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authorRick Macklem <rmacklem@FreeBSD.org>2020-07-15 01:26:28 +0000
committerRick Macklem <rmacklem@FreeBSD.org>2020-07-15 01:26:28 +0000
commit7477442fdd8200b44273c3ddd60c70a15f256635 (patch)
tree1dff10dfe7fea35897bc924050bff8e19771e4de
parent984c1095a403ea176424aceedf0f24a4d5893fac (diff)
downloadsrc-7477442fdd8200b44273c3ddd60c70a15f256635.tar.gz
src-7477442fdd8200b44273c3ddd60c70a15f256635.zip
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
Notes
Notes: svn path=/head/; revision=363210
-rw-r--r--sys/fs/nfsclient/nfs_clrpcops.c11
1 files changed, 9 insertions, 2 deletions
diff --git a/sys/fs/nfsclient/nfs_clrpcops.c b/sys/fs/nfsclient/nfs_clrpcops.c
index c42661af6c62..e2207696bc3f 100644
--- a/sys/fs/nfsclient/nfs_clrpcops.c
+++ b/sys/fs/nfsclient/nfs_clrpcops.c
@@ -6248,10 +6248,17 @@ nfscl_dofflayoutio(vnode_t vp, struct uio *uiop, int *iomode, int *must_commit,
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,