git: 5171310e661d - main - vfs: use finstall_refed in openat

[Mateusz Guzik]

The branch main has been updated by mjg:

URL: https://cgit.FreeBSD.org/src/commit/?id=5171310e661d6c85f6208d86c6f651e3d499e346

commit 5171310e661d6c85f6208d86c6f651e3d499e346
Author:     Mateusz Guzik <mjg at FreeBSD.org>
AuthorDate: 2021-01-12 16:11:15 +0000
Commit:     Mateusz Guzik <mjg at FreeBSD.org>
CommitDate: 2021-01-13 03:30:38 +0000

    vfs: use finstall_refed in openat
    
    This avoids 2 atomic ops in the common case: 1 to grab an extra
    reference and 1 to release it.
---
 sys/kern/vfs_syscalls.c | 16 ++++------------
 1 file changed, 4 insertions(+), 12 deletions(-)

diff --git a/sys/kern/vfs_syscalls.c b/sys/kern/vfs_syscalls.c
index 560a003765d5..c1b6c70ab0ac 100644
--- a/sys/kern/vfs_syscalls.c
+++ b/sys/kern/vfs_syscalls.c
@@ -1129,15 +1129,11 @@ kern_openat(struct thread *td, int fd, const char *path, enum uio_seg pathseg,
 
 	/*
 	 * Allocate a file structure. The descriptor to reference it
-	 * is allocated and set by finstall() below.
+	 * is allocated and used by finstall_refed() below.
 	 */
 	error = falloc_noinstall(td, &fp);
 	if (error != 0)
 		return (error);
-	/*
-	 * An extra reference on `fp' has been held for us by
-	 * falloc_noinstall().
-	 */
 	/* Set the flags early so the finit in devfs can pick them up. */
 	fp->f_flag = flags & FMASK;
 	cmode = ((mode & ~pdp->pd_cmask) & ALLPERMS) & ~S_ISTXT;
@@ -1210,21 +1206,17 @@ success:
 		else
 #endif
 			fcaps = NULL;
-		error = finstall(td, fp, &indx, flags, fcaps);
-		/* On success finstall() consumes fcaps. */
+		error = finstall_refed(td, fp, &indx, flags, fcaps);
+		/* On success finstall_refed() consumes fcaps. */
 		if (error != 0) {
 			filecaps_free(&nd.ni_filecaps);
 			goto bad;
 		}
 	} else {
 		filecaps_free(&nd.ni_filecaps);
+		fdrop_close(fp, td);
 	}
 
-	/*
-	 * Release our private reference, leaving the one associated with
-	 * the descriptor table intact.
-	 */
-	fdrop(fp, td);
 	td->td_retval[0] = indx;
 	return (0);
 bad: