Date: Wed, 15 Jul 2020 01:26:28 +0000 (UTC) From: Rick Macklem <rmacklem@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r363210 - head/sys/fs/nfsclient Message-ID: <202007150126.06F1QSFu075828@repo.freebsd.org>
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Author: rmacklem Date: Wed Jul 15 01:26:28 2020 New Revision: 363210 URL: https://svnweb.freebsd.org/changeset/base/363210 Log: Fix the pNFS flexible file layout client for servers with small write size. The code in nfscl_dofflayout() loops when a flexible file layout server provides a small write data limit (no extant server is known to do this). If/when it looped, it erroneously reused the "drpc" argument for the mirror worker thread, corrupting it. This patch fixes the problem by only using the calling thread after the first loop iteration. Found during testing by simulating a server with a small write size. Since no extant pNFS server is known to provide a small write size, this fix it not needed in practice at this time. MFC after: 2 weeks Modified: head/sys/fs/nfsclient/nfs_clrpcops.c Modified: head/sys/fs/nfsclient/nfs_clrpcops.c ============================================================================== --- head/sys/fs/nfsclient/nfs_clrpcops.c Wed Jul 15 00:13:15 2020 (r363209) +++ head/sys/fs/nfsclient/nfs_clrpcops.c Wed Jul 15 01:26:28 2020 (r363210) @@ -6248,10 +6248,17 @@ nfscl_dofflayoutio(vnode_t vp, struct uio *uiop, int * NFSCL_DEBUG(4, "mcopy reloff=%d xfer=%jd\n", rel_off, (uintmax_t)xfer); /* - * Do last write to a mirrored DS with this + * Do the writes after the first loop iteration + * and the write for the last mirror via this * thread. + * This loop only iterates for small values + * of nfsdi_wsize, which may never occur in + * practice. However, the drpc is completely + * used by the first iteration and, as such, + * cannot be used after that. */ - if (mirror < flp->nfsfl_mirrorcnt - 1) + if (mirror < flp->nfsfl_mirrorcnt - 1 && + rel_off == 0) error = nfsio_writedsmir(vp, iomode, must_commit, stateidp, *dspp, off, xfer, fhp, m, dp->nfsdi_vers,
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