@@ -109,8 +109,12 @@ static struct p9_fid *v9fs_fid_find(struct dentry *dentry, kuid_t uid, int any)
dentry, dentry, from_kuid(&init_user_ns, uid),
any);
ret = NULL;
+
+ if (d_inode(dentry))
+ ret = v9fs_fid_find_inode(d_inode(dentry), uid);
+
/* we'll recheck under lock if there's anything to look in */
- if (dentry->d_fsdata) {
+ if (!ret && dentry->d_fsdata) {
struct hlist_head *h = (struct hlist_head *)&dentry->d_fsdata;
spin_lock(&dentry->d_lock);
hlist_for_each_entry(fid, h, dlist) {
@@ -120,9 +124,6 @@ static struct p9_fid *v9fs_fid_find(struct dentry *dentry, kuid_t uid, int any)
}
}
spin_unlock(&dentry->d_lock);
- } else {
- if (dentry->d_inode)
- ret = v9fs_fid_find_inode(dentry->d_inode, uid);
}
return ret;
A previous patch fixed the "create-unlink-getattr" idiom: if getattr is called on an unlinked file, we try to find an open fid attached to the corresponding inode. We have a similar issue with file permissions and setattr: open("./test.txt", O_RDWR|O_CREAT, 0666) = 4 chmod("./test.txt", 0) = 0 truncate("./test.txt", 0) = -1 EACCES (Permission denied) ftruncate(4, 0) = -1 EACCES (Permission denied) The failure is expected with truncate() but not with ftruncate(). This happens because the lookup code does find a matching fid in the dentry list. Unfortunately, this is not an open fid and the server will be forced to rely on the path name, rather than on an open file descriptor. This is the case in QEMU: the setattr operation will use truncate() and fail because of bad write permissions. This patch changes the logic in the lookup code, so that we consider open fids first. It gives a chance to the server to match this open fid to an open file descriptor and use ftruncate() instead of truncate(). This does not change the current behaviour for truncate() and other path name based syscalls, since file permissions are checked earlier in the VFS layer. With this patch, we get: open("./test.txt", O_RDWR|O_CREAT, 0666) = 4 chmod("./test.txt", 0) = 0 truncate("./test.txt", 0) = -1 EACCES (Permission denied) ftruncate(4, 0) = 0 Signed-off-by: Greg Kurz <groug@kaod.org> --- fs/9p/fid.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) ------------------------------------------------------------------------------ Attend Shape: An AT&T Tech Expo July 15-16. Meet us at AT&T Park in San Francisco, CA to explore cutting-edge tech and listen to tech luminaries present their vision of the future. This family event has something for everyone, including kids. Get more information and register today. http://sdm.link/attshape