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kill d_instantiate_no_diralias()

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The only user is fuse_create_new_entry(), and there it's used to
mitigate the same mkdir/open-by-handle race as in nfs_mkdir().
The same solution applies - unhash the mkdir argument, then
call d_splice_alias() and if that returns a reference to preexisting
alias, dput() and report success.  ->mkdir() argument left unhashed
negative with the preexisting alias moved in the right place is just
fine from the ->mkdir() callers point of view.

Cc: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro
2018-05-28 18:27:19 -04:00
parent b0c6108ecf
commit c971e6a006
3 changed files with 11 additions and 32 deletions
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15
fs/fuse/dir.c
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@@ -539,6 +539,7 @@ static int create_new_entry(struct fuse_conn *fc, struct fuse_args *args,
{
struct fuse_entry_out outarg;
struct inode *inode;
struct dentry *d;
int err;
struct fuse_forget_link *forget;
@@ -570,11 +571,17 @@ static int create_new_entry(struct fuse_conn *fc, struct fuse_args *args,
}
kfree(forget);
err = d_instantiate_no_diralias(entry, inode);
if (err)
return err;
d_drop(entry);
d = d_splice_alias(inode, entry);
if (IS_ERR(d))
return PTR_ERR(d);
fuse_change_entry_timeout(entry, &outarg);
if (d) {
fuse_change_entry_timeout(d, &outarg);
dput(d);
} else {
fuse_change_entry_timeout(entry, &outarg);
}
fuse_invalidate_attr(dir);
return 0;