Re: pre9/final-Bug, introduced in pre8

Linus Torvalds (torvalds@transmeta.com)
Sun, 24 Jan 1999 21:50:42 -0800 (PST)

On Sun, 24 Jan 1999, Kurt Huwig wrote:
>
> I narrowed down my problem and it was introduced in pre8:
>
> Compile this code
>
> ---- cut here ----
> #include <fcntlbits.h>
> void main( int argc, char *argv[] ) {
> open( argv[ 1 ], O_WRONLY|O_CREAT|O_TRUNC, 0666 );
> }
> ---- and here ----
>
> and run it like this
>
> strace ./a.out >(cat - )
>
> with 2.0.36 & 2.2.0-pre[67] you get:
>
> open("/dev/fd/63", O_WRONLY|O_CREAT|O_TRUNC, 0666) = 3
>
> with 2.2.0-pre[89] you get:
>
> open("/dev/fd/63", O_WRONLY|O_CREAT|O_TRUNC, 0666) = -1 ENOENT (No
> such file or directory)

Ok, this seems to be due to pre9 removing some rather bogus code that
happened to hide another problem in open_namei().

I haven't actually tested this, but it looks really obvious, so does this
patch fix it for you? (This should also fix a potential performance
bogosity - there's absolutely no reason why we should get the directory
lock when we don't need to for a normal open of an existing file).

Linus

-----
--- v2.2.0-pre9/linux/fs/namei.c Wed Jan 20 23:14:06 1999
+++ linux/fs/namei.c Sun Jan 24 21:48:39 1999
@@ -678,9 +678,12 @@
if (flag & O_CREAT) {
struct dentry *dir;

- error = -EEXIST;
- if (dentry->d_inode && (flag & O_EXCL))
+ if (dentry->d_inode) {
+ if (!(flag & O_EXCL))
+ goto nocreate;
+ error = -EEXIST;
goto exit;
+ }

dir = lock_parent(dentry);
if (!check_parent(dir, dentry)) {
@@ -723,6 +726,7 @@
goto exit;
}

+nocreate:
error = -ENOENT;
inode = dentry->d_inode;
if (!inode)

-
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