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>hifive-unleashed-5.1
Trond Myklebust
parent
039c4d7a82
commit
834f2a4a15
12
fs/exec.c
12
fs/exec.c
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@ -126,8 +126,7 @@ asmlinkage long sys_uselib(const char __user * library)
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struct nameidata nd;
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int error;
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nd.intent.open.flags = FMODE_READ;
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error = __user_walk(library, LOOKUP_FOLLOW|LOOKUP_OPEN, &nd);
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error = __user_path_lookup_open(library, LOOKUP_FOLLOW, &nd, FMODE_READ);
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if (error)
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goto out;
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@ -139,7 +138,7 @@ asmlinkage long sys_uselib(const char __user * library)
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if (error)
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goto exit;
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file = dentry_open(nd.dentry, nd.mnt, O_RDONLY);
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file = nameidata_to_filp(&nd, O_RDONLY);
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error = PTR_ERR(file);
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if (IS_ERR(file))
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goto out;
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@ -167,6 +166,7 @@ asmlinkage long sys_uselib(const char __user * library)
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out:
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return error;
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exit:
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release_open_intent(&nd);
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path_release(&nd);
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goto out;
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}
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@ -490,8 +490,7 @@ struct file *open_exec(const char *name)
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int err;
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struct file *file;
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nd.intent.open.flags = FMODE_READ;
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err = path_lookup(name, LOOKUP_FOLLOW|LOOKUP_OPEN, &nd);
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err = path_lookup_open(name, LOOKUP_FOLLOW, &nd, FMODE_READ);
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file = ERR_PTR(err);
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if (!err) {
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@ -504,7 +503,7 @@ struct file *open_exec(const char *name)
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err = -EACCES;
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file = ERR_PTR(err);
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if (!err) {
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file = dentry_open(nd.dentry, nd.mnt, O_RDONLY);
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file = nameidata_to_filp(&nd, O_RDONLY);
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if (!IS_ERR(file)) {
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err = deny_write_access(file);
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if (err) {
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@ -516,6 +515,7 @@ out:
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return file;
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}
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}
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release_open_intent(&nd);
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path_release(&nd);
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}
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goto out;
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93
fs/namei.c
93
fs/namei.c
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@ -28,6 +28,7 @@
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#include <linux/syscalls.h>
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#include <linux/mount.h>
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#include <linux/audit.h>
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#include <linux/file.h>
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#include <asm/namei.h>
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#include <asm/uaccess.h>
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@ -317,6 +318,18 @@ void path_release_on_umount(struct nameidata *nd)
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mntput_no_expire(nd->mnt);
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}
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/**
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* release_open_intent - free up open intent resources
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* @nd: pointer to nameidata
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*/
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void release_open_intent(struct nameidata *nd)
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{
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if (nd->intent.open.file->f_dentry == NULL)
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put_filp(nd->intent.open.file);
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else
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fput(nd->intent.open.file);
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}
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/*
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* Internal lookup() using the new generic dcache.
