Date: Wed, 8 Feb 2023 22:27:13 GMT From: Rick Macklem <rmacklem@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: 847967bc4e19 - main - nfscl: Fix interaction between mmap'd and VOP_WRITE file updates Message-ID: <202302082227.318MRDaE081981@gitrepo.freebsd.org>
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The branch main has been updated by rmacklem: URL: https://cgit.FreeBSD.org/src/commit/?id=847967bc4e198a258b030a5864e64e029e7452e5 commit 847967bc4e198a258b030a5864e64e029e7452e5 Author: Rick Macklem <rmacklem@FreeBSD.org> AuthorDate: 2023-02-08 22:25:01 +0000 Commit: Rick Macklem <rmacklem@FreeBSD.org> CommitDate: 2023-02-08 22:25:01 +0000 nfscl: Fix interaction between mmap'd and VOP_WRITE file updates asomers@ found a problem with the NFS client, where a write to an NFS mounted file done via mmap(2) was lost when fspacectl(2) was done before it. This turned out to be caused by clearing the dirty bit on pages when the client was doing commit RPCs, due to the second argument to vfs_busy_pages() being set to 1. Commit RPCs tell the server to commit previously written data to stable storage. However, Commit RPCs do not write data from the client to the server. As such, if the dirty bit on the page has been set by a mmap'd write to an address in the page, it should not be cleared. Clearing it causes the mmap'd write to by lost. This patch fixes the problem by changing the 2nd argument to vfs_busy_pages() to 0 for this case. I doubt this bug has affected many, since it was inherited from the old NFS client and was in 4.3 FreeBSD twenty years ago. Although fspacectl(2) is FreeBSD 14 specific, a write(2) would cause the same failure. Reviewed by: kib Tested by: asomers PR: 269328 MFC after: 1 week --- sys/fs/nfsclient/nfs_clvnops.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/sys/fs/nfsclient/nfs_clvnops.c b/sys/fs/nfsclient/nfs_clvnops.c index eeffce65a7db..3e9cf7e3a475 100644 --- a/sys/fs/nfsclient/nfs_clvnops.c +++ b/sys/fs/nfsclient/nfs_clvnops.c @@ -3015,7 +3015,7 @@ again: wcred = bp->b_wcred; else if (wcred != bp->b_wcred) wcred = NOCRED; - vfs_busy_pages(bp, 1); + vfs_busy_pages(bp, 0); BO_LOCK(bo); /*
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