[O_TMPFILE] it's still short a few helpers, but infrastructure should be OK now...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

12 files changed, 164 insertions, 5 deletions

diff --git a/arch/alpha/include/uapi/asm/fcntl.h b/arch/alpha/include/uapi/asm/fcntl.h
index 6d9e805f18a7..dfdadb0b4bef 100644
--- a/arch/alpha/include/uapi/asm/fcntl.h
+++ b/arch/alpha/include/uapi/asm/fcntl.h
@@ -32,6 +32,7 @@
 #define O_SYNC          (__O_SYNC|O_DSYNC)
 
 #define O_PATH          040000000
+#define O_TMPFILE       0100000000
 
 #define F_GETLK         7
 #define F_SETLK         8
diff --git a/arch/parisc/include/uapi/asm/fcntl.h b/arch/parisc/include/uapi/asm/fcntl.h
index 0304b92ccfea..cc61c475f277 100644
--- a/arch/parisc/include/uapi/asm/fcntl.h
+++ b/arch/parisc/include/uapi/asm/fcntl.h
@@ -20,6 +20,7 @@
 #define O_INVISIBLE     004000000 /* invisible I/O, for DMAPI/XDSM */
 
 #define O_PATH          020000000
+#define O_TMPFILE       040000000
 
 #define F_GETLK64       8
 #define F_SETLK64       9
diff --git a/arch/sparc/include/uapi/asm/fcntl.h b/arch/sparc/include/uapi/asm/fcntl.h
index d0b83f66f356..d73e5e008b0d 100644
--- a/arch/sparc/include/uapi/asm/fcntl.h
+++ b/arch/sparc/include/uapi/asm/fcntl.h
@@ -35,6 +35,7 @@
 #define O_SYNC          (__O_SYNC|O_DSYNC)
 
 #define O_PATH          0x1000000
+#define O_TMPFILE       0x2000000
 
 #define F_GETOWN        5       /*  for sockets. */
 #define F_SETOWN        6       /*  for sockets. */
diff --git a/fs/dcache.c b/fs/dcache.c
index f09b9085f7d8..b7f049c31526 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -2968,6 +2968,22 @@ rename_retry:
         goto again;
 }
 
+void d_tmpfile(struct dentry *dentry, struct inode *inode)
+{
+        inode_dec_link_count(inode);
+        BUG_ON(dentry->d_name.name != dentry->d_iname ||
+                !hlist_unhashed(&dentry->d_alias) ||
+                !d_unlinked(dentry));
+        spin_lock(&dentry->d_parent->d_lock);
+        spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
+        dentry->d_name.len = sprintf(dentry->d_iname, "#%llu",
+                                (unsigned long long)inode->i_ino);
+        spin_unlock(&dentry->d_lock);
+        spin_unlock(&dentry->d_parent->d_lock);
+        d_instantiate(dentry, inode);
+}
+EXPORT_SYMBOL(d_tmpfile);
+
 /**
  * find_inode_number - check for dentry with name
  * @dir: directory to check
diff --git a/fs/ext2/namei.c b/fs/ext2/namei.c
index 73b0d9519836..256dd5f4c1c4 100644
--- a/fs/ext2/namei.c
+++ b/fs/ext2/namei.c
@@ -119,6 +119,29 @@ static int ext2_create (struct inode * dir, struct dentry * dentry, umode_t mode
         return ext2_add_nondir(dentry, inode);
 }
 
+static int ext2_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode)
+{
+        struct inode *inode = ext2_new_inode(dir, mode, NULL);
+        if (IS_ERR(inode))
+                return PTR_ERR(inode);
+
+        inode->i_op = &ext2_file_inode_operations;
+        if (ext2_use_xip(inode->i_sb)) {
+                inode->i_mapping->a_ops = &ext2_aops_xip;
+                inode->i_fop = &ext2_xip_file_operations;
+        } else if (test_opt(inode->i_sb, NOBH)) {
+                inode->i_mapping->a_ops = &ext2_nobh_aops;
+                inode->i_fop = &ext2_file_operations;
+        } else {
+                inode->i_mapping->a_ops = &ext2_aops;
+                inode->i_fop = &ext2_file_operations;
+        }
+        mark_inode_dirty(inode);
+        d_tmpfile(dentry, inode);
+        unlock_new_inode(inode);
+        return 0;
+}
+
 static int ext2_mknod (struct inode * dir, struct dentry *dentry, umode_t mode, dev_t rdev)
 {
         struct inode * inode;
@@ -398,6 +421,7 @@ const struct inode_operations ext2_dir_inode_operations = {
 #endif
         .setattr        = ext2_setattr,
         .get_acl        = ext2_get_acl,
+        .tmpfile        = ext2_tmpfile,
 };
 
 const struct inode_operations ext2_special_inode_operations = {
diff --git a/fs/minix/namei.c b/fs/minix/namei.c
index 0db73d9dd668..cd950e2331b6 100644
--- a/fs/minix/namei.c
+++ b/fs/minix/namei.c
@@ -54,6 +54,18 @@ static int minix_mknod(struct inode * dir, struct dentry *dentry, umode_t mode,
         return error;
 }
 
+static int minix_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode)
+{
+        int error;
+        struct inode *inode = minix_new_inode(dir, mode, &error);
+        if (inode) {
+                minix_set_inode(inode, 0);
+                mark_inode_dirty(inode);
+                d_tmpfile(dentry, inode);
+        }
+        return error;
+}
+
 static int minix_create(struct inode *dir, struct dentry *dentry, umode_t mode,
                 bool excl)
 {
@@ -254,4 +266,5 @@ const struct inode_operations minix_dir_inode_operations = {
         .mknod          = minix_mknod,
         .rename         = minix_rename,
         .getattr        = minix_getattr,
+        .tmpfile        = minix_tmpfile,
 };
diff --git a/fs/namei.c b/fs/namei.c
index 402eda351d07..778e253e3d48 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2902,6 +2902,61 @@ stale_open:
         goto retry_lookup;
 }
 
+static int do_tmpfile(int dfd, struct filename *pathname,
+                struct nameidata *nd, int flags,
+                const struct open_flags *op,
+                struct file *file, int *opened)
+{
+        static const struct qstr name = QSTR_INIT("/", 1);
+        struct dentry *dentry, *child;
+        struct inode *dir;
+        int error = path_lookupat(dfd, pathname->name,
+                                  flags | LOOKUP_DIRECTORY, nd);
+        if (unlikely(error))
+                return error;
+        error = mnt_want_write(nd->path.mnt);
+        if (unlikely(error))
+                goto out;
+        /* we want directory to be writable */
+        error = inode_permission(nd->inode, MAY_WRITE | MAY_EXEC);
+        if (error)
+                goto out2;
+        dentry = nd->path.dentry;
+        dir = dentry->d_inode;
+        if (!dir->i_op->tmpfile) {
+                error = -EOPNOTSUPP;
+                goto out2;
+        }
+        child = d_alloc(dentry, &name);
+        if (unlikely(!child)) {
+                error = -ENOMEM;
+                goto out2;
+        }
+        nd->flags &= ~LOOKUP_DIRECTORY;
+        nd->flags |= op->intent;
+        dput(nd->path.dentry);
+        nd->path.dentry = child;
+        error = dir->i_op->tmpfile(dir, nd->path.dentry, op->mode);
+        if (error)
+                goto out2;
+        audit_inode(pathname, nd->path.dentry, 0);
+        error = may_open(&nd->path, op->acc_mode, op->open_flag);