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* SMP-safe
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@ -1052,6 +1065,70 @@ out:
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return retval;
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}
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static int __path_lookup_intent_open(const char *name, unsigned int lookup_flags,
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struct nameidata *nd, int open_flags, int create_mode)
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{
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struct file *filp = get_empty_filp();
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int err;
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if (filp == NULL)
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return -ENFILE;
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nd->intent.open.file = filp;
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nd->intent.open.flags = open_flags;
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nd->intent.open.create_mode = create_mode;
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err = path_lookup(name, lookup_flags|LOOKUP_OPEN, nd);
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if (IS_ERR(nd->intent.open.file)) {
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if (err == 0) {
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err = PTR_ERR(nd->intent.open.file);
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path_release(nd);
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}
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} else if (err != 0)
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release_open_intent(nd);
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return err;
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}
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/**
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* path_lookup_open - lookup a file path with open intent
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* @name: pointer to file name
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* @lookup_flags: lookup intent flags
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* @nd: pointer to nameidata
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* @open_flags: open intent flags
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*/
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int path_lookup_open(const char *name, unsigned int lookup_flags,
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struct nameidata *nd, int open_flags)
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{
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return __path_lookup_intent_open(name, lookup_flags, nd,
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open_flags, 0);
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}
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/**
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* path_lookup_create - lookup a file path with open + create intent
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* @name: pointer to file name
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* @lookup_flags: lookup intent flags
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* @nd: pointer to nameidata
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* @open_flags: open intent flags
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* @create_mode: create intent flags
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*/
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int path_lookup_create(const char *name, unsigned int lookup_flags,
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struct nameidata *nd, int open_flags, int create_mode)
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{
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return __path_lookup_intent_open(name, lookup_flags|LOOKUP_CREATE, nd,
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open_flags, create_mode);
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}
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int __user_path_lookup_open(const char __user *name, unsigned int lookup_flags,
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struct nameidata *nd, int open_flags)
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{
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char *tmp = getname(name);
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int err = PTR_ERR(tmp);
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if (!IS_ERR(tmp)) {
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err = __path_lookup_intent_open(tmp, lookup_flags, nd, open_flags, 0);
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putname(tmp);
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}
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return err;
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}
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/*
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* Restricted form of lookup. Doesn't follow links, single-component only,
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* needs parent already locked. Doesn't follow mounts.
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@ -1416,27 +1493,27 @@ int may_open(struct nameidata *nd, int acc_mode, int flag)
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*/
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int open_namei(const char * pathname, int flag, int mode, struct nameidata *nd)
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{
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int acc_mode, error = 0;
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int acc_mode, error;
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struct path path;
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struct dentry *dir;
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int count = 0;
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acc_mode = ACC_MODE(flag);
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/* O_TRUNC implies we need access checks for write permissions */
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if (flag & O_TRUNC)
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acc_mode |= MAY_WRITE;
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/* Allow the LSM permission hook to distinguish append
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access from general write access. */
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if (flag & O_APPEND)
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acc_mode |= MAY_APPEND;
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/* Fill in the open() intent data */
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nd->intent.open.flags = flag;
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nd->intent.open.create_mode = mode;
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/*
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* The simplest case - just a plain lookup.
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*/
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if (!(flag & O_CREAT)) {
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error = path_lookup(pathname, lookup_flags(flag)|LOOKUP_OPEN, nd);
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error = path_lookup_open(pathname, lookup_flags(flag), nd, flag);
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if (error)
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return error;
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goto ok;
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@ -1445,7 +1522,7 @@ int open_namei(const char * pathname, int flag, int mode, struct nameidata *nd)
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/*
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* Create - we need to know the parent.
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*/
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error = path_lookup(pathname, LOOKUP_PARENT|LOOKUP_OPEN|LOOKUP_CREATE, nd);
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error = path_lookup_create(pathname, LOOKUP_PARENT, nd, flag, mode);
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if (error)
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return error;
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@ -1520,6 +1597,8 @@ ok:
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exit_dput:
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dput_path(&path, nd);
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exit:
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if (!IS_ERR(nd->intent.open.file))
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release_open_intent(nd);
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path_release(nd);
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return error;
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79
fs/open.c
79
fs/open.c
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@ -739,7 +739,8 @@ asmlinkage long sys_fchown(unsigned int fd, uid_t user, gid_t group)
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}
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static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
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int flags, struct file *f)
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int flags, struct file *f,
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int (*open)(struct inode *, struct file *))
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{
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struct inode *inode;
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int error;
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@ -761,11 +762,14 @@ static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
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f->f_op = fops_get(inode->i_fop);
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file_move(f, &inode->i_sb->s_files);
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if (f->f_op && f->f_op->open) {
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error = f->f_op->open(inode,f);
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if (!open && f->f_op)
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open = f->f_op->open;
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if (open) {
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error = open(inode, f);
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if (error)
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goto cleanup_all;
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}
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f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
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file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping);
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@ -814,28 +818,75 @@ struct file *filp_open(const char * filename, int flags, int mode)
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{
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int namei_flags, error;
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struct nameidata nd;
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struct file *f;
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namei_flags = flags;
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if ((namei_flags+1) & O_ACCMODE)
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namei_flags++;
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if (namei_flags & O_TRUNC)
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namei_flags |= 2;
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error = -ENFILE;
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f = get_empty_filp();
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if (f == NULL)
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return ERR_PTR(error);
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error = open_namei(filename, namei_flags, mode, &nd);
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if (!error)
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return __dentry_open(nd.dentry, nd.mnt, flags, f);
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return nameidata_to_filp(&nd, flags);
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put_filp(f);
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return ERR_PTR(error);
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}
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EXPORT_SYMBOL(filp_open);
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/**
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* lookup_instantiate_filp - instantiates the open intent filp
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* @nd: pointer to nameidata
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* @dentry: pointer to dentry
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* @open: open callback
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*
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* Helper for filesystems that want to use lookup open intents and pass back
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* a fully instantiated struct file to the caller.
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* This function is meant to be called from within a filesystem's
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* lookup method.
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* Note that in case of error, nd->intent.open.file is destroyed, but the
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* path information remains valid.
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* If the open callback is set to NULL, then the standard f_op->open()
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* filesystem callback is substituted.
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*/
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struct file *lookup_instantiate_filp(struct nameidata *nd, struct dentry *dentry,
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int (*open)(struct inode *, struct file *))
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{
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if (IS_ERR(nd->intent.open.file))
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goto out;
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if (IS_ERR(dentry))
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goto out_err;
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nd->intent.open.file = __dentry_open(dget(dentry), mntget(nd->mnt),
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nd->intent.open.flags - 1,
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nd->intent.open.file,
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open);
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out:
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return nd->intent.open.file;
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out_err:
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release_open_intent(nd);
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nd->intent.open.file = (struct file *)dentry;
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goto out;
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}
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EXPORT_SYMBOL_GPL(lookup_instantiate_filp);
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/**
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* nameidata_to_filp - convert a nameidata to an open filp.
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* @nd: pointer to nameidata
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* @flags: open flags
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*
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* Note that this function destroys the original nameidata
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*/
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struct file *nameidata_to_filp(struct nameidata *nd, int flags)
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{
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struct file *filp;
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/* Pick up the filp from the open intent */
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filp = nd->intent.open.file;
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/* Has the filesystem initialised the file for us? */
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if (filp->f_dentry == NULL)
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filp = __dentry_open(nd->dentry, nd->mnt, flags, filp, NULL);
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else
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path_release(nd);
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return filp;
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}
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struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags)
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{
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int error;
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@ -846,7 +897,7 @@ struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags)
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if (f == NULL)
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return ERR_PTR(error);
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return __dentry_open(dentry, mnt, flags, f);
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return __dentry_open(dentry, mnt, flags, f, NULL);
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}
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EXPORT_SYMBOL(dentry_open);
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@ -8,6 +8,7 @@ struct vfsmount;
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struct open_intent {
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int flags;
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int create_mode;
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struct file *file;
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};
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enum { MAX_NESTED_LINKS = 5 };
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@ -65,6 +66,13 @@ extern int FASTCALL(link_path_walk(const char *, struct nameidata *));
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extern void path_release(struct nameidata *);
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extern void path_release_on_umount(struct nameidata *);
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extern int __user_path_lookup_open(const char __user *, unsigned lookup_flags, struct nameidata *nd, int open_flags);
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extern int path_lookup_open(const char *, unsigned lookup_flags, struct nameidata *, int open_flags);
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extern struct file *lookup_instantiate_filp(struct nameidata *nd, struct dentry *dentry,
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int (*open)(struct inode *, struct file *));
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extern struct file *nameidata_to_filp(struct nameidata *nd, int flags);
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extern void release_open_intent(struct nameidata *);
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extern struct dentry * lookup_one_len(const char *, struct dentry *, int);
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extern struct dentry * lookup_hash(struct qstr *, struct dentry *);
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