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fdesc_lookup(): the condition to use vn_vget_ino() is always true

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The ix number for the fdescfs root is 1, while any fd vnode has the ix
value at least 3.

Reviewed by:	markj
Tested by:	pho
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D39207
This commit is contained in:
Konstantin Belousov 2023-03-23 21:28:08 +02:00 committed by Oscar Zhao
parent 1864ffd1e7
commit 3a8f50e898
1 changed files with 18 additions and 20 deletions
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38
sys/fs/fdescfs/fdesc_vnops.c
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@ -337,26 +337,24 @@ fdesc_lookup(struct vop_lookup_args *ap)
goto bad;
fdropped = false;
/* Make sure we're not looking up the dvp itself. */
if (VTOFDESC(dvp)->fd_ix != FD_DESC + fd) {
/*
* Unlock our root node (dvp) when doing this, since we might
* deadlock since the vnode might be locked by another thread
* and the root vnode lock will be obtained afterwards (in case
* we're looking up the fd of the root vnode), which will be the
* opposite lock order. Vhold the root vnode first so we don't
* lose it.
*/
arg.ftype = Fdesc;
arg.fd_fd = fd;
arg.ix = FD_DESC + fd;
arg.fp = fp;
arg.td = td;
arg.fdropped = fdropped;
error = vn_vget_ino_gen(dvp, fdesc_get_ino_alloc, &arg,
LK_EXCLUSIVE, &fvp);
fdropped = arg.fdropped;
}
/*
* Make sure we do not deadlock looking up the dvp itself.
*
* Unlock our root node (dvp) when doing this, since we might
* deadlock since the vnode might be locked by another thread
* and the root vnode lock will be obtained afterwards (in case
* we're looking up the fd of the root vnode), which will be the
* opposite lock order.
*/
arg.ftype = Fdesc;
arg.fd_fd = fd;
arg.ix = FD_DESC + fd;
arg.fp = fp;
arg.td = td;
arg.fdropped = fdropped;
error = vn_vget_ino_gen(dvp, fdesc_get_ino_alloc, &arg,
LK_EXCLUSIVE, &fvp);
fdropped = arg.fdropped;
if (!fdropped) {
/*