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allow the temp files created by open() to be linked to

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O_TMPFILE | O_CREAT => linkat() with AT_SYMLINK_FOLLOW and /proc/self/fd/<n>
as oldpath (i.e. flink()) will create a link
O_TMPFILE | O_CREAT | O_EXCL => ENOENT on attempt to link those guys

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2013-06-11 08:34:36 +04:00
parent 60545d0d46
commit f4e0c30c19
3 changed files with 18 additions and 3 deletions
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4
fs/inode.c
View File

@ -333,8 +333,10 @@ EXPORT_SYMBOL(set_nlink);
*/
void inc_nlink(struct inode *inode)
{
if (WARN_ON(inode->i_nlink == 0))
if (unlikely(inode->i_nlink == 0)) {
WARN_ON(!(inode->i_state & I_LINKABLE));
atomic_long_dec(&inode->i_sb->s_remove_count);
}
inode->__i_nlink++;
}

16
fs/namei.c
View File

@ -2948,8 +2948,14 @@ static int do_tmpfile(int dfd, struct filename *pathname,
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(nd->path.mnt);
out:
@ -3628,12 +3634,18 @@ int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_de
mutex_lock(&inode->i_mutex);
/* Make sure we don't allow creating hardlink to an unlinked file */
if (inode->i_nlink == 0)
if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE))
error = -ENOENT;
else if (max_links && inode->i_nlink >= max_links)
error = -EMLINK;
else
error = dir->i_op->link(old_dentry, dir, new_dentry);
if (!error && (inode->i_state & I_LINKABLE)) {
spin_lock(&inode->i_lock);
inode->i_state &= ~I_LINKABLE;
spin_unlock(&inode->i_lock);
}
mutex_unlock(&inode->i_mutex);
if (!error)
fsnotify_link(dir, inode, new_dentry);

1
include/linux/fs.h
View File

@ -1744,6 +1744,7 @@ struct super_operations {
#define I_REFERENCED (1 << 8)
#define __I_DIO_WAKEUP 9
#define I_DIO_WAKEUP (1 << I_DIO_WAKEUP)
#define I_LINKABLE (1 << 10)
#define I_DIRTY (I_DIRTY_SYNC | I_DIRTY_DATASYNC | I_DIRTY_PAGES)