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vfs: create vfs helper vfs_tmpfile() 

Factor out some common vfs bits from do_tmpfile()
to be used by overlayfs for concurrent copy up.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This commit is contained in:
Amir Goldstein 2017-01-17 06:34:52 +02:00 committed by Miklos Szeredi
parent 7ce7d89f48
commit af7bd4dc13
2 changed files with 46 additions and 25 deletions
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68
fs/namei.c
View File

@ -3353,13 +3353,50 @@ out:
return error;
}
struct dentry *vfs_tmpfile(struct dentry *dentry, umode_t mode, int open_flag)
{
static const struct qstr name = QSTR_INIT("/", 1);
struct dentry *child = NULL;
struct inode *dir = dentry->d_inode;
struct inode *inode;
int error;
/* we want directory to be writable */
error = inode_permission(dir, MAY_WRITE | MAY_EXEC);
if (error)
goto out_err;
error = -EOPNOTSUPP;
if (!dir->i_op->tmpfile)
goto out_err;
error = -ENOMEM;
child = d_alloc(dentry, &name);
if (unlikely(!child))
goto out_err;
error = dir->i_op->tmpfile(dir, child, mode);
if (error)
goto out_err;
error = -ENOENT;
inode = child->d_inode;
if (unlikely(!inode))
goto out_err;
if (!(open_flag & O_EXCL)) {
spin_lock(&inode->i_lock);
inode->i_state |= I_LINKABLE;
spin_unlock(&inode->i_lock);
}
return child;
out_err:
dput(child);
return ERR_PTR(error);
}
EXPORT_SYMBOL(vfs_tmpfile);
static int do_tmpfile(struct nameidata *nd, unsigned flags,
const struct open_flags *op,
struct file *file, int *opened)
{
static const struct qstr name = QSTR_INIT("/", 1);
struct dentry *child;
struct inode *dir;
struct path path;
int error = path_lookupat(nd, flags | LOOKUP_DIRECTORY, &path);
if (unlikely(error))
@ -3367,25 +3404,12 @@ static int do_tmpfile(struct nameidata *nd, unsigned flags,
error = mnt_want_write(path.mnt);
if (unlikely(error))
goto out;
dir = path.dentry->d_inode;
/* we want directory to be writable */
error = inode_permission(dir, MAY_WRITE | MAY_EXEC);
if (error)
child = vfs_tmpfile(path.dentry, op->mode, op->open_flag);
error = PTR_ERR(child);
if (unlikely(IS_ERR(child)))
goto out2;
if (!dir->i_op->tmpfile) {
error = -EOPNOTSUPP;
goto out2;
}
child = d_alloc(path.dentry, &name);
if (unlikely(!child)) {
error = -ENOMEM;
goto out2;
}
dput(path.dentry);
path.dentry = child;
error = dir->i_op->tmpfile(dir, child, op->mode);
if (error)
goto out2;
audit_inode(nd->name, child, 0);
/* Don't check for other permissions, the inode was just created */
error = may_open(&path, 0, op->open_flag);
@ -3396,14 +3420,8 @@ static int do_tmpfile(struct nameidata *nd, unsigned flags,
if (error)
goto out2;
error = open_check_o_direct(file);
if (error) {
if (error)
fput(file);
} else if (!(op->open_flag & O_EXCL)) {
struct inode *inode = file_inode(file);
spin_lock(&inode->i_lock);
inode->i_state |= I_LINKABLE;
spin_unlock(&inode->i_lock);
}
out2:
mnt_drop_write(path.mnt);
out:

3
include/linux/fs.h
View File

@ -1561,6 +1561,9 @@ extern int vfs_unlink(struct inode *, struct dentry *, struct inode **);
extern int vfs_rename(struct inode *, struct dentry *, struct inode *, struct dentry *, struct inode **, unsigned int);
extern int vfs_whiteout(struct inode *, struct dentry *);
extern struct dentry *vfs_tmpfile(struct dentry *dentry, umode_t mode,
int open_flag);
/*
* VFS file helper functions.
*/