git: cfd6c9b99f49 - stable/13 - vfs: slightly rework vn_rlimit_fsize

[Mateusz Guzik]

The branch stable/13 has been updated by mjg:

URL: https://cgit.FreeBSD.org/src/commit/?id=cfd6c9b99f49dd24860456742eecccabfc100326

commit cfd6c9b99f49dd24860456742eecccabfc100326
Author:     Mateusz Guzik <mjg at FreeBSD.org>
AuthorDate: 2021-05-29 17:33:50 +0000
Commit:     Mateusz Guzik <mjg at FreeBSD.org>
CommitDate: 2021-06-13 02:15:25 +0000

    vfs: slightly rework vn_rlimit_fsize
    
    (cherry picked from commit 478c52f1e3654213c7d79096a2bc7f908e0b501d)
---
 sys/kern/vfs_vnops.c | 21 +++++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)

diff --git a/sys/kern/vfs_vnops.c b/sys/kern/vfs_vnops.c
index cf6a1f715d83..fc5118e8aa24 100644
--- a/sys/kern/vfs_vnops.c
+++ b/sys/kern/vfs_vnops.c
@@ -2364,12 +2364,25 @@ vn_rlimit_fsize(const struct vnode *vp, const struct uio *uio,
 	off_t lim;
 	bool ktr_write;
 
-	if (vp->v_type != VREG || td == NULL ||
-	    (td->td_pflags2 & TDP2_ACCT) != 0)
+	if (td == NULL)
 		return (0);
+
+	/*
+	 * There are conditions where the limit is to be ignored.
+	 * However, since it is almost never reached, check it first.
+	 */
 	ktr_write = (td->td_pflags & TDP_INKTRACE) != 0;
-	lim = ktr_write ? td->td_ktr_io_lim : lim_cur(td, RLIMIT_FSIZE);
-	if ((uoff_t)uio->uio_offset + uio->uio_resid <= lim)
+	lim = lim_cur(td, RLIMIT_FSIZE);
+	if (__predict_false(ktr_write))
+		lim = td->td_ktr_io_lim;
+	if (__predict_true((uoff_t)uio->uio_offset + uio->uio_resid <= lim))
+		return (0);
+
+	/*
+	 * The limit is reached.
+	 */
+	if (vp->v_type != VREG ||
+	    (td->td_pflags2 & TDP2_ACCT) != 0)
 		return (0);
 
 	if (!ktr_write || ktr_filesize_limit_signal) {