*/
void release_open_intent(struct nameidata *nd)
{
if (nd->intent.open.file->f_dentry == NULL)
put_filp(nd->intent.open.file);
else
fput(nd->intent.open.file);
}
/*
* Internal lookup() using the new generic dcache.
* SMP-safe
@ -1052,6 +1065,70 @@ out:
return retval;
}
static int __path_lookup_intent_open(const char *name, unsigned int lookup_flags,
struct nameidata *nd, int open_flags, int create_mode)
{
struct file *filp = get_empty_filp();
int err;
if (filp == NULL)
return -ENFILE;
nd->intent.open.file = filp;
nd->intent.open.flags = open_flags;
nd->intent.open.create_mode = create_mode;
err = path_lookup(name, lookup_flags|LOOKUP_OPEN, nd);
if (IS_ERR(nd->intent.open.file)) {
if (err == 0) {
err = PTR_ERR(nd->intent.open.file);
path_release(nd);
}
} else if (err != 0)
release_open_intent(nd);
return err;
}
/**
* path_lookup_open - lookup a file path with open intent
* @name: pointer to file name
* @lookup_flags: lookup intent flags
* @nd: pointer to nameidata
* @open_flags: open intent flags
*/
int path_lookup_open(const char *name, unsigned int lookup_flags,
struct nameidata *nd, int open_flags)
{
return __path_lookup_intent_open(name, lookup_flags, nd,
open_flags, 0);
}
/**
* path_lookup_create - lookup a file path with open + create intent
* @name: pointer to file name
* @lookup_flags: lookup intent flags
* @nd: pointer to nameidata
* @open_flags: open intent flags
* @create_mode: create intent flags
*/
int path_lookup_create(const char *name, unsigned int lookup_flags,
struct nameidata *nd, int open_flags, int create_mode)
{
return __path_lookup_intent_open(name, lookup_flags|LOOKUP_CREATE, nd,
open_flags, create_mode);
}
int __user_path_lookup_open(const char __user *name, unsigned int lookup_flags,
struct nameidata *nd, int open_flags)
{
char *tmp = getname(name);
int err = PTR_ERR(tmp);
if (!IS_ERR(tmp)) {
err = __path_lookup_intent_open(tmp, lookup_flags, nd, open_flags, 0);
putname(tmp);
}
return err;
}
/*
* Restricted form of lookup. Doesn't follow links, single-component only,
* needs parent already locked. Doesn't follow mounts.
@ -1416,27 +1493,27 @@ int may_open(struct nameidata *nd, int acc_mode, int flag)
*/
int open_namei(const char * pathname, int flag, int mode, struct nameidata *nd)
{
int acc_mode, error = 0;
int acc_mode, error;
struct path path;
struct dentry *dir;
int count = 0;
acc_mode = ACC_MODE(flag);
/* O_TRUNC implies we need access checks for write permissions */
if (flag & O_TRUNC)
acc_mode |= MAY_WRITE;
/* Allow the LSM permission hook to distinguish append
access from general write access. */
if (flag & O_APPEND)
acc_mode |= MAY_APPEND;
/* Fill in the open() intent data */
nd->intent.open.flags = flag;
nd->intent.open.create_mode = mode;
/*
* The simplest case - just a plain lookup.
*/
if (!(flag & O_CREAT)) {
error = path_lookup(pathname, lookup_flags(flag)|LOOKUP_OPEN, nd);
error = path_lookup_open(pathname, lookup_flags(flag), nd, flag);
if (error)
return error;
goto ok;
@ -1445,7 +1522,7 @@ int open_namei(const char * pathname, int flag, int mode, struct nameidata *nd)
/*
* Create - we need to know the parent.
*/
error = path_lookup(pathname, LOOKUP_PARENT|LOOKUP_OPEN|LOOKUP_CREATE, nd);
error = path_lookup_create(pathname, LOOKUP_PARENT, nd, flag, mode);
if (error)
return error;
@ -1520,6 +1597,8 @@ ok:
exit_dput:
dput_path(&path, nd);
exit:
if (!IS_ERR(nd->intent.open.file))
release_open_intent(nd);
path_release(nd);
return error;

79
fs/open.c
View File

@ -739,7 +739,8 @@ asmlinkage long sys_fchown(unsigned int fd, uid_t user, gid_t group)
}
static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
int flags, struct file *f)
int flags, struct file *f,
int (*open)(struct inode *, struct file *))
{
struct inode *inode;
int error;
@ -761,11 +762,14 @@ static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
f->f_op = fops_get(inode->i_fop);
file_move(f, &inode->i_sb->s_files);
if (f->f_op && f->f_op->open) {
error = f->f_op->open(inode,f);
if (!open && f->f_op)
open = f->f_op->open;
if (open) {
error = open(inode, f);
if (error)
goto cleanup_all;
}
f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping);
@ -814,28 +818,75 @@ struct file *filp_open(const char * filename, int flags, int mode)
{
int namei_flags, error;
struct nameidata nd;
struct file *f;
namei_flags = flags;
if ((namei_flags+1) & O_ACCMODE)
namei_flags++;
if (namei_flags & O_TRUNC)
namei_flags |= 2;
error = -ENFILE;
f = get_empty_filp();
if (f == NULL)
return ERR_PTR(error);
error = open_namei(filename, namei_flags, mode, &nd);
if (!error)
return __dentry_open(nd.dentry, nd.mnt, flags, f);
return nameidata_to_filp(&nd, flags);
put_filp(f);
return ERR_PTR(error);
}
EXPORT_SYMBOL(filp_open);
/**
* lookup_instantiate_filp - instantiates the open intent filp
* @nd: pointer to nameidata
* @dentry: pointer to dentry
* @open: open callback
*
* Helper for filesystems that want to use lookup open intents and pass back
* a fully instantiated struct file to the caller.
* This function is meant to be called from within a filesystem's
* lookup method.
* Note that in case of error, nd->intent.open.file is destroyed, but the
* path information remains valid.
* If the open callback is set to NULL, then the standard f_op->open()
* filesystem callback is substituted.
*/
struct file *lookup_instantiate_filp(struct nameidata *nd, struct dentry *dentry,
int (*open)(struct inode *, struct file *))
{
if (IS_ERR(nd->intent.open.file))
goto out;
if (IS_ERR(dentry))
goto out_err;
nd->intent.open.file = __dentry_open(dget(dentry), mntget(nd->mnt),
nd->intent.open.flags - 1,
nd->intent.open.file,
open);
out:
return nd->intent.open.file;
out_err:
release_open_intent(nd);
nd->intent.open.file = (struct file *)dentry;
goto out;
}
EXPORT_SYMBOL_GPL(lookup_instantiate_filp);
/**
* nameidata_to_filp - convert a nameidata to an open filp.
* @nd: pointer to nameidata
* @flags: open flags
*
* Note that this function destroys the original nameidata
*/
struct file *nameidata_to_filp(struct nameidata *nd, int flags)
{
struct file *filp;
/* Pick up the filp from the open intent */
filp = nd->intent.open.file;
/* Has the filesystem initialised the file for us? */
if (filp->f_dentry == NULL)
filp = __dentry_open(nd->dentry, nd->mnt, flags, filp, NULL);
else
path_release(nd);
return filp;
}
struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags)
{
int error;
@ -846,7 +897,7 @@ struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags)
if (f == NULL)
return ERR_PTR(error);
return __dentry_open(dentry, mnt, flags, f);
return __dentry_open(dentry, mnt, flags, f, NULL);
}
EXPORT_SYMBOL(dentry_open);

8
include/linux/namei.h
View File

@ -8,6 +8,7 @@ struct vfsmount;
struct open_intent {
int flags;
int create_mode;
struct file *file;
};
enum { MAX_NESTED_LINKS = 5 };
@ -65,6 +66,13 @@ extern int FASTCALL(link_path_walk(const char *, struct nameidata *));
extern void path_release(struct nameidata *);
extern void path_release_on_umount(struct nameidata *);
extern int __user_path_lookup_open(const char __user *, unsigned lookup_flags, struct nameidata *nd, int open_flags);
extern int path_lookup_open(const char *, unsigned lookup_flags, struct nameidata *, int open_flags);
extern struct file *lookup_instantiate_filp(struct nameidata *nd, struct dentry *dentry,
int (*open)(struct inode *, struct file *));
extern struct file *nameidata_to_filp(struct nameidata *nd, int flags);
extern void release_open_intent(struct nameidata *);
extern struct dentry * lookup_one_len(const char *, struct dentry *, int);
extern struct dentry * lookup_hash(struct qstr *, struct dentry *